Vaniver comments on Trusting Expert Consensus - Less Wrong

27 Post author: ChrisHallquist 16 October 2013 08:22PM

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Comment author: Vaniver 17 October 2013 04:14:25AM *  18 points [-]

I haven't spent as much time studying the global warming debate as I have studying the creation-evolution debate, but to the extent I have studied it, the evidence seems uniformly supportive of the view that human activity has caused significant warming.

I'll note that most of the resistance to global warming that I've seen on LW is not on these points. (Bias note: I think my position is roughly central of global warming resistance I've seen on LW, but if I err in describing opinion on LW it will be by pushing the opinion too far towards myself.) The evidence seems very solid that human activity has altered the atmospheric concentrations of CO2, and that this results in higher temperatures.

The primary issues are:

  • Predictive climate models are in a class of computational problems known to computational modeling experts to be extremely vulnerable to fudging. That is to say, by judicious choice of parameters, you can get the models to say basically whatever you'd like them to say, and the models make several assumptions which are obviously wrong which could totally nullify their predictive ability.
  • Climate science has incentives that seem unusually pointed away from truth-discovery compared to other fields, and there seems to be evidence of climate scientists (rationally!) responding to those incentives.
  • The question of which temperature / global climate is optimal is rarely discussed, suggesting that the current climate is unlikely to be optimal.
  • Specific solutions to the problems of climate change are generally seen as moral and political goals, rather than seeing the problem as an engineering challenge. Geoengineering techniques in particular receive a surprisingly small amount of research, in part because it is perceived as 'damaging the cause' by making emission reduction seem less necessary. (If emission reduction is less necessary...)
Comment author: ChrisHallquist 17 October 2013 05:21:31AM 2 points [-]

Upvoted. This is much better than other reactions I've seen to discussion of global warming on LW, which often amount to knee-jerk downvoting paired with comments that amount to "global warming is politics and politics is the mindkiller!"

That said, regarding what climate is optimal, that's not something that can be answered in isolation. Existing people and ecosystems are adapted to current conditions, so it isn't surprising that rapid change away from those conditions would cause problems, at least on net (and note that the IPCC doesn't claim effects of global warming will be universally negative, just negative on net). It's like how a flood is a bigger problem than water that's always been there. Same thing with sea levels rising - it means people need to move or build dikes or something, which is costly.

Comment author: roystgnr 17 October 2013 03:21:55PM 0 points [-]

The best reaction I've seen to discussion of global warming anywhere was on LW. Your post here is much better about specifically defining what the "expert consensus" says, but note that it's a bar so low that all the well-informed "skeptics"/"deniers" I've read would agree with the majority of AGW experts on the second bullet point.

Comment author: ChrisHallquist 17 October 2013 05:58:36PM 3 points [-]

I saw that thread too, and was horrified - horrified that people were downvoting Stuart. And actually, on reflection, that that comment was upvoted is pretty horrifying too. The comment claims ambiguity in Stuart's post when there is none: it brings up value judgments and policy and so on when Stuart was very specific that he was talking about denial of the very existence of AGW, rather than about disagreements on appropriate policy responses. That tells me the commenter - and everyone who voted it up - was emotionally uncomfortable with the idea that AGW delialists were just completely wrong, so they read ambiguity into Stuart's statement that wasn't there.

Comment author: Vaniver 17 October 2013 10:55:31PM 5 points [-]

I saw that thread too, and was horrified - horrified that people were downvoting Stuart. And actually, on reflection, that that comment was upvoted is pretty horrifying too. The comment claims ambiguity in Stuart's post when there is none

Strong disagreement. Stuart_Armstrong uses interchangeably the phrases "global warming denial," "someone who denies the existence of anthropogenic global warming (AGW)," and "global warming skeptic." There is significant ambiguity there- many people identify as "global warming skeptics" in that they are skeptical of the moral and political claims of the global warming movement, not that they deny the existence of AGW. Similarly, many people identify as "global warming deniers" because they deny the moral, predictive, or prescriptive claims put forward by the global warming movement.

(Note that Thomas, who did express doubt in AGW, got downvoted to -3.)

when Stuart was very specific that he was talking about denial of the very existence of AGW, rather than about disagreements on appropriate policy responses.

I didn't see any effort on Stuart_Armstrong's part to disambiguate those or notice that he needed to. For example, in your post, it looked like you carefully limited the consensus to the actual scientific consensus on historical anthropogenic climate change, and if Stuart_Armstrong had mentioned that he was just talking about the historical record, there wouldn't have been a need for steven0461's comment.

Note this subthread in particular.

Comment author: buybuydandavis 26 October 2013 10:12:13AM *  5 points [-]

There is significant ambiguity there- many people identify as "global warming skeptics" in that they are skeptical of the moral and political claims of the global warming movement, not that they deny the existence of AGW.

I'm not skeptical of CO2 as a greenhouse gas, or of the increase of atmospheric CO2, or that increasing CO2 levels will generally lead to higher temperatures, or that we have had higher temperatures in the last few decades.

But I am skeptical of the model projections into the future, and even more skeptical of the claims that the accuracy of those models have been established when they've proven inaccurate for the last decade. When you make predictions that fail, you should be decreasing your certainty in the model that gave those predictions.

Comment author: Vaniver 27 October 2013 07:39:24PM 0 points [-]

I put "predictive or prescriptive claims" into my second bit, but I probably should have included it there as well.

Comment author: ChrisHallquist 18 October 2013 12:08:49AM 0 points [-]

if Stuart_Armstrong had mentioned that he was just talking about the historical record, there wouldn't have been a need for steven0461's comment

That demands seems a little strange. Should he have disclaimed any claim about future warming? But given past warming caused by human CO2 (and other) emissions, we should expect more warming if we continue that activity (actually, the IPCC thinks warming would continue even if CO2 were kept at current levels).

On the other hand, I'm not seeing any way to read Stuart's statement as anything like, "if your estimate of future warming is only 50% of the estimate I prefer you're irrational."

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