A tropical Arctic?

A series of articles in this week's Nature shows one of the possible consequences of global warming: a tropical Arctic. Paleoclimate studies show that 55 million years ago, when the global climate was, on average, 6 degrees warmer than it is at present, the area that is now the ice-bound Arctic ocean basked in a balmy tropical climate similar to that of Florida. This is far greater warming than current climate models predict, and suggests that we're missing an important feedback mechanism which magnifies the effects of increased CO₂ concentration. Needless to say, this isn't good news. The IPCC is currently predicting a midrange figure of three degrees of warming by 2100, which as VUW geologist Peter Barret recently pointed out, is quite dangerous enough. But if we've missed something, then we may be in for a far warmer world than expected, with devastating consequences for both people and the environment.