Climate Model Predicts Wet Winters, Dry Summers For Northwest

RICHLAND, Wash. - Farming and snow skiing may not be the same in the Northwest if carbon dioxide levels double as projected by 2080, according to a scenario produced by a new regional climate change model.

The model, created by researchers at the Department of Energy’s Pacific Northwest National Laboratory, indicates the Northwest will have significantly warmer and wetter winters in 80 years unless carbon dioxide emissions are reduced greatly. PNNL scientists tested the new regional climate model on the Northwest - Washington, Oregon, Idaho and western Montana. Assuming carbon dioxide levels will double in the next 80 years as many experts predict, the model shows that in 2080 there will be:

• A 50 percent decrease in snow cover over the entire state of Washington;

• A 50 to 90 percent decrease in snowpack near the existing snow line in Washington state;

• An increase in winter precipitation in the form of rain;

• An average increase of winter temperatures of 3 to 5 degrees Fahrenheit;

• An average increase of summer temperatures of 2 degrees Fahrenheit.

The impacts to water resources could be significant, say PNNL project managers.

“With less winter snow, we would have less snow melt in the spring,” said Ruby Leung, principal investigator. “We would not have enough stream flow for irrigating crops when we need it most - in June or July.”

“By bringing the issue to a regional level, we help people understand how a global problem could impact them directly,” Leung said. “It’s easier to understand if you know your crops could suffer from lack of irrigation water or your favorite ski resort has to scale back operations.”

The information compiled from this regional climate model is being supplied to the U.S. Environmental Protection Agency. The EPA also will use the regional climate change data to estimate how these predicted changes in water resources could impact vegetation.

PNNL’s new regional climate model is a more accurate way of determining global warming’s effects on targeted areas. PNNL scientists begin by using a global climate model to determine the environmental influences in a specific region, such as the Northwest. Influences include surface temperatures, precipitation and snow cover. Then the model merges environmental information such as soil conditions, existing vegetation and surface elevations from subareas within that region to create a more detailed picture of global warming’s impacts. This method is similar to that used in other regional climate models developed in the United States.

However, the PNNL model uses a novel approach that utilizes surface topographic information in the model’s analysis. Therefore, PNNL’s regional climate model can provide climate change data at higher resolutions, which are needed to assess local impacts. The laboratory’s regional climate model incorporates environmental data from areas as small as one square kilometer. Other regional models typically generate climate change data at resolutions between 40 and 120 square kilometers.

Development of the regional climate model began in 1992. PNNL funded the first three years of research through $300,000 of internal funds. The EPA funded further development with $500,000 over three years, ending in October 1998. The model can be applied to other regions throughout the United States.

In June, Leung began a three-year contract with the National Oceanic and Atmospheric Administration to use the new regional model to predict climate variability and the impact on water resource management of seasonal changes such as El Niño.

Pacific Northwest is one of the nation's leaders in climate change research. The laboratory is a participant in the Atmospheric Radiation Measurement project, DOE’s largest global climate change program, and the international Surface Heat Budget of the Arctic, or SHEBA, project. Pacific Northwest researchers also have been key contributors to the United Nations’ panel of scientific experts assessing the impacts of climate change.

Pacific Northwest is one of DOE’s nine multiprogram national laboratories and conducts research in the fields of environment, energy, health sciences and national security. Battelle, based in Columbus, Ohio, has operated Pacific Northwest for DOE since 1965.