Transcript - Atmospheric Chemistry Modeling Group

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
Organic Carbon (OC) contribution
to W. United States fine aerosol:
40% in low fire years
55% in high fire years.
Mean summertime OC emissions over the Western United States 1980 – 2004
used in GEOS-Chem Model
Biogenics
232 Gg
Biogenics
Biofuel & fossil fuel
39 Gg
Fossil fuels
Biomass burning
97 Gg
Biomass burning
[Park et al., 2003; Spracklen et al., 2007]
hn
Ozone…
NO2
NO
OH
HO2
Ozone is generally
limited by the
supply of NOx
Primary constituent of smog in
surface air
Third most important greenhouse
gas
VOCs
Summertime NOx emissions over lower United States July 1 – August 15 2004 (ICARTT)
Stratosphere
1.33 Tg NO
0.02 Tg NO
0.58 Tg NO
0.04 Tg NO
Lightning
0.26 Tg NO
Soils
Fossil fuels
Biomass burning
[Hudman et al., 2007a]
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]
Interannual variability in summertime
OC driven by wildfires.
[Hudman et al., 2007b]
Wildfires can have hemispheric
scale effects on surface ozone
GISS GCM METEROLOGOICAL OUTPUT USED TO PROJECT FUTURE
EMISSIONS AND AIR QUALITY CHANGES
GISS general circulation model
1950 Spin-up 2000
Area Burned
Regressions
2025
changing greenhouse gases (A1B scenario)
2050
2075
archived met fields
GEOS-CHEM
Predict Area
Burned
Calculate
emissions
2100
Global chemistry model
Predicted change to summertime (June-Aug) Organic Carbon
concentrations over the US
Current (1996-2000)
Future-current
Future (2046-2050)
Future / current
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*
Biomass burning NOx emissions
2000
Mean of 5 ppbv
enhancement due
to fires a > 2 SD
2051
[Gg NO]
[ppbv]
* note: Changes due to climate change
alone have been subtracted out
OBSERVED JULY 2005 OZONE AT
MOUNT BACHELOR OBSERVATORY
In terms of air quality 3-6 ppbv means a lot in
the summer…..
U.S 8hr AQS
Courtesy of Dan Jaffe, University of Washington
http://research.uwb.edu/jaffegroup/modules/Rawdata/
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 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.