Climate warming may first show up in forests as increased growth, which occurs as warmer temperatures, increased carbon dioxide, and more precipitation encourage higher rates of photosynthesis. The second way that climate change may show up in forests is through changes in disturbance regimes-the long-term patterns of fire, drought, insects, and diseases that are basic to forest development. Advanced computer models are producing the first national-scale simulations of how ecosystems and fire regimes could change in the 21st century. In six of seven future scenarios run through one model, the Western United States gets wetter winters and warmer summers throughout the 21st century (as compared to current climate), with expanded woody growth across the West and thus, increased fire risk. These results have been used in national and global assessments of global climate change. The computer model can now produce 7-month forecasts of possible fire risks for the conterminous United States, made possible by incorporating year-to-year changes in climate, fuel loadings, and moisture into the model. The accuracy of 2002 and 2003 forecasts has validated the model's approach, suggesting it can eventually be a useful planning tool for fire managers. Research results were produced by scientists from the USDA Forest Service Pacific Northwest (PNW) Research Station, working with others from Oregon State University and from around the world. The team's research has led to the key insight that fire and fuel load issues in Western forests are linked to global carbon balance issues. The full story is inside.