An inconvenient lack of footnotes

During Seattle’s recent mini-heat wave, my wife Lisa and I decided to hide out in an air-conditioned movie theater. One of the films we saw was the Al Gore global-warming movie, An Inconvenient Truth. We both agreed it was one of the most slicky produced campaign ads we’d ever seen.

I was less impressed by the environmental message. Although Gore makes a superficially compelling case, his presentation raised a number of red flags as well.

An example of the kind of thing that bugged me: one of the nastier potential consequences of global warming is that it could melt the Greenland ice cap, which would raise sea level by around 20 feet. Gore uses computer-generated maps to show how this would put large portions of Florida, the Netherlands, the San Francisco Bay area, the Yangtze River Valley, and Manhattan underwater. Then he asks the audience to imagine the hundreds of millions of people currently living in those regions being turned into “refugees.”

Scary, if true: it’s the Hurricane Katrina disaster, multiplied a thousandfold. Still, I couldn’t help noticing that Gore didn’t provide a timetable for when the flood waters were likely to arrive. Gore does give dates for some other global-warming related disasters—like the complete disappearance of the Arctic ice cap in summer, slated to happen as early as 2050—and the clear implication is that the drowning of Manhattan will happen Very Soon, too. But he doesn’t actually say that.

So when we got home from the theater, I went on Google and found this report, which suggests that the complete melting of Greenland’s ice sheet would take between 500 and 1000 years. In the nearer term, the UN’s Intergovernmental Panel on Climate Change predicts that over the next century, sea level will rise, not 20 feet, but somewhere between 4 and 30 inches, with runoff from the Greenland ice sheet contributing, at most, 3½ inches.

Of course even a 30-inch rise in sea level would cause big problems. But it’s nowhere near as bad as 20 feet—it wouldn’t create all those refugees, and it wouldn’t allow Gore to evoke, as he does, the image of the World Trade Center Memorial being underwater. Likewise, telling people that the worst effects of global warming won’t be felt for centuries would undermine the sense of urgency he’s trying to instill.

I had some other questions, so I decided to visit Gore’s website to take a closer look at his evidence. But when I went to the section of the site marked The Science, all I found was a brief recap of the claims made in the film, with no links or citations to the supporting data. Next I checked Gore’s book. It was only a little better: although most of the charts and graphs do have captions listing sources, the text is unfootnoted, and the references often so vague—”Scientists now believe…,” “Two recent studies confirm…”–that it would be difficult if not impossible to verify the cites.

This combination of exaggeration and poor documentation seems like a really bad strategy to me. It creates a ready weapon for skeptics, who will rightly ask why you are shading the truth you claim to love, and it also sets you up for a backlash when the promised apocalypse doesn’t materialize (a thousand Tuesdays have come and gone since I first saw Soylent Green, and I haven’t had to resort to cannibalism even once yet).

P.S. We also saw The Da Vinci Code. I agree with the critics who found it mediocre, but still enjoyed it more than X-Men 3 (not that that’s a hard film to top). It also reminded me of a really good story in the same genre that didn’t enjoy a fraction of D. V. Code‘s success: Wilton Barnhardt’s 1993 novel Gospel (currently out of print, but findable in Amazon’s used book section). No albino monk in that one, but it’s a great read, definitely worth the trouble of tracking down.