Strategic Panorama 2009 - 2010 - IEEE

Climate change and its security implications
of global average surface air warming associated with each of these scenarios.
The best estimate for scenario B1 (low) is 1.8°C (the likely range
is 1.1°C to 2.9°C), and the best estimate for scenario A1FI (high) is 4.0°C
(from 2.4°C to 6.4°C). Table 1 also shows the projections of global average
sea level rise at the end of the 21st century (2090–2099) compared to
1980-1999 based on models that exclude future rapid dynamical changes
in ice flow.
On the whole, the results show that global warming tends to reduce the
atmospheric carbon dioxide uptake on land and at sea, thereby increasing
the airborne fraction of anthropogenic emissions. Anthropogenic warming
and sea level rise will continue for centuries owing to the timescales associated
with climate processes and feedback, even if the concentration of
greenhouse gases were to stabilise.
Table 1: Projected global average surface warming and sea level rise
at the end of the 21st century (2090-2099) relative to 1980-1999 (*)
Temperature change (ºC)
Sea level rise (m)
Case Best estimate Likely range
Constant year 2000 concentrations
0.6 0.3 – 0.9 NA
(a)
Scenario B1 1.8 1.1 – 2.9 0.18 – 0.38
Scenario A1T 2.4 1.4 – 3.8 0.20 – 0.45
Scenario B2 2.4 1.4 – 3.8 0.20 – 0.43
Scenario A1B 2.8 1.7 – 4.4 0.21 – 0.48
Scenario A2 3.4 2.0 – 5.4 0.23 – 0.51
Scenario A1FI 4.0 2.4 – 6.4 0.26 – 0.59
(a) Year 2000 constant composition is derived from Atmosphere-Ocean General
Circulation Models only.
(*) Source: IPCC-4AR (5).
The regional findings are as follows:
• Warming is expected to be greatest over land and at most high
northern latitudes, and least over the Southern Ocean and parts of
the North Atlantic Ocean.
• Snow cover is projected to contract. Widespread increases in thaw
depth are projected in most permafrost regions.
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