Cascade Snow Pack. By Meg Coyne and Allison Blonden

Transcription

1 Cascade Snow Pack By Meg Coyne and Allison Blonden

2 Is the Cascade snowpack decreasing? Cliff Mass vs. Alan Hamlet Future decrease on snowpack is inevitable Percentage change from the baseline in the April 1 snowpack in four areas of the western US as simulated for the 21st century by the Canadian and Hadley models. April 1 snowpack is important because it stores water that is released into streams and reservoirs later in the spring and summer. The sharp reductions are due to rising temperatures and an increasing fraction of winter precipitation falling as rain rather than snow. The largest changes occur in the most southern mountain ranges and those closest to the warming ocean waters By the National Assessment Synthesis Team, US Global Change Research Program Published in 2000

3 Is the Cascade snowpack decreasing? MASS: Though previous measurements of the 20th century estimated a 30% decrease in snow pack, this data was recently reviewed by University of Washington meteorologist, Cliff Mass. Mass s study theorizes that it all depends on which years are examined. Because snowpack measurements before the 1950 s are spotty and because snowpack levels during the 1950 s were unusually high, Mass believes that the 30% estimated drop in snowpack is distorted. Taking these errors into account Mass and his colleagues hypothesized a new estimate of 23% lower snowpack measurements. Though this estimate still seems detrimental, Mass also adds that many of these changes could be attributed to the Pacific Ocean s affect on weather patterns. HAMLET: Refuting Mass s hypothesis is his colleague, Alan Hamlet. Hamlet disagrees with Mass on the idea that snowpack decrease could be blamed on fluctuating ocean conditions, claiming that there is too much correlation with increasing temperatures to not take global warming into account. Also, Hamlet points out the large amount of error in measuring oceanic fluctuations. CONSENSUS: Though there is an ongoing debate between Pacific Northwest scientists, everyone agrees on one thing: that future global warming will indeed impact the Cascades in a number of detrimental ways, including a significant loss of snowpack. Dr. Cliff Mass Dr. Alan Hamlet

4 What are the effects of decreased snowpack? February 1, 2008 February 1, 2009 Earlier snow melt/runoff Altered salmon migration/spawning Decreased hydroelectric energy Recreational loss Water pollution

5 Effects on Precipitation Due to warmer temperatures more precipitation will fall as rain instead of snow, decreasing the snow pack. Furthermore, the snow that does accumulate will melt much earlier in the spring (as snow recedes there is less water to feed into rivers). Concurrently, melting will occur so much in advance that summer water supplies will be affected. This reduced summer streamflow will be detrimental to such things as agricultural irrigation, drinking water supply, fish and wildlife, and hydropower production. Grand Coulee Dam, the largest electric power producing facility in the United States

6 Effect on Salmon Salmon rely on timely, abundant, cold, clean water to spawn effectively. Climate change puts numerous stresses on them including less oxygen and uncomfortable water temperatures. Washington s warm ocean temperatures in 2005 reduced juvenile salmon by 20-30%. Apart from it s negative affect on spawning, warmer river flow will decrease water volume. Warmer water holds less oxygen and will likely put stresses on fish that require cold water to thrive because of their need for oxygen and also because it changes the amount of food that is able to grow in the water for them like algae. Effects on Water Pollution Increased runoff from melting snowpacks and rain precipitation carries numerous pollutants including car oil, antifreeze, fertilizer, and pesticides, which collect in flood-prone river basins.

7 Effects on Hydropower Electricity Dams generate 72% of Washington s electricity (compared to the national average of 7% from dams). Increased temperatures will affect hydropower by reducing the demand for heating in winter, when Northwest hydropower is cheap, and increasing demand in summer for air conditioning, when Northwest hydropower is more expensive. Grand Coulee Dam, the largest electric power producing facility in the United States Effects on Recreation Winter recreational activity will continue to be hurt by decreased snowpack. Over 40% of Washington s snow recreation occurs at lower altitudes where snowpack has, and will continue to decrease exponentially.

8 Sources: "Climate Change Impacts on the United States." US Global Change Research Program. 19 Feb < "Mountain Snowpack Maps." Natural Resources Conservation Service. United States Department of Agriculture. "Reduced Snowpack and Earlier Runoff." Climate Change. Washington State Department of Ecology. < "Reduced Snow Pack and Earlier Runoff." Department of Ecology. Department of Ecology. 24 Feb 2009 <