Climate Change in the Arctic - The Changing Arctic Environment: The Arctic Messenger - page 303

The shading indicates the degree of confidence that observed climate change has played a
major role in the observed impacts. Note that we humans are a part of the ecosystem and
are ourselves impacted.
Figure 10.11
Selected cascades of observed impacts in the Arctic attributed to observed climate change
It all begins with the physical reaction of the cryosphere and the resulting domino effect
through ecosystems to indigenous and nonindigenous Arctic communities. According to
Derksen and Brown, by 2012, the extent of summer snow had declined 17.6% per decade
relative to the 1979-2000 mean. Snow cover now vanishes earlier and is reestablished later
ineachyear.Thenextdominotofallispermafrost,which,lackingprotectionfromthesum-
mer warmth, is thawing in many areas, while its southern limit is migrating northward (for
example, 30-80 km in Russia between 1970 and 2005 and 130 km in northern Québec over
the last 50 years). At the same time, the extent of summer sea ice is declining (by 2012)
at a rate of 13.0% per decade relative to the 1979-2000 average and the magnitude of the
trend has increased every year since 2001. An exposed Arctic ocean develops weather sys-
tems that lead to greater wave activity and to an increase in precipitation of about 8% in