By David Appell
When sea ice melts, the ocean loses its reflective surface and the dark water absorbs more heat.
“The Arctic is a region that’s probably seen some of the most dramatic changes over the past few decades. And I think possibly one of the most iconic images is the decline in the Arctic sea ice.” That’s Kristina Pistone of the National Aeronautics and Space Administration’s Ames Research Center. She said melting Arctic sea ice is not only a symptom of global warming, it’s also an important contributor because of the “albedo effect.”
“Albedo is basically the whiteness of something. So if you think about sea ice, it’s very white, it’s very bright and very reflective. It will reflect a lot of the sunlight that hits it back to space. And you can compare this to the ocean surface, which is a very dark surface, it absorbs a lot of the heat that hits it,” she said.
So when Arctic sea ice melts, the underlying ocean water absorbs more of the sun’s energy and heats up. That, in turn, melts more sea ice.
Since 1979, more than 600,000 square miles of winter sea ice has disappeared—an area more than twice as big as Texas.
Pistone said that rate of loss could lead to ice-free summers in the Arctic within the next two decades. Which would be tragic for local ecosystems, accelerate global warming and affect weather patterns worldwide.
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