The melting of the world's ice is often blamed on global warming. The Antarctic sea ice, however, poses a conundrum because it has been expanding to record levels.
On Sept. 20, the sea ice extent in the Antarctic has reached 7.78 million square miles breaking the record it has set in 2013 but while it may appear that this record discredits claims of global warming, scientists said that climate change still has something to do with the phenomenon.
Researchers from the National Aeronautics and Space Administration (NASA) offered some explanations on the expanding sea ice in Antarctic amidst a warming climate.
Claire Parkinson, from the U.S. space agency's Goddard Space Flight Center, said that sea ice as a whole has been declining but just like with global warming, not all of the world's frozen sea waters are characterized by decreasing ice extent.
"It's really not surprising to people in the climate field that not every location on the face of Earth is acting as expected - it would be amazing if everything did," Parkinson said. "The Antarctic sea ice is one of those areas where things have not gone entirely as expected."
Goddard scientist Walt Meier said that the warming climate brings about changes in weather patterns and some of these may bring cooler air to some areas. Thus, it is possible to attribute the growing sea ice extent to the weather patterns that move cold air over the ocean and spur the formation of more frozen sea water.
Still, it appears that the expansion of the sea ice is also caused by other factors. Antarctica, for instance, does not have natural barriers. Meier said that frozen sea water surrounds the continent and covers a large area making it easier for ice to expand.
"Part of it is just the geography and geometry. With no northern barrier around the whole perimeter of the ice, the ice can easily expand if conditions are favorable," Meier said.
The National Snow and Ice Data Center (NSIDC) also noted that the areas with unusual ice growth are also the ones that exhibit upward trends in ice extent and this suggest that wind patterns are playing a role in the rapid growth of ice extent in Antarctica. The ice sheet melt also causes surface water to become slightly less dense and this leads to conditions that favor the expansion of sea ice.
"While the change in saltiness is too small to significantly affect the freezing temperature, the increase in slightly less dense water surrounding Antarctica inhibits mixing, creating conditions that favor ice growth," the NSIDC said.