Scientists
link frozen spring to dramatic Arctic sea ice loss
Melting
sea ice, exposing huge parts of the ocean to the atmosphere, explains
extreme weather both hot and cold
Arctic ice loss adds heat to the ocean and atmosphere which shifts the position of the jet stream, which affects weather in the northern hemisphere. Photograph: Owen Humphreys/PA
25
March, 2013
Climate
scientists have linked the massive snowstorms and bitter spring
weather now being experienced across Britain and large parts of
Europe and North America to the dramatic loss of Arctic sea ice.
Both
the extent and the volume of the sea ice that forms and melts each
year in the Arctic Ocean fell to an historic low last autumn, and
satellite records published on Monday by the National Snow and Ice
Data Centre (NSIDC) in Boulder, Colorado, show the ice extent is
close to the minimum recorded for this time of year.
"The
sea ice is going rapidly. It's 80% less than it was just 30 years
ago. There has been a dramatic loss. This is a symptom of global
warming and it contributes to enhanced warming of the Arctic,"
said Jennifer Francis, research professor with the Rutgers Institute
of Coastal and Marine Science.
According
to Francis and a growing body of other researchers, the Arctic ice
loss adds heat to the ocean and atmosphere which shifts the position
of the jet stream – the high-altitude river of air that steers
storm systems and governs most weather in northern hemisphere.
"This
is what is affecting the jet stream and leading to the extreme
weather we are seeing in mid-latitudes," she said. "It
allows the cold air from the Arctic to plunge much further south. The
pattern can be slow to change because the [southern] wave of the jet
stream is getting bigger. It's now at a near record position, so
whatever weather you have now is going to stick around," she
said.
Francis
linked the Arctic temperature rises to extreme weather in mid
latitudes last year and warned in September that 2012's record sea
ice melt could lead to a cold winter in the UK and northern Europe.
She
was backed by Vladimir Petoukhov, professor of Earth system analysis
at Potsdam Institute in Germany, whose research suggests the loss of
ice this year could be changing the direction of the jet stream.
"The
ice was at a record low last year and is now exceptionally low in
some parts of the Arctic like the Labrador and Greenland seas. This
could be one reason why anticyclones are developing," he said.
The
heavy snowfall and freezing temperatures which have marked March 2013
across the northern hemisphere are in stark contrast to March 2012
when many countries experienced their warmest ever springs. The
hypothesis that wind patterns are being changed because melting
Arctic sea ice has exposed huge swaths of normally frozen ocean to
the atmosphere would explain both the extremes of heat and cold, say
the scientists.
A
recent paper by the US government's National Oceanic and Atmospheric
Administration (NOAA) also found that enhanced warming of the Arctic
influenced weather across the northern hemisphere.
"With
more solar energy going into the Arctic Ocean because of lost ice,
there is reason to expect more extreme weather events, such as heavy
snowfall, heat waves, and flooding in North America and Europe,"
said the researchers.
The
Met Office's chief scientist has previously said the melting Arctic
ice is in part responsible for the UK's recent colder winters.
The
possible links between Arctic sea ice loss and extreme weather were
made as the UK's government's outgoing chief scientific adviser Sir
John Beddington warned that the world could expect more extremes of
weather.
"The
[current] variation we are seeing in temperature or rainfall is
double the rate of the average. That suggests that we are going to
have more droughts, we are going to have more floods, we are going to
have more sea surges and we are going to have more storms." He
said that said there was a "need for urgency" in tackling
climate change.
"These
are the sort of changes that are going to affect us in quite a short
timescale," he warned. Last year saw record heat, rainfall,
drought and floods in the northern hemisphere.
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