Friday, April 25, 2014

How Guy McPherson gets it wrong

How Guy McPherson gets it wrong
SCOTT K. JOHNSON, 02/17/2014

Recently, a few Ars Technica commenters have been posting references to the work of Guy McPherson on climate articles. McPherson is a retired professor of ecology at the University of Arizona, and he runs a blog called Nature Bats Last. In recent years, he has turned his energies to dire warnings of impending climate catastrophe. Those warnings go far beyond what you’ll find anywhere else: McPherson believes humans will go extinct in as little as two decades.

Now, lots of people run blogs that make wild claims, so why am I spending time on this one? McPherson claims to simply be passing along scientific data to the public— data that most scientists are unwilling to talk about and governments are trying to keep secret. As a result, his followers (I mean to use that term more in the Twitter sense than a religious one) seem confident that they have the weight of science behind them. It takes careful examination of McPherson’s references, and a familiarity with the present state of climate science, to uncover that his claims aren’t scientific at all. I also get the feeling that his internet following might not be insignificant (as noted by climate scientist Michael Tobis) and could be growing, yet I couldn’t find any direct challenges with a web search. This makes one.

Bizarro denial

First, I want to go over general problems with McPherson’s claims and talk about what climate science is really telling us. For those wanting specifics, I’ll post a list of point-by-point corrections of McPherson’s main “Climate Change Summary and Update” post in the third section.

In many ways, McPherson is a photo-negative of the self-proclaimed “climate skeptics” who reject the conclusions of climate science. He may be advocating the opposite conclusion, but he argues his case in the same way. The skeptics often quote snippets of science that, on full examination, doesn’t actually support their claims, and this is McPherson’s modus operandi. The skeptics dismiss science they don’t like by saying that climate researchers lie to keep the grant money coming; McPherson dismisses inconvenient science by claiming that scientists are downplaying risks because they’re too cowardly to speak the truth and flout our corporate overlords. Both malign the IPCC as “political” and therefore not objective. And both will cite nearly any claim that supports their views, regardless of source— putting evidence-free opinions on par with scientific research. (In one example I can’t help but highlight, McPherson cites a survivalist blog warning that Earth’s atmosphere is running out of oxygen.)

McPherson bills himself as a scientist simply passing along the science (even as he dismisses climate scientists and their work), but he cites nearly as many blog posts and newspaper columns as published studies. When he does cite a study, it’s often clear that he hasn’t taken the time to actually read it, depending instead on a news story about it. He frequently gets the information from the study completely wrong, which is a difficult thing for most readers to check given that most papers are behind paywalls (not to mention that scientific papers aren’t easy to understand).

McPherson leans heavily on claims from people associated with the “Arctic News” blog about a catastrophic, runaway release of methane that supposedly is already underway in the Arctic. Unfortunately (or, rather, fortunately), the data don’t match their assertions. The latest IPCC and NAS assessment reports, in fact, deemed such a release “very unlikely” this century. One reason for that is that the Arctic has been this warm or warmer a couple times in the last 200,000 years, yet that methane stayed in the ground. Another reason is that scientists actually bother to study and model the processes involved. One thing McPherson and others like to point to is the recent work by Natalia Shakhova’s group observing bubbling plumes of methane coming up from the seafloor on the Siberian Shelf. Since we’ve only been sampling these plumes for a few years, we have no idea whether that release of methane is increasing or if these are long-term features. Similar plumes off Svalbard, for example, appear to be thousands of years old. (More to put this methane in context here.)

That’s exactly the kind of detail and nuance that’s absent from McPherson’s claims. Instead, he’s content to link to YouTube videos or blog posts (some ludicrously unscientific— see below) and run with the idea that catastrophic warming is guaranteed as a result. He just latches onto anything that sounds scary. McPherson is especially fast and loose with timeframes. He likes to point to the magnitude of past climate changes (which took thousands of years or more) as proof that we are about to undergo similar changes in the next couple decades. That’s quite clearly a fallacious argument, but McPherson never concerns himself with the details. All the casual reader learns it that there was a huge change in the past analogous to the present that shows just how screwed we really are.

And that’s McPherson’s thing— despair. We’re absolutely doomed, he tells us, and there’s nothing we can do about it. Everything is lost. He derides any sort of optimism or action as “hopium”. He notes in one recent post that “With an eye to improving my ‘bedside manner’ when I deliver presentations, I’ve recently become a certified grief-recovery counselor.” With such an extraordinary view, you would expect him to make the scientific case for extinction very clearly. But he does not. His argument fundamentally reduces to “positive feedbacks exist, ergo extinction”. That is, he lists examples of positive feedbacks (things that amplify change, like the added sunlight absorption of ocean water that has lost its sea ice cover) for a while, intending to overwhelm you with the number of processes that could add to global warming. And that’s it. There are no numbers explaining how big an effect each could have, no analysis of likely warming impacts, nothing. The fact is that climate scientists know about all these processes. But instead of throwing their hands up and saying “Oh, shit”, they actually do science.

Again, specific examples of these things are given in the last section of this post. If you take a look at some of his mistakes and demonstrably false claims, you’ll have a hard time thinking of him as a credible source of information.

[Update 3-13-14: Michael Tobis has covered some of the points I skipped over—namely, McPherson's discussion of feedbacks— in a new post.]

This is just an excerpt of SJ's article. Read more here
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