Less Arctic Ice; More Antarctic Ice - What’s Cooking?

Climate change scientists have been puzzling over what is happening at the opposite Poles of the earth. Whilst there has been a recognisable medium-term contraction of summer Arctic sea-ice at the North Pole, the South Pole has been experiencing an increase in sea-ice to record levels this year. Attempting to explain this apparent contradiction is guiding climate experts to a deeper understanding of the factors involved in climate change processes and impacts

Arctic temperatures have been rising over recent decades leading to less of the Arctic Ocean being covered by ice in summer. The seasonal expansion of sea ice in winter, and contraction during the warmer summer months varies from year to year, but the medium-term trend is one of a retreating summer perimeter. It is thought this has resulted in a mass beaching of walrus in recent weeks on the shore of north-west Alaska, as their usual ice-floes on which they give birth and raise their young have retreated further north into waters that are too deep for the walrus to feed.

Wildlife experts have called on the world's news media to keep away from the heavy concentration of walrus, worried that a sudden panic of the massive creatures could lead to the crushing of many juvenile walruses.

Over the last 34 years a rise of seven degree celcius in October temperatures has been experienced in the Alaskan town of Barrow. A positive feedback-cycle is taking place as sea-ice, that previously reflected much sunlight back into space is being replaced by darker Arctic ocean waters which absorb more summer radiation.

As the Arctic ocean warms it means that the extent of sea-ice is reduced by a more absorbant surface of sea-water. This helps explain why the impact of climate change is being experienced more rapidly in Arctic areas than regions further from the Poles. The retreat of the southern margin of summer sea-ice explains why more frequent walrus beachings are being observed by wildlife experts.

And yet the reverse is taking place at the South Pole. Reports of record sea-ice around the Antarctic have had climate scientists scratching their heads to explain the apparent contradiction in a model of a warming planet. And yet, it is possible that warmer air over the Antarctic due to a different human impact - the growth of the ozone hole above the South Pole in recent decades - is responsible.

Whilst there are signs it is now in recovery, the greater absence of ozone may have led to more ferocious storm patterns driving frigid air out from the Antarctic centre towards the perimeter waters and chilling sea temperatures below normal. Other factors may well be at play, but the signals are there that climate change is impacting both Poles, but in different ways.