Yu. M. Svirezhev, W. von Bloh, and H.-J. Schellnhuber
Potsdam Institute for Climate Impact Research (PIK)
PO Box 601203, D-14412 Potsdam, Germany
Environmental Modelling and Assessment 4, 287-294 (1999)
A novel approach to the problem of estimating climate impact on social systems is suggested. This approach is based on a risk concept, where the notion of critical events is introduced and the probability of such events is estimated. The estimation considers both the inherent stochasticity of climatic processes and the artificial stochasticity of climate predictions due to scientific uncertainties.
The method is worked out in some detail for the regional problem of crop
production and the risks associated with global climate change, and illustrated
by a case study (Kursk region of the FSU). In order to get local climatic
characteristics (weather) a so-called ``statistical weather generator'' is used.
One interesting finding is that the 3%-risk level remains constant up to
1.0 - 
C rise of mean seasonal temperature, if the variance does
not change. On the other hand, the risk grows rapidly with increasing variance
(even if the mean temperature rises very slowly).
The risk approach allows to separate two problems: (i) assessment of Global Change impact and (ii) decision making. The main task for the scientific community is to provide the politicians with different options; the choice of admissible (from the social point of view) critical events and the corresponding risk levels is the business of decision makers.
Keywords: Risk analysis, global change, agriculture