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 burningFossil fuelsBiogenics

Biogenics232 Gg

Biofuel & fossil fuel39 Gg

Biomass burning97 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 burningFossil fuelsSoils

Lightning

1.33 Tg NO

0.26 Tg NO

0.02 Tg NO

Stratosphere

0.58 Tg NO

OH HO2

VOCs

NONO2

h

[Hudman et al., 2007a]

Ozone is generally limited by the supply of NOx

Summertime NOx emissions over lower United States July 1 – August 15 2004 (ICARTT)

0.04 Tg NO

Interannual variability in summertime OC driven by wildfires.

Jun-Aug mean IMPROVE sites W of 100oW

PRESENT DAY EFFECTS OF WILDFIRES ON ATMOSPHERIC CONCENTRATIONS

[Spracklen et al., 2007]

Simulated July 2004 ozone enhancementfrom 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

1950 2000 2025 2050 2075 2100

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 (1996-2000) Future (2046-2050)

Future-current Future / 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 NOx 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 http://research.uwb.edu/jaffegroup/modules/Rawdata/

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 NOx emissions by 2045-2054 (relative to 1996-2004).

•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

http://fire.cfs.nrcan.gc.ca/research/environment/cffdrs/fwi_e.htm

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 2000-2050, 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+00 1.07E+02 3.20E-01 6.00E-01 9.00E-01 6.70E-01 1.00E+00 2.50E-01 2.20E+00 6.00E-01 1.00E+00 1.40E+00 5.60E-01 9.70E+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:10.1029/2002JD003190, 2003.

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), 595-604.

Flannigan, M., K. Logan, B. Amiro, W. Skinner, and B. Stocks (2005), Future areaburned in Canada, Climatic Change, 72 (1-2), 1-16.

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:10.1029/2006JD007912.

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:10.1029/2006JD007801.

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:10.0129/GL030037.