Some implications of climatic change for agriculture in Europe

Initial results are reported of a study to evaluate the broad-scale sensitivity of agriculture in Europe to climatic change. The study relates an agroclimatic index, effective temperature sum (ETS), to the cultivable limits of grain maize. A computer mapping system for the European region is adopted to map ETS on the basis both of present-day and of possible future mean temperatures. In this way, changes in climate can be depicted as geographical shifts of the limit of potential grain maize cultivation. The results indicate that a mean annual temperature increase of only 1 degree C (within the present-day range of inter-annual variability) would open up large areas in southern England, the Low Countries, eastern Denmark, northern Germany, and northern Poland to potential grain maize cultivation. An increase of 4 degrees C would move the limit into central Fennoscandia and northern Russia. The latter changes are similar to those projected by general circulation models (GCMs) for an equivalent doubling of atmospheric carbon dioxide, and represent rates of northward shift of approximately 200-350 km/degree C in western Europe and 250-400 km/degree C in eastern Europe. Results using information from GCM transient-response experiments indicate that such shifts could occur as soon as the 2050s if the current exponential growth in emission rates of greenhouse gases were to continue unabated. The rate of shift of the grain maize limit implied for this high (and improbable) emissions scenario is in the order of 150-200 km per decade over the next 70 years, slower than this during the next few decades, but faster thereafter. It is probable that the actual rate will be lower than this, but even values of half those calculated, if sustained, would still represent rates of shift in agroclimatic potential that are unprecedented in the historical record.