(Rolf Schuttenhelm/Bits of Science, 20 December 2010) -- The albedo effect still acts as a positive feedback to warming and
melting. In fact the general circulation model study shows Arctic sea
ice melting will speed up over recent years. From 2020 to 2030 more than
2.5 million square kilometres of ice will be lost. Although this
decline is much faster than the current rate of melting, it would be
more or less linear with temperature rise and time. According to the study that was published in Nature last week,
albedo effects would not lead to a runaway melting phase beyond any
threshold. Reason for this is the pile-up of Siberian winter sea ice on
the Canadian Arctic shores, with increased ice dynamics as the ice sheet
gets thinner and wind fetch increases over spots of open water.
If GHG emissions are unabated, the study shows, only a tiny bit of
sea ice [less than 0.1 million square kilometres] could survive the
coming decades. This would not be enough to sustain the iconic Arctic
species like seals, walruses and polar bears. However, as sea ice loss would act in a linear fashion to temperature
rises, once these are slowed down and controlled to no more than 2
degrees of warming on average [the official UN climate target], part of
the Arctic summer sea ice could recover.
As there is such a large thermal inertia at play in the Earth’s
climate system [delay between emitting a CO2 molecule and optimum of
warming suggested to be more than 40 years] emission reduction would
have to be implemented fast, to achieve any results.
Posted by Amanda Graham – 19 December 2010; 7:03:51 PM – Permalink
Tagged: News, Research