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
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
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 rrstar.com and Climate Change Adaptation