The main point of this work has been separating two problems from each other: the analysis of consequences of the climate change for different social systems and the decision which is connected to them. In other words, we tried to solve a well-known ``business dilemma''. By applying the ``risk-assessment'' approach, we show how the risk probability can be estimated, but the choice of admissible level of the risk is a problem beyond of the scope of our work.
Usually only one factor of climate change, namely the shift of mean temperature, was taken into account, when its influence on agriculture was considered. We have shown that another consequence, an increase of the variability of climatic parameters, would be the leading factor influencing on agriculture.