Long-term Climate Projections - Climate Change: Identification and Projections - page 110

extrapolation results from the simulation of the free model from 2013
(Figure 10.2, middle graph).

Figure 10.2. Reconstructed (---) and anticipated ( …. ) input signals

Finally, since volcanic activity is unpredictable, an estimate is used based
on its average value over the last millennium.

10.3. Long-term projections

In the previous chapters, in accordance with our option of leaving the
identification free of all constraints, we did not want to assign a lower limit
to anthropogenic sensitivity. Therefore, the estimated value is occasionally
negative, which even the most radical climate skeptics dare not claim. In this
chapter and the next, dedicated to future projections, the highest negative
sensitivities identified would consequently lead to significant cooling, likely
to give rise to pointless discussions. The free models will therefore include
the weak constraint

c S . This is the only slight adjustment that we will
make to the principle of identification free of all a priori knowledge, with
the risk of being accused of lacking boldness in the exploration of what is
possible.

> 0

lim

Figure 10.3 shows two bundles of projections. The first (a) is obtained by
simulating up to 2300 (like in Figure 10.1), with the input data in Figure 10.2