The North Pole has been losing ice cover at an alarming rate in recent years as the Arctic region steadily warms up. For those not in denial about climate change, it’s a constant and potent reminder that something needs to be done, and done quickly. But if the planet really is getting warmer, how is it possible that Antarctic ice cover has not only remained stable, but actually grown in recent years? It’s a question that has proven difficult to answer and provided interesting fodder for the climate change debate, but now a team of researchers from NASA believe they may have put the issue to bed.
In a study published in the journal Remote Sensing of Environment, the authors show that the reason the Antarctic is not melting like the Arctic is due to differences in topography, climate and ocean levels between the two regions. “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,” explained lead researcher Son Nghiem.
Every year, Antarctic ice expands and shrinks according to seasonal cycles in the Southern Hemisphere. The NASA team used satellite radar, sea temperature, ocean levels and other data to track this ice formation and identify any contributing factors. They found that as new ice forms in the Antarctic, it is pushed northwards by winds and forms a kind of “protective shield” around the continent. The winds continue to pack ice up against the shield, increasing its thickness up to 1,000 kilometers (620 miles) in parts. As the ice shield continues to drift away from the continent, it leaves behind an area of open water where new ice can form, protected from waves.
All of this occurs in a region where the sea surface temperature remains below freezing at -1 degrees celsius (30F). This “temperature boundary” is dictated by ocean currents which are particular to the surrounding area, and are influenced by sea floor creatures the researchers identified in their study. So far from being a paradox, the behaviour of the surrounding ocean and wind patterns influenced by the topography of the Antarctic create an environment that’s well-suited to the formation and persistence of ice. The same factors are not present in the Arctic, which leaves the region more vulnerable to the effects of global warming.
NASA’s study has given us the most cohesive explanation to date for the disparate behaviour of Arctic and Antarctic ice cover. The growth of sea ice in the southern region might appear to contradict everything we know about global warming, but in fact, it’s simply a product of differences in climate and topography between the two poles. Despite their obvious similarities, the Arctic and Antarctic are quite different. So if you encounter anyone who cites the ice cover paradox as evidence against climate change, point them to this study and explain they’re comparing apples and oranges.
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Last modified: March 17, 2017