August 28, 2012

expert reaction to the lowest Arctic sea ice level on record, as announced by the National Snow and Ice Data Center (NSIDC)

The NSIDC in Colorado reported that the Arctic sea ice extent was at its lowest level since satellite measurements began in 1979, breaking the previous record set on 18 September 2007.

Prof Peter Wadhams, Professor of Ocean Physics at Cambridge University, said:

“For 40 years I have been measuring sea ice thickness in the Arctic from UK submarines. I first detected substantial thinning in 1990, and since the most recent submarine voyage in 2007 I have been warning that the combination of sea ice retreat and a massive amount of thinning will lead to the disappearance of the summer sea ice by as early as 2015.

“Despite the fact that this is a simple extrapolation of a clear and measured trend I have been vilified by scientific colleagues for making such a seemingly alarmist prediction. I am pleased to see that these same colleagues now support this prediction.

“What is happening is that the Arctic is warming up 3-4 times as fast as the rest of the world. The sea ice grows less thick in winter, and melts more in summer, such that the entire ice cover is now on the point of collapse. The extra open water already created by the retreating ice allows bigger waves to be generated by storms, which are sweeping away the surviving ice. It is truly the case that it will be all gone by 2015.

“The consequences are enormous and represent a huge boost to global warming from two sources: the reduction in global albedo caused by the replacement of ice by open water, and an acceleration of methane release into the atmosphere as the warm open water causes seabed permafrost to melt. A third, indirect effect is that the retreat of sea ice from around Greenland gives a warmer air flow over the ice cap and a faster summer melt, increasing Greenland’s contribution to global sea level rise.

“What can we do about it? The best thing, and only answer in the long term, is to cut down our carbon emissions and replace fossil fuels by nuclear power (thorium for safety) and renewables. But the human race is not doing that. So what else can we do? A sticking plaster solution is geoengineering, with techniques proposed such as whitening low-level clouds by injecting very fine sprays of water particles into them (proposed by Prof Salter, Edinburgh University). This and other possible techniques must be investigated with the utmost urgency.”

Prof Jeff Kargel, glaciologist at the University of Arizona, said:

“This latest dramatic season of record-fast meltback of sea ice is an indisputable indicator of historically unprecedented rapid climate change over a vast area. This is not a fluke, not an anomaly; it’s not a short-term random variation, some minor phenomenon with negligible impact, or something operative over geologic time scales. This is huge, and it’s fast. It’s also something that has been underway for several decades now, but something particularly dramatic seems to have been happening the last few years, as we have also seen with Greenland ice sheet melting right to the summit, and extreme weather events around the globe. I really don’t understand why something in the global system seems to have switched. I do understand that the deep-time record in ice cores and sediment cores points to dramatic climate switches having been thrown (naturally) in Earth’s past. This time, a period of climatic stability lasting for millennia–with some minor fluctuations– may be unsettled by anthropogenic changes in atmospheric composition.

“It may be that something in the Earth’s oceans has reached a point where expected climate change due to greenhouse gases is forcing a “catch-up” with modelled predictions. Whether a global ocean dynamics switch has been thrown, or whether the Arctic Ocean is operating as its own little system at the poleward edge of the global system, I don’t know. But even the layperson can see that climate far outside the Arctic of the last several years is different than climate of preceding decades. Now we are seeing it hit the Arctic very hard. It does make one wonder what’s next and how this Arctic shift will play out globally as feedbacks take hold.

“The seasonally minimum late summer coverage by Arctic sea ice is now close to half of what it was when I was starting my science career. The Arctic sea ice reduction is a continuation of decades of reduced sea ice. When I was at Tuktoyaktuk, Northwest Territories, Canada, about 3 years ago, I was shocked to see the sea ice far out to sea in July, on the distant horizon, and a few days later its edge was beyond the horizon, nowhere to be seen, when I had expected the sea ice still to be washing ashore and only beginning the break up near the land. I was there to study the lowland permafrost, which also was undergoing rapid degradation due to the same global warming influences that were being felt around the globe.

“This phenomenon underscores the complex realities of climate change, where one change induces another and another and another…. In this case, global and Arctic warming has caused reduction in the frozen ice of the Arctic Ocean; that is causing a reduction in reflectivity of the Arctic, which causes further absorption of sunlight and further heating of the surface, and further melting. As the Arctic Ocean warms, the consequences will be felt far and wide. We already have heard about impacts on polar bears, but impacts will be felt far inland as weather patterns and long-term climate undergoes secondary shifts on top of what the direct influence of greenhouse gases already is. This will be manifested in changing glaciers in the northern high latitudes and changing winter weather in North America, Europe, and Asia.”

Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science, said:

“The record set today is a stark sign that global warming is radically altering the planet, with sea ice extent in the Arctic now 40 per cent less than the average between 1979 and 2000.

“Sea ice has been disappearing over the past few weeks at an average rate of about 75,000 square kilometres per day, and there are still a few more weeks before we reach the minimum for the year, which typically occurs in middle or late September. Polar scientists agree that it is the rise in global average temperature, driven by increasing levels of greenhouse gases in the atmosphere, that is driving this rapid loss of Arctic ice. At the current rate of warming, we can expect within a few decades that Arctic sea ice will disappear completely during the summer months.

“Not only is this having a big impact on Arctic wildlife, such as polar bears, that rely on sea ice for their habitats, but the rapid loss in sea ice is accelerating global warming. Ice reflects more sunlight than sea water, so more heat is being absorbed, increasing the amount of warming. This record-breaking melt in the Arctic is a clear indicator for governments meeting next week in Bangkok, Thailand, at the latest round of international negotiations about climate change, that the current pace and scale of reductions in greenhouse gases are a wholly inadequate response to the magnitude of the impacts of global warming.”