PACIFIC NORTHWEST REGIONAL ASSESSMENT: THE IMPACTS OF CLIMATE VARIABILITY AND CLIMATE CHANGE ON THE WATER RESOURCES OF THE COLUMBIA RIVER BASIN¹

Abstract

The Pacific Northwest (PNW) regional assessment is an integrated examination of the consequences of natural climate variability and projected future climate change for the natural and human systems of the region. The assessment currently focuses on four sectors: hydrology/water resources, forests and forestry, aquatic ecosystems, and coastal activities. The assessment begins by identifying and elucidating the natural patterns of climate vanability in the PNW on interannual to decadal timescales. The pathways through which these climate variations are manifested and the resultant impacts on the natural and human systems of the region are investigated. Knowledge of these pathways allows an analysis of the potential impacts of future climate change, as defined by IPCC climate change scenarios. In this paper, we examine the sensitivity, adaptability and vulnerability of hydrology and water resources to climate variability and change. We focus on the Columbia River Basin, which covers approximately 75 percent of the PNW and is the basis for the dominant water resources system of the PNW. The water resources system of the Columbia River is sensitive to climate variability, especially with respect to drought. Management inertia and the lack of a centralized authority coordinating all uses of the resource impede adaptability to drought and optimization of water distribution. Climate change projections suggest exacerbated conditions of conflict between users as a result of low summertime streamfiow conditions. An understanding of the patterns and consequences of regional climate variability is crucial to developing an adequate response to future changes in climate. (KEY TERMS: integrated regional assessment; climate sensitivity and vulnerability; management adaptability; long-term water resources planning; hydroclimatology; Columbia River Basin; climate variability; climate change.)

Seasonal flows of international British Columbia-Alaska rivers: The nonlinear influence of ocean-atmosphere circulation patterns

“…Many of the specific hydroclimatic processes inferred, such as higher autumn-winter streamflows or earlier snowmelt freshets under warmer air temperatures, have been widely observed either in this region, or alternatively in other areas of western North America (e.g., [3,22,25,68]). Our inference of higher-thannormal precipitation and streamflow in fall and early winter during ENSO and PDO warm phases is opposite to what is observed for the Pacific Northwest (PNW; [54,58]), to the south of our study area. This is consistent with a previously noted north-south see-saw in ENSOand PDO-related precipitation variations along the northern Pacific coast of North America [20,77], which is analogous to another, perhaps better-known see-saw in ENSO precipitation teleconnections between the US PNW and the US Southwest (e.g., [69]).…”

Trends in Precipitation, Streamflow, and Evapotranspiration in the Great Plains of the United States

“…Hu et al ͑1998͒ detected a gradual increase in precipitation since the mid1960s in the Central United States, and Garbrecht and Rossel ͑2002͒ identified a marked increase over the last two decades of the 20th Century for many regions of the Great Plains. The importance of such decade-scale variations in precipitation on the hydrologic system and on various weather dependent segments of our society has been recognized in numerous studies ͑Mantua et al 1997;Miles et al 2000;Hotchkiss et al 2000;Morehouse 2000͒. Lins and Slack ͑1999͒ found that streamflow trends in the contiguous United States were consistent with precipitation changes described by Karl and Knight ͑1998͒.…”

An approach to designing a national climate service

“…These include the following. , forest productivity and risk of forest fire, salmon returns, and quality of coastal and near-shore habitat (9,(19)(20)(21). Y Identifying 20th century trends in PNW temperature, precipitation, and snowpack.…”

“…CIG research on the impacts of climate change on the PNW projects significant challenges in the decades ahead for the region's water resources, salmon, forests, and coasts as a result of human-caused global warming. These include increased risk of winter flooding and summer drought; salmon mortality in freshwater habitats; forest fires; changes in Puget Sound ecosystem structure and function; and coastal erosion and flooding (9,26,27). Y Identifying barriers to the effective use of climate information and characteristics of adaptive institutions.…”

“…The true strength of the NCS concept is the regional focus of the service. Experience has shown that connections between climate scientists and stakeholders are most effective at the local, regional, statewide, and multistate scales at which the stakeholders operate (5,(9)(10)(11). It is also clear, as is shown in Evolution of the CIG as a Regional Resource in the PNW, that partnerships between long-lasting regional research and assessment teams such as the NOAA's RISA teams and groups of stakeholders lead to increased utility of decision tools and climate forecasts.…”