How fast are glaciers in the Himalyas disappearing? This is suddenly a hugely contentious issue. For years, there's been this estimate floating around that glaciers in the region could vanish as early as 2035 if current warming trends continue. Suffice to say, that would be bad news, given that the glaciers help regulate the water supply for rivers in India and China. Anyway, that 2035 figure snuck into the IPCC's 2007 report. And it's been repeated by a number of journalists—including me.
But it turns out there's no solid basis for saying Himalyas's glaciers will vanish by 2035. They may be melting quickly, but many of those glaciers are hundreds of feet thick and could take centuries to vanish. So where did 2035 come from? As New Scientist's Fred Pearce reports, this number has an iffy origin—namely, Fred Pearce. Back in 1999, he was reporting a story and asked an Indian glaciologist, Syed Hasnain, about the glaciers. Hasnain suggested by e-mail they could disappear by 2035. Later, the World Wildlife Foundation wrote a report about India's glaciers that cited Pearce's article. And then the IPCC ended up citing the WWF report. But the 2035 figure was never published in a peer-reviewed journal. It was just a guess. Even Hasnain agrees the figure should've never been cited.
In any case, the IPCC is now going to re-examine the Himalayan glacier question. It's an embarrassing lapse. I'm guessing the figure wasn't caught earlier because the line only appeared once in the IPCC's report, on page 493 of chapter ten of the second volume—and it wasn't included in any of the technical summaries or the synthesis report, which were far more widely read and debated. Still, it goes without saying that the IPCC should only rely on peer-reviewed science, not poorly sourced WWF reports.
Sadly, this doesn't mean everything's fine with the glaciers. A 2008 paper published in Geophysical Research Letters found, for instance, that the Himalayan region seems to be warming about twice as fast as the global average, and its glaciers are still retreating at an alarming rate, with implications for the water supply. (More recent studies have suggested that soot pollution from India may be making the melt even worse.) But that 2035 date needs to be scrapped—which, for a lot of reasons, counts as a small relief.
(Flickr photo credit: kevkerkev)