Effects of climate change on forest fires over North America and impact on U.S. air quality and visibility Rynda Hudman, Dominick Spracklen, Jennifer Logan, Loretta Mickley, Shiliang Wu, Rose Yevich Mike Flannigan, Tony Westerling

Aerosols…  Degrade visibility  Impact health  Have highly uncertain impacts on climate forcing Biomass burning Fossil fuels Biogenics 232 Gg Biofuel & fossil fuel 39 Gg Biomass burning 97 Gg [Park et al., 2003; Spracklen et al., 2007] Mean summertime OC emissions over the Western United States 1980 – 2004 used in GEOS-Chem Model Organic Carbon (OC) contribution to W. United States fine aerosol: 40% in low fire years 55% in high fire years.

Ozone…  Primary constituent of smog in surface air  Third most important greenhouse gas Biomass burning Fossil fuels Soils Lightning 1.33 Tg NO 0.26 Tg NO 0.02 Tg NO Stratosphere 0.58 Tg NO OHHO 2 VOCs NO NO 2 h [Hudman et al., 2007a] Ozone is generally limited by the supply of NO x Summertime NO x emissions over lower United States July 1 – August (ICARTT) 0.04 Tg NO

Interannual variability in summertime OC driven by wildfires. Jun-Aug mean IMPROVE sites W of 100 o W PRESENT DAY EFFECTS OF WILDFIRES ON ATMOSPHERIC CONCENTRATIONS [Spracklen et al., 2007] Simulated July 2004 ozone enhancement from NA biomass burning 0-2 km Wildfires can have hemispheric scale effects on surface ozone [Hudman et al., 2007b]

Calculate emissions archived met fields GEOS-CHEM Global chemistry model GISS general circulation model Spin-up changing greenhouse gases (A1B scenario) Predict Area Burned Area Burned Regressions GISS GCM METEROLOGOICAL OUTPUT USED TO PROJECT FUTURE EMISSIONS AND AIR QUALITY CHANGES

Current ( )Future ( ) Future-currentFuture / current Predicted change to summertime (June-Aug) Organic Carbon concentrations over the US Summertime OC concentrations predicted to increase by 25-50% over much of the western US. [Spracklen et al., in preparation]

PREDICTED AFTERNOON (1-5pm) JULY MEAN OZONE INCREASE DUE TO WESTERN U.S. BIOMASS EMISSIONS 3-6 PPBV* 2051 [ppbv] Biomass burning NO x emissions 2000 [Gg NO] * note: Changes due to climate change alone have been subtracted out Mean of 5 ppbv enhancement due to fires a > 2 SD

U.S 8- hr AQS OBSERVED JULY 2005 OZONE AT MOUNT BACHELOR OBSERVATORY Courtesy of Dan Jaffe, University of Washington In terms of air quality 3-6 ppbv means a lot in the summer…..

Conclusions Regressions of annual area burned in western US capture 50-57% of interannual variability. Temperature and fuel moisture are best predictors. Using GCM output in these regressions predict a 50-90% increase in area burned over the Western United States  50% increase in OC and NO x emissions by (relative to ). These emissions lead to a predicted increase in mean summertime OC by up to 50% and ozone by 3-6 ppbv, with important implications for meeting air quality standards. Future Work We will use the same methodology to produce Alaskan and Canadian AB predictions thru 2054 and examine subsequent impact on aerosol and ozone air quality over the Eastern United States.

Some extras….

Canadian Fire Weather Index

NOTES ON A1B SCENARO “The A1 scenario family further distinguishes three sub-scenarios (A1FI, A1T, A1B) by technological emphasis. These scenarios have been extensively applied for climate change projections using general circulation models (GCMs) [IPCC 2001, 2007]. All scenarios project a global increase of anthropogenic emissions of ozone precursors for , largely driven by economic growth in developing countries, but most project decreasing emissions in OECD countries including the United States. CO2 reaches 522 ppm 2050 in A1B scenario” [Extracted from Wu et al., 2007a]

Emission Factors (g molec/kg dry mass or gC/kg dry mass as specified) TRACERS Ecosystem Type Extratropical Forests (b) NO CO ALK4(C) ACET MEK(C) ALD2(C) PRPE(C) C3H8 CH2O C2H6 SO2 NH3 BC(C) OC(C) 3.00E E E E E E E E E E E E E E+00 From...Andrae and Merlet recent updates (personal communication via J. Logan)

References Park, R. J., D. J. Jacob, M. Chin and R. V. Martin, Sources of carbonaceous aerosols over the United States and implications for natural visibility, J. Geophys. Res., 108(D12), 4355, doi: /2002JD003190, Westerling, A., A. Gershunov, T. Brown, D. Cayan, and M. Dettinger (2003), Climate and wildfire in the western united states, Bulletin of the American Meteorological Society, 84 (5), Flannigan, M., K. Logan, B. Amiro, W. Skinner, and B. Stocks (2005), Future area burned in Canada, Climatic Change, 72 (1-2), Hudman, R. C., et al. (2007), Surface and lightning sources of nitrogen oxides over the United States: magnitudes, chemical evolution, and outflow, J. Geophys. Res., 112, D12S05, doi: /2006JD Wu, S., L.J. Mickley, D.J. Jacob, J.A. Logan, R.M. Yantosca, and D. Rind (2007), Why are there large differences between models in global budgets of tropospheric ozone?, J. Geophys. Res., 112, D05302, doi: /2006JD Spracklen, D. V., J. A. Logan, L. J. Mickley, R. J. Park, R. Yevich, A. L. Westerling, and D. Jaffe (2007), Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer, Geophys. Res. Lett., 34, L16816, doi: /GL