Climate Change in the Arctic - The Changing Arctic Environment: The Arctic Messenger - page 251

The B2 storyline and family portray a future characterized by local solutions to
economic, social and environmental sustainability. Economic development and
technological change is less rapid and more diverse than in the B1 and A1
storylines, while the global population continues to increase but at a rate lower
than in A2.
Altogether, 40 scenarios were developed under the SRES framework. The GHG emissions
anticipated from these scenarios have been fed into AOGCMs. The model runs usually be-
gin in preindustrial times using observed natural forcing agents (such as changes in solar
luminosity) and observed values for GHG and aerosol concentrations. They then proceed
into the future, “feeding” on the GHG and aerosol atmospheric concentrations computed
for whichever of the SRES scenarios is under study (such as A1FI). At least 20 different
climate models have been used to examine these scenarios.
When AOGCMs are run using the SRES scenarios, we can see what the future may
hold depending on how aggressively we continue to pump GHGs into the atmosphere.
When the models are focused on the Arctic north of 60°, we find that Arctic air mean tem-
peratures are projected to be 7°C and 5°C above present-day climate for the A2 and B2
scenarios, respectively, by the year 2100. It is sobering to remember that A2 and B2 are not
the most fossil fuel-intensive economic scenarios. In fact, now that we are in the second
decade of the twenty-first century, A2 and B2 are beginning to look sadly optimistic. The
mean temperature increases for 2100 show considerable regional variation. Under the B2
scenario, the increase for Scandinavia and East Greenland is projected as about 3°C, for
Iceland as 2°C and for the Canadian Arctic archipelago and the Russian Arctic as up to
5°C. The mean summer temperature increase in the central Arctic Ocean by the end of this
century is projected at below 1°C but to be up to 9°C between autumn and winter due to
interaction between the air and warmer surface waters that have lost their continuous ice
cover. In contrast, warming over northern Eurasia and Arctic North America for the same
period is projected to be more pronounced in summer than in winter.