Geoscience Reference
In-Depth Information
6
Tol survey
DICE model
5
4
3
IPCC
estimate
2
1
0
-1
-2
-3
0.0
0.5
1.0
1.5 2.0 2.5
Global mean temperature increase (°C)
3.0
3.5
4.0
4.5
5.0
Figure 22. Estimates of the impact of global warming on the global economy. The
fi gure shows a compilation of estimates of the aggregate damages from global
warming for each temperature increase. Dots are individual studies. The solid line is
the global damage function used in the DICE model. The arrow is the estimate
from the most recent IPCC survey of impacts. The estimates generally include only
partial estimates of damages to nonmarket sectors.
earlier chapters, because of the diffi culty of estimating impacts in areas
such as the value of lost species and damage to ecosystems.
The fi nal estimate is shown by the vertical arrow at 4°C. This esti-
mate is a range that was provided by the IPCC in its Third Assessment
Report. It is drawn largely from the same studies that Tol surveyed and
is therefore an expert appraisal rather than an independent estimate. 4
Finally, note that the impacts are estimated to be nonlinear and
convex (with increasing slope). Some studies fi nd that the fi rst degree
or so of warming may have economic benefi ts (see the example of agri-
culture in Chapter 7). But after some point, the damages begin to rise,
 
 
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