What Happens in the Arctic Doesn't Stay in the Arctic
Posted September 19, 2012
UPDATED IMAGE (credit: NASA with 1979 boundary redrawn by NRDC)
Arctic sea ice extent dropped to the lowest level ever recorded, bottoming out at 3.41 million square kilometers on September 16, according to the National Snow and Ice Data Center (NSIDC). That’s 49 percent below the average minimum recorded during the 1980s and 1990s.
Scientists are confident that this trend is due to pollution. While there are year-to-year fluctuations in the location and extent of arctic sea ice, driven primarily by wind patterns, the best estimates are that the minimum extent never dropped below 9.8 million square kilometers in the first half of the 20th Century and probably not below 9 million in the last 1000 years. Since around 1950 there has been a clear trend toward less ice, with the minimum extent dropping below 4 million square kilometers for the first time this year.
Wind-driven reorganization of the sea ice also can’t explain the progressive reduction of ice thickness and the declining fraction of ice that has persisted for more than one year. These trends not only bear the fingerprint of human-caused climate change, they mean that the arctic ice is ever more vulnerable to collapse. In fact, arctic sea ice is melting much faster than climate models had predicted.
Unfortunately, what happens in the arctic doesn’t stay in the arctic. The dramatic loss of arctic ice contributes to more extreme weather in the United States in at least three ways.
First, the dramatic reduction in reflective ice in the Arctic Ocean changes the flow of energy in the climate system throughout the northern hemisphere. In particular, it alters the position and shape of the jet stream, favoring a pattern with more pronounced waves. That means that tropical air can penetrate further north and that arctic air can penetrate further south. It also means that weather systems tend to move more slowly from west to east. This is a formula for increasing extreme weather—both persistent excessive heat and severe snow storms.
Second, reduced arctic sea ice amplifies warming over the arctic, speeding the melting of the Greenland ice sheet and raising global sea levels. When sea ice melts there is no direct effect on sea levels because floating ice displaces exactly the same volume as the melt water. That’s not the case with land-based ice, such as the massive Greenland ice sheet. Excessive warmth in the arctic has led to surface melting throughout Greenland. Any runoff from the Greenland ice sheet contributes directly to increasing sea levels. And that means more coastal flooding in the United States, particularly on the East and Gulf coasts.
Third, arctic warming increases the total amount of heat absorbed by Earth and releases carbon from the not-so-permafrost, both of which amplify global warming. Sea ice acts like a windshield sunshade keeping your car cool. Replacing shiny ice surfaces with dark open ocean ones means the Earth as a whole absorbs more solar energy. The effect is equivalent to 20 years’ worth of carbon dioxide emissions according to Cambridge University physicist Peter Wadhams. In addition, as the arctic warms billions of tons of carbon dioxide and methane currently trapped in the permafrost could be released, directly adding to the blanket of heat-trapping gases in the Earth’s atmosphere. All of which means even faster climate change, and even more extreme weather across the United States.
So as you look at the astonishing pictures coming out of the arctic remember that this is not just a problem for polar bears. Unlike what promoters claim for Vegas, what happens in the arctic doesn’t stay in the arctic.
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