On the coast: Small islands, where people and infrastructure are
Areas facing multiple stresses from climate change highly exposed to projected impacts, including sea
include mangroves and salt marshes. level rise which is the main problem, as well as re-
duced rainfall in summer projected for these regions).
In the ocean: This would reduce freshwater availability which may
Coral reefs are ecosystems that are very vulnerable to leave some unable to meet their demand. Increased
thermal stress and find it hard to adapt. Increases in rainfall in winter is “unlikely” to compensate this de-
sea surface temperature of about 1–3°C are projected velopment due to lack of storage and high runoff
to result in more frequent coral bleaching and wide- during storms. In the Pacific, for example, a 10 per
spread mortality, unless there is thermal adaptation cent reduction in average rainfall (by 2050) would
or acclimatization by corals. They face other climate- lead to a 20 per cent reduction of freshwater on
change related stresses such as increasing acidity
and non climate-related ones (overfishing) in addition.
Sea-ice biomes (communities) are also very sensitive
Population flooded in coastal areas in 2080
to small changes in temperature, when ice turns to
Million people per year (logarithmic scale)
water for example.
1000
Other risk sectors include low-lying coasts, water
resources in some dry areas and those that depend
100
on melting snow and ice, low-latitude agriculture,
and human health in poorer countries. The increased
10
frequency and intensity of extreme weather is “very
likely” to worsen other impacts.
1
Regions expected to be especially hard-hit by climate
change include:
Sea-level rise
0.1
cm
The Arctic, because of the high rates of projected
0 25 50 75 100
warming and its impact on people and the natural
no additional efforts undetaken
more protection efforts than today
world. The thickness and extent of glaciers is ex-
strong efforts to protect coastal populations against floods
pected to decline, and ice sheets and sea ice will
Note: The upper margin of each band shows the amount of people affected in
also be affected. Invasive species may become a the A2 scenario according to which global population will reach 14 thousand
growing problem.
million by 2080 with the lowest GDP of all IPCC scenarios. Therefore little
capacity exists to adapt, and more people will be affected by floods. The lower
end of each curve shows the impact for the A1/B1 scenario assuming the
Africa, with the expected impacts on the continent
highest per captia income and world population at 8 thousand million,
allowing for higher investments in the protection of the population.
and its low capacity for adaption. Yields from rain-fed
Source: H. Ahlenius, GEO Ice and Snow, 2007, based on Nicholls, R.J. and Lowe,
agriculture, for example, could in some countries fall
J.A., 2006.
by half by 2020.
Projected climate change and its impacts 33
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