| Abstract: | Initial results are reported of a study to evaluate the broad-scalesensitivity of agriculture in Europe to climatic change. Thestudy relates an agroclimatic index, effective temperature sum(ETS), to the cultivable limits of grain maize. A computer mappingsystem for the European region is adopted to map ETS on thebasis both of present-day and of possible future mean temperatures.In this way, changes in climate can be depicted as geographicalshifts of the limit of potential grain maize cultivation. The results indicate that a mean annual temperature increaseof only 1 °C (within the present-day range of inter-annualvariability) would open up large areas in southern England,the Low Countries, eastern Denmark, northern Germany, and northernPoland to potential grain maize cultivation. An increase of4°C would move the limit into central Fennoscandia and northernRussia. The latter changes are similar to those projected bygeneral circulation models (GCMs) for an equivalent doublingof atmospheric carbon dioxide, and represent rates of northwardshift of approximately 200–350 km/°C in western Europeand 250–400 km/°C in eastern Europe. Results using information from GCM transient-response experimentsindicate that such shifts could occur as soon as the 2050s ifthe current exponential growth in emission rates of greenhousegases were to continue unabated. The rate of shift of the grainmaize limit implied for this high (and improbable) emissionsscenario is in the order of 150–200 km per decade overthe next 70 years, slower than this during the next few decades,but faster thereafter. It is probable that the actual rate willbe lower than this, but even values of half those calculated,if sustained, would still represent rates of shift in agroclimaticpotential that are unprecedented in the historical record. |
