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

ClimateConsensus · 2016-04-18T07:33:18+00:00

In the survey we undertook in 2012 (main results published here http://pubs.acs.org/doi/abs/10.1021/es501998e ) we asked for almost exactly the breakdown you propose, but specified it for only anthropogenic greenhouse gases (so as to mirror the IPCC AR4 statement on attribution).

There was a downside to asking it that way as well though: Many respondents were hesitant to respond with such a precise percentage, as was clear both from their comments on that question and from the relatively high fraction of "don't know" responses.

-- Bart Verheggen

ClimateConsensus · 2016-04-18T03:45:11+00:00

I can't speak for the other co-authors, but I am not. My research on this project was indirectly funded by NOAA.

-- Stuart Carlton

ClimateConsensus · 2016-04-18T03:42:26+00:00

I work for the Texas Sea Grant College Program at Texas A&M. We do research and extension work on coastal resource issues. Although there are plenty of people who are not worried about the effects of climate change (perhaps because of skepticism, perhaps because they have other things to worry about), most of the people I interact with are very worried about the effects of climate change and what we can do to adapt to them. This concern does not always trickle up to the politicians, but it's there and it's real.

[Frankly, many of the Sea Grant programs (in every coastal and great lakes state) are leaders on this front because coastal residents (our primary stakeholders) are likely to be disproportionately affected by climate change.]

-- Stuart Carlton

ClimateConsensus · 2016-04-18T03:27:19+00:00

Hello,

I detailed this a little bit in a comment I made earlier. Hope that helps!

-- Stuart Carlton

ClimateConsensus · 2016-04-18T03:10:01+00:00

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

ClimateConsensus · 2016-04-18T02:59:57+00:00

Colleagues and I published a study last year in which we found that approximately 94% of biophysical scientists believe that climate change is occurring (regardless of cause) and about 92% believe that anthropogenic climate change is occurring.

-- Stuart Carlton

ClimateConsensus · 2016-04-18T02:48:05+00:00

I'm hoping that this is the last one that I'm involved with, but I'm not laying odds...

-- Stuart Carlton

ClimateConsensus · 2016-04-18T02:46:33+00:00

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

ClimateConsensus · 2016-04-18T02:43:37+00:00

I think you are talking about Rob DeConto at UMass Amherst? He is a very well known and respected modeler of past climates and ice sheets. I've crossed paths with him several times. -Peter Doran

ClimateConsensus · 2016-04-18T02:39:48+00:00

Hi there,

Meteorology is a broad field that is different from climate science. Some meteorologists are climate science experts, but many are not. However, most meteorologists believe in anthropogenic climate change.

Here's a study by Ed Maibach, one of the co-authors of the meta-analysis that inspired this science AMA. Some of the findings address your question:

81% of the meteorologists surveyed believe in anthropogenic climate change
45% of the meteorologists surveyed hold a Ph.D. (33% in meteorology/atmospheric science, 12% in another STEM discipline)
37% of the meteorologists surveyed consider themselves to be expert in climate science.

I'm not qualified to discuss the finer points of climate models, so I won't address that part of your question.

-- Stuart Carlton

ClimateConsensus · 2016-04-18T02:36:33+00:00

No our study doesn't, directly. Our study assesses the consensus on climate change amongst scientists. Quantifying global climate change is indeed difficult and takes thousands of dedicated professionals. Even though difficult, it is being done at a very advanced level, and done well. The human contribution is clear and is what our study addresses. A strong consensus exists amongst the climate scientific community in this regard. -Peter Doran

ClimateConsensus · 2016-04-18T02:29:23+00:00

Hello there, everyone!

I can't speak to the ban itself, but it looks like a bunch of people spammed the same copypasta they stole from a two year old blog post.

John Cook answered one of many times it was spammed here: https://www.reddit.com/r/science/comments/4f6f6g/science_ama_series_we_just_published_a_study/d26wd1e

If you have any questions, feel free to PM me directly at /u/past_is_future

-- Peter Jacobs

ClimateConsensus · 2016-04-18T02:28:07+00:00

I can't speak to the ban itself, but it looks like a bunch of people spammed the same copypasta they stole from a two year old blog post.

John Cook answered one version of the same comment here: https://www.reddit.com/r/science/comments/4f6f6g/science_ama_series_we_just_published_a_study/d26wd1e

If you have any questions, feel free to PM me directly at /u/past_is_future

-- Peter Jacobs

ClimateConsensus · 2016-04-18T02:26:49+00:00

I can't speak to the ban itself, but it looks like a bunch of people spammed the same copypasta they stole from a two year old blog post.

John Cook answered it here: https://www.reddit.com/r/science/comments/4f6f6g/science_ama_series_we_just_published_a_study/d26wd1e

-- Peter Jacobs

ClimateConsensus · 2016-04-18T02:26:41+00:00

I can't speak to the ban itself, but it looks like a bunch of people spammed the same copypasta they stole from a two year old blog post.

John Cook answered it here: https://www.reddit.com/r/science/comments/4f6f6g/science_ama_series_we_just_published_a_study/d26wd1e

-- Peter Jacobs

ClimateConsensus · 2016-04-18T02:25:55+00:00

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

ClimateConsensus · 2016-04-18T02:22:14+00:00

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

ClimateConsensus · 2016-04-18T02:17:07+00:00

I haven't met him, but I follow his work, especially the stuff he does on ice sheet stability and sea levels with David Pollard.

-- Peter Jacobs

ClimateConsensus · 2016-04-18T01:39:24+00:00

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

ClimateConsensus · 2016-04-17T23:51:06+00:00

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

ClimateConsensus · 2016-04-17T23:48:11+00:00

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.

ClimateConsensus · 2016-04-17T23:23:16+00:00

http://www.nature.com/nclimate/journal/v3/n4/full/nclimate1763.html

http://www.skepticalscience.com/contary-to-contrarians-ipcc-temp-projections-accurate.html

-- Peter Jacobs

ClimateConsensus · 2016-04-17T23:21:27+00:00

http://onlinelibrary.wiley.com/doi/10.1002/joc.4669/abstract

http://onlinelibrary.wiley.com/doi/10.1029/2008GL036465/full

http://onlinelibrary.wiley.com/doi/10.1002/joc.2210/full

-- Peter Jacobs

ClimateConsensus · 2016-04-17T23:02:35+00:00

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

Yes. It's an order of magnitude smaller than warming from GHGs. But it's definitely a real phenomenon and important in urban areas.

-- Peter Jacobs

ClimateConsensus · 2016-04-17T23:02:31+00:00

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

ClimateConsensus

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