For some time climate change scientists have been predicting that warming should accelerate in the arctic, rising faster than the global mean increase in temperatures. The reason? Warmer temperatures in the arctic mean the formation of less seasonal winter ice, as well as the loss of permanent ice to melt. More of the ocean’s surface is thus exposed to solar radiation, and will warm up. That heat will be released back into the atmosphere when winter approaches, delaying the drop in air temperatures and seasonal winter ice formation. And so it goes, in a feedback loop of enormous consequences not only for the arctic but for climate in the Northern hemisphere more generally.
New research confirms the existence of this effect. A study by Julienne Stroeve of the US National Snow and Ice Data Center measured Arctic autumn (September, October, November) air temperatures for the period 2004-2008 and compared them to the long term average (1979 to 2008).
“You see this large warming over the Arctic ocean of around 3C in these last four years compared to the long-term mean,” explained Dr Stroeve.
“You see some smaller areas where you have temperature warming of maybe 5C; and this warming is directly located over those areas where we’ve lost all the ice.”
This will place even more urgency on the political process in the lead up to the Copenhagen summit later this year. It also raises the larger question of whether any emissions reductions targets agreed to at Copehagen will be sufficient for meaningful climate change mitigation. Climate change is now moving faster than most models predicted (even the worst-case models) and evidence of runaway climate change is mounting. Copenhagen must act on mitigation, but equaly it must act on adaptation, because it is clear that climate change impacts will be happening sooner, and on a greater scale, than initially anticipated.