Despite the fact that Arctic sea ice is melting, a persistent growth of sea ice is observed in Antarctica. Now, researchers supported by the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) claim to have found the answer for the differences in the ice sheet coverage between these two regions.
Arctic sea ice has reached an all-time low and thinned by 65 percent between the years 1975 and 2012. However, Antarctica has shown gains in sea ice coverage despite continued concerns over global warming and glacier melting.
In the current study, the team examines temperature, topographical and bathymetric data to identify why Antarctica's ice is being preserved. They discovered that local ocean depth and continental surface temperatures influence the region's wind and ocean currents, which sustains the production and protection of sea ice. Conversely, conditions in the Arctic are conductive to the ongoing melt that it is currently experiencing.
"Our study provides strong evidence that the behavior of Antarctic sea ice is entirely consistent with the geophysical characteristics found in the southern polar region, which differ sharply from those present in the Arctic," said Son Nghiem of NASA's Jet Propulsion Laboratory and first author of the study.
NASA's QuikScat satellite provided data that allowed the team to get a look at the formation and routes of Antarctic sea ice and the various types of ice coverage in the Southern Ocean. The team concluded that the winds push building ice out and around the continent from June to September, which is sea ice growth season. The result is a "Great Shield" zone (GSZ) that protects young interior ice.
On the other end of the spectrum is the Arctic's marginal ice zone (MIZ), which is a boundary of thin, new ice that is easily disturbed by wind and waves. Furthermore, it experiences warmer waters more often than the GSZ, which explains the region's ice conditions.
Despite the persistent growth of sea ice in Antarctica, global warming and climate change are still causing record high global temperatures and melting glaciers, and scientists are still worried that the continent could be at a risk of ice loss. Further research should be conducted into the protective ice zones of Antarctica and the Arctic in order to better understand polar ice production and melting.
The findings were published in the May 11 issue of the journal Remote Sensing of Environment.
