Half of Greenland's Warming Tied to Natural Causes
About half of the surface warming that's helping shrink Greenland's glaciers is due to temperatures in the tropical Pacific Ocean, not greenhouse gases, a new study reports.
Sea-surface temperatures in the Pacific are already known to influence global weather patterns at lower latitudes. For example, the El Niño cycle shifts rainfall around the world, delivering precipitation to western North America and causing drought in Australia and Central America.
The new findings could explain why Greenland and the Canadian Arctic are getting hotter more quickly than other regions of the planet. The feverish temperature rise has puzzled scientists: The most up-to-date climate models, such as those in the fifth assessment report of the Intergovernmental Panel on Climate Change, fail to reproduce the rapid warming seen in the Arctic.
The new study seee a link between tropical sea-surface temperatures and the North Atlantic Oscillation, a climate pattern that dominates Arctic weather. Since the 1990s, warm sea-surface temperatures in the western Pacific and cool waters in the eastern Pacific have pushed the North Atlantic Oscillation (NAO) into a pattern that allows high pressure above Greenland and the Canadian Arctic. (High atmospheric pressure leads to warmer temperatures.)
Climate conditions and weather events associated with extreme phases of the North Atlantic Oscillation.
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