This year was one of extremes at the two poles, researchers from the US National Snow and Ice Data Center (NSIDC) reveal in their latest report. While Arctic sea ice extents established a new record low, ices in Antarctica reached a new record high.
This significant difference highlights the varied factors that act around each of the poles, and illustrates the fact that global warming and climate change are affecting the two regions through diverse mechanisms. More studies need to be conducted in order to figure out these complex interplays.
At the North Pole, September 16 marked the point of lowest sea ice extent. The average values for last month were 3.61 million square kilometers (1.39 million square miles), which is 3.43 million square kilometers (1.32 million square miles) below the 1979 to 2000 average.
This year's record exceeded that established in September 2007 by a relatively wide margin. At this point, ices are forming again in the Arctic, as the Sun has already set for the 6-month-long winter.
While all these things were happening at the North Pole, Antarctica was experiencing the most significant increase in sea ice extent ever to happen within the last few years. It is important to keep in mind here that the increase occurred during the winter.
This remarkable increase can be considered as an interesting response to the changes that occurred in circulation patterns in the Southern Hemisphere lately, the NSIDC research team explains.
The 2012 winter maximum extent at the South Pole was reached on September 26, when 19.44 million square kilometers (7.51 million square miles) of Antarctica were covered in ice. The September average for the continent is 19.39 million square kilometers (7.49 million square miles).
However, this increase only exceeded the 1979 to 2000 average by a very narrow margin, of just 16,000 square kilometers per year (6,200 square miles). This represents an area about the size of the state of Connecticut. By comparison, Arctic ice loss amounts to the surface of the state of Indiana.
“Comparing winter and summer sea ice trends for the two poles is problematic since different processes are in effect. During summer, surface melt and ice-albedo feedbacks are in effect; winter processes include snowfall on the sea ice, and wind,” NSIDC investigators write in their new report.
“Small changes in winter extent may be a more mixed signal than the loss of summer sea ice extent. An expansion of winter Antarctic ice could be due to cooling, winds, or snowfall, whereas Arctic summer sea ice decline is more closely linked to decadal climate warming,” the researchers conclude.