Lettenmair, D.P., Wood, W.W., Palmer, R.N., Wood, E.F., Stakhiv, E.Z. “Water Resources Implications of Global Warming: A U.S. Regional Perspective” Climatic Change 43 (1999): 537–579. (reviewed by Martin Anderson)
Summary:
The purpose of this article is to examine via statistical and predictive models the effect of global warming on six watersheds around the continental United States and is a compilation of 6 separate studies performed by the lead author. The watersheds are: the Columbia River, Missouri River, Apalachicola-Chatahoochee-Flint (ACF) Rivers, Tacoma River, Boston River, and Savannah River. This broad selection of rivers allows for a better understanding of overall total hydrological changes across different regions of the United State. The authors include a detailed description (major dams, human population, water usage, annual flow, etc.) and diagram outlining the current condition of each watershed.
The authors focus on how global warming will affect the human usage and availability of water resources. Two different global warming simulation protocols were used during this study. A General Circulation Model (GCM) (involving ocean and wind heat currents) with transient increased in local greenhouse gases (run by three separate climate prediction programs) and a fixed carbon dioxide GCM were used to gauge hydrological and climate changes as result of global warming in each watershed. The purpose of this was to compare the protocols and to gauge the effects of a fixed versus transient level of greenhouse gas in the atmosphere for predictive purposes. These models were set to express watershed data every ten model-years for 5 decades and took into account human and natural factors affecting the quality and quantity of water used.
The authors found that the Columbia River basin would experience an increase in evaporation and transpiration as the climate warmed which would be accompanied by increased precipitation for each model-decade of both simulations. These situations would allow for the increase in evaporation to be offset by precipitation such that total run-off would be maintained or exceed current levels. The run-off of the river tributaries (particularly those close to the headwaters) would probably decrease due to lower snow pack and melt earlier because of higher late winter temperatures. Run-off would increase at the Snake River due to increased precipitation making up for the lower level in other tributaries. This would cause problems for power generation and water reserves above the Snake River and within the Snake Rive potentially disrupt the water usage system due to excess water. Overall, this process would be very disruptive for water usage purposes and shift the peak flow of the river to the winter and early spring.
Each of the other rivers has a similar diagnosis whether it is from excess or scarce water due to climate change, but the authors conclusions are the same. The process of global warming will disrupt the flow and usage of many of the nation's river basins and negatively impact humans so long as current water usage levels are maintained.
Critique:
This article is useful to someone researching the effect of global warming on the hydrology of the Columbia River basin. The language is easy to understand and technical terms are defined by the authors. The paper is divided into the findings, description, and conclusion for each river making the information about each easy to find. The authors are very good about providing background information and maps of the watershed in this study.
It is important to remember that the predictions which the authors come to are generated by a limited computer model. This is a prediction based on a set of numbers. The implications however are quite profound. That global warming, a climate condition created by man, could potentially disrupt human activity as it pertains to the Columbia and other rivers in the ultimate feedback mechanism. It is interesting to see not only the effect that global warming has on the Columbia River but also other river systems. It is easy to look too closely at one example and forget that global warming is truly a global phenomenon with global implication.
43 Pages with 21 references
Robert D. Clark Honors College, University of Oregon
HC 441: Science Colloquium, Columbia River Ecology
Fall term, 2005
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