Geoscience Reference
In-Depth Information
11
The Uncertain Future
Overview
The broad picture of Arctic change projected through the twenty-first
century is a warming climate, with this warming outsized in comparison
to the globe as a whole, and a continued reduction in sea ice extent in
all seasons, but especially in summer and early autumn. We are also
likely to see warming and thawing of permafrost, gradual replacement
of tundra with shrub vegetation, a shorter snow-covered season and a
modest increase in precipitation. The Greenland Ice Sheet will continue
to lose mass, likely at an accelerating rate, contributing to sea level rise.
This picture of the Arctic's future, however, is muddied by unknowns.
The Arctic is home to strong natural variability in climate, and it would
come as no surprise if the general trend toward warming was interrupted
by decadal-scale periods of little temperature change or even cooling.
There are unknowns with global or hemispheric-scale ramifications,
key among these being the timing and strength of the permafrost carbon
feedback, responses of the atmospheric circulation to sea ice loss, future
rates of greenhouse gas emissions, and changes in aerosol concentration
and type. A massive release of methane from seafloor sediments along the
Arctic continental shelves appears to be a remote possibility. As the Arctic
becomes more accessible, it is likely to see increased activity linked to
development of oil and gas resources, shipping, and tourism, bringing
economic benefits along with the danger of environmental degradation
and disruption of traditional lifestyles. This brief closing chapter explores
some of these issues.
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