Just because it's conventional wisdom, doesn't mean it's wrong

When I was in law school, it was very common for professors to begin a classroom discussion of some theoretical topic or another by saying: “The conventional wisdom is….”  This was always a sure sign that, whatever the conventional wisdom, the professor was about to disagree with it.  Don’t get me wrong, they weren’t setting up straw men, there really was a conventional wisdom.  But they never agreed with it.

Setting out to takedown consensus opinion is a very natural inclination for an academic.  Professors are far more apt to get attention, get published, and get tenure by coming up with a clever argument that set expectations on their head.  The same is true of journalists.

As sure as the changing of the seasons, you can bet that once a narrative establishes itself in the public’s mind there will be a journalistic propensity to write stories about why it’s wrong, often regardless of the evidence.  Indeed, some publications are so well known for such “counterintuitive journalism,” that it’s become something of a running joke.

All of which brings me to Andrew Revkin’s most recent piece on polar bears in DotEarth.  It’s pretty much conventional wisdom now that polar bears are in serious danger of extinction from global warming.  So, right on cue, DotEarth has a piece up discussing the bits of evidence that could run counter to this assumption.  The problem is, though, that there’s just not that much evidence to be found.  Essentially, Revkin points to three things:

  • A jawbone discovered a couple of years ago that may indicate that polar bears lived in the Arctic during the Eemian interglacial period, which was significantly warmer than today.  As I noted at the time the jawbone was first reported, however, the problem with reading to much into this discovery is the fact (which, in fairness, Revkin notes) that current models predict Arctic temperatures significantly above temperatures reached during the Eemian.
  • A study by scientists at the Museum of Natural History that report observations of western Hudson Bay polar bears eating goose eggs and speculates that the eggs could provide a substitute source of food for polar bears forced to spend longer and longer periods on land.  While this finding is interesting, I know of no polar bear biologists who believe that bears can survive in habitat completely free of summer sea ice.  And current models predict that the Arctic is on track to be completely ice free by 2040—perhaps much sooner.
  • And finally, the most questionable evidence of all: a critique of global warming models used to justify the polar bear listing, written by J. Scott Armstrong, a professor of marketing at the Wharton School.  The critique, which as been loudly trumpeted by global-warming skeptics has a number of flaws, not least of which is the fact that the methods it draws on (used primarily in economic forecasting) are simply inappropriate in the context of environmental protection.  For example, one of the paper’s central points is that the polar bear population models are not sufficiently “conservative.”  Armstrong et al. says that “[b]eing conservative means moving forecasts towards ‘no change’ in the face of long-term and uncertain trends.”  Yet in the environmental context (particularly when we’re talking about extinction) being conservative should mean exactly the opposite.  In the face of uncertainty, we should err on the side of avoiding irreversible damage to the natural world

Is the goose egg study wrong? I don’t know.  But it should take more than that to overturn conventional wisdom, no matter how tempting it may be.