Icebergs float in a bay off Ammassalik Island, Greenland. Ice melt could result in extreme weather this winter in North America and Europe, according to climate scientists. (John McConnico / Associated Press)
The loss of Arctic ice has several effects. Ice reflects heat and solar energy back into space. With less ice cover, that heat energy is instead absorbed by the ocean, which warms and melts more ice. Currently, the Arctic region is the fastest-warming region on the planet, and the change in temperature will probably influence weather patterns here and in Europe, according to Francis.
The heating and cooling of Arctic seawater has been affecting the jet stream -- the river of air that flows from west to east high above the Earth’s surface -- and has slowed it down, Francis said. The jet stream controls the formation and movement of storm systems, so when its movement slows, weather conditions persist for longer periods of time over the same area. They get “stuck.”
The extent of Arctic sea ice on Aug. 26, 2012, the day the sea ice dipped to its smallest extent ever recorded in more than three decades of satellite measurements. The line on the image shows the average minimum extent from the period covering 1979-2010. Click on the image for a larger version. Credit: NASA/JPL.
During the fall, when the sun sets once again and the Arctic Ocean begins to refreeze, the heat in the ocean gets released back into the atmosphere. Since the jet stream, which is a corridor of strong winds at upper levels of the atmosphere that generally blows from west to east across the northern mid-latitudes, is powered by the temperature difference between the Arctic and areas farther south, any alteration of that temperature difference is bound to alter the jet stream — with potentially profound implications. It just so happens that the jet stream steers day-to-day weather systems.
Recent scientific studies have shown that the dramatic warming that has been occurring in the Arctic during the past few decades, along with the associated loss of sea ice cover, may be changing atmospheric circulation patterns throughout the northern hemisphere. This could be contributing to the recent outbreaks of unusually cold and snowy weather. Sea ice loss during the spring and summer melt season, which leaves a thinner and more sparse ice cover throughout the fall and early winter, is a key suspect in influencing winter weather patterns. When the ice melts, it allows incoming solar radiation to warm water and air temperatures, which in turn has an influence on atmospheric pressure and circulation, and may help shift Arctic air southward, while the Arctic remains unusually warm.
One meteorologist has described the pattern this way: "This pattern is kind of like leaving the refrigerator door ajar — the refrigerator warm up, but all the cold air spills out into the house."