Antarctic Sea Ice Growth: A Climate Change Paradox

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Over the course of the last few years, the growth of Antarctica’s sea ice was well­ documented and discussed. In 2014, NASA reported that it had “reached a new record high extent” (20 million square kilometers) for the period of time since monitoring began in 1979, noting that its growth does not offset Arctic melting. This growth was attributed to winds, snowfall, and feedback loops due to minor melting of the edges of the Antarctic ice shelves, with scientists explaining how the Arctic and Antarctic respond in opposite ways to the forces of climate change. The growth, ultimately, was explained by natural changes that though they may be intensified by climate change ­ were not alarming or unexpected. Now, scientists warn that changes may be on the horizon.

Different accounts have been given for the paradox at Earth’s poles. Despite warming oceans, decline of the sea ice has been trumped by the interdecadal pacific oscillation cycle according to research conducted by a team of American and Australian scientists in a study published in Nature Geoscience. Around the turn of the century, the cycle entered a negative phase in which sea ice growth has been observed. That cycle will soon switch back to a positive cycle for the next few decades. Another take is that Antarctica is protected and isolated by the Antarctic Circumpolar Current. A forthcoming study in R emote Sensing of Environment invokes the idea of “ice factories” to describe how the winds of that current enable the expansion of Antarctic sea ice.

On Sept. 19, 2014, the five-day average of Antarctic sea ice extent exceeded 20 million square kilometers for the first time since 1979, according to the National Snow and Ice Data Center. The red line shows the average maximum extent from 1979-2014. Credits: NASA's Scientific Visualization Studio/Cindy Starr

On Sept. 19, 2014, the five-day average of Antarctic sea ice extent exceeded 20 million square kilometers for the first time since 1979, according to the National Snow and Ice Data Center. The red line shows the average maximum extent from 1979-2014.
Credits: NASA’s Scientific Visualization Studio/Cindy Starr

With these two studies set to be published this summer, others already shaping the discourse, and more to come, this paradox is a hot topic in climatology. Expect more to come, as a more complete understanding of this phenomenon can help inform our expectations of the future of our planet.