Projected climate change
and its impacts
The previous sections have dealt with changes and Backed up by new studies and observations, the
effects happening today. The rest of the guide con- IPCC is more certain of the accuracy of the projected
centrates on what is yet to come. warming patterns and other regional climatic effects
than it was in the Third Assessment Report. These in-
If current policies to mitigate climate change and re- clude wind-pattern changes, precipitation, and some
lated steps towards sustainable development remain changes in weather extremes and sea ice.
unchanged, global GHG emissions will continue to
grow over the next few decades. The growth will not Regional-scale changes include:
be modest, either: The IPCC projects an increase in most warming over land and at the highest northern
global GHG emissions from 25 to 90 per cent between latitudes, and least over the Southern Ocean and
2000 and 2030. (There is a wide margin of uncertain- parts of the North Atlantic;
ty because of the very different assumptions made contraction of the area covered by snow, increases
in each socio-economic scenario considered by the in the depth at which most permafrost will thaw, and
IPCC). It expects the fossil fuels, oil, coal and gas, to a decrease in the extent of sea ice;
continue to dominate the energy mix till beyond 2030, increase in the frequency of extremes of heat, heat
regardless of the scenario. waves and heavy precipitation;
a likely increase in tropical cyclone intensity;
Continued GHG emissions at or above current rates will a shift towards the poles of storms outside the tropics;
cause further warming and induce many changes in the increases in precipitation in high latitudes, and likely
global climate system during this century that would be decreases in most sub-tropical land regions.
larger than those observed during the 20th century.
Today’s emissions influence the
The IPCC scenarios (often referred to as the SRES scenarios,
for “Special Report on Emissions Scenarios” published by
atmosphere for years to come
the IPCC in 2000) explore alternative development pathways.
They take into account demographic, economic and techno-
Even if GHG and aerosol concentrations were kept logical factors and their resulting GHG emissions. The emis-
constant at today’s levels (2000), some anthropogenic
sions projections based on those different assumptions are
warming and sea level rise would continue for many
widely used in forecasting future climate change, vulnerability
centuries. The climate reacts over long periods to in-
and impacts. It is open to anyone to decide which of the dif-
ferent scenarios seems most probable, as the IPCC doesn’t
fluences upon it; many GHGs remain in the atmos-
take the risk of attaching any probability to any of them.
phere for thousands of years.
24 Planet in Peril
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