Stubborn ice

Some glaciers, it turns out, are growing, not shrinking. There's a lesson here, about jumping to over-simplified conclusions.

Up on the roof of the world, where China and India and Pakistan meet, something strange is happening to the glaciers: they're growing.

Between 1999 and 2008, French scientists measured the 20,000 sq kilometres of glaciers in the western Karakorum mountains. Their findings, published this week in the journal Nature Geoscience, were unexpected after all the climate warnings of recent years: more than half the glaciers are stable or have gained, on average, 11 cm per year. Temperatures in valleys below the ice are falling.

In fact there is no clear contradiction: it's a big planet with a complicated climate. Lead scientist Julie Gardelle of the University of Grenoble, France, noted that "anomalous" localised expansion of some glaciers is to be expected. In the eastern and central Himalayas, meanwhile, many glaciers are undeniably shrinking.

If there is no clear lesson here about global warming, there is certainly one about politico-scientific oversimplification. It was after all just five years ago that the Intergovernmental Panel on Climate Change claimed that all Himalayan glaciers would be utterly gone by 2035. There is still an awful lot that we don't know about climate and how it changes.