An index of dry-matter productivity is used to assess the sensitivity of bioresources in Alberta, western Canada, to changes in the thermal and precipitation regimes, particularly to climatic warming. Results suggest that warming would improve productivity in northern Alberta, but reduce it, because oF the associated increased moisture stress, in the relatively warm, dry southeastern part of the province. Estimated productivity generally increased with precipitation regardless of location or temperature. Warming induced by C0 a quadrupling would apparently give a net increase of about. 18% in bioresource productivity for the province, and C02 doubling would lead to a 16% increase. However, the bioclimate would be changed much more than this might suggest. For CO 2 quadrupling, Alberta would acquire a thermal regime similar to that of present-day Nebraska, some a,000 km to the southeast. Also, the increase in productivity of plants due to the effects of C02 on photosynthesis might be much larger than the climate-related effects. Climate impact assessment in Canada is made especially challenging by the shortness of the period of instrumental record, the relatively high degree of sensiti%ty to climatic change, and the sparseness of the station network, particularly in the most sensitive areas.