Study: Why Antarctic Sea Ice Continues to Expand Despite Global Warming

A new study revealed that the increase of sea ice in the Antarctic despite global warming caused by climate change can be largely explained by a natural climate fluctuation.

The study, published in the journal Nature Geosciences, suggests that the change of phase of the Interdecadal Pacific Oscillation (IPO) from positive to negative, or vice versa, could initiate chain reaction of climate impact that may affect the sea ice formation in the Antarctic region.

Since the IPO shifted to its negative phase in 1999, the rate of sea ice growth in the Antarctic rose nearly fivefold between 2000 and 2014. The negative phase of IPO is characterized by cooler-than-average sea surface temperatures in the Eastern Pacific, facilitating the expansion of Antarctic sea ice.

"Compared to the Arctic, global warming causes only weak Antarctic sea ice loss, which is why the IPO can have such a striking effect in the Antarctic," explained study's co-author Cecilia Bitz from University of Washington in a statement.

According to the study, the above average coolness of sea surface in the Eastern Pacific changes precipitation, resulting to large-scale changes to the wind that extends all the way to Antarctica. This may lead to the deepening of a low pressure system off the coast of Antarctica known as Amundsen Sea Low. This system forces the wind from its western flank to blow the sea ice northward, away from Antarctica, which in turn results to the expansion of the extent of the sea ice coverage.

However, scientists believe that the IPO has once again shifted to its positive phase in 2014. The change of IPO from negative to positive means upcoming period of warmer Eastern Pacific Ocean temperature. Following the trend of IPO shifts, researchers predicted that the increase in the area of sea ice in the Antarctic might begin to slow down, or even retreat in the next ten years.