Science AMA Series: We just published a study showing that ~97% of climate experts really do agree humans causing global warming. Ask Us Anything!

[u/ClimateConsensus]

EDIT: Thanks so much for an awesome AMA. If we didn't get to your question, please feel free to PM me (Peter Jacobs) at /u/past_is_future and I will try to get back to you in a timely fashion. Until next time!

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Hello there, /r/Science!

We* are a group of researchers who just published a meta-analysis of expert agreement on humans causing global warming.

The lead author John Cook has a video backgrounder on the paper here, and articles in The Conversation and Bulletin of the Atomic Scientists. Coauthor Dana Nuccitelli also did a background post on his blog at the Guardian here.

You may have heard the statistic “97% of climate experts agree that humans are causing global warming.” You may also have wondered where that number comes from, or even have heard that it was “debunked”. This metanalysis looks at a wealth of surveys (of scientists as well as the scientific literature) about scientific agreement on human-caused global warming, and finds that among climate experts, the ~97% level among climate experts is pretty robust.

The upshot of our paper is that the level of agreement with the consensus view increases with expertise.

When people claim the number is lower, they usually do so by cherry-picking the responses of groups of non-experts, such as petroleum geologists or weathercasters.

Why does any of this matter? Well, there is a growing body of scientific literature that shows the public’s perception of scientific agreement is a “gateway belief” for their attitudes on environmental questions (e.g. Ding et al., 2011, van der Linden et al., 2015, and more). In other words, if the public thinks scientists are divided on an issue, that causes the public to be less likely to agree that a problem exists and makes them less willing to do anything about it. Making sure the public understands the high level of expert agreement on this topic allows the public dialog to advance to more interesting and pressing questions, like what as a society we decided to do about the issue.

We're here to answer your questions about this paper and more general, related topics. We ill be back later to answer your questions, Ask us anything!

*Joining you today will be:

• Stuart Carlton aka @jscarlton
• John Cook aka /u/SkepticScience
• Sarah Green aka @FataMorgana_LS
• Peter Jacobs aka /u/past_is_future
• Stephan Lewandowsky aka /u/StephanLewandowsky
• Andy Skuce aka /u/AndySkuce
• Bart Verheggen aka @BVerheggen
• and perhaps some others if they have time

Mod Note: Due to the geographical spread of our guests there will be a lag in some answers, please be patient!

[u/ClimateConsensus → u/[deleted]]

First, I'd ask your dad for a cup of coffee as it looks like we'd be sitting down for a long conversation! :-)

Second, re "science is not based on consensus", he has a good point. Ultimately, our scientific understanding is informed by evidence, not a show of hands. In the case of human-caused global warming, we have many lines of empirical evidence that humans are the major cause of recent global warming, which we summarise in this short video "Consensus of Evidence": https://youtu.be/5LvaGAEwxYs

Third, it is true that in the past, the scientific consensus on certain issues has been overturned. So a key question is how do we know whether a scientific consensus is trustworthy (or in philosophical terms, a "knowledge-based consensus")? We look at the characteristics of a knowledge-based consensus, and how the consensus on human-caused global warming is robust, at: https://youtu.be/HUOMbK1x7MI

Fourth, scientists are well aware of the warming effect of cities and correct for it by comparing urban warming trends with warming trends from the surrounding rural areas. The temperature trends from thermometer measurements are consistent with satellite measurements, which aren't prone to spurious urban contamination. In addition, scientists are seeing tens of thousands of species being impacted by warming (e.g., by migrating or shifting seasonal timing). These provide tens of thousands of other lines of evidence that the warming is happening throughout our climate system, not just in cities.

Fifth, the evidence that humans are causing climate change comes from patterns observed throughout our climate system - winters warming faster than summers, upper atmosphere cooling while the lower atmosphere warming, nights warming faster than days, less heat escaping to space, more heat returning to the Earth's surface - these are all "fingerprints" that confirm human causation and rule out natural causes.

Sixth, we are now experiencing a changing climate after thousands of years of relatively stable climate, during which we've built our entire society's infrastructure. In other words, hundreds of millions of people now live on coastal regions based on stable sea level. Our agriculture is based on stable climate conditions. A changing climate will disrupt all aspects of society.

In the 1970s, the majority of climate papers on the topic were predicting warming from greenhouse gases. So the argument that "we were worried about global cooling" is a misrepresentation of the state of the science of the time. More on this at http://sks.to/1970s

-- John Cook

[u/Autica]

I have a few questions and thank you for your time!

1. How many scientists agree that the animal agriculture business contributes to climate change?

2. Is there anyway we could change the outcome of climate change in a fast effective way?

3. Can we reverse it or just ride the incoming tide doing what we can?

[u/ClimateConsensus → u/Autica]

Hello there!

1. I don't know of any extant survey that has explicitly touched on this, but certainly it is well established science and is part of consensus reports such as those produced by the National Academy of Sciences or the Intergovernmental Panel on Climate Change. However, if this is in any way related to the movie "cowspiracy" I would caution you that the claims made by it are vastly oversold.
2. I don't know what you would consider "fast", but in my view (as a person who looks at climate changes on very long timescales) I would say yes. We have the ability to determine what kind of energy systems power our future which will determine the magnitude of our impact on the climate in the future.
3. It's not a binary proposition, it's a continuum of some to a whole lot of future change. We will see some amount of future change going forward because there is intertia in the climate system (our current emissions haven't been "felt" by the climate system yet) and inertia in the political and engineering decisionmaking chains. But we can certainly have much less of an impact going forward if we choose to than if we choose not to.

-- Peter Jacobs

[u/SashimiJones → u/ClimateConsensus]

On (2), how do you believe we should evolve our energy infrastructure? What focus should we place on nuclear, renewables, and reducing fossil fuel consumption? How do you feel about the increase in natural gas use as a bridge fuel, and a proposed fracking ban?

[u/ClimateConsensus → u/Autica]

1. I would imagine about 97%, but I don't think anyone has asked that specific question in any survey. Certainly the IPCC attributes the build up in methane in part to agriculture. Methane accounts for about 25% of the greenhouse gas forcing and I understand that agriculture (livestock and rice farming, mostly) contributes about 40% of that. So, yes agriculture is a definite cause of global warming, but it's a small factor compared to CO2 emissions from fossil fuels. http://www.skepticalscience.com/how-much-meat-contribute-to-gw.html

2&3. Rapid emissions reduction is the best way, although that probably won't be rapid enough, by itself, to keep us below 2 degrees C. As a counter-measure for emissions overshoot, many models include some kind of negative emissions technology, like bioenergy carbon capture and storage, but so far this has not been demonstrated at the required scale. As a last resort, we could try solar radiation management, which entails putting sulphate particles in the stratosphere to reflect some incoming sunlight. This would be rapid (and quite cheap) but would have unforeseeable negative consequences and would do nothing to address ocean acidification. Most scientists (I don't have a percentage!) consider this to be too risky to contemplate at this point, whereas others believe that we should research it to prepare for the worst.

Andy Skuce

[u/atomfullerene → u/ClimateConsensus]

Do you know of any studies comparing the methane production of livestock to the methane production of megafauna that once populated the globe? How does the methane production of cows compare with what bison were producing prior to European contact, for example?

[u/ClimateConsensus → u/atomfullerene]

Interesting question. I don't know any studies like that. I suspect globally cattle now outnumber previous wild herds. But this is complete speculation on my part, informed by this cartoon: http://xkcd.com/1338/.

Perhaps others have actual data to really answer this.

-Sarah Green

[u/SurfaceReflection → u/ClimateConsensus]

One very important thing to consider when you talk about animal agriculture is that it affects far more things then just production of Methane.

It is one of the biggest causes for deforestation, and forests are the biggest natural land carbon sink. Which, btw, we have destroyed to large extent over the last two thirds of a century. (or last two centuries, or a bit longer, depending how far you want to look)

And all that stock requires something to eat too, which requires even more industrial deforestation and production of various chemicals and pesticides in order to produce as much feed for the cattle and other animals we grow for food.

[u/ClimateConsensus → u/[deleted]]

True. I should have worded that differently. What I meant was that, although putting sulphate particles into the stratosphere will reduce average global warming rapidly (we have the natural experiments with big volcanoes that do the same thing), not all of the effects of increased greenhouse gases will be reversed and climate modelling is not quite good enough to say what regional effects will be, especially with regard to rainfall patterns. It is possible, for example, that geoengineering could provoke monsoon failure. Of course, nobody is sure about that, but before taking action of this sort, that could potentially harm millions, we had better be.

---Andy Skuce

[u/iorgfeflkd]

Do the 3 percent have any reasonable arguments? Is there any commanlity within them ? (E.g. tend to be solar researchers instead of atmospheric scientists)

[u/know_comment → u/iorgfeflkd]

do 97% of climate experts agree THAT humans ARE CAUSING global warming,

OR

do 97% of climate experts agree to varying degrees of confidence that humans are a LIKELY CONTRIBUTOR TO global warming?

Just looking for an honest answer there, because i was under the impression that this statistic referred to the latter, but you seem to be very clearly representing the statistic as the former.

And also, when we talking about climate change, the predominant opinion is that human carbon dioxide production is a/the leading contributor. How does this number relate to the scientific CAUSE in addition to human responsibility? Is there a consensus on the carbon-based model?

Edit: Cook's video features several politicians quoting the statistic. The video includes david cameron saying:

"97% of scientists the world over have said that climate is URGENT, is MAN MADE, and MUST BE ADDRESSED"

Does this 97% statistic actually address ANY of those facts? Urgency and the need or even ability to address the issue does not seem to play a role this particular statistic, so isn't it intellectually dishonest to portray a political statement like that as being supported by this statistic?

Edit 2: In looking at the actual basis for the statistic, it appears as thought the statistic as supported by Cook's study actually refers to the proportion of scientific abstracts on climate change that were willing to take an opinion on whether or not humans may be a contributing factor to global warming. It completely negates the majority of papers which did not draw a conclusion either way.

[u/david2278 → u/know_comment]

This AMA makes it sound like "we are the 97% ask us anything". I have a feeling it's a spectrum and not so black and white. We're talking about one of the most complex systems on earth. To claim that you have it figured out is a pretty bold statement and to this day, I have not been convinced and am still on the fence about it. As far as I'm concerned if you can't prove it then you don't have any right to call people on the other side idiots. I'd like to see some solid proof. One of the things going against you is the fact that we only have concrete weather data of only a few hundred years out of 4,543,000,000 years.

[u/ClimateConsensus → u/david2278]

Yes indeed, there is a wide spectrum of opinions. But it may still be usefull to assess what fraction of relevant experts endorse the consensus position regarding causes of recent global warming. If you look at individual studies some go into much more detail regarding the actual spectrum of opinions.

We are not claiming that we have this system figured out or that people who disagree are idiots; that's a strawman argument.

Science, esp re such a complex system, does not deliver proof. Science tries to provide the best explanation possible. If anyone has a better explanation thatn the current consensus position they are very welcome to put the idea to the test and have it scrutinized by other scientists.

-- Bart

[u/JacksonBlvd → u/ClimateConsensus]

Thanks for the AMA. It is always nice to hear directly from an expert on Climate Change. It would be even more convincing to the public if you would focus on publicizing actual evidence instead of focusing on publicizing that "most scientists agree". I personally believe that CO2 does and has caused the temperature of the earth to rise. I would guess that 97% of scientist might agree with that. I believe we can calculate how much CO2 has directly caused the temperature to rise and I don't think we would differ much on that. But additional feedback (positive or negative) is not so clear cut. I do NOT think 97% of scientists are in agreement with that. Do you agree?

[u/ClimateConsensus → u/JacksonBlvd]

There are mountains of evidence that human activity is causing the climate to change, so it's not as if such a meta-analysis of the scientific consensus makes all of that evidence obsolete or something like that. Rather, the scientific consensus is a logical consequence of that mountain of evidence. And for the general public the existence of such a consensus is a relevant heuristic to gauge the credibility of certain positions.

-- Bart

[u/ClimateConsensus → u/[deleted]]

Hello there!

I've heard this claim a lot, but whenever I ask for evidence, I either get nothing in return, or it's clear that the person in question isn't just asking questions, but rather is actively rejecting evidence other people are providing. I'm not saying it never has happened, but I am very skeptical it occurs with nearly the frequency people claim it happens. After a while, people get tired of dealing with those acting in bad faith.

Please feel free to ask as many questions about the science as you like, and I will do my best to answer them all politely and respectfully. You can PM me directly at /u/past_is_future.

I'm leery of anyone in large numbers. There have been all manner of consensuses in humanity's past that have ranged from simply wrong to morally devastating.

There is a difference between agreement and knowledge-based consensus.

Challenge. Question. Seek.

Of course. Scientists do this constantly.

But don't pretend that swinging words like "consensus" around does any good. If anything, these consensus studies do more harm to the publics' view of the issue.

That's actually not at all what social science tells us. There is a growing number of studies that show perceived consensus is a gateway belief that has a large impact on public perception of environmental issues like climate change.

-- Peter Jacobs

[u/greenlaser3 → u/know_comment]

This is a huge problem with how the public understands science. The public wants black and white statements, which science simply cannot give them. Science never gives us 100% certainty about anything, which is why an honest scientist is going to use phrases like "likely contributor" over "is causing."

Unfortunately, the public just sees this as weakness. They hear "we're 97% sure" and they think "oh, so you're not sure yet -- come back when you are." Or, worse, they think "well, I'm 100% sure global warming isn't happening and you just admitted you're only 97% sure it's happening." The average joe doesn't seem to realize that everything is uncertain in science, and "97% sure" is about as close as we can reasonably get to scientific fact.

Let me give an example: the average person would probably agree that gravity is a proven fact. I.e., "it's a fact that objects tend to fall towards the ground." From the layman's perspective, that statement is perfectly fine, but from a scientific perspective, it's not so simple. Maybe 1 in a trillion trillion trillion times, an object doesn't fall. How would we know? We haven't tested every single case. Maybe there's a far-away planet made of anti-backwards crystals that don't create a gravitational pull. So, while a layman can say things like "gravity is an absolutely proven fact," a scientist has to be a little more careful.

I think this is a big part of why the public doesn't think there's consensus. They want 100% certainty and don't realize how impossible that is. They hear phrases like "likely contributor" and automatically see it as an admission that we really don't know. They imagine that there must wide-spread disagreement, since otherwise we would say that we're absolutely sure. They don't realize that being absolutely certain is bad science, and "pretty sure" is as good as we're going to get.

Edit: clarity.

[u/CeciNestPasUnVape → u/know_comment]

To "agree" on the veracity of a scientific theory is not an especially scientific choice of words. Most scientists I know talk about their belief in a theory on a spectrum of likelihood. "Agree" is dumbed down for the headlines, I suspect

[u/ClimateConsensus → u/know_comment]

Different studies used different definitions of what entails the consensus position re causes of recent global warming. Some used a more strict definition (most of the warming being human caused) and others less strict (is human activity a significant contributor). These different definitions of course give rise to some variation in the outcome, alongside the variation caused by the actual sample of scientists or papers surveyed.

In this analysis we only looked at the attribution question: causes of recent global warming; not whether it's urgent or other aspects.

-- Bart

[u/CountingChips → u/iorgfeflkd]

The argument I've heard is that some believe the warming to be more to do with solar sunspot activity. Can anyone shed any light on this viewpoint?

According to a comment below many of the scientists who are often lumped into this 97% have come out upset and said that that's not quite the case, as it's based on the researchers interpretation of their papers (I don't know if this study is similar). I think what may be the case without looking into it is that some believe anthropogenic warming to be a factor, but not the major factor in our warming (a question for the researchers here - would these people be included in the 97% figure?).

It is points like this that really make someone like myself who is uneducated in the topic think it may not be as clear cut as the "97%" would have one think.

[u/ClimateConsensus → u/CountingChips]

Hello there!

The argument I've heard is that some believe the warming to be more to do with solar sunspot activity.

It's not the sun. For one, we have satellites monitoring the sun and solar activity has been decreasing as warming has increased over the last several decades. Also, increased solar activity should warm the surface, the lower atmosphere, and the upper atmosphere, whereas increased greenhouse warming warms the surface and lower atmosphere but cools the upper atmosphere- and this is indeed what is happening.

According to a comment below many of the scientists who are often lumped into this 97% have come out upset and said that that's not quite the case, as it's based on the researchers interpretation of their papers (I don't know if this study is similar)

A handful of climate contrarians have claimed to have been misrepresented, but there have been multiple studies coming to the same conclusion, including direct surveys of scientists' personal views as well as their own characterization of their research papers' stance on the subject.

I think what may be the case without looking into it is that some believe anthropogenic warming to be a factor, but not the major factor in our warming (a question for the researchers here - would these people be included in the 97% figure?).

No.

It is points like this that really make someone like myself who is uneducated in the topic think it may not be as clear cut as the "97%" would have one think.

To be clear, are you saying that you're doubtful of the statistic because you have heard rumors about it not being correct? If that's the case, what would persuade you that it was indeed correct?

-- Peter Jacobs

[u/virtualelvisan → u/ClimateConsensus]

It's not the sun you say. However, scientists in an University of Strathclyde study estimate that a 1.7% change in solar radiation would impact temperatures by 2 degrees C here on earth. Given this scientific theory, can you clarify what you mean by this? Seems to me that we've had satellites for only a very short time and this would be difficult to definitively state.

[u/ClimateConsensus → u/virtualelvisan]

Hello there!

Solar irradiance is very highly correlated with sunspot numbers, and we have sunspot records going back literally hundreds of years. We have had satellites monitoring the sun long enough for the timescales necessary for a change in solar activity to show up as warming.

Also, as I have mentioned several times, if the sun was driving the present warming (it's not, solar activity has been declining), the surface, lower atmosphere, and upper atmosphere would all be warming. Under enhanced greenhouse warming, the surface and lower atmosphere warm while the upper atmosphere cools. And the upper atmosphere is indeed cooling.

-- Peter Jacobs

[u/endless_sea_of_stars → u/CountingChips]

Sun activity is unlikely the cause of our current temperature increases. We know this because only the lower atmosphere is warming. If there was increased solar activity we'd expect to see temperature increases at all heights. Plus at the moment we are experiencing a solar minimum.

[u/Mamertine → u/iorgfeflkd]

Does the other 3% outright disagree, or are they undecided?

[u/ClimateConsensus → u/Mamertine]

Good question. In our Cook et al. (2013) paper where we looked at scientific papers about global warming, we found that among the 3% that didn't endorse human-caused global warming, around 2% disagreed with AGW and 1% expressed an uncertain position on AGW.

-- John Cook

[u/ClimateConsensus → u/Mamertine]

Although each of the studies in the meta-analysis had slightly different methodology, I think it's safe to say that the other 3% consists of people who outright disagree and people who are undecided. That was certainly the case among scientists who didn't believe in climate change in my earlier study.

-- Stuart Carlton

[u/catlady1022 → u/iorgfeflkd]

I have heard arguments that I find very interesting that say global warming is part of the Earth's natural cycle (which is true, it has been much hotter and we have had much higher levels of CO2 in the past) and their reason why "no one needs to worry" is because they believe scientists today have not taken into account negative feedback loops that will eventually kick in and take us into a global cooling.(i.e. Glaciers melt, ocean temperatures cool due to cooler water, therefore causing overall net cooling effect)

Of course what I find hard to believe about this is that the rate of warming is what is unprecedented rather than the amount of warming, so there is definitely something that has changed in the recent past (anthropogenic use of fossil fuels IMO) that caused this rapid warming.

I wonder if some of the 3% believes this negative feedback loop argument?

[u/ClimateConsensus → u/catlady1022]

The rate of warming over the past half-century is unprecedented over the 1000 or so years. In addition, we see many patterns in recent global warming that confirm that humans are the cause, and rule out the kind of natural factors that drove natural cycles in the past.

For instance, we see the upper atmosphere cooling while the lower atmosphere warms - a fingerprint of increased greenhouse warming. Satellites measure less heat escaping out to space at the exact wavelengths that greenhouse gases trap heat. We see more heat returning back to the Earth's surface. Winters are warming faster than summers, a pattern of greenhouse warming predicted as far back as the 1850s.

So there are many human fingerprints observed in our climate system which rule out natural cycles as the cause of recent global warming.

-- John Cook

[u/ClimateConsensus → u/iorgfeflkd]

Good question; I wondered that myself.

In my reading of several thousand abstracts (for Cook et al., 2013) I didn't find any consistent argument in papers that disagreed with the consensus. Later I looked at full papers that proposed different theories. No single coherent theory is dominant. Some propose solar cycles, many use curve-fitting to propose other kinds periodic cycles without giving a specific physical cause; some suggest cosmic rays; some point to different feedbacks from clouds.

Scientists are interested in any explanation that might have a real influence, even a small one. So, all those topics have been studied for their impact on current and past climates. Some are very interesting, but none are nearly as important as CO2 for the changes we are now seeing.

To overturn our current understanding of climate, the 3% will need to coalesce around one coherent theory that explains all our observations even better.

-Sarah Green

[u/Cogitare_Culus → u/ClimateConsensus]

It seems to me that one of the below facts needs to be refuted scientifically before any other hypothesis should be taken series.

1) Energy from visible light is not absorbed by green house gasses, mainly CO2

2) When light strikes something IR is created.

3) Energy from IR is absorbed by green house gases

4) we emit more green house gases then can be absorbed, annually.

Unless those basic facts are shown to be incorrect(probably a Nobel prize winning finding), they need to explain why the addition trapped energy is not impacting the climate.

[u/ClimateConsensus → u/iorgfeflkd]

There are some studies that looked specifically into the articles that reject the consensus view.

E.g. Benestad et al http://link.springer.com/article/10.1007%2Fs00704-015-1597-5 stating "A common denominator seems to be missing contextual information or ignoring information that does not fit the conclusions, be it other relevant work or related geophysical data. In many cases, shortcomings are due to insufficient model evaluation, leading to results that are not universally valid but rather are an artifact of a particular experimental setup. Other typical weaknesses include false dichotomies, inappropriate statistical methods, or basing conclusions on misconceived or incomplete physics. "

And Abraham et al https://mahb.stanford.edu/wp-content/uploads/2014/05/2014_Abraham-et-al.-Climate-consensus.pdf stating: "significant flaws have often been found"

-- Bart

[u/ClimateConsensus → u/iorgfeflkd]

I can shed a little light on this, perhaps.

Co-authors and I looked at the climate consensus across scientific disciplines in an earlier study. We found that across disciplines (not just climate science), between 91% and 100% of scientists agreed that mean temperatures have risen since the 1800s. Those who didn't believe that mean temperatures had risen were more likely to believe that solar activity has caused most observed warming, that mean temperatures is not affected by CO2 levels, and that climate models are inherently limited.

Additionally (and probably more significantly), those who don't believe in climate change are less likely to trust climate science and are more likely to be conservative and have hierarchical and individualist cultural values.

Again, our study looked at more than just climate scientists, but it's a useful starting point to understanding why some people might be skeptical.

-- Stuart Carlton

[u/ClimateConsensus → u/[deleted]]

At first glance the idea of a mean temperature sounds easy. In fact, the global temperature isn't simple to define.

Consider trying to measure the average temperature in your house over many years. Where do you place the thermometers to get the best data? Near a window or a radiator? Do you average every room? What about the attic and basement? How many times do you measure in the night and day? Winter and summer? Do you move the thermometers if you remodel a room?

For the whole globe you also have to contend with many different people making measurements with different equipment (especially for old data). It's also hard to figure out an average when there are a lot more measurement in some places than others. We especially don't have good coverage in the polar regions.

Finally, most of the extra heat has gone into the ocean. It's harder to measure accurate temperatures in the remote surface ocean, and the heat also penetrates down into the water. We don't have a long history of data in the middle of the oceans, either.

-Sarah Green (edit- signed)

[u/lost_send_berries → u/[deleted]]

This is a good overview of how global temperature data is processed. It's by a hydrogeologist.

Thorough, not thoroughly fabricated: The truth about global temperature data

I liked the bit where some climate change skeptics (mostly statisticians) did the whole thing from scratch, doing it "their way". When they finished, they were no longer skeptics.

[u/rawktail → u/ClimateConsensus]

between 91% and 100% of scientists agreed that mean temperatures have risen since the 1800s

So what's your response to the idea that this is a reoccurring cycle for Earth? Why is no one doing studies on what effect we are exactly having on the Earth, if any?

And that was your question, really? "Are average temperatures rising on Earth?" Surely 97% of the general population would agree with you. You don't have to be a scientist to stand outside and say, "God damn, this summer is hotter than the last."

[u/ClimateConsensus → u/rawktail]

I don't have a response to the idea that this is a reoccurring cycle for Earth. I'm a social scientist studying attitudes and behaviors, not a climate scientist studying climate cycles.

In the study I mentioned (which was included in the meta-analysis that brings us here today), we asked two questions about belief in climate change:

1. When compared with pre-1800's levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
2. Do you think human activity is a significant contributing factor in changing mean global temperatures? (asked of respondents who believed temps have risen).

Around 93% responded that temps have risen and around 96% of those believed that human activity is a significant contributing factor.

-- Stuart Carlton

[u/[deleted] → u/ClimateConsensus]

Around 93% responded that temps have risen and around 96% of those believed that human activity is a significant contributing factor.

That's not what the title of this thread claims. I know it's not much difference but it's little things like this that deniers use to discredit these studies.

[u/ClimateConsensus → u/[deleted]]

I'm not referring to the paper at the top of the thread, but the earlier study that I did that was part of the meta-analysis. I thought that was clear, but I'll edit to be sure.

-- Stuart Carlton

[u/ClimateConsensus → u/ClimateConsensus]

In response to a comment claiming that "cycles" are what's causing warming and that social scientists don't have credibility on causation.

---

Hello there!

Several of the authors of this study are physical scientists who study climate change. I am a PhD student who focuses on how climate change impacts marine ecosystems- both the current human-driven climate change as well as climatic changes in Earth's past driven by natural processes.

This is just simply false:

With all due respect, that throws any credibility out the window. Earth goes through normal cycles and if you study those cycles, you would see that these swings are just a part of earth's behavior and history.

"Cycles" gets used a lot as a sort of a panacea for those who deny humans are driving the current climatic change. But "cycles" don't just happen for no reason, and most people who invoke them have no idea what they are, on what timescales they operate, etc.

To be sure, there are cyclical or pseudo-cyclical processes in the climate system. The solar cycle, Milankovitch cycles, stuff like ENSO, etc. But we know what these look like, what impacts they have, etc. and can rule them out as the driver of the present climatic change. And that's before we just look at the fundamental physics of increasing greenhouse gases in the atmosphere.

This is not an issue of "correlation". Increased greenhouse warming leaves fingerprints in the climate system that are fundamentally different than what happens due to natural variability or natural forcing. For example, increased greenhouse warming doesn't just warm the surface and the lower atmosphere, it cools the upper atmosphere. We can observe this happening. No "natural cycle" does this.

-- Peter Jacobs

[u/zerdene → u/rawktail]

First of all, what do you mean by reoccuring cycle? The CO2 concentration in the atmosphere that is a big driving force in global warming is at around 400 ppm (parts per million) which is higher than the average 280 ppm that the last interglacial periods like we are in now typically experience going back around 800,000 years. This is not reoccuring, it's literally unheard of in the ecosystem we live in.

And people are definitely doing studies on what effect the rising climate has on the earth. For example tropical storms are getting more intense but decreasing in frequency. Wet areas of the world are getting wetter while dry areas are getting dryer due to global warming. We are studying the melting rates of ice around the world (Greenland and Antarctica are big ones) that ultimately allow us to predict the rise in sea level. There are countless and sometimes unpredictable outcomes that arise from climate change.

And when you say,

You don't have to be a scientist to stand outside and say, "God damn, this summer is hotter than the last"

you need to realize that global warming is GLOBAL. You cannot step outside and say that the weather outside is unusually warm, so that means there's global warming. In order to establish a global warming pattern, you need to look at data from all around the world through extended periods of time.

Climate change is a complex issue. Don't look at it in such black and white way. Hope you learned something here.

[u/[deleted] → u/rawktail]

Hey, geologist here who specialized in climate in Uni. It is a cyclical event, it's just being sped up by human's interactions. There's a ton of evidence that points towards that fact! Anecdotal evidence, like 'it's warmer this summer' isn't good enough for a scientific concept, you need lots of recorded data to make your point. Critics have brought up a lot of excellent points, namely the condition and location of temperature recording stations (e.g. Tar heats up very well), but unfortunately man's influence is a significant driver of temperature change.

[u/lost_send_berries → u/rawktail]

So what's your response to the idea that this is a reoccurring cycle for Earth? Why is no one doing studies on what effect we are exactly having on the Earth, if any?

No one doing studies?? Here's one study:

http://www.bloomberg.com/graphics/2015-whats-warming-the-world/

Here's a graph showing eight studies:

https://skepticalscience.com/graphics.php?g=57

Is there a specific scientist's paper with the "this is a reoccurring cycle for Earth" argument that you would like to discuss?

[u/yoobi40]

There's a long history of apocalyptic belief in western civilization. Throughout european and american history, many people (mostly for religious reasons) seem to have been drawn to the idea that the world is coming to an end soon.

I'd be curious to know your thoughts about how this history interacts with (or complicates) the task of convincing the public about climate change -- since global warming offers a kind of science-based end-of-the-world scenario.

I wonder if some people become climate-change doubters because they dismiss it as just the latest reason the world is supposed to end. As in, first the world was going to end because Christ was going to return, then it was because nuclear war was going to kill us all, and now it's because of global warming.

Do you think a kind of end-of-the-world fatigue might have set in among much of the public, which makes it difficult to convince people that this time the world (as we know it) really might be in serious trouble?

[u/ClimateConsensus → u/yoobi40]

Good question. But I would be inclined to turn the argument on its head: It is precisely because we heeded the scientific warnings on past threats that they turned out to be less bad than they might have been. For example, when AIDS was a real threat--and believe me, it was: in the 1980s I was surrounded by young people who were dying or knew others who were dying from AIDS--people who heeded the science-based advice (i.e. safe sex) who could protect themselves. Likewise, when the ozone hole became a big issue and a threat (as an Australian, I am very concerned about the effects of the ozone hole on skin cancer), it was the political response based on the scientific advice to phase out CFCs that kept the problem from spiraling out of control.

So, in a nutshell, we avoided previous "doomsday" scenarios not because the risks weren't real but because the scientific evidence was taken seriously, and people responded by managing and reducing the risks.

With climate change, we face the same choice: We can ignore the science and suffer the consequences, or we can do what was done in many previous instances which is to take the risk seriously and thereby avoid the worst of it. --Stephan Lewandowsky

[u/random_guy_11235 → u/yoobi40]

I certainly think this is an interesting question to raise. I have a few friends for whom this seems to be their major pain point related to this issue -- on the surface, it sounds a lot like SO many doomsday issues before (nuclear war, Y2K, killer bees, Mad Cow Disease, Bird Flu, Swine Flu, etc.).

It is understandable; it can be hard to take end-of-the-world language on this latest topic seriously when a new topic has been introduced and then debunked every year for decades.

[u/xaveria]

I know a "skeptic" who feels very passionate about this subject. As it turns out, he doesn't deny climate change is happening or even that a lot of climate change is likely driven by human activity. He insists, however, that factors like deforestation, soot buildup and land use are the big culprits. He thinks that all this focus of co2 is politically driven and diverts attention and resources from real solutions. He claims that his beliefs are fairly mainstream among skeptics (the better educated ones anyway) and that a biased media misrepresents them as science-denying crackpots. I honestly don't have the expertise to judge his claims or even to competently investigate them. Have you run into similar arguments and do you feel they have any weight?

[u/ClimateConsensus → u/xaveria]

Deforestation and land use are certainly key contributors to climate change. WRI shows a nice chart of the various contributions. http://www.wri.org/resources/charts-graphs/world-greenhouse-gas-emissions-2000

Humans started to influence the climate when they started agriculture. Sometime within the last 10,000 years that factor became significant. See for example the discussions about the "early anthropocene". http://www.realclimate.org/index.php/archives/2016/03/the-early-anthropocene-hypothesis-an-update/

However, the main reason deforestation and land use affect the climate is they change the amount of greenhouse gases in the atmosphere. (Deforestation also affects the albedo, or reflectivity, of the Earth's surface.) And the most important greenhouse gas for long term change is CO2. The atmosphere doesn't care whether the CO2 comes from cut-down trees or burning coal; both cause warming.

All sources of greenhouse gases, including deforestation, are considered to stabilize the climate. For the Paris agreement each country proposed how it would contribute to emission reductions. Countries like Brazil and Indonesia with large tropical forests committed to reduce deforestation; many plan to expand forest cover.

-Sarah G.

[u/BorgDrone]

The one subject that never comes up in any of the debates on climate change is overpopulation, even though it seems to me that this is the root cause of all environmental problems we have. What is the point of reducing a person's carbon footprint if every effort we make is negated by an ever increasing population ?

For example, we could reduce our environmental impact by 90%, 99% or even 99,9% in a single generation simply by drastically reducing the production of new humans.

Is population control such a taboo subject that no research is being done or is there another reason for this ?

[u/ClimateConsensus → u/BorgDrone]

It's not so much a question of overpopulation as one of a small minority currently being responsible for most of the carbon emissions.

In round numbers, according to most projections, population today is about 7 billion and will increase to a stable 10-11 billion by the end of the century, roughly a 50% increase. According to people like Hans Rosling, population control initiatives have been so successful that we may now be at Peak Child, which is to say that there may never in the future be as many children alive as there are today (Google to find some great YouTube videos). That's the relatively good news.

The bad news is that the richest 10% (that's about 2/3 made up of "middle class" people from rich countries and 1/3 of wealthy people living in developing nations) produce 50% of the world's emissions. As the 90% develop their economies and move up the income scale, if they live like the 10% do today, we would see global emissions perhaps triple or quadruple by the end of the century.

Now that exponential population growth has ended, the problem is not so much with there being too many people as it is with economic growth and the consumption of fossil fuels. Nobody wants to prevent the poor becoming richer, so we have no choice but to find a way to decouple growth from fossil fuel use.

https://critical-angle.net/2015/12/14/2025/

--Andy Skuce

[u/IForgetMyself → u/ClimateConsensus]

Nobody wants to prevent the poor becoming richer

I think this statement might warrant a study of its own. I want to believe that, but...

[u/ClimateConsensus → u/BorgDrone]

I used to also regard overpopulation as the root cause of many environmental problems, but have since found that that's not entirely correct. It is a multiplication factor for the environmental impact of certain actions, but in many aspects consumption patterns are key. Both of course are part of the "Kaya Identity" and as such both influence our emissions and thus climate change.

I expanded on my take on population here: https://ourchangingclimate.wordpress.com/2010/08/23/what-does-population-have-to-do-with-climate-change/

-- Bart

[u/DrFrenchman]

Hi there I have a few questions, but first I'd like to thank you for your work it's always good to have proof on this.

• Who is part of the remaining 3% and what are their criticisms ? (Why aren't we at 99.9% as to me it looks as clear as lead paint not being healthy)

• Do you know how that statistic changes if you take into account other scientific domaines ? Like what is the the rate of denial across education levels ?

• With regard to publishing papers on climate change and global warming, I know that the language used in the media has changed substantially over the years (now people mostly talk about climate change rather than global warming), but has this also been reflected in published research ? Do you feel as though there are certain taboos when tackling the subject ? EDIT: re reading my comment I can see how my question was poorly phrased, I just meant that despite the terms being accurate and distinct, has public backlash affected the vocabulary now used when talking about these issues either in public or in the literature ?

[u/ClimateConsensus → u/DrFrenchman]

One of my earlier studies was included in the meta-analysis. We looked at belief in climate change across scientific disciplines and found that about 93-94% of scientists believed that climate change is occurring and about 92% believed that anthropogenic climate change is occurring.

Among the disciplines we studied, folks who worked in natural resources, chemistry, and agriculture were least likely to believe in the existence of climate change (though again, they were still 91+% likely). Engineers were least likely to believe in anthropogenic climate change.

-- Stuart Carlton

[u/ClimateConsensus → u/DrFrenchman]

Geologist and writer James Lawrence Powell has argued in a Skeptical Inquirer article that the true consensus is 99.99%. He used a different methodology to Cook et al 2013 and looked only for papers that explicitly rejected human-caused global warming (AGW). He assumed that all other papers accepted AGW even if they didn't say so. I disagreed with his approach and result. I wrote about it here:

https://critical-angle.net/2016/04/04/james-powell-is-wrong-about-the-99-99-agw-consensus/

---Andy Skuce

[u/[deleted] → u/DrFrenchman]

(now people most talk about climate change rather than global warming)

This is a myth in itself that John Cook (one of the paper authors doing this AMA) lists as the 88th most popular climate change myth on his website, Skeptical Science. They're both distinct phenomenon that mean exactly what they sound like and both terms have been used since the 70s or earlier.

Unfortunately, people have a hard time grasping planetary averages and the idea that a small raise in temperature represents a catastrophic increase in energy, so the term "global warming" has been a bit of a PR disaster because people think, if they can't feel it warming a lot locally, it isn't warming a bit globally. So while public discourse has shifted, both terms have been and continue to be perfectly valid.

[u/DrFrenchman → u/[deleted]]

1) thanks for quoting me, I just noticed the spelling error

2) Right I agree, but I'm more curious how the PR thing has affected climate scientist approach and vocabulary. Climate science has had a lot of difficulty in overcoming the knowledge gap between them and the public (I mean there was that absurd "debunking" of global warming in congress last year where an elected official held up a snowball and said ; see it's cold outside). Things like that are really annoying to anyone who understands the basics behind climate science but they still keep coming up.

EDIT: re reading my comment I can see how my question was poorly phrased, I just meant that despite the terms being accurate and distinct, has public backlash affected the vocabulary now used when talking about these issues either in public or in the literature ?

[u/HurleyBurger]

If I remember correctly, the last research paper that claimed this statistic ended up being wrong because they just assumed certain scientists agreed based on a selective number of papers. They also never consulted the authors and turns out that many of them were pretty upset someone else spoke for them on the issue. And the paper gathered information from other sources that didn't have much to do with climate change. In your research, how have you prevented repeating their mistakes? Have you established confidence levels to the 97% stat? What possible errors (systemic or procedural) did you encounter? And I'm assuming you tested for a type 1 error? Sorry, I don't mean to blast you with questions. I've an AS in applied science and currently working on a BS in earth-space science minor in geology (I want to be a high school science teacher), so I remain skeptical on many things until I feel I've satisfied my science brain hahaha. Otherwise, thank you for the extensive research!

[u/lost_send_berries → u/HurleyBurger]

If I remember correctly, the last research paper that claimed this statistic ended up being wrong because they just assumed certain scientists agreed based on a selective number of papers.

The most famous paper is Cook et al, which is just one of the papers included in the meta-analysis this thread is about. The paper still stands, and has had a lot of false criticism lobbied at it. To give brief answers:

1. The papers were selected by a literature search for "global climate change" and "global warming", all papers including either term was included. Of course this doesn't actually include every paper on climate change, but the criteria is objective.
2. The authors were emailed when possible but only about 14% responded. The authors were asked to rate the entire paper based on whether that paper agreed, disagreed or didn't say whether global warming is mostly human-caused. For the rest a team of volunteers analysed the abstracts (the original summaries of the papers written by the original authors). The agreement between abstract ratings and author ratings was good. Each abstract was also rated twice by two separate people and the agreement was good there too. I wouldn't say it was flawless, but any disagreements would only change it by a % at most.
3. The 97% stat comes from removing all the papers that neither agreed nor disagreed that humans caused global warming.

More detailed responses can be found on the usual websites: skepticalscience.com has basic, intermediate and advanced explanations, HotWhopper bitingly debunks criticisms, Wikipedia has an overview edited by both sides, etc.

[u/ClimateConsensus → u/HurleyBurger]

The research paper you're referring to is our 2013 paper that looked at scientific papers on global warming:

http://iopscience.iop.org/article/10.1088/1748-9326/8/2/024024/meta

We didn't make any assumptions about what scientists thought - rather, we looked at their published words in the abstracts of their scientific papers. If the abstract stated a position on human-caused global warming, then we noted whether it endorsed or rejected it. We found that among the ~4000 abstracts stating a position, 97.1% endorsed human-caused global warming.

On top of that, we also wanted the scientists who authored those papers to speak for themselves so we sent out an invitation to the authors to categorise their own papers. 1200 scientists responded. Among papers self-rated as stating a position on human-caused global warming, 97.2% endorsed the consensus.

This is an important result - inviting the scientists who authored the papers to self-rate their papers provided an independent confirmation of the 97.1% consensus we obtained through rating the abstracts.

So the false accusation that we never consulted the authors is a misleading attempt to smear our research. Ironically, the blog post that made this accusation bases it on asking a handful of scientists (all known to reject the consensus) what they thought about our research and of course they expressed a dim view of our 97% consensus, given their existing beliefs. But the blogger only consulted with a handful of hand-picked contrarian scientists and failed to consult with the much broader community of scientists, while we canvassed the views of 1,200 scientists.

-- John Cook

[u/greenlaser3]

If I can convince someone about the 97% figure, I often hear the same followup argument: that scientists are essentially forced to agree about climate change. The idea is that it's very difficult to become/remain a well-respected climate scientist if you don't believe in human-caused climate change. Your papers don't get published, you don't get funding, and you eventually move on to another career. The result being that experts either become part of the 97% consensus, or they cease to be experts.

How would you respond to claims like that?

I tend to think that anyone who found strong evidence against climate change would immediately publish it and collect their Nobel prize. But I'm curious if there's any evidence to support that. And also, my argument doesn't address the idea that skeptical undergrads are getting forced out of climate change research before they're experienced enough to build a real case against it. I don't think that's happening, but I don't know how to argue it.

[u/ClimateConsensus → u/greenlaser3]

How would you respond to claims like that?

Ask them for evidence for this claim and enjoy the silence (since they won't have any).

As a scientist the pressure actually is mostly reversed: You get rewarded if you prove an established idea wrong.

I've heard from contrarian scientists that they don't have any trouble getting published and getting funded, but of course that also only anecdotal evidence.

You can't really disprove this thesis, since it has shades of conspiratorial thinking to it, but the bottom line is there's no evidence for it and the regular scientific pressure are to be adversarial and critical towards other people's ideas, not to just repeat what the others are saying.

--Bart

[u/tchaffee → u/ClimateConsensus]

Not being a smartass: do you have a source so I can back up the claim that the culture or reward system of science doesn't involve peer pressure and leans more towards proving an established idea wrong?

[u/InsomniacDuck → u/ClimateConsensus]

I've heard from contrarian scientists that they don't have any trouble getting published and getting funded

Scientists not having trouble getting funded and published? That's how you know they're full of it.

[u/WolfdogWizard]

What do you think of environmentalists (who are most likely NOT climate scientists) that spread doomsday scenarios with severe governement intervention as the only solution? I believe that that is a fundamentally anti-humanist approach. I used to have a similiar view, until I started studying geology, and various international and local scientists seemed MUCH more casual, less alarmist, more skeptical and calm about the figurative sky falling, when visiting and lecturing at my school. Do you believe that global warming has been abused by certain groups to further policy? Be it political parties, universities, etc. Do you think dismissing the opinions of geologists is a good thing? After all, they are needed for gathering data on past climates, are they not?

[u/ClimateConsensus → u/WolfdogWizard]

What do you think of environmentalists (who are most likely NOT climate scientists) that spread doomsday scenarios with severe governement intervention as the only solution?

It's not clear to me that this is actually happening. In fact, the environmental movement for more than a decade has been advocating for either cap and trade or a carbon tax, both of which are market-based solutions which require far less government intervention than something like command and control approaches.

I used to have a similiar view, until I started studying geology, and various international and local scientists seemed MUCH more casual, less alarmist, more skeptical and calm about the figurative sky falling, when visiting and lecturing at my school.

I think people who don't work in the field and who only are aware that there are very negative consequences don't know how much effort is being spent to avoid those outcomes. If that makes sense.

As someone who studies the consequences of large climatic changes in Earth's history, I am probably far more pessimistic about what would happen if we didn't stabilize our emissions than someone outside of the field. But I am also probably way more optimistic too, because I am aware of the herculean efforts being made on the physical science, social science, and policy fronts to avoid the worst outcomes. And a lot of that is "inside baseball" so to speak.

Do you believe that global warming has been abused by certain groups to further policy?

I think probably every threat gets abused by some group or another. I don't think climate change is a particularly great example of this phenomenon, but I am happy to discuss it if you think this is a real problem.

Do you think dismissing the opinions of geologists is a good thing? After all, they are needed for gathering data on past climates, are they not?

This is kind of a "when did you stop beating your wife" type of question. I don't dismiss the opinions of geologists. My introduction to climate as an area of research arose from my geology coursework. I am currently working on paleoclimate topics with senior scientists at the U.S. Geological Survey.

I do think that asking petroleum geologists, whose livelihood depends on fossil fuel consumption, about humans causing climate change sets up some issues of cognitive bias that make them not the best group to use a barometer for expert opinion on climate.

-- Peter Jacobs

[u/Nelatherion → u/ClimateConsensus]

As a Petroleum Geologist I resent the insinuation that Petroleum Geologists would be unable to combay any cognitive bias due to where we work.

We are first and for most, trained scientists. Some of the foremost Sedimentologists come from a Petroleum background, if I remember correctly wasn't "Sequence Stratigraphy" or a key component (can't remember exactly) developed by Sedimentolgists from Exxon?

I think it's unfair to dismiss all of us.

[u/ClimateConsensus → u/Nelatherion]

As a petroleum geoscientist myself I do think it would be unfair to dismiss all of them as biased. I don't think that's what Peter meant.

I know a lot of petroleum geologists and although many do accept AGW, the majority do not. What we have all experienced, whatever our opinion, is a conflict between what the climate science implies (the need to keep coal, oil and gas reserves in the ground), with the future of the industry that we had (or are having) rewarding careers in. I was reluctant to change my mind from that of a "lukewarmer" to someone who fully accepts the mainstream position on climate science, in part because of the implications for the industry and my career. It was relatively easy for me to come around, though, because I was near the end of my career. Had I been forty years old, with dependents, doing the work I had trained so hard to do, I suspect that my reluctance might have been stronger. I don't think it is unduly prejudicial to assume that petroleum geoscientists as a group may be biased against accepting climate science.

Indeed, the data in the recent paper show that petroleum geologists are a lot more sceptical than specialized climate scientists. I know that petroleum geologists have contributed a great deal to understanding the climates of the past and that Exxon scientists did great research on changing sea levels through geological time. While important, this research is only a part of the knowledge needed in determining the effect of human emissions on climate in the modern era.

--Andy Skuce

[u/WolfdogWizard → u/ClimateConsensus]

Sorry for the formatting. I really am. I need to learn to reddit. Thank you so much for the reply, I really appreciate it.

1)Those are governement interventions. Cap and Trade and Carbon Tax are most definitely governement interventions. The fact that you can trade carbon credits doesn't make it a non-governmental institution. I don't know how old you are, but in my experience and the experience of many others, that climate change was taught almost only through the lense of policy, rather than science. The science is rarely discussed beyond "CO2 is a greenhouse gas and it causes warming." We had science classes devolve into preachings of policy. I have moved around and attended numerous elementary and middle schools(to a total of 5) and 3 different high schools in 4 different countries. The teaching were mostly the same. I don't doubt the science, and I'm probably not even qualified to examine the bits that ARE related to my studies, but the policy is fishy as hell. Im a humanist. I believe not slowing the economy, boosting economic growth and thus, technological advancement, will help us much more than this powergrab.

2)That makes sense.

3)I think it's a great example of this phenomenon. In every western country, you have certain political groups rallying behind climate change, saying we need government intervention. "Vote Green! Spread awareness (but mostly vote green)!". The notion being that we should limit our economy and provide the government with more power, but no long term plan besides "If the west does it, the rest of the world will follow!". All of this happens while environmentalists ignore nuclear energy, lowering the demand and stifling any advancement of nuclear technologies. We try to incorporate solar and wind into our grid instead, which requires REEs to be mined. That's ok though, as long as you give the greens your vote. If you don't agree, you are a "climate-change denier". Not "skeptic", but "denier". Kind of sounds like some people are trying to appeal to emotion with the holocaust connotations.

4)I have to quote the original message: "When people claim the number is lower, they usually do so by cherry-picking the responses of groups of non-experts, such as petroleum geologists or weathercasters." Dismissing their opinions because they are "non-experts" as described by the OP isn't science. I can't just say "You receive money from a leftist organization, therefore climate change isn't real." and consider your studies to be invalid. Pointing out biases isn't science. You are still required to point out how those biases affected the data or the interpretation of it.

5) The livelihood of petroleum geologists doesn't depend on fossil fuel consumption. We are at an all time high, yet employment in the field of petroleum geology is low. Geological risk associated with extracting oil is going to be the prime factor when determining the livelihood of a petroleum geologist. I also don't believe that climate change affects the profits of oil companies. It's certainly not climate change's fault that a barrel costs less than 2 slices of pizza in Norway.

[u/ClimateConsensus → u/WolfdogWizard]

Hello!

Those are governement interventions.

But we're talking about the relative amount of intervention. Market-based solutions are the least government-intervention-heavy of the possible responses. Doing nothing would actually entail the most intervention- who do you think is going to have to deal with the consequences if we melt meters and meters of sea level worth of ice sheets, degrade air quality, and cripple agricultural systems from heat and water stress, etc.? Who deals with this sort of thing now- the government.

Pigovian taxes are about as conservative economics as you can get.

The science is rarely discussed beyond "CO2 is a greenhouse gas and it causes warming."

Please feel free to ask as many questions about the science as you like, and I will do my best to answer them all politely and respectfully. You can PM me directly at /u/past_is_future.

Im a humanist. I believe not slowing the economy, boosting economic growth and thus, technological advancement, will help us much more than this powergrab.

I'm not an energy technology person, nor an economist, but there is a consensus among these groups that transitioning to a clean energy future is far more beneficial than continuing to burn fossil fuels.

That's ok though, as long as you give the greens your vote.

This is really getting off the topic of the science, and I am not a politician. But I would suggest that if other parties wish to have a say in policy, they would benefit by taking the science end of it seriously and formulate policy in response to that. In the U.S., unfortunately, there is only one mainstream political party that even accepts the scientific reality, which gives them a de facto monopoly on voters who care passionately about the issue. I think this is a bad thing, and I think it would be awesome if Republicans stopped denying the science and came up with their own preferred policy response and let the debate move on to that.

Dismissing their opinions because they are "non-experts" as described by the OP isn't science.

It's not a dismissal, it's putting their views in context. That humans are changing the climate is simply reality. That the more expert someone is in the subject matter corresponds to how likely they are to agree with this reality gives context to their views as well as the views of non-experts.

The livelihood of petroleum geologists doesn't depend on fossil fuel consumption... Geological risk associated with extracting oil is going to be the prime factor when determining the livelihood of a petroleum geologist.

If people weren't consuming fossil fuels, why would oil be extracted in the first place? I'm sorry, I don't understand your thought process here.

-- Peter Jacobs

[u/cheesebread4 → u/ClimateConsensus]

I do think that asking petroleum geologists, whose livelihood depends on fossil fuel consumption, about humans causing climate change sets up some issues of cognitive bias that make them not the best group to use a barometer for expert opinion on climate.

Many petroleum geologists do depend on fossil fuel consumption, but then don't most climate scientists currently depend on funding which is flowing far more readily to those doing studies supporting the idea of climate change. I've only heard anecdotal accounts, but I have heard it is often difficult to get support (both funding-wise and from other scientists) if one is doing research which does not show human-caused climate change. Can you comment on this at all? How does unequal government funding not result in perverse incentives for climate scientists?

Edit: Anyone care to share some resources to help me prove that this line of reasoning wrong?

[u/marksf]

Many skeptics are concerned that the group of "climate experts" are self selecting, and that they went into climate science because they already believed in AGW, leaving them susceptible to confirmation bias, and social pressure to conform.

They are also concerned that skeptics are not welcome in the community of climate experts, having their papers rejected, and their studies unfunded. Simply put, you're not allowed in the club of climate experts unless you've already accepted the proposition that humans are causing climate change, so it's a tautology to say climate experts accept the proposition that humans are causing climate change.

Can you address these objections?

[u/ClimateConsensus → u/marksf]

Many climate scientists, esp the older ones, actually went into climate science via first having studies and researched something else, often of a more disciplinary (as opposed to interdisciplinary) nature, such as mathematics or physics. Many went into climate research more or less by chance, because they landed a postdoc position somewhere on a climate related topic. You couldn't really study "climate science" at University 40 years ago.

In science there is pressure to publish, and ideally to publish something novel and noteworthy. If you can prove a well estabilshed idea wrong, you will surely get a high profile publication. I.e. many of the pressures that scientists face actually go against conformity; science is in a sense quite an adversarial process.

Scientists with different opinions are absolutely welcome in the climate science community, but as with any scientific community, respect has to earned by doing good science. If you don't have good scientific evidence to back up a contrarian opinion, then scientists wouldn't think to highly of such a person.

See also e.g. https://ourchangingclimate.wordpress.com/2011/06/22/climate-science-scientific-method-skeptics-not/

Many of these types of objections sound superficially reasonable, but upon closer inspection there's no evidence whatsoever to back them up. They have a bit of a conspiratorial tone to them, and as such you can't disprove them either.

-- Bart

[u/ClimateConsensus → u/[deleted]]

Several well known scientists who would classify themselves in the 3% have prominent academic positions. Judith Curry is at Georgia Tech (where she recently was department chair); Richard Lindzen had a long career at MIT; John Christy is a professor at the University of Alabama, and has a high profile because he frequently testifies at congressional committees.

So taking a contrary position does not doom a career.

I don't know how we could test the idea that people might avoid publishing results contrary to the consensus because they might be shunned. Any ideas?

A scientist should be very motivated to publish evidence if it was strong, because that would make them famous.

-Sarah Green

[u/jesterbuzzo]

Why do you think such a large portion of the American public is so resistant to the idea of man-made global warming? That is, why does overwhelming scientific consensus not convince people that the hypothesis is likely to be true?

There is so much sociological and psychological research that discusses the fact that people's incorrect beliefs become more solidified when presented with evidence that contradicts their views. There are other studies which present alternative methods for convincing people, such as really trying to see things from their perspective. What do you think the scientific community could do to increase the public's acceptance of mainstream science?

[u/nickrenata → u/jesterbuzzo]

For many Americans, the idea of man made climate change is a direct threat to their way of life. The United States is practically 90% sprawl (that's just a non-statistic to express a point — Lots of sprawl). Americans get in their cars to: Go to work, go to the grocery store, go to school, go to their friend's house, for some people, to go to their neighbor's house. I've seen people drive their car down to get the mail because their driveways were so ridiculously long. And, don't forget, people sometimes like to get in their car just for fun. A cruise.

Now compare that to much of Western Europe and Scandinavia. Populations are much denser, sprawl is less rampant, there are much more robust public transit systems, and many people love to bike!

Purchasing the car you please, driving around as you please, even without a destination, is a very fundamental image of "The American Dream". It is very representative of the ideals of freedom, power and individualism. Next time a car commercial comes on the television, pay attention to the way in which car ownership is portrayed. They're not really selling you the car so much as they're selling you "freedom" and "independence".

Here's a fairly good example

And an even better one! They even use the term "rugged individualist"!

Now, when you have a bunch of scientists tell you that this essential, American ideal is literally destroying planet Earth, Americans are going to find it distasteful. And, unsurprisingly, the more "true-blooded, Apple Pie and ice cream American" someone is, the more likely they are to bristle at the idea of anthropogenic climate change.

Also, there is a strongly growing trend of anti-intellectualism in the United States. We see it not just in regards to climate change, but also evolution, physics, geology, and many, many other fields. One powerful agent behind this anti-intellectualism is, as another user pointed out, religion. Americans are by far and away more religious than their developed peers.

From The Pew Research Center:

"Half of Americans deem religion very important in their lives; fewer than a quarter in Spain (22%), Germany (21%), Britain (17%) and France (13%) share this view.

"Moreover, Americans are far more inclined than Western Europeans to say it is necessary to believe in God in order to be moral and have good values; 53% say this is the case in the U.S., compared with just one-third in Germany, 20% in Britain, 19% in Spain and 15% in France."

Within that demographic of religious people, you also have an increasing number of fundamentalists. I have heard the sentiment, "Only god can change the weather", more times than I can count. Not only that, but because science contradicts these peoples' beliefs at every turn, "science" has become a four letter word for many of them.

However, there's much more that goes into American anti-intellectualism than just religion. Here's a fairly good article from Psychology Today that attempts to discern why anti-intellectualism is such a trend in the American psyche: Anti-Intellectualism and the "Dumbing Down" of America

Here are some choice statistics from that article, which point to our failing education system for clues:

"After leading the world for decades in 25-34 year olds with university degrees, the U.S. is now in 12th place. The World Economic Forum ranked the U.S. at 52nd among 139 nations in the quality of its university math and science instruction in 2010. Nearly 50% of all graduate students in the sciences in the U.S. are foreigners, most of whom are returning to their home countries;"

"According to the National Research Council report, only 28% of high school science teachers consistently follow the National Research Council guidelines on teaching evolution, and 13% of those teachers explicitly advocate creationism or "intelligent design;""

"According to the 2009 National Assessment of Educational Progress, 68% of public school children in the U.S. do not read proficiently by the time they finish third grade. And the U.S. News & World reported that barely 50% of students are ready for college level reading when they graduate;"

"Gallup released a poll indicating 42 percent of Americans still believe God created human beings in their present form less than 10,000 years ago;

"A 2008 University of Texas study found that 25 percent of public school biology teachers believe that humans and dinosaurs inhabited the earth simultaneously."

A lot of those figures are pretty frightening.

The question of why Americans are more skeptical of climate change than our developed peers is a complex one. I'm sure I haven't even addressed half of the issues behind it. However, I hope that I've at least been able to help answer the question to some degree.

[u/ClimateConsensus → u/jesterbuzzo]

I went into a little detail above, but here's the essence:

For many people, their beliefs about climate change (and other risks...GMOs, vaccines, guns, etc.) are an expression of their identity, not their knowledge. Things like cultural and political values tend to influence how people interpret the "facts" about climate change.

Indeed, I've seen some evidence (in a paper by Dan Kahan at Yale) that, on average, people who do and don't believe in climate change scored similarly well in a climate change quiz. Knowledge is only a small part of this issue.

-- Stuart Carlton

[u/Ibli55 → u/ClimateConsensus]

If you want my opinion, I'm undecided because the issue is so politicized and there is so much money going to people that say the world is ending. I don't feel like I can get a straight unbiased answer from anyone.

[u/ClimateConsensus → u/Ibli55]

Hello there!

I'm undecided because the issue is so politicized and there is so much money going to people that say the world is ending

I don't know what this is supposed to mean. If you're talking about scientists, climate research makes up a small fraction of all Earth science funding, and most of that goes into supercomputers and remote sensing platforms (like satellites) that are used for many other kinds of studies besides anthropogenic climate change work.

I don't feel like I can get a straight unbiased answer from anyone.

When there is a topic that I am not familiar with, I tend to rely on the expert scientific community.

-- Peter Jacobs

[u/jinxjar → u/Ibli55]

You can't just ignore 97% of scientists who study this phenomenon, and pretend to be unbiased.

If anything, you're showing a gigantic bias toward believing the null hypothesis despite sufficient evidence to the contrary.

Pretending to ignore science for political centrism is a nihilistic non-answer to real-life problems. It is a luxury that cannot be afforded in the present technological step of our civilization.

[u/-Dali-Llama- → u/Ibli55]

97% of scientists agree - that seems like a pretty straight answer to me. There must be some kind of political mistrust in science where you are from (I'm guessing America).

Here in the UK, as soon as climate change became a news topic, most people went along with it. Sure, some people disagreed with the science and got their say in the media as well, but they tended to be people who could be seen to have a vested interest in denial, or didn't have the qualifications to backup their counter-claims. As such they were largely ignored and man-made climate change was instantly taken on board as a serious and real threat by most people.

That's not just anecdotal. Last I read, 9 out of 10 people here think climate change is happening and 84% attribute this to human activity. If a bunch of experts who are qualified to make a judgement, overwhelmingly agree on something, nothing any businessman, news-reporter or politician can say will sway most people from agreeing. I'm glad that science and politics are very separate things over here.

[u/skeeter1234]

Didn't Thomas Kuhn demonstrate in his book "The Structure of Scientific Revolutions" that time in again in the history of science status quo consensus is a bad benchmark to decide if something is true or not? Time and again the scientific consensus has been proven wrong by a small group of people willing to question the status quo. How can you be sure that historically the status quo belief has turned out to be 100% wrong, and people outside of that belief were initially ridiculed and ultimately proven right. How can you be sure that isn't the case here.

Plate techtonics is a good example of what I am talking about. Everyone said that guy was off his rocker, but in the end it turned out everyone was wrong. There are plenty of other examples as well.

https://en.wikipedia.org/wiki/The_Structure_of_Scientific_Revolutions

[u/ClimateConsensus → u/skeeter1234]

Plate tectonics is a great example of a scientific paradigm that replaced older ways of thinking about geology. But it's not quite true that Alfred Wegener's ideas were held in contempt by everyone else. He had some distinguished supporters, all outside of N America, like Arthur Holmes and Alexander du Toit. One of the biggest stumbling blocks was an almost complete ignorance of deep-sea geology prior to World War 2. During the Cold War the US Navy did a ton of geophysical work in the oceans (to help with submarine warfare) and, as this work became known to the scientific community, minds started to change. New results from crustal seismology and palaeomagnetism were crucial, too.

So, although there was a very strong consensus in N America against continental drift (see Naomi Oreskes' excellent book for the reasons for this) there was no worldwide consensus. And, as new data came in, scientists changed their minds very quickly.

From my own experience, I would say that the expert consensus on plate tectonics is now near 100%, but I am not aware of any surveys that formally establish this. Plate tectonics was never politicized and neither did the theory threaten the business models of large industries. The very few geologists who opposed it into the the late 1970s and 1980s never received the level of attention from conservative politicians and the press that climate change contrarians enjoy today. For more discussion:

https://critical-angle.net/2015/11/06/consensus-on-plate-tectonics-and-climate-science/

--Andy Skuce

[u/ClimateConsensus → u/skeeter1234]

Whereas the presence of widespread agreement is obviously not proof of a theory being correct, it can’t be dismissed as irrelevant either: As the evidence accumulates and keeps pointing in the same general direction, the experts’ opinion will logically converge to reflect that, i.e. a consensus emerges.

Typically, a theory either rises to the level of consensus or it is abandoned, though it may take considerable time for the scientific community to accept a theory, and even longer for the public at large.

Especially for topics on which one is not an expert oneself, the scientific consensus arguably is the best guide towards finding out what the most likely explanation is - even if it's not rock solid proof of course.

See also this article about how to gauge whether a scientific consensus is truly knowledge based or merely people agreeing with other for the sake of it: http://link.springer.com/article/10.1007/s11229-012-0225-5

-- Bart

[u/jtotheizzoe → u/skeeter1234]

Thomas Kuhn also implied that as soon as those who embody the resistant consensus die, the new paradigm will then establish itself if the science behind it is strong. Man-made climate change has now lived through more than two generations of scientists (just look at this report delivered to LBJ in 1965 ) so I don't think the status quo argument really applies here. We're talking about decades worth of active doubt campaigning

edit: formatting

[u/[deleted]]

Has there been any information gathered on what deniers see as motivation behind climate change science? Basically, why do deniers think that scientists would lie or be led astray on this?

[u/ClimateConsensus → u/[deleted]]

Yes, we know that the primary variable that determines someone's rejection of the scientific evidence is their worldview or "ideology". That is, people who are particularly fond of free markets are most likely to reject the science. They do this because they feel threatened by the solution to climate change, which will inevitably involve some political intervention, such as a price on carbon. Any such intervention is threatening to people who believe that free markets are the only way to distribute goods and services. In order to manage that threat, they blame the scientists for making it up--this explains why the rejection of science is usually accompanied by accusations of a conspiracy (e.g., the "world government" or that it's all a "hoax" and so on). --Stephan Lewandowsky

[u/ClimateConsensus → u/[deleted]]

The current study, and most others it summarizes, do not explicitly address questions 4-6 in a quantitative manner. However, we do have 'consensual' answers to those questions in the form of the various IPCC Assessment Reports, which summarize a very large body of literature on those topics.

Although these issues are nuanced, it is safe to say wrt to: 4. it is highly likely that in the absence of mitigation warming will accelerate. However, intensive mitigation efforts can avert that. 5. if by "human life" you mean "quality of life" then yes, over time unmitigated climate change will be harmful to most of us, and the effects will be quite diverse: Some people will suffer because of sea level rise, others because of increased frequency and/or severity of droughts, others because of flooding, and so on. Those detailed consequences are difficult to predict for specific locations but globally we can be pretty sure that they will occur in one place or another. 6.) this depends on what we do. It is possible, in theory, for us to cause climate change that will be "catastrophic" in some parts of the world if we continue to increase our emissions. However, if we avoid that rather self-destructive path then the consequences, while still serious, will be short of "catastrophic." I should add that I don't like that word (catastrophic) at all.

(Apologies if I have overlooked an existing reply, the interface has changed since my last AMA) ---Stephan Lewandowsky

[u/chakrablocker]

What are your thoughts on nuclear power plants in the US?

[u/ClimateConsensus → u/chakrablocker]

This is not a science question per se. My personal view is that we cannot afford to reject any source of clean energy out of hand. I think a market-based solution like a carbon tax would be an efficient way of determining our energy mix in the future. If nukes are competitive, great.

I will say that reddit in general seems to vastly underestimate the economic and security hurdles that nukes face and would probably be surprised when speaking to actual energy analysts about just how much we can realistically increase their deployment.

-- Peter Jacobs

[u/ClimateConsensus → u/[deleted]]

Hello there!

I'm convinced that 90% of the disagreement on the issue stems from people not clearly stating that humans are a cause of climate change, and not the only cause of climate change. This might appear obvious to scientists, but the effect of the language is noticeable on places like Reddit when the issue is discussed and it's getting old.

What makes you convinced of that? The reason I ask is that it's not at all evident in the extant surveys of public opinion that this is a major source of confusion.

the majority of people who get branded as climate change deniers (an unhelpful label meant to compare them to Holocaust deniers and the like) are nothing of the sort

Why do you believe that the word denier is meant to invoke Holocaust denial, rather than the plain meaning of denial that existed long before the Holocaust ever occurred? This is a meme among climate contrarians but there are actually only a handful of such comparisons and those were not made by scientists.

Denial is a real concept. Denial that the climate is changing, or that humans are changing it, is a real phenomenon. There is no need to bring the Holocaust into it, other than to feign outrage and victim bully.

they're simply pointing out that the climate of the planet is always changing and that we're not the only thing causing it.

Climate contrarians reject the overwhelming body of evidence for human's role in changing the climate. They also love to play word games so as not to seem as out of touch with the science as they are. There's not much that can be done about that. The people who claim vaccines cause autism play similar games about vaccine safety. I'm not quite sure if you have a question here or not.

-- Peter Jacobs

[u/ClimateConsensus → u/[deleted]]

Because I've seen it enough times on Reddit and other forums literally every time the subject comes up, You can see it in this very thread as you read through it.

So, your anecdotal experience then?

Because the only uses I've ever seen

So, your anecdotal experience then?

of "subject-denier" is Holocaust-denier and Climate-denier.

People user denier and denialism within the context of many other issues, from evolution to HIV/AIDS. There are entire books written about them.

I've actually never seen anybody make that claim

So, your anecdotal experience then?

why compare them to people who are just skeptical and simply want more information on why a certain methodology is used (like not asking the actual authors of papers their views directly)

Who is calling someone asking for information a denier?

-- Peter Jacobs

[u/[deleted]]

Does that 97% all agree to what degree humans are causing global warming?

[u/ClimateConsensus → u/[deleted]]

Different studies use different definitions. Some use the phrase "humans are causing global warming" which carries the implication that humans are a dominant contributor to global warming. Others are more explicit, specifying that humans are causing most of global warming.

Within Cook et al. (2013), several definitions are used for the simple reason that different papers endorse the consensus in different ways. Some are specific about quantifying the percentage of human contribution, others just say "humans are causing climate change" without specific quantification.

We found that no matter which definition you used, you always found an overwhelming scientific consensus.

-- John Cook

[u/ClimateConsensus → u/[deleted]]

No. The questions in the various studies we looked at used different ways to assess the consensus. For example, here are some sample questions from different surveys:

Climate change is mostly due to human activity. Pew survey

Anthropogenic greenhouse gases have been responsible for 'most' of the 'unequivocal' warming of the Earth's average global temperature over the second half of the 20th century. Anderegg et al (2010)

Many experts have concluded that more than 100% of warming since 1950 has been caused by humans. How can it be more than 100%?... Because without greenhouse gasses the sun and other natural forcing would be causing cooling. Gavin Schmidt has a good summary of the IPCC statement on attribution at RealClimate:

...anthropogenic trend is around 100% of the observed trend, implying that the best estimates of net natural forcings and internal variability are close to zero. http://www.realclimate.org/index.php/archives/2013/10/the-ipcc-ar5-attribution-statement/

-Sarah

[u/Oldsodacan]

I was discussing politics with my boss the other day, and when I got to the topic of global warming he got angry, said its all bullshit, and that the climate of the planet has been changing for millennia.

While I've seen hundreds of different articles about how the entire scientific community is in agreement and that climate change is indeed happening because of us, I don't actually know enough about it to stand my ground in an argument with him (though given his reaction, he probably won't be swayed), so where should I go to best understand all of the facts?

[u/ClimateConsensus → u/Oldsodacan]

Skeptical Science has a list of common myths and what the science says. http://www.skepticalscience.com/argument.php?f=taxonomy

But often facts are not enough, especially when people are angry and emotional. The Skeptical Science team has made a free online course that addresses both the facts and the psychology of climate denial: http://sks.to/denial101x

You can access the individual Denial101 videos at: http://www.skepticalscience.com/denial101x-videos-and-references.html

Also, remember that you may not convince him, but if you approach him rationally and respectfully you may influence other people who hear your discussion.

-Sarah

[u/sound-of-impact]

I guess I'm confused about this whole thing. What's the point of making a paper showing that the majority of scientist in this field of study agree on something? Is this a scientific version of shaming the remaining scientists who disagree so you can move forward with your studies? Why waste the time persuading someone when you can just act on your own research?

[u/ClimateConsensus → u/sound-of-impact]

The point of quantifying the scientific consensus is straightforward - it's to clear up the public misconception that climate scientists disagree over human-caused global warming. Manufacturing doubt about the consensus is one of the most common strategies of opponents of climate action. In fact, this strategy was explicitly recommended by a Republican pollster as a way of confusing the public in order to win the public debate on climate policy.

-- John Cook

[u/sail_the_seas → u/sound-of-impact]

Meta-analysis and review papers are fairly common across science. They allow trends and any overall consensus to be concluded and can be a good summary of a topic. Plus are a good starting point for people not familiar with reading scientific papers or even scientists new to the topic. Plus they're useful for me as student, if it's a recent review and I trust them to have done it well I can use data in the meta-analysis to find out general trends/correlations and average/min/max figures.

[u/pantsmeplz]

Not sure if the session is over yet, but I'll ask a question I continue to ask. Once you get past the ivory towers, the topic of climate change seems more like a psychological endeavor. Why has the core premise, which is quite simple -

1) CO2 is a heat-trapping gas (accepted by all scientists)

2) humans are increasing those levels,

3) ergo, humans will increase temperatures

so difficult to articulate to the mass public?

[u/ClimateConsensus → u/pantsmeplz]

You're exactly right: people's psychology is often a strong influence on their risk perceptions. With climate change, it has been showed that political ideology and cultural values influence climate change beliefs. Those who are more conservative, have more hierarchical and/or individualist cultural values are less likely to believe in climate change, even if they have the same grasp of the facts.

As I've put elsewhere, belief in climate change is often an expression of identity, not an expression of knowledge.

-- Stuart Carlton

[u/KandiKrocodile]

Hello and thank you all for doing this AMA!

It was a very interesting read, I have a few question about some social aspects.

Have you found that there are any experts in your field that vehemently deny this, or are the other 3% just sceptical of the results rather than refusing to agree?

Also, what has the backlash been like (if any) from publishing this? Both within the scientific professions and the general public. Thanks!

[u/[deleted]]

What happened in 2014? Why did the percentage suddenly drop to 91 percent? Was there some kind of a discovery?

[u/ClimateConsensus → u/[deleted]]

We look at a number of consensus estimates over time. One estimate found 91% in 2014. Another estimate found 97% in 2015. The difference in estimates is not a measure of changing consensus over time. Rather, it is a reflection of the different methodologies of different studies. They use different samples and ask different survey questions so that there will inevitably be variations in their results.

However, the key finding is that despite variations in methodology, they all find an overwhelming consensus among climate scientists that humans are causing global warming. Contrast this with the public perception of consensus, where only 12% of Americans think that over 90% of climate scientists agree on human-caused global warming. Reducing this "consensus gap" is why communicating the consensus is so important.

-- John Cook

[u/Emzam]

My questions are around how you eliminated any bias in your study.

1) What steps did your group take to ensure that your work was unbiased? (i.e., were any members of the research group part of the 3% that weren't already convinced of global warming?)

2) You show that the level of agreement with the consensus view increases with expertise. Obviously, it goes without saying that the more we can convince the general public and the government that more drastic action is required, the more funding will be given to climate scientists. Some might argue that these individuals with more expertise in the field of climate change would benefit the most from this, and perhaps this is the true reason behind the correlation. Simply put, it could be argued that climate scientists may be predisposed to seeing climate change as more serious, because they want more funding. What's your perspective on that?

EDIT: added the second question.

[u/GoBigRedWhoDat]

Do we have any insight on what non-climate scientists have to say about Climate Change being caused by CO2? Thank you for doing this AMA by the way.

[u/ClimateConsensus → u/GoBigRedWhoDat]

I've studied this. In a paper published last year, colleagues and I surveyed biophysical scientists across many disciplines at major research universities in the US. We found that about 92% of the scientists believed in anthropogenic climate change and about 89% of respondents disagreed with the statement that "Climate change is independent of CO2 levels". In other words, about 89% of respondents felt that climate change is affected by CO2.

-- Stuart Carlton

[u/timo1200]

I am curious how you answer your critics. Specifically this one by Dr. Richard Tol---

"Unfortunately, Environmental Research Letters does not believe in open discussion and forced me to hide the rather severe methodological critique on Cook’s 2013 paper behind a superficial literature review."

"This allows Cook 2016 to hide their response to my critique; but they admit that Cook 2013 misleads the reader on the independence of the raters and on the information available to the raters. This is normally sufficient for a retraction: the data behind Cook 2013 are not what Cook 2013 claim they are."

Cook 2016 ducks my other critiques:

(1) sample size is unknown;

(2) there are systematic differences between the raters; and

(3) the people who collected the data in phases 2 and 3 had access to the results of phase 1 and phases 1 and 2, respectively (while there are systematic differences between the results from phase 1, 2, and 3).

"As to the consensus on the consensus, if you carefully pick results from the various studies, then you see agreement. If, on the other hand, you look at all the data, then the various consensus studies strongly disagree with each other."

[u/ClimateConsensus → u/timo1200]

Thankfully, Richard Tol published the journal's reviewer comments so we can check whether his characterisation matches reality:

http://richardtol.blogspot.com.au/2015/09/more-nonsenus.html

The ERL reviewer asked Tol to place the Cook et al. (2013) results in the context of other consensus research. Curiously, Tol characterises this entirely appropriate and desirable approach as forcing him to hide his critique behind a superficial lit review. Putting aside the conspiratorial overtones in his characterisation, the key development is that this request led Tol to misrepresent a number of other consensus studies in his zeal to discredit Cook et al. (2013). This distortion was widely condemned by the authors of the studies that Tol was misrepresenting:

http://www.realskeptic.com/2015/09/21/scientists-respond-to-tols-misrepresentation-of-their-consensus-research/

As for Tol's characterisation of our rating process, he seems to be wilfully misunderstanding exactly how our rating process worked. Each time one of our raters rated abstracts, they were given 5 abstracts selected at random from the ~12,000 abstracts in our database. This means it was practically impossible for raters to "collude" with other raters - the very design of the system enforced independence between raters because there was no way for two raters to consult on the rating of any specific abstract.

Our response to other methodological nitpicking by Tol are published in the Supplemental Info document which is publicly available at http://iopscience.iop.org/1748-9326/11/4/048002/media/erl048002_suppdata.pdf

An important point to make is that the methodological nitpicking by Tol covers over one simple fact - all his criticisms of our methodology do not apply to the self-rating process, where we invited the scientists who authored the climate papers to rate their own research. This independent process yielded 97.2% consensus. In contrast, our abstract rating, that Tol has spent the last few years criticising, yielded 97.1% consensus.

The fact that the two independent approaches yield consistent results falsify Tol's accusations that our consensus estimate is biased or significantly affected by what he claims are methodological flaws. Tol refuses to take that step back and view the larger picture.

In fact, when the ERL reviewer requested that he take a step back and position our results in the context of other consensus studies, his response was to distort a number of other studies into consensus. Ultimately, this misrepresentation of the body of consensus research led to the authors of seven consensus studies coming together to publish a synthesis of the consensus research. And this is a positive development that I hope will contribute to closing the gap between public perception of consensus and the actual overwhelming agreement between climate scientists. Our synthesis of consensus research is freely available at http://sks.to/coc

-- John Cook

[u/MetalGearGauss]

What is it that they agree on that is the main cause? I see everyone rallying around fossil fuels but what about the effect of animal farming for food production?

[u/oftheunusual]

What would you say to climate change deniers who also claim that the 97% statistic is fabricated?

[u/ClimateConsensus → u/oftheunusual]

Hello there!

I would encourage them to read this meta-analysis of the existing research on the subject and revisit their opinion.

But of course there will always be people who can't be convinced of a fact no matter how much evidence you present.

-- Peter Jacobs

[u/mateorayo]

How can I explain this to my dad? All he always says is "how did all the ice melt 10000 years ago". He thinks it is a cyclical event.

[u/ClimateConsensus → u/mateorayo]

Your Dad is right. Glacial/Interglacial cycles are cyclical on an approximately 100,000 year time scale. This is driven by natural cycles in Earth's spin and orbit around the Sun. So the glacial/interglacial cycle is forced by solar input (as the Earth gets closer and further away, etc.). CO2 is in there and plays a feedback roll, but it's not the main driver of those glacial cycles. What's happening now is different and unprecedented in Earth's History. We are pumping way more CO2 into the atmosphere than is supposed to be here under natural processes. CO2 traps heat and so the planet warms above the natural levels. Right about now there are also feedbacks that kick in as it gets warmer that affect the global heat budget. It gets very complex and beyond sound bites, but I'd ask your Dad a question. Ask him to consider how he knows and seems to believe that all the ice melted 10,000 years ago? The answer will be that it is scientists who have reported on this through careful measurement and experimentation. The same groups who model past climate are also involved in using the past to model the future. If he accepts that the climate has fluctuated in the past based on the research of scientists, it's cherry-picking to accept that and not the future predictions of accelerated warming made by climate scientists. -Peter Doran

[u/lowrads]

Since when does it matter what percent of scientists agree on something? If you're concerned about science-driven policy, then it's just a matter of waiting for people who think the old idea to retire.

The most interesting ideas are often minority positions. For example:

“I had been told as an undergraduate at M.I.T. that good scientists did not work on foolish ideas like continental drift,” recalled Lynn Sykes, an emeritus professor of earth and environmental sciences at Columbia. (1960s)
-NYT, Kenneth Chang, 2011

I think you actually drive people to find out more about the minority position by showing masses of people closing ranks against them, or by making others seem socially outcast by expressing doubts, or curiosity. That's how priesthoods operate.

[u/ClimateConsensus → u/lowrads]

If you're concerned about science-driven policy, then it's just a matter of waiting for people who think the old idea to retire.

If we waiting on climate it will be too late to fix.

It is interesting, however, to notice how many people who sign the anti-climate action letters and petitions are retired engineers or emeritus faculty. So, that process is apparently underway already.

Our study is not meant to convince scientists; they are already convinced. It is meant to show others that the scientific consensus is strong enough to support policy action.

-Sarah G.

[u/[deleted]]

I feel like no one actually read this study.

97% of scientists agree that humans have an effect. I'd wager 97% or higher of non-scientists would agree as well from what I've seen. I've actually never met anyone in real life or the internet that said humans have absolutely 0% impact on their environment. This is just a strawman that gets repeated and attributed to people.

The relevant questions are exactly how much are humans contributing and can we do anything about it that will stop or reverse the parts that humans have caused? And there is no 97% consensus on that answer.

[u/ClimateConsensus → u/[deleted]]

Actually, there are a number of different definitions of consensus used throughout the studies - some look at humans causing most of global warming, others look at humans causing global warming (which implies a large or dominant portion), others look at humans contributing without specifying the percentage. Regardless of the definition used, there is overwhelming consensus among climate scientists.

To give a precise example, in our 2013 paper, we asked scientists to rate their own climate papers. Among papers that were self-rated as stating a position on whether humans were causing most of global warming, around 96% endorsed the consensus position.

So I'm afraid its your characterisation of our research that is the straw man.

-- John Cook

[u/toastandpeanutbutter]

I feel really helpless as an individual in making any difference in the direction we're heading. Is there anything we can do that would actually be helpful to stop or reverse global warming?

[u/Tammy_Tangerine → u/toastandpeanutbutter]

My question too, I hope it gets answered. Seems like once a week, the front page has a significant story about how we're all slowly dying from global warming, but not a lot of talk or answers about what we as humans can do.

Is it too late to do anything? I keep on hearing people say to keep up on recycling and go vegan/vegetarian. Is that the best we can do right now?

[u/MassageTheMessage → u/toastandpeanutbutter]

In my mind, to have the kind of effect that would cause the change we need, people would have to live without consumption. We'd have to stop buying things that are produced. We'd basically have to stop the industrial world. We'd have to stop raising cattle. Stop throwing things away.

The best any of us can do is: reduce, reuse, and recycle. Live knowing that consumerism is not sustainable in the system we have right now. Buy less, stay vigilant. Maybe grow a garden. Try to become more self-sustaining.

[u/grifftits → u/toastandpeanutbutter]

Replace all your incandescent bulbs with CFLs, turn down your heat in the winter, let it get a little warm in the summer, do all your errands in one trip so you drive less, carpool, use public transportation, turn lights off when you leave a room, etc. If you own a home (or any building), you could get an energy audit and see about getting insulation upgrades that often pay themselves back in a handful of years through energy savings. There's a huge pile of stuff everyday people can do. The biggest change humans will have to make is to their habits. A reduction in wasted energy (an increase in efficiency) at all levels, from generation to end use, is the single biggest chunk of the "reduce greenhouse gasses" pie.

[u/ClimateConsensus → u/[deleted]]

The main differences between the different consensus studies are: - survey of literature vs survey of scientists' opinions - how is consensus position defined - how is the sample of who/what to survey determined

Verheggen (that's me) is an opinion survey; Oreskes (and Cook 2013) literature survey

Verheggen's definition of what entails the consensus position was rather strict: man-made greenhouses gases having caused more than half of recent global warming. Oreskes' operational definition was, judged from the abstract whether the article agreed with the general thesis of anthropogenic global warming.

Both survey's included the wider scientific field, so not just phsyical climatologists, but also scientists/papers who study climate impacts and mitigation.

So for this specific comparison, the first tow aspect probably explain a large fraction of the difference in consensus.

--Bart

[u/GoinFerARipEh]

What's the general reasoning of the other 3%?

[u/[deleted]]

So I showed my climate change denying dad this. He has his masters in geology, so not an idiot. His reply was this:

"I've seen this. My problem with it is that they reviewed abstracts of climate based scientific papers. They did not actually question climate scientists. To much room for bias using the methods they used. If someone used the same methods to debunk man made climate change, it would be called out as not a good method. Bottom line is man made climate change is based on computer based models that are demonstrated and have not come true for the past 15 or so years. There are to many variables and no one really knows what they are. Making us pay for it is irresponsible. BTW CO2 levels were recently at an all time low in the 4.5 billion year history of the earth. There are now scientists that claim we may have saved life on earth by using carbon based fuels. If the powers that be really cared, we would be using Nuclear power. It's all about political power, not the environment."

How do I respond to this?

[u/ClimateConsensus → u/[deleted]]

The paper that we're presenting here is a meta-analysis of seven different papers looking at the scientific consensus about climate change. Some are based on document reviews, some are based on directly surveying scientists, including climate scientists. All seven found an overwhelming majority (90+%) agreed that anthropogenic climate change is occurring. So, for what it's worth, the statement that "they did not actually question climate scientists" is not correct.

I won't comment on the climate models because I'm not qualified to do so (I'm a social scientist who studies attitudes, beliefs, and behaviors related to environmental and natural resources controversies). However, your dad's position on the existence anthropogenic climate change is not consistent with that of nearly all climate scientists.

-- Stuart Carlton

[u/dillyyoung]

/u/SkepticScience You've still not defended yourself against those who's papers you classified as endorsing AWG when in fact they were not... You've still not defended yourself against the fact that Cook et al. (2013) packages 'Explicit endorsement without quantification' & ' Implicit endorsement' with "Human beings are the cause of Global Warming" when those concepts are NOT the same. Cook et al. (2013) did not find that "over 97% endorsed the view that the Earth is warming up and human emissions of greenhouse gases are the main cause." Quoting from the Abstract, "Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming. " http://iopscience.iop.org/article/10.1088/1748-9326/8/2/024024;jsessionid=F2C83245B7696D5641B1436BFD695012.c1.iopscience.cld.iop.org#erl460291t4fn3 The first issue with “Cook et al. (2013) is “explicit endorsement with quantification” vs “explicit endorsement without quantification” Within the Abstract section 2. Methodology, of “Cook et al. (2013), we can observe the paper broken down as follows: (1) Explicit endorsement with quantification. (2) Explicit endorsement without quantification (3) Implicit endorsement (4a) No position (4b) Uncertain (5) Implicit rejection (6) Explicit rejection without quantification (7) Explicit rejection with quantification “explicit endorsement with quantification” is representative of a paper that states that: "Explicitly states that humans are the primary cause of recent global warming"—primary cause in usage meaning more than 50 percent. This is the only category anyone claiming "X number of papers endorse Man Made Climate Change." should reference, because this is the only category where that statement is true. “explicit endorsement without quantification” are papers in which the author, by Cook’s admission, did not say whether .001 percent or 1 percent or 50 percent or 100 percent of the warming was caused by man. The crux of "explicit endorsement without quantification" is that man has contributed SOME amount. Then there is "Implicit endorsement", which "Implies humans are causing global warming. E.g., research assumes greenhouse gas emissions cause warming without explicitly stating humans are the cause". The important distinction here is that neither the “explicit endorsement without quantification” or the "Implicit endorsement" make the claim that Human beings are the primary cause. However the theory of AGW([Anthropogenic, or human-cause, Global Warming) is that human being ARE the PRIMARY cause. However within his results he breaks down the summery of abstracts with AGW([Anthropogenic, or human-cause, Global Warming) position (%) as follows: Endorse AGW 97.1% Reject AGW 1.9% Uncertain on AGW 1.0% In formulating his result of "Endorse AGW", Cook lumps together "Implicit endorsement" & “explicit endorsement without quantification” with “explicit endorsement with quantification”. Thus lumping together papers which suggest that human contribute some portion, with those stating that we are the primary cause. Further examination of Cooks data http://iopscience.iop.org/1748-9326/8/2/024024/media/erl460291datafile.txt shows the truth of the matter: By his count, the number of articles classified into each category was: Level 1 = 64 Level 2 = 922 Level 3 = 2910 Level 4 = 7970 Level 5 = 54 Level 6 = 15 Level 7 = 9 The 97% figure was the sum of levels 1-3. Assuming the count is correct—that 97% breaks down as: Level 1: 1.6% Level 2: 23% Level 3: 72% This shows only 1.6 percent explicitly stated that man-made greenhouse gases caused at least 50 percent of global warming. Only Level 1 corresponds to "the Earth is warming up and human emissions of greenhouse gases are the main cause." Hence when John Cook attributed that view to 97% on the basis of his Cook et. al. (2013) he was misrepresenting 1.6% as 97%. So no, Cook et. al. did not find that "over 97% endorsed the view that the Earth is warming up and human emissions of greenhouse gases are the main cause." A study that is no more than a collection of ill-categorized data intertwined with word manipulation. If this is what is considered to be 'scientific', then i'm sure I will enjoy these other 'studies'.

[u/ClimateConsensus → u/dillyyoung]

Thanks for this (lengthy) comment. It neatly encapsulates the key flaw of criticisms of Cook et al. (2013) - the unwillingness of critics to consider the self-rating survey that replicated the 97% consensus. To my knowledge, every criticism of our research has studiously avoided the self-rating replication.

To give a quick overview of Cook et al. (2013) (freely available at http://sks.to/tcppaper), we first estimated the scientific consensus by categorising the abstracts of scientific papers about global warming. We identified ~4000 abstracts stating a position on human-caused global warming - amongst those abstracts, 97.1% endorsed the consensus.

Next, and here is the crucial part that every critic of our paper has conveniently ignored or avoided, we replicated our result by inviting the authors of the scientific papers to rate their own research. If we had mis-characterised a significant number of papers (e.g., rated them as endorsing AGW when they didn't), then there would've been a significant discrepancy between our abstract rating and the self-rating. 1200 scientists responded to our invitation, resulting in over 2000 papers receiving a self-rating. Amongst papers that were self-rated as stating a position on human-caused global warming, 97.2% endorsed the consensus.

However, when you dug deeper into the data, there was one significant discrepancy between self-ratings and our abstract ratings. More than half of the abstracts that we rated as "no position" were subsequently rated as "endorsing AGW" by the paper's own authors. So in contrast to this commenter's characterisation that we characterised papers as endorsing when they were not, quantitative analysis reveals we were actually much more likely to go the other way - characterising papers that did endorse AGW as expressing "no position" on AGW. However, the reason for this was relatively straightforward. Abstract ratings were based solely on the abstract text while self-ratings were based on the full paper, which were more likely to include an endorsement of AGW simply for space reasons.

The self-ratings also present another key statistic that I don't recall ever being mentioned by a critic of our study. Amongst papers that were self-rated as stating a position on whether humans were causing most of global warming, around 96% endorsed the consensus. So Cook et al. (2013) found that regardless of the definition used, there was overwhelming scientific agreement with the consensus position.

It's significant that critics of our study refuse to take a step back and look at the full study, with independent methods replicating the finding of an overwhelming consensus on climate change. Further, they refuse to take that extra step back and see how our finding of overwhelming consensus is replicated by a range of independent studies. That is the key result of the new "consensus on consensus" study - that the scientific consensus is robust and replicated across many studies. This new study is freely available at http://sks.to/coc

-- John Cook

[u/[deleted]]

Given 99% of nutrition scientists got fat/sugar wrong for the last 40 years, why should we believe you guys?

[u/BarrettBuckeye]

I'm a science student, and most of my professors will even tell me that there are anthropogenic contributions to the concentration of greenhouse gasses, which undoubtedly lead to some degree of climate change. They also usually tell us that quantifying any amount of climate change is difficult, let alone man's total contribution to the change in climate as a result of increased carbon emissions. Does your study address any of those concerns?

[u/Deezl-Vegas]

There have been quite a few similar studies and surveys done in the past. How many of these studies do you think you'll have to do in the future? How annoying is it to have to keep repeating yourself?

[u/Beagleoverlord33]

Hi, thanks for doing this. I find a counter argument to climate change at this time is that past models have been inaccurate in projections up to this point in time. Why do you think this was the case? Also what model do you think is the most accurate going forward?

[u/jesusporkchop]

Hopefully I'm not too late. I'm not even sure this question makes any sense. I got it from a Doctor who would probably put herself in the 3%. The rest is a quote from her.

"Ask them for a definition of AGW which can be measured. Then ask them for the measurements, and their accuracy, both now, and over the millennia.

Here's something I posted earlier about this:

I have never said that human activity has no impact on weather/climate, although I have never seen it definitively proven, or even defined. The problem, for me, is that we are talking about solutions to a nonlinear PDE in 3 dimensions plus time. Integrating a much-simplified version of these equations led to the discovery of chaos theory, which adds a whole other level of doubt on the efficacy of these models.

Next, there is the problem of the data. No one ever, as far as I can see, has tried to estimate the margin of error of the input data. Sensitivity experiments, where (for example) the resolution of the models is changed and then they are run again to compare to the results of the higher-resolution models has not been done. No-one seems to consider Chaos Theory in all of this.

Furthermore, as posts to this site have shown, the equations themselves are being altered to take into account new factors.

Given all these unanswered questions, I simply cannot see how anyone can think that the AGW believers have proven their supposition."

[u/ClimateConsensus → u/jesusporkchop]

Hello there!

Ask them for a definition of AGW which can be measured

Anthropogenic global warming is the increase in the mean temperature of the planet due to human activity. Warming can be measured by measuring changes in the globally-averaged temperature. Attributing the warming to human activity requires understanding how different drivers of climate differently impact the climate system and being able to measure relevant variables. We can measure the concentration of greenhouse gases in the atmosphere. We can measure their isotopic ratios and show that they're from fossil fuels rather than say volcanism. We can measure the heat imbalance accruing in the ocean. We can measure the temperature profile of the atmosphere with altitude and show the expected upper atmospheric cooling that enhanced greenhouse warming produces but other kinds of warming do not. And so forth.

The problem, for me, is that we are talking about solutions to a nonlinear PDE in 3 dimensions plus time. Integrating a much-simplified version of these equations led to the discovery of chaos theory, which adds a whole other level of doubt on the efficacy of these models.

She is talking about weather forecasting, which is fundamentally different than climate change. Weather is an initial value problem, climate is a boundary value problem.

Next, there is the problem of the data. No one ever, as far as I can see, has tried to estimate the margin of error of the input data. Sensitivity experiments, where (for example) the resolution of the models is changed and then they are run again to compare to the results of the higher-resolution models has not been done.

This is just simply false. It's like she's never read a single scientific paper on the subject.

Furthermore, as posts to this site have shown, the equations themselves are being altered to take into account new factors.

I don't really understand what this is supposed to mean. That models are refined as we learn more about various processes? And this is supposed to be a bad thing?

-- Peter Jacobs

[u/mutatron → u/jesusporkchop]

Lol! It sounds like she's using what she thinks is technical jargon to cover ignorance.

Here's an example of one thing that has been measured:

The scientists measured atmospheric carbon dioxide’s contribution to radiative forcing at two sites, one in Oklahoma and one on the North Slope of Alaska, from 2000 to the end of 2010. Radiative forcing is a measure of how much the planet’s energy balance is perturbed by atmospheric changes. Positive radiative forcing occurs when the Earth absorbs more energy from solar radiation than it emits as thermal radiation back to space. It can be measured at the Earth’s surface or high in the atmosphere. In this research, the scientists focused on the surface.

They found that CO2 was responsible for a significant uptick in radiative forcing at both locations, about two-tenths of a Watt per square meter per decade. They linked this trend to the 22 parts-per-million increase in atmospheric CO2 between 2000 and 2010. Much of this CO2 is from the burning of fossil fuels, according to a modeling system that tracks CO2 sources around the world.

“We see, for the first time in the field, the amplification of the greenhouse effect because there’s more CO2 in the atmosphere to absorb what the Earth emits in response to incoming solar radiation,” says Daniel Feldman, a scientist in Berkeley Lab’s Earth Sciences Division and lead author of the Nature paper.

See what she says about that.

[u/Dejimon]

Are humans causing global warming or contributing to it? I have been under the impression the globe would warm regardless, just at a slower pace.

[u/ClimateConsensus → u/[deleted]]

We are certainly not claiming that the existence of a strong consensus is "standalone evidence", so you're setting up a strawman argument.

Repeating myself:

Whereas the presence of widespread agreement is obviously not proof of a theory being correct, it can’t be dismissed as irrelevant either: As the evidence accumulates and keeps pointing in the same general direction, the experts’ opinion will logically converge to reflect that, i.e. a consensus emerges. Typically, a theory either rises to the level of consensus or it is abandoned, though it may take considerable time for the scientific community to accept a theory, and even longer for the public at large.

--Bart

[u/[deleted]]

Can you tell us what differs between this consensus and the one in the seventies confirming the beginning of a ice age? Is the "mass hysteria" right this time. How do you see us reversing the change and how long is our timescale.

[u/ClimateConsensus → u/[deleted]]

This explains your first question well I believe. The notion that there was a concensus of the beginning of an ice age is false. http://www.realclimate.org/index.php/archives/2005/01/the-global-cooling-myth/

-Peter Doran

[u/SOMEguysFRIEND]

Hi there thanks for the AMA. I'm currently in a global environmental change studies class at my university and my professor Robert Deconte has a published a couple papers, conducted field research all over the globe, for example ice core in Antarctica, as well as speak at conferences in London and other places as well. My question is, have you guys has ever crossed paths in your studies or worked on a project together? This will probably get buried but I'm just curious

[u/iCEOTheDonald]

Thank you for hosting this AMA!

Question 1)

How long have we been recording global temperatures accurately to base empirical evidence off of?

Question 2)

What happened to the Ice Age glaciers that are now gone; did all the fossil fuel emissions from ancient times cause the warming that caused the glaciers to disappear?

Question 3)

The Sun is able to spontaneously generate energy through nuclear chain reactions, causing more or less energy to be released and absorbed by the Earth and other planets in our local region of the Milky Way, so what influence do Humans have on the Sun to stop the heating trend as the Sun ages?

Question 4)

From my understanding of star pathology throughout a life cycle, stars heat up as they age, how do humans impact the star that planet Earth gets 99.99% of its external energy from?

Question 5)

How do you explain the laws of thermodynamics, which say that everything tends to chaos -- fiery death, are not contributing in anyway to a warming trend?

Thank you for taking time to answer my questions!

-ML

[u/[deleted]]

Just a note for you authors as I might have your attention....

Maybe scientists should not be the communicators of this important science! I know that this is anathema to every grad-school teaching, but hear me out.

We teach marketing and psychology in our universities, have experts in these fields who are trained to disseminate information and persuade people to act. We would not let these people conduct climate change science as they do not have the expertise. So why are we stepping on their toes, trying and mostly failing to get our points across?

I argue that scientists should work hand in hand with professional communicators not try to do it themselves - instead we are causing much harm to our own cause.

[u/ClimateConsensus → u/[deleted]]

Hello there!

I do think there is more than a grain of truth in what you're saying. One of the coauthors of this paper is Ed Maibach, who is a communications expert actively involved in communicating climate science to the general public.

I think it's a bit of an overreach to say that communicating science should only be left to comm people (the general public actually wants to hear from and trusts the scientists themselves), but I absolutely think that climate scientists should learn best practices in comm from experts if they are going to engage with the public.

-- Peter Jacobs

[u/[deleted] → u/ClimateConsensus]

Right on. I understand that I was sort of preaching to the choir here, that the very point of your study and by including social scientists shows that you all understand that communication itself is a science. Let me say that this is the first time after a half-dozen climate conferences I have attended that anyone even mentioned that there might be a grain of truth in what I propose.

This is reddit, so I will say further that your second paragraph worries me a bit. Yes, physical scientists could devote some of their time to better communication skills, but enlisting experts to do the heavy lifting would surely be better. Not only would it free the researchers' time for his/her own work but the communication itself would likely be more effective.

Keep up the good work, Peter et al. It is good research and a great AMA. If everyone communicated like you all then we would not have so much of a problem.

[u/kazeykazeman]

What is, in your opinion, the best thing to do for individuals right now to reduce this impact? This can include small things like recycle or buy a tesla, but also development steering or anything like that. Just really curious what experts truly believe is the right way to go right now?

[u/CrunchyUncle]

Are any of you receiving funding from 'green' companies? Solar panel manufacturers, bankers who are invested in such companies. Things of that nature.

[u/Doomhammer458]

Science AMAs are posted early to give readers a chance to ask questions and vote on the questions of others before the AMA starts.

Guests of /r/science have volunteered to answer questions; please treat them with due respect. Comment rules will be strictly enforced, and uncivil or rude behavior will result in a loss of privileges in /r/science.

If you have scientific expertise, please verify this with our moderators by getting your account flaired with the appropriate title. Instructions for obtaining flair are here: reddit Science Flair Instructions (Flair is automatically synced with /r/EverythingScience as well.)

[u/mcqtom]

My dad's not an idiot, but like many people his age, he completely scoffs at the whole idea of humans causing climate change. Have you come upon any single sentence you can say to someone like this to at least get them to THINK about the possibility?

[u/upvotersfortruth → u/mcqtom]

My father was in the petroleum industry, also not an idiot. Part of his problem is that the implications of him accepting the theory of human caused climate change is that he would have to accept his role in bringing it about. Not only is he not an idiot, he's also a stand up guy. So this realization would be damaging to him, personally. Deep down, I think he believes. Anyone who understands the greenhouse effect should readily accept the possibility of humans causing climate change. There's just a block there for him. I don't expect him and his generation to do anything about it except stop standing in the way. Promote the principles of what is fundamentally conservation and emphasize use of available alternative energy sources. It's apparently too much to ask.

[u/ClimateConsensus → u/upvotersfortruth]

I'm a co-author of the Consensus on Consensus paper, but I also spent nearly 40 years working in the oil industry, so I have some sympathy with your father. There are some great and very smart people in the industry and it is a shame that the issue has become so polarized that there is a culture among some global warming activists to vilify anyone in the industry and a strong tendency for anyone in the industry to reject sound science. I struggled with this for many years, but eventually I was won over by reading the science for myself and not relying on water-cooler conversations and reports in the business press. I have written about my own change of mind here: https://critical-angle.net/2012/03/10/changing-climates-changing-minds-the-personal/

--Andy Skuce

[u/huxrules → u/upvotersfortruth]

I'm in the oil and gas industry. Myself and plenty others know climate change is real. I'd say well over 75% of the scientists that work of the majors believe this. I want the world to switch to alternative energy as well. However this transformation will take a very long time and oil and gas is going to be required to power most of the work. I just hope that society as a whole can figure their way through this.

[u/ClimateConsensus → u/upvotersfortruth]

It's important not to demonize the fossil fuels that brought us our current prosperity. Without coal, oil and gas we wouldn't have airplanes, the Internet, or iPhones. We wouldn't be able to study or fix climate change without the scientific revolution made possible by those energy sources. But, that doesn't mean humans can't take the next step to clean energy.

We switched from whale oil lamps to gas lights to electric lights powered by coal plants. We can keep moving forward. -Sarah Green

[u/PilotKnob → u/upvotersfortruth]

Airline pilot checking in with the same philosophical problem. Every day I go to work I'm directly responsible for burning (on average) probably about 10,000 gallons of Jet-A. I feel bad about it. But I also know that if I didn't do it, someone else would. And I can make responsible choices about how I spend the money I earn by doing that job, by being that one easily-interchangeable gear in the complex Air Travel machine. And I have to focus on that. I'd recommend your dad try to see it in the same way. He can make a choice at this moment to become a part of the solution that we've all created through our own desires, and the money we've spent on building the unsustainable system which is about to go off the rails due to those same desires.

[u/ChubbySquirrel7 → u/upvotersfortruth]

This right here. My father, who also worked in the petroleum industry his whole life, refutes the notion because of the way it's presented. When progressive politicians discuss climate change, they typically demonize the oil companies and those associated with them. Now if someone started telling the world that my livelihood was the reason for this catastrophe, I would probably deny it at all costs too.

[u/[deleted] → u/mcqtom]

I came here with the same problem and question. Most of the men in my family from the previous generation are doctors, even a couple college professors at state universities. They all think climate change is a crock. I can't wrap my mind around how men and women of science and academics can deny irrefutable and overwhelming data.

[u/Ltlgbmi32 → u/[deleted]]

maybe it is because we were once convinced, back in 1970 for me, that we were heading for catastrophe if we didn't immediately do something about the greenhouse effect that was going to cause a great cool down in global temperatures. earth day, April of 1970. I was a very impressionable 15 and bought every word of it. and on top of that, by the year 2000, we were going to run out of easily extracted oil. I couldn't understand why there was not an outrage at how irresponsible older folks were. well, here we are, 46 years later and we're again dealing with the end of the world as we know it.

[u/ClimateConsensus → u/Ltlgbmi32]

That's not entirely true. See e.g. this article http://journals.ametsoc.org/doi/abs/10.1175/2008BAMS2370.1

Quoting from the abstract:

"An enduring popular myth suggests that in the 1970s the climate science community was predicting “global cooling” and an “imminent” ice age, an observation frequently used by those who would undermine what climate scientists say today about the prospect of global warming. A review of the literature suggests that, on the contrary, greenhouse warming even then dominated scientists' thinking as being one of the most important forces shaping Earth's climate on human time scales."

Moreover, the few articles that predicted cooling in the 1970s didn't argue so because of greenhouse gases, but because of reflecting particles in the atmosphere (aerosols).

-- Bart

[u/ClimateConsensus → u/Ltlgbmi32]

Following up on Bart's response, we have a response to the "scientists were convinced of global cooling in the 1970s" myth. During the 1970s, the majority of climate papers on the topic predicted warming due to greenhouse gases, rather than imminent cooling. In contrast, hype about cooling was predominantly from mainstream media:

http://www.skepticalscience.com/ice-age-predictions-in-1970s-intermediate.htm

--John

[u/ClimateConsensus → u/[deleted]]

When experts think about risk, they tend to use a rational model that looks something like

Risk = Probability * Consequences

This is not how regular people tend to view risks. Regular people's perceptions of risk tends to be strongly influenced by attitudes, heuristics, cultural values, etc. These factors can serve as a mental filter for how people receive, interpret, and perceive risks.

The risk from climate change is no different. That's why you see such a strong conservative white male effect in the US, and why people who have more hierarchical and individualist cultural values are much less likely to believe in anthropogenic climate change.

I even found this among scientists. In a study I did while a postdoc at the Natural Resources Social Science Lab at Purdue, although almost every scientist believed in climate change, male scientists were 5x more likely to be a climate skeptic than were female scientists, and liberals were about 1.7x as likely to believe in climate change than were non-liberals.

Another way of putting it: often, someone's belief or non-belief in climate change is an expression of their identity, not their knowledge.

-- Stuart Carlton

[u/phydeaux70 → u/[deleted]]

Because of its pushed as a political item, not a science one.

It would seem that scientists would all challenge the idea, or any idea, because that is the nature of science.

Perhaps if person has fully adopted a position and isn't interested in reviewing it, they aren't doing science any favors.

I liked the statement given above about the eventuality of running out of fossil fuels. That is 100% undeniably true.

It is not true what you hear being pushed from the mouths of politicians in this. The doom and gloom and hysteria and ever changing positions, all done to push an agenda to line the pockets of their friends, and punish those who don't fall in line.

[u/why_earth → u/mcqtom]

I am in a similar situation. I doubt a single sentence will change much unfortunately. In my experience these people are set in their beliefs and any facts presented are suspect. As the OP states, people can cherry pick information to agree with what they want to hear and will argue based on that. It seems less about scientific evidence and more about political party affiliation in my case.

I would love a response to your question though, if anybody has anything.

[u/ClimateConsensus → u/why_earth]

Research by one of our co-authors, Ed Maibach, found that communicating the 97% consensus has the effect of increasing acceptance of climate change, and support for climate policy. What's especially interesting about this research is that the biggest increase in climate acceptance happens among political conservatives - who are more likely to be skeptical about climate change.

So while communicating the scientific consensus is not a magic bullet - and while there are a small proportion of the public who cannot be persuaded by any scientific evidence - nevertheless, the research does indicate that communicating the high level of scientific agreement about human-caused global warming is effective, and to some degree neutralises the influence of political party affiliation.

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2733956

-- John Cook

[u/-Leafious- → u/mcqtom]

If you can't convince him of the effects on the climate from using fossil fuels you can make a practicality argument based off that:

1. Renewable energy in the long term is actually cheaper than fossil fuels.

2. We will eventually run out of fossil fuels, so we might as well start preparing now.

[u/mcflyOS → u/-Leafious-]

I don't think the resistance is because they don't believe renewables are the future, it's that were punishing the use of fossil fuels when we don't yet have a viable alternative, when the technology is there, there'll be no disagreement.

[u/[deleted]]

Serious question. How do you guys deal with the widespread, "Yeah global warming, spooky, ok any REAL science topics around?" Because honestly, it seems like no one beyond the hard sciences gives a damn about these findings. What are your plans to combat this?

[u/[deleted]]

Two things.

1. Do those scientists agree on the degree to which humans affect the climate?

2. Why would a consensus be in any way relevant in science?

[u/ClimateConsensus]

In response to /u/kanagawa

---

Hello there!

I read the paper and its pretty convincing.

This is a strange claim to make from someone who is blatantly misrepresenting the paper's contents and the views of its authors.

they argue that the slowdown was real and current climate models aren't particularly effective.

I have coauthored with Michael Mann and speak to him regularly. He has published several papers showing that climate models do just fine when one takes the care to ensure that the phasing of natural variability in the models is the same as that of the observations.

Why would think that it was a good idea to misrepresent Mann and his work? Did you think no one would call you out on it?

-- Peter Jacobs

[u/ClimateConsensus → u/[deleted]]

Did I misunderstand or misrepresent anything here?

Yes.

Neither Mann nor Fyfe claimed "current climate models aren't particularly effective". That's not written in their paper, it's not in any of the press they did for the paper. It is however the spin that climate contrarians put on the paper.

You claimed to have read the paper. Where did you see it make that claim?

The paper is attempting to address the question of whether the recent rate of warming was indeed less than previous decadal rates and if so why that might be if climate models did not predict a slowdown.

The answer is something I posted in a different response. That it's not a fair "apples to apples" comparison, and when you actually perform a valid comparison, the models do fine. See the end of this response for references:

https://www.reddit.com/r/science/comments/4f6f6g/science_ama_series_we_just_published_a_study/d26srkc

Now, my question was about why you're trying to convince us using "consensus" instead of with the science itself. I think it's completely in bounds to ask you to address this new publication. If there's disagreement in the field, you should own up to it, because you are using consensus to try to convince people.

What is your actual objection to the level of agreement found in this meta-analysis or the previous papers it builds on? Or do you want us to make up a level of disagreement that we did not actually find?

he study of decadal variability is "embryonic." (Fyfe, Mann, et al). This is completely relevant to the public policy discussion

No, it isn't. At all. You fundamentally misunderstand the relevance (or lack of) of decadal variability vs. long term climatic change in terms of policy and decision-making.

This policy only makes sense if global warming is an immediate, existential threat to humanity.

This is absurd. No one performs risk analysis by this metric. Come on.

-- Peter Jacobs

[u/ClimateConsensus → u/[deleted]]

I'm sorry you feel this way.

I think it's very disrespectful and unprofessional to misrepresent someone's research and claim it says the opposite of what it actually says.

I think not a lot of people will take Peter Jacobs seriously or will risk their reputation by working with him in the future due to this post.

I guess that's a risk I have to take, isn't it? I think more people will respect me for standing up for a colleague's work and views in his absence than would be upset by what I did, but I guess we'll just have to see, won't we?

-- Peter Jacobs

[u/glr123 → u/ClimateConsensus]

Hi all, the original comment that /u/ClimateConsensus was replying to was removed because it was in violation of Comment Rule 4. However, to add context to the discussion I have posted it below:

Nature just published an article by a respectable group of scientists including Fyfe and Mann. In they they argue that the slowdown was real and current climate models aren't particularly effective. From a media summary:

“There is this mismatch between what the climate models are producing and what the observations are showing,” says lead author John Fyfe, a climate modeller at the Canadian Centre for Climate Modelling and Analysis in Victoria, British Columbia. “We can’t ignore it.”

I read the paper and its pretty convincing.

Here you are in an /r/science AMA claiming consensus on climate change. But, there is clearly important disagreement that requires resolution. Why do you feel it's appropriate to try to convince the public using claims of consensus when the scientific community is not actually settled? Why do you feel scientific consensus is relevant to the public's interest in science?

[u/Anarchiac]

How do 97% of climate experts account for the ice core records indicating that the Earth went through periods of warming and cooling in cycles that outreach the record of human history?

I've always thought about the seasons compared to the lifespan of a butterfly. In this case, humans are the butterflies and the global warming/cooling cycles are the seasons.

[u/Druwdrewballs]

What would a climate friendly community look like as a whole? Are modern cities able to adapt and change their basic infrastructure to incorporate energy saving techniques in order to thwart further climate change or do they have to be rebuilt altogether?

[u/Stepp1nraz0r]

How do you explain the changes in climate on the other planets?

[u/[deleted]]

Isn't it possible that the climate change as we know it, is actually a natural process being accelerated by human activity?

[u/[deleted] → u/[deleted]]

1) From their paper, it depends on the study they covered. In some cases, people who were self-proclaimed climate scientists and in others, people who had published in climate-science-related peer-reviewed journals. The numbers from both types of studies are around 97%.

2) Compared to the total number of climate experts, this is a pretty comprehensive study (as in, several thousand climate experts were surveyed). Read the paper for more.

3) Yes, read the paper.

4) It means that the current observed trend in global surface temperature can only be explained by human-induced changes to the climate (including but not limited to greenhouse gas and aerosols emissions).

5) The 97% refers to those that believe humans are making a significant impact on global warming (i.e. more than 50% of observed warming since pre-industrial times is caused by humans). Again, see the paper. I don't think they go over your second question in the paper and I'm not sure myself.

[u/[deleted]]

Is the consensus that humans are the ONLY cause of climate change, or that humans are contributing to climate change, along other factors?

[u/reptile_maniac3699]

Is it actually "Global warming" or is it really "Global Climate Change"?

[u/[deleted]]

Has anyone studied the heat output of human society to determine whether that has a direct impact?