How much Arctic sea ice was there?
Draw your line on the chart
Sea ice extent in the northern hemisphere, monthly averages
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Did I trick you? This year did not, in fact, break the record of least Arctic sea ice. Even as global warming has triggered a long-term trend of shrinking sea ice, seasonal randomness still nudges the numbers up and down from year to year.
Sea ice is whiter than water, so an icy Arctic cools the atmosphere by reflecting more sunlight back to space than open ocean does. As ice disappears, its cooling effect wanes. That causes more global warming, which in turn causes more ice loss, and on and on. The feedback loop helps explain why the Arctic is warming faster than the rest of the planet, a phenomenon called “Arctic amplification.”
Sea ice floats on water, so when it melts, it does not raise the level of the ocean. But Arctic amplification is hastening the retreat of the nearby Greenland ice sheet, which is based on land and so does contribute to sea level rise as it melts by the ton.
Sea ice loss has other negative consequences, not least for the creatures like polar bears and seals — and human beings — who depend on it. But where some see environmental catastrophe, others see economic opportunity. At the current rate of retreat, Arctic summers will be free of ice by mid- to late-century, exposing new shipping lanes and, perhaps, a rush for freshly accessible natural resources, including oil and gas.
Could the Arctic ever be completely ice-free? “I probably don’t even want to think about that. That could be centuries from now or longer than that,” said Mark Serreze, director of the National Snow and Ice Data Center. “It depends on what humans do. Are we going to go on a ‘burn, baby, burn’ scenario of greenhouse gas emissions? Or take a more modest emissions scenario? In many ways, the future is up to us.”
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