Climate models can be good tools for predicting future sea ice levels — unless, of course, they are completely wrong.
In the case of Antarctica, the climate models were dead wrong, according to a new study by Chinese scientists published in the journal Cryosphere. The study found that most climate models predicted Antarctic sea ice coverage would shrink as the world warmed and greenhouse gas levels increased.
The opposite happened. Most climate models analyzed in the study predicted Antarctica would shrink between 1979 and 2005, but instead south pole sea ice levels increased during that time. Going a step further, sea ice levels have only increased since 2006, hitting all-time highs for sea ice coverage in September of last year.
“For the Antarctic, the main problem of the [climate] models is their inability to reproduce the observed slight increase of sea ice extent,” researchers wrote in their study.
“Both satellite-observed Antarctic [sea ice extent] and [satellite measured] Antarctic [sea ice volume] show[s] increasing trends over the period of 1979–2005, but [climate models’] Antarctic [sea ice extent] and [sea ice volume] have decreasing trends,” researchers added. “Only eight models’ [sea ice extent] and eight models’ [sea ice volume] show increasing trends.”
Chinese scientists only looked at sea ice projections until 2005. Had they kept going, they would find more than a trend of “slightly increasing” sea ice levels. Last year was the first year on record that Antarctic sea ice coverage rose above 7.72 million square miles.
By Sept. 22, 2014, sea ice extent reached its highest level on record — 7.76 million square miles. Antarctica is now in its melt season, but even so, sea ice levels were very high for late December and early January.
The same can’t be said for Arctic sea ice coverage. The Chinese study notes that for the Arctic “both climatology and linear trend are better reproduced.” Climate models predicted Arctic sea ice extent and volume would decrease as the world warmed, which it has.
In January 1979, sea ice extent averaged about 6 million square miles for the month. By 2006, sea ice extent averaged above 5.2 million square miles for January — one of the lowest sea ice levels for January on record.
Since 2006, however, the Arctic has stabilized and has even increased slightly. Sea ice extent for January 2015 was 19,000 square miles above the record low extent in January 2011. The National Snow and Ice Data Center reported that “Arctic sea ice extent for January was the third lowest in the satellite record. Through 2015, the linear rate of decline for January extent over the satellite record is 3.2% per decade.”
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