There appears to be less light and heat reflecting from Arctic ice than scientists had suspected and that means, among other things, that ice loss is likely speeding up global warming more than anticipated too (in addition to raising sea levels), new research using NASA instruments shows.

The retreat of sea ice in the Arctic Ocean is diminishing Earth’s albedo, or reflectivity, by an amount considerably larger than previously estimated. … The researchers calculated that the overall albedo of the Arctic region fell from 52 percent to 48 percent between 1979 and 2011, NASA writes in its news release. The magnitude of surface darkening is twice as large as that found in previous studies. … As the sea ice melts, its white reflective surface is replaced by a relatively dark ocean surface. This diminishes the amount of sunlight being reflected back to space, causing Earth to absorb an increasing amount of solar energy.

The agency also provided this history lesson:

The National Science Foundation-funded study appears in the journal Proceedings of the National Academy of Sciences 45 years after atmospheric scientists Mikhail Budyko and William Sellers hypothesized that the Arctic would amplify global warming as sea ice melted. “Scientists have talked about Arctic melting and albedo decrease for nearly 50 years,” said Veerabhadran Ramanathan, a professor of climate and atmospheric sciences at Scripps Institution of Oceanography. “This is the first time this darkening effect has been documented on the scale of the entire Arctic.”

And this grim conclusion:

Eisenman, an assistant professor of climate dynamics, said that the results of the study show that the heating resulting from albedo changes caused by Arctic sea ice retreat is “quite large.” Averaged over the entire globe, it’s one-fourth as large as the heating caused by increasing atmospheric CO 2 concentrations during the same period.

But, hey, the weekend is still coming!

Gallery: 2013 global temperatures:

Gallery: Global warming summary by Intergovernmental Panel on Climate Change

Jake Ellison can be reached at 206-448-8334 or jakeellison@seattlepi.com. Follow Jake on Twitter at twitter.com/Jake_News. Also, swing by and *LIKE* his page on Facebook.

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