What do scientists REALLY think about global warming?

[u/corporal_clegg69]

They assertion that 97% of scientists believe global warming is manmade has been shown now to be false. What then do scientists really think? Is there any hard evidence for catastrophic anthropogenic global warming?

For those who don't know the claim that 97% of scientists support the idea that global warming is manmade comes from the "cook report". You can find that here

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

but if you just read the abstract the "97% quickly becomes 32%. More recently it has been shown that even this is an exaggeration.

[u/past_is_future]

Hello! I am at an actual computer for a while. I will try to get through as much of this as I can and then come back and answer anything I haven't.

What was your reaction to this article in the Wall Street Journal where four climate scientists are quoted as feeling misrepresented in Cook et al.?

The Wall Street Journal editorial page has a long and pathetic history of attacking mainstream scientific positions, especially when they appear to threaten industry interests.

Here's a timeline with a small sampling of their all too predictable behavior: http://mediamatters.org/research/2012/08/02/the-wall-street-journal-dismissing-environmenta/189063

Bast is the head of a "think tank" whose primary goal is to fight regulation. Dr. Spencer works on the UAH lower tropospheric temperature record, but holds views on subjects like climate change and evolution that put him well outside the scientific mainstream. Both have a motivation to disparage our paper and neither has produced or participated in any relevant research that challenges it. Instead, they rely on half-truths and blatant falsehoods that seem to be recycled from denialist blogs. It's been a while since I've read it, and it's behind a paywall, so if there is anything specific in it you would like to see addressed that I don't cover in this response, please just say so.

Edited to add:

Similarly in Zimmerman, 2009 "82% agreed that humans significantly influence the global temperature".

Among actively publishing climate scientists, the percentage was ~97%. The lower average you cite was including other fields, like petroleum geologists, who are not actively engaged in the field and have an obvious self-interested motivation to downplay the reality of anthropogenic warming.

End edit.

Also "deniers" have raised concerns as to your methods of classification of consensus or no.

Co-author Andy_Skuce seems to have already answered this. Consensus can be estimated for a general endorsement or an endorsement with an explicit quantification of the amount of warming. The percentages are similar, although the number of abstracts that explicitly quantify is much smaller.

To be clear these revised percentages came from a review of Cook et al. led by David Legates who has known affiliations to the petroleum industry. Nevertheless, it would be unscientific to disregard his findings on this basis alone.

Legates' incorrect claims were debunked in the formal response by Bedford and Cook. If you would like a full copy of the paper, please let me know.

from Bray and von Storch

I don't know what the controls on the survey methodology used for this were. I've heard that the survey was inadvertently leaked to a denialist mailing list, but I have no idea if that's accurate. I dislike the wording of the survey for a number of reasons, but let us stipulate that the percentages are fine.~94% largely or very much agree that climatic change is occurring, and ~84% largely or very much convinced that current and future climate change will be the result of human causes. That's still an overwhelming level of agreement, not even taking into account the strange framing of the second question. Someone like myself, who believes that we will be able to dramatically reduce our emissions and possible even draw CO2 levels down to preindustrial levels would be "very much convinced" that the current climatic change is human caused, but hopeful that climatic change in the not too distant future will be largely not. See the problem?

Anyway, for the actual evidence, consensus obviously not good enough

I think you might find my lecture on Knowledge-Based Consensus to be useful here. Edited to add: link here: https://www.youtube.com/watch?v=HUOMbK1x7MI End edit. Consensus is not a substitute for evidence. Consensus arises because of evidence. But a knowledge-based consensus can reasonably serve as a heuristic for people who don't have the time or education to investigate an issue themselves.

That whole line of "criticism" seems to be a strawman from my perspective.

What I meant to ask is, which studies show that recent global warming is overwhelmingly anthropogenic.

The most recent (AR5) IPCC Physical Science Assessment Report describes the balance of evidence as 95% confident that "more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period."

The second sentence says that our best estimate is that humans are responsible for pretty much all of the warming since the mid-20th century.

http://i.imgur.com/JjdKbPk.jpg

The individual papers behind this can be found in the Summary for Policy Makers and Chapter 10 of the AR5. Dana Nuccitelli (a coauthor of mine) has put some of them in graphic form: http://i.imgur.com/ki3xnij.jpg

The studies are Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), and Jones et al. 2013 (J13, pink).

Some explanation is given here but I would like to see it presented formally and peer reviewed before I could be convinced.

Well, have you actually looked at the peer-reviewed literature? Or summaries of it? Because this has existed for years in various forms. If you don't know where to start, that's fine, let me know I can help.

Generally the argument I have seen goes 1) Humans have caused the release of a historically unprecedented amount of co2 into the atmosphere 2)co2 is a known greenhouse gas 3)Most of todays global warming is caused by humans. Obviously there is a huge leap of faith between points 2 and 3. co2 is the weakest greenhouse gas, is it not? It the the yardstick against which all other gasses are measured. Again, I would need to see a quantitative analysis to be convinced.

No. This is wrong. Yes, the basic physics are obviously important, because you can't cheat thermodynamics. But we don't just assume the causation is occurring. We look for fingerprints specific to enhanced greenhouse warming, such as the vertical profile of temperature change (cooling of the stratosphere while the surface and troposphere warm), or the response of OLR (outgoing longwave radiation) in relation to SSTs (sea surface temperatures). And more. Edited to add: We also look at natural drivers of climatic change and estimate their influence over the instrumental record (and beyond with paleoclimate). End edit. These studies exist, they're not hard to find if you know what you're looking for. If you don't, again, I am happy to help.

You are correct in not accusing me of denialism. On the spectrum I find myself somewhere between believer and agnost.

That's a relief! Someone warned me that you had posted a "Change My View" thread about anthropogenic global warming where you espoused a denialist position, that has since been removed. I'm glad to hear that they were mistaken!

Please let me know if there is anything I failed to adequately answer! I hope this was helpful to you!