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Global climate change

Likely cause for the expansion of Antarctic sea ice this century

7/05/2016, 11:41:13 AM

New research indicates that the accelerated growth of Antarctic sea ice this century (2000-2014) is mostly related to a phase change of the Interdecadal Pacific Oscillation (IPO).

Iceberg off Antarctica.


The study, which was just published in the journal Nature Geoscience, explains that the IPO, which is an internally generated mode of climate variability, switched from a positive phase to a negative phase in 1998. This change led to a decrease in the tropical sea surface average temperature, a slowdown in the global warming trend and a change in atmospheric circulation patterns in the Ross Sea region, which in turn was conducive to the observed sea ice expansion in the Antarctic region.


Other key points from the report.......

--The increase in Antarctic sea ice extent from 2000 to 2014 was nearly five times larger than the increase from 1979 to 1999. A new all-time record sea ice extent for the Antarctic region was set in September of 2014. Records go back to 1979.

Antarctic sea ice extent changes from September 1979 to September 2014. Courtesy the NSIDC and YouTube.

--The IPO index is based on the difference between the sea surface temperature average over the central equatorial Pacific (box 2 below) and the average of the sea surface temperature anomalies over the NW and SW Pacific (see boxes 1 and 3 in the image below).


--In order to reach their conclusion, the research team used global coupled climate modeling, which showed that the negative phase of the IPO since 2000 produced anomalies similar to the observed sea-level pressure and near-surface 850 mb wind changes near Antarctica. These changes and other contributions were conducive to an expanding sea ice extent in the Antarctic region in the models.

**This study was performed by researchers from the National Center for Atmospheric Research (NCAR) and the University of Washington.


Chris Mooney of the Washington Post has also just written an article on this new study with some quotes from the authors.

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Global climate change