Geoscience Reference
In-Depth Information
8
7
Unconstrained
T
<
2 °C
SRES A1B
_
6
5
4
3
2
1
0
2000
2100
2200
2300
2400
2500
Figure 17.
Projected sea level relative to 2000 for uncontrolled and temperature-limited
scenarios. The fi gure shows illustrative sea-level projections over the coming half
millennium from the DICE model. Note that even in the case of strong climate-change
policies, substantial SLR is projected because of the inertia in ocean response.
Figure 17 shows illustrative projections for the next 500 years. These
are even more uncertain than those in Figure 16 because of diffi culties in
modeling the response of the ice caps, but they are consistent with cur-
with extremely ambitious climate policies, there will be substantial SLR
over the coming centuries. The model suggests that limiting climate
change to 2°C will still lead to around 1.5 meters (5 feet) of eventual SLR
over the next fi ve centuries, with more in the pipeline after that.
The really worrisome projection, however, is the impact of an un-
controlled emissions scenario. This is projected to produce SLR of more
than 7 meters (23 feet) over the next half millennium—with a further
rise beyond the period covered by this projection. This upper-end result
is produced by a combination of thermal expansion, substantial melting
of the Greenland Ice Sheet, and discharge from the West Antarctic Ice
Sheet. While these projections come from a highly stylized integrated
