Satellite images show Arctic surface darkening due to ice melt

By Liji Varghese | Last Updated: Wednesday, February 19, 2014 - 15:58

Zee Media Bureau/Liji Varghese

New Delhi: Earth’s ability to reflect sunlight is diminishing due to drastic melting of sea ice in Arctic Ocean, a new study says.

The researchers from Scripps Institution of Oceanography, at the University of California, San Diego came on to the conclusion after analysing data from the Clouds and Earth`s Radiant Energy System, or CERES, instrument on board several NASA satellites.
Due to the rapid sea ice melt the reflective surface of the Arctic is replaced by a relatively dark ocean surface, eventually reducing the amount of sunlight being reflected back to space. This is causing Earth to absorb an increasing amount of solar energy, thus amplifying global warming.

The Arctic has warmed by 3.6 F (2 C) since the 1970s and the summer minimum Arctic sea ice extent has decreased by 40 percent during the same time period leading to a decrease in the regions albedo, or reflectivity.

A total black surface has an albedo of zero percent and a perfectly white surface has an albedo of 100 percent. According to researchers overall albedo of the Arctic region fell from 52 percent to 48 percent between 1979 and 2011.
“The results of the study show that the heating resulting from albedo changes caused by Arctic sea ice retreat is quite large," said the study`s lead author, Ian Eisenman, a climate scientist at the Scripps Institution of Oceanography in California.

“Averaged over the entire globe, it`s one-fourth as large as the heating caused by increasing atmospheric CO2 concentrations during the same period,” he added.

The National Science Foundation-funded study was published in the journal Proceedings of the National Academy of Sciences.

First Published: Wednesday, February 19, 2014 - 15:58
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