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A 10% increase in precipitation alone resulted in a uniform increase in percentage of wet basins throughout the regions studied (Table 2). Parkland wet basins increased by 11%, whereas wet basins in the United States and the Canadian grassland increased by 12%. The 10% increase in precipitation compensated for some of the effect of increased temperature, but results varied by region (Table 2). In the Canadian grassland, a 10% increase in precipitation nearly balanced a 3 °C increase in temperature. Parkland wet basins still declined by 39%, while United States wet basins declined 12% from the current average conditions.

Decreasing precipitation alone by 10% resulted in roughly similar declines in wet basins among the three regions (Table 2). When decreased precipitation was examined in concert with a 3 °C temperature increase, the models again revealed the heightened sensitivity of wetlands in parkland to temperature compared with wetlands in grasslands: parkland wet basins declined by 74%, compared with 31% and 56% declines in Canadian and United States grassland wet basins, respectively (Table 2).

Figure 3. Yearly estimates of percentage of basins holding water for current climate (red line) and climate with a 6 °C increase in temperature (blue line) in parkland, Canadian grassland, and United States grassland.

Figure 4. Comparison of percentage of basins holding water in parkland (red line) and United States grassland (blue line) for current climate and climate with a 3 °C increase in temperature.