How fast is Arctic sea ice disappearing? | Brussels Blog

How fast is Arctic sea ice disappearing?

posted by Geoff on 30th Jul 2010
30th,Jul

Do individual scientists and government advisers take climate change seriously or extremely seriously? Arctic sea ice is one touchstone that can help. Who thinks its disappearance is fast? Who thinks its disappearance is super-fast?

In 2007, the summer extent of Arctic sea ice reached its lowest since satellite records began, significantly lower than previous years. Some interpreted this loss as a significant change in the speed with which sea ice is being lost. Senior Scientist Mark Serreze at the The Snow and Ice Data Centre said at the time, “The sea ice cover is in a downward spiral and may have passed the point of no return. As the years go by, we are losing more and more ice in summer, and growing back less and less ice in winter. We may well see an ice-free Arctic Ocean in summer within our lifetimes.”

In the subsequent years, 2008 and 2009, the summer extent of the sea ice was higher than the 2007 minimum. This led some scientists to criticise exaggerated claims. A Times piece quoted Vicky Pope, head of climate change advice at the Met Office as saying

“It isn’t helpful to anybody to exaggerate the situation. It’s scary enough as it is. The problem with saying that we’ve reached a tipping point is that when the extent starts to increase again — as it has — the sceptics will come along and say, ‘Well, it’s stopped’.”

Professor Myles Allen, head of the Climate Dynamics Group at Oxford, was also quoted: “Some claims that were made about the ice anomaly were misleading. A lot of people said this is the beginning of the end of Arctic ice, and of course it recovered the following year and everybody looked a bit silly.”

Peter Wadhams, Professor of Ocean Physics at Cambridge, says differently “The case of Arctic ice is somewhat of a tipping point since the open water created during summer warms up, to about 5ºC at present, and this slows down the subsequent autumn freeze up, giving less winter growth. It may grow back a little in a cold winter but in my view it can never get back to its original situation of, say, 40 years ago.”

But the extent of Arctic Ice is not the touchstone we choose here. The volume of ice is a better indicator than the extent of ice. While the ice extent did recover somewhat in 2008 and 2009 from the low in 2007, the ice volume continued to fall. David Barber’s talk at the recent Oslo Science Conference described not just the change in the thickness of Arctic sea ice but also its deteriorating quality. The ice is getting crumbly and full of holes.

Vicky Pope and Myles Allen are serious people but will they be the ones that look silly?

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