Earth’s climate is maintained through radiation balance of solar heating and infrared cooling, moderated through the effects of clouds and trace gases, and the present temperatures at the surface of the Earth where we live are sustained through the action of a greenhouse effect. There is a scientific consensus that increases of trace gases including carbon dioxide have already increased the mean temperature of the Earth system of land, oceans, and ice. Moreover, this warming process is expected to accelerate, not only because of the continued accumulation of carbon dioxide, but also because of positive feedbacks from changes that have already occurred. Subsequently, the social, economic, and biological responses to these changes will be large and will include unexpected consequences.
Although the Columbia River Basin (CRB) is only a small fraction of the globe, this basin is extraordinarily important as a fresh water resource for agriculture, fisheries, power-generation, First Nations, and urban users in the Pacific Northwest. The mountain snowpack and glaciers of the CRB are critical, since 30% of the annual flow is derived from these natural storage resources. Moreover, this resource is shared between Canada and the United States. The critical issues of water resources management in the Pacific Northwest have been identified in several studies over the past 10 years. Climate impacts on the CRB may be inferred, and some differentiation between the northern and southern portions of the basin can be estimated.
