The National Snow and Ice Data Center has announced that Arctic sea ice melted to its yearly minimum extent last Sunday, which was the smallest extent since measurements began in 1979 and a whopping 49% below the 1979 to 2000 average. With ice vanishing at rates that exceed even the most sophisticated computer models there is one guarantee, that it’s going to shrink even more
We know Arctic sea ice will continue to shrink for two reasons. First, we are continuing to spew greenhouse gases into the atmosphere. And second, solar radiation and melting sea ice interact as a system known as a positive feedback loop. Sunlight that hits white arctic sea ice is largely reflected back to space. Throughout modern civilization Arctic sea ice has acted as a sort of thermostat, regulating the earth’s temperature. But as the climate warms, and the Arctic ice melts, the sunlight instead hits much darker seawater. Rather than reflecting that energy back to space, open-ocean waters absorb vastly more of the sun’s energy, which in turn warms the water, accelerating the rate of melt.