THE COLUMBIA RIVER AND CLIMATE CHANGE: CONNECTING GEOLOGY WITH SOCIETY ON A REGIONAL SCALE

The Columbia River (CR) provides an exemplary topic of study for climate change education. The CR is central to any narrative of the geology, environment, cultural history, and economy of the Pacific Northwest (PNW). It has a relatively steep gradient and the highest average discharge of any Western Hemisphere river entering the Pacific Ocean. Many geology students have heard tell of the Cascade volcanic arc, CR flood basalts and glacial Lake Missoula outburst floods, which formed the geological basis of the modern river. Through engineering, the CR provides most of the electric power in the PNW at low cost, irrigates millions of hectares of fields and orchards which produce billions of dollars of agricultural sales each year, and provides a shipping corridor from the inland basin to the ocean. The CR is also habitat for several populations of salmon classified as threatened or endangered under the Endangered Species Act (ESA).

ESA requirements, cessation of federal funding for large engineering projects on the river and competition among interest groups limit the ability of the CR to deliver demanded amounts of electricity, irrigation water, and salmon. On top of these limitations, climate change is beginning to take a toll. During the last hundred years, the average annual discharge of the CR has declined by perhaps 10% while average water temperature has increased, particularly during summer. The CR is a snowmelt-fed river. The annual snowpack in PNW mountains has been shrinking and the date of peak snowmelt moving earlier in the spring. In addition, all glaciers that are being measured in the CR watershed are shrinking and some of the lower-elevation glaciers have disappeared. If these climate change effects continue, as forecast by global and regional climate models, the CR will become an even warmer river with even less discharge. Using El Niño and warm North Pacific Ocean decadal events as proxies of a warmer climate future, the CR system can be expected to continue decreasing its production of electricity, crops, and salmon, with major economic and ecosystem fallout. The CR is an example of the effects of climate change on a major river upon which people have come to depend. For teaching climate change and environmental geology, a number of ways to investigate the CR will be presented.