Perilous
Times
Effects of climate change in the Arctic more extensive than
expected
The decrease in the snow- and ice-covered surfaces means that less
solar radiation is reflected back out into the atmosphere. It is
absorbed instead, with temperatures rising as a result. Thus the
Arctic has entered a stage where it is itself reinforcing climate
change.
by Staff Writers
Lund, Sweden (SPX) May 06, 2011
A much reduced covering of snow, shorter winter season and thawing
tundra. The effects of climate change in the Arctic are already
here. And the changes are taking place significantly faster than
previously thought.
This is what emerges from a new research report on the Arctic,
presented in Copenhagen this week. Margareta Johansson, from Lund
University, is one of the researchers behind the report.
Together with Terry Callaghan, a researcher at the Royal Swedish
Academy of Sciences, Margareta is the editor of the two chapters
on snow and permafrost.
"The changes we see are dramatic. And they are not coincidental.
The trends are unequivocal and deviate from the norm when compared
with a longer term perspective", she says.
The Arctic is one of the parts of the globe that is warming up
fastest today. Measurements of air temperature show that the most
recent five-year period has been the warmest since 1880, when
monitoring began. Other data, from tree rings among other things,
show that the summer temperatures over the last decades have been
the highest in 2000 years.
As a consequence, the snow cover in May and June has decreased by
close to 20 per cent. The winter season has also become almost two
weeks shorter - in just a few decades. In addition, the
temperature in the permafrost has increased by between half a
degree and two degrees.
"There is no indication that the permafrost will not continue to
thaw", says Margareta Johansson.
Large quantities of carbon are stored in the permafrost.
"Our data shows that there is significantly more than previously
thought. There is approximately double the amount of carbon in the
permafrost as there is in the atmosphere today", says Margareta
Johansson.
The carbon comes from organic material which was "deep frozen" in
the ground during the last ice age. As long as the ground is
frozen, the carbon remains stable. But as the permafrost thaws
there is a risk that carbon dioxide and methane, a greenhouse gas
more than 20 times more powerful than carbon dioxide, will be
released, which could increase global warming.
"But it is also possible that the vegetation which will be able to
grow when the ground thaws will absorb the carbon dioxide. We
still know very little about this. With the knowledge we have
today we cannot say for sure whether the thawing tundra will
absorb or produce more greenhouse gases in the future", says
Margareta Johansson.
Effects of this type, so-called feedback effects, are of major
significance for how extensive global warming will be in the
future. Margareta Johansson and her colleagues present nine
different feedback effects in their report. One of the most
important right now is the reduction of the Arctic's albedo.
The decrease in the snow- and ice-covered surfaces means that less
solar radiation is reflected back out into the atmosphere. It is
absorbed instead, with temperatures rising as a result. Thus the
Arctic has entered a stage where it is itself reinforcing climate
change.
The future does not look brighter. Climate models show that
temperatures will rise by a further 3 to 7 degrees. In Canada, the
uppermost metres of permafrost will thaw on approximately one
fifth of the surface currently covered by permafrost. The
equivalent figure for Alaska is 57 per cent.
The length of the winter season and the snow coverage in the
Arctic will continue to decrease and the glaciers in the area will
probably lose between 10 and 30 per cent of their total mass.
All this within this century and with grave consequences for the
ecosystems, existing infrastructure and human living conditions.
New estimates also show that by 2100, the sea level will have
risen by between 0.9 and 1.6 metres, which is approximately twice
the increase predicted by the UN's panel on climate change, IPCC,
in its 2007 report. This is largely due to the rapid melting of
the Arctic icecap. Between 2003 and 2008, the melting of the
Arctic icecap accounted for 40 per cent of the global rise in sea
level.
"It is clear that great changes are at hand. It is all happening
in the Arctic right now. And what is happening there affects us
all", says Margareta Johansson.
The report "Impacts of climate change on snow, water, ice and
permafrost in the Arctic" has been compiled by close to 200 polar
researchers. It is the most comprehensive synthesis of knowledge
about the Arctic that has been presented in the last six years.
"The work was organised by the Arctic Council's working group for
environmental monitoring (the Arctic Monitoring and Assessment
Programme) and will serve as the basis for the IPCC's fifth
report, which is expected to be ready by 2014.
Besides Margareta Johansson, Torben Christensen from Lund
University also took part in the work.