Some of the models foresee wetter conditions, others drier, but all indicate an increase in temperatures worldwide, Lettenmaier said. Information from the large-scale climate simulations was plugged into existing historical precipitation and temperature data sets. Those data sets were then used to drive a hydrology model for the Columbia River Basin. Simulations of natural streamflow from that model in turn were used to drive another model that simulates reservoir operations at the major dams in the basin. The results reduced snowpack and lower summer streamflow highlight a number of thorny issues for the region.
Water storage is one.
If you lose the snow storage, you need storage from somewhere else, Lettenmaier said. But from an environmental standpoint, no one is ready to run out and build more dams. The boundaries between grasslands and forests could shift, which could affect the animals that live in those habitats. The projected changes could also have an impact on fisheries, hydroelectric power generation and recreational activities. Given this year s record snowfall in the Pacific Northwest, the findings may seem contradictory to some, Lettenmaier said.