Wildfires & Changing Vegetation
As our Pacific Northwest summers become warmer and drier under climate change, conditions are expected to become ideal for larger, more destructive wildfires. This conclusion has been arrived at by multiple studies, including several by CIRC researchers. Climate change is also believed to be responsible for the recent growth in wildfires in Western U.S. forests. (A sampling of our work on this subject can be found below.)
The very large fires projected under climate change are expected to be destructive both in the short term—leading to property damage, safety concerns, and poor air quality—and in the long term. Over the long term, larger, more destructive fires are projected to contribute to major ecological changes. These changes in turn are expected to accelerate a related impact of our warming climate: plant migration.
As our climate warms, plant species in the northern hemisphere are responding by moving to higher latitudes and higher elevations. This process has already happened here in the Pacific Northwest and is projected to continue into the future. The increased prevalence of very large fires under climate change is expected to accelerate these vegetation shifts, making it harder for the Pacific Northwest’s current plant inhabitants—species that are already becoming out of synch with the local climate—to reestablish themselves in the aftermath of these fires. Simultaneously, very large fires are expected to help clear the way for migrating species from the south.
To make this more concrete, consider Oregon’s fertile Willamette River Basin. As part of our Integrated Scenarios and Willamette Water 2100 projects, CIRC researchers simulated future conditions we might expect under climate change. By the end of this century, the basin’s lower elevation vegetation is expected to shift from maritime conifer forests to subtropical mixed forests of conifer and broadleaf species, according to our analysis. Likely plant beneficiaries of this climatic and ecological change are Pacific madrone and tanoak, two species now commonly found in the Coastal Mountains as well as the Sierra Nevada Mountains some 800 kilometers (500 miles) to the south.
Abatzoglou, John T., and A. Park Williams. “Impact of anthropogenic climate change on wildfire across western US forests.” Proceedings of the National Academy of Sciences 113, no. 42 (2016). doi: 10.1073/pnas.1607171113.
Bachelet, Dominique, Ken Ferschweiler, Timothy J. Sheehan, Benjamin M. Sleeter, and Zhiliang Zhu. “Projected carbon stocks in the conterminous USA with land use and variable fire regimes.” Global Change Biology 21, no. 12 (2015): 4548–4560. doi:10.1111/gcb.13048.
Barbero R., John T. Abatzoglou, N. K. Larkin, C. A. Kolden, and B. Stocks. “Climate change presents increased potential for very large fires in the contiguous United States.” International Journal of Wildland Fire (2015). http://dx.doi.org/10.1071/WF15083.
“Integrated Scenarios of the Future Northwest Environment,” University of Idaho, accessed December 13, 2016, http://climate.nkn.uidaho.edu/IntegratedScenarios/.
Rupp, David E., John T. Abatzoglou, Katherine C. Hegewisch, and Philip W. Mote. "Evaluation of CMIP5 20th century climate simulations for the Pacific Northwest USA." Journal of Geophysical Research: Atmospheres 118, no. 19 (2013).doi:10.1002/jgrd.50843.
Stavros, E. Natasha, John T. Abatzoglou, Donald McKenzie, and Narasimhan K. Larkin. "Regional projections of the likelihood of very large wildland fires under a changing climate in the contiguous Western United States." Climatic Change 126, no. 3-4 (2014): 455-468.doi:10.1007/s10584-014-1229-6.
Sheehan, Tim, Dominique Bachelet, and Ken Ferschweiler. “Projected major fire and vegetation changes in the Pacific Northwest of the conterminous United States under selected CMIP5 climate futures.” Ecological Modeling 317 (2015): 16–29. http://dx.doi.org/10.1016/j.ecolmodel.2015.08.023.
Turner, David P., William D. Ritts, Robert E. Kennedy, Andrew N. Gray, and Zhiqiang Yang. "Effects of harvest, fire, and pest/pathogen disturbances on the West Cascades ecoregion carbon balance." Carbon balance and management 10, no. 1 (2015): 12. doi:10.1186/s13021-015-0022-9.
Turner, David P., David R. Conklin, and John P. Bolte. "Projected climate change impacts on forest land cover and land use over the Willamette River Basin, Oregon, USA." Climatic Change 133, no. 2 (2015): 335-348. doi:10.1007/s10584-015-1465-4.