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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…

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slide1

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

slide2

Aerosols…

Organic Carbon (OC) contribution to W. United States fine aerosol:

40% in low fire years

55% in high fire years.

  • Degrade visibility
  • Impact health
  • Have highly uncertain impacts on climate forcing

Mean summertime OC emissions over the Western United States 1980 – 2004 used in GEOS-Chem Model

Biogenics

232 Gg

Biomass burning

97 Gg

Biofuel & fossil fuel

39 Gg

Biogenics

Biomass burning

Fossil fuels

[Park et al., 2003; Spracklen et al., 2007]

slide3

hn

Ozone…

Ozone is generally limited by the supply of NOx

  • Primary constituent of smog in surface air
  • Third most important greenhouse gas

NO

NO2

OH

HO2

VOCs

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

Stratosphere

1.33 Tg NO

0.04 Tg NO

0.02 Tg NO

0.58 Tg NO

Lightning

0.26 Tg NO

Biomass burning

Soils

Fossil fuels

[Hudman et al., 2007a]

slide4

PRESENT DAY EFFECTS OF WILDFIRES ON ATMOSPHERIC CONCENTRATIONS

Jun-Aug mean

IMPROVE sites W of 100oW

Simulated July 2004 ozone enhancement

from NA biomass burning 0-2 km

[Spracklen et al., 2007]

[Hudman et al., 2007b]

Interannual variability in summertime OC driven by wildfires.

Wildfires can have hemispheric scale effects on surface ozone

slide5

GISS GCM METEROLOGOICAL OUTPUT USED TO PROJECT FUTURE EMISSIONS AND AIR QUALITY CHANGES

changing greenhouse gases (A1B scenario)

GISS general circulation model

1950 2000 2025 2050 2075 2100

Spin-up

Area Burned Regressions

archived met fields

GEOS-CHEM

Global chemistry model

Predict Area Burned

Calculate emissions

slide8

Predicted change to summertime (June-Aug) Organic Carbon concentrations over the US

Current (1996-2000)

Future (2046-2050)

Future-current

Future / current

Summertime OC concentrations predicted to increase by 25-50% over much of the western US.

[Spracklen et al., in preparation]

slide9

PREDICTED AFTERNOON (1-5pm) JULY MEAN OZONE INCREASE DUE TO WESTERN U.S. BIOMASS EMISSIONS 3-6 PPBV*

Biomass burning NOx emissions

2000

Mean of 5 ppbv

enhancement due

to fires a > 2 SD

2051

[Gg NO]

* note: Changes due to climate change alone have been subtracted out

[ppbv]

slide10

OBSERVED JULY 2005 OZONE AT MOUNT BACHELOR OBSERVATORY

In terms of air quality 3-6 ppbv means a lot in the summer…..

U.S 8-hr AQS

Courtesy of Dan Jaffe, University of Washington

http://research.uwb.edu/jaffegroup/modules/Rawdata/

slide11

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.
slide13

Canadian Fire Weather Index

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

slide14

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]

slide15

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)

slide16

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 area

burned 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.