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Winter Flowers, Summer Floods, Melting Ice and Feedback Loops

Posted By Prucia Buscell, Thursday, March 29, 2012

The dramatic shrinkage of Arctic sea ice may be linked to weird weather that fluctuates wildly and is often oddly out of season, with Halloween snow and flowers in February in the northeastern U.S.

Jennifer A. Francis, a Rutgers University climate researcher, believes the loss of sea ice is impacting atmospheric circulation on a large scale. A report released this week by the Intergovernmental Panel on Climate Change, the United Nations body with scientists from 62 countries who researches climate science, reports that strong evidence links global warming to increasingly frequent heat waves, more heavy rainfall, more frequent coastal flooding, and more intense droughts.


A New York Times story by Justin Gillis and Joanna M. Foster notes it is hard to link any one weather event to global warming, and scientists studying tornadoes are challenged by poor statistics that could be obscuring significant trends. But long term trends toward higher temperatures, and declining Arctic ice, are well documented. So far this year, the U.S. has set 17 new daily temperature highs for every new daily low, according to Climate Central, a New Jersey research group hired by The Times. Because greenhouse gases are causing the Arctic to warm faster than the rest of the planet, the story says, the sea ice cap has shrunk some 40 percent since the early 1980s. Francis thinks declining temperature contrasts between the Arctic and the middle latitudes is causing "kinks” in the jet stream, which in turn impacts weather. Martin Hoerling, a NOAA researcher, agrees global warming is a problem, but he is less sure about the global impact of melting Arctic ice. Many scientists, however, have been concerned about the shrinkage for years.

A ScienceDaily story reports multi-year ice, the thicker ice that survives cyclical summer melts, has been disappearing even faster than the thinner ice on the edges of ice masses. In fact, multi-year ice area has been shrinking at the rate of more than 17 percent per decade. So the surface temperature of the Arctic rises, the ice becomes more vulnerable to melting.

A story in The Economist reports there is probably less floating ice in the Arctic Ocean now than at any time since a warm period after the last ice age ended 8,000 years ago. The story predicts if current trends continue, the Arctic maybe free of floating summer ice by 2050. Most scientists think global warming brought on by greenhouse gas emissions are warming the Arctic. But not all the changes are understood.

As snow and ice melt, uncovering dark land and water, the dark areas absorb more heat from the sun and reflect less back into space, The Economist story says. That creates a feedback loop that accelerates warming. But it doesn’t explain changes in the appearance of the ice. Some scientists think black carbon, or soot, coming from badly serviced diesel engines, forest fires, wood stoves and burned crops, is being released into the air, and absorbing sunlight that warms the atmosphere. Then, when rain and snow wash soot particles back onto an ice floe, they darken the surface, which hastens melting.

images from and Climate Change Adaptation

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