April 28th, 2010 by Joshua S Hill
The diminishing Arctic sea ice cover has largely been blamed on climate change and human global warming. New research from Norway suggests this may not be the case.
[social_buttons]The past 30 years have seen the ice cover surrounding the North Pole diminish significantly, specifically within the last decade. Many experts, including the UN Intergovernmental Panel on Climate Change (IPCC), believed that this was a direct result of man-made global warming and climate change.
Researchers from the Norwegian Component of the Ecosystem Studies of Sub-Arctic Seas (NESSAS) believe that they have discovered the real reason why there has been such a dramatic decrease in the sea ice cover around the North Pole.
However climate conditions over the Arctic have never been fully understood. US researchers have been studying the Arctic climate for several decades, and a few years ago they discovered what they termed the “Arctic climate paradox.”
They first thought that the positive phase of the Arctic Oscillation (AO) was a primary factor in the receding ice cover. The AO is normally influenced by three different pressure systems: the Azores, Iceland and the Northern Pacific Ocean. Since the year 2000 the AO has been in a negative phase, which led researchers to believe that the speed with which the ice was retreating would diminish.
It did not.
“The US researchers argued that the ice was responding to something else, another factor that nobody had considered,” explains Asgeir Sorteberg, Associate Professor at the Geophysical Institute at the University of Bergen, a member of NESSAS.
Sorteberg and his colleagues noticed a particular change in the weather pattern in the Arctic beginning around the turn of this century. The particular change corresponded to the point in time when the diminishing sea ice in the Arctic began to increase.
“We found that these patterns can explain in large part why the ice cover decreased so much more rapidly after 2000. Wind patterns depend on the position of major high-pressure and low-pressure systems. We discovered that months with very little ice cover and high temperatures corresponded with crucial variations in the wind patterns,” explains Mr Sorteberg.
“Up until 2000, the Arctic Oscillation (AO) had the greatest impact on the winter ice cover in the Arctic. But the change around 2000 meant that more of the weather and wind over the Arctic after that year was determined by high-pressure and low-pressure systems in northern Russia. In other words, the AO, which was usually so crucial, played a much less important role.”
As a result of the changed climate conditions large ice masses are pushed away from the Arctic and down along the eastern coast of Greenland. Conversely less ice forms when the winds blowing in over the Arctic are determined by pressure systems in northern Russia.
“The dramatic changes in the extent of Arctic sea ice in recent years have mainly been caused by atmospheric circulation patterns that have tended to reduce ice cover, combined with a slow process of climate change. Variations in the circulation patterns are part of the natural fluctuations in the weather. In certain periods these fluctuations will reinforce human-made changes, while at other times they will mask them,” says Mr Sorteberg.
Significantly, the researchers state that the extent of the ice cover around the North Pole should not be used as a barometer for whether climate change is affecting the ice coverage, and whether climate change is occurring in the Arctic at all. They also believe that the recent decrease in ice cover should not be used as an indicator that the Arctic will be ice free in 10 to 20 years.
Nevertheless Sorteberg emphasizes that he and his colleagues do not reject the premise put forward by the IPCC and other experts that climate change is affecting Arctic ice cover. “There is no doubt that the Arctic sea ice has become thinner in recent years. The thickness of the sea ice is a much better indicator than the extent of the ice cover if we want to study how climate change may affect the ice in the Arctic,” says Mr Sorteberg.
Source: Research Council of Norway
Image Source: U.S. Geological Survey
Keep up to date with all the most interesting green news on the planet by subscribing to our (free) Planetsave newsletter.