Climate Models Predict Wetter Winters, Warmer Summers In The West

Scientists have now developed computer models that are producing the first simulations of how ecosystems and fire regimes could change in the 21st century. Some of these simulations are showing that the Western United States may get wetter during the winter and experience warmer summers throughout the 21st century. These results have been used in national and global assessments of global climate change.

The research, conducted by scientists from the USDA Forest Service Pacific Northwest Research (PNW) Station, Oregon State University, and others from around the world, provides key evidence that fire and fuel loads in Western forests are linked to global carbon balance.

The research team, led by PNW Research Station bioclimatologist Ron Neilson, developed the mapped-atmosphere-plant-soil system model (MAPSS) that can simulate vegetation type in any area of the world and can determine the impact of global climate change.

"Climate change shows up in forests first as changes in growth," says Neilson. "The second way is through changes in disturbance regimes--the long-term patterns of fire, drought, insects, and diseases that are basic to forest development."

Because fire plays a big role in changing ecosystems, Neilson and his team combined the MAPPS model with CENTURY (MC1), a biogeochemical model produced by a team at Colorado State University, as well as a new fire model.

"MC1 accurately simulated the fire pulses of the last 100 years, with the big fires in the same areas where they actually occurred," says Neilson. "It simulated the 1910 fires in Idaho, and it nailed Yellowstone in 1988. It was in the ballpark on the Tillamook Burn of the 1930s and a year early on the Biscuit Fire in southwest Oregon, which actually burned in 2002."

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For more information go to http://www.fs.fed.us/pnw/corvallis/mdr/mapss/consensus