Transcript ppt - Berkeley Atmospheric Sciences Center

EFFECTS OF CLIMATE CHANGE ON FOREST FIRES
OVER NORTH AMERICA AND IMPACT ON U.S. OZONE
AIR QUALITY AND VISIBILITY
Rynda Hudman 1,2, Dominick Spracklen 1,3, Jennifer Logan1,
Loretta J. Mickley1, Maria Val Martin1,4, Shiliang Wu1,5, Rose Yevich1,
Alan Cantin6, Mike Flannigan6, Tony Westerling7
UC BERKELEY
GEOGRAPHY SEMINAR
DECEMBER 10, 2008
Affiliations: 1 School of Engineering, Harvard
2 Now at UC Berkeley
3 Now at University of Leeds
4 Now at Barcelona Supercomputing Center
5 Now at Michigan Tech
6 Canadian Forest Service
7 UC Merced
WHY DO ATMOSPHERIC SCIENTIST CARE ABOUT
WILDFIRES?
• Releases 1-4 Pg C / yr (~30-50% of the fossil fuel source)
• Accounts for 2/3 of the variability in CO2 growth rate between
1997 and 2001
• 20-60% of the global organic carbon aerosol (particulate)
emission, 30% of the black carbon (soot) emission
• Potential for climate feedbacks
•Impacts ozone/aerosol air quality, visibility, human health
TROPICS DOMINATE FIRE ACTIVITY BUT NORTH AMERICAN
RECORD PUNCTUATED BY LARGE FIRE YEARS
[Bowman et al., 2009]
Mean area burned:
~3 million hectares
2x size of Connecticut
Large fire years 
increase emissions by
X10
NORTH AMERICAN FIRES AFFECT ATMOSPHERIC
COMPOSITION ON A HEMISPHERIC SCALE
In 2004, a blocking ridge set up over Canada and Alaska creating one of the
largest fire seasons on record.
http://asl.umbc.edu/pub/mcmillan/www/index_INTEXA.html
LOCAL EFFECTS OF WILDFIRE EMISSIONS
Hayman fire caused worst air quality ever in Denver
 56000 ha, June 8-22, 2002
 30 miles from Denver and Colorado Springs
 EPA 24-hr standard = 35 µg/m3, and annual standard = 15 µg/m3.
June 8, 2002
PM10 = 40 μg/m3
PM2.5 = 10 μg/m3
Colorado Department of Public Health and Environment
Vedal et al., Env Res, 2006
June 9, 2002
PM10 = 372 μg/m3
PM2.5 = 200 μg/m3
WILDFIRE DRIVES INTERANNUAL VARIABILITY IN
ORGANIC CARBON AEROSOL IN THE SUMMER
Model gives same variability as
observed OC in summer at
IMPROVE sites in the West
OC contribution to total fine
aerosol:
40% in low fire years
55% in high fire years
same fires every year
[Spracklen et al., 2007]
[Spracklen et al., 2007]
PRESENT DAY FIRE IMPACTS ON OZONE
Ozone enhancement from NA biomass burning 0-2 km
Simulated July 2004 mean
Max enhancement during July 15-24 2004
8-hr max ozone air quality standard in the United States = 75 ppbv
[Hudman et al., 2009]
CLIMATE DRIVES FIRE ACTIVITY OVER NORTH AMERICA
Temperature
Rainfall
Wind speed
Relative Humidity
Other factors:
Large Scale circulation
Fuel availability
Ignition Source
Fire Suppression
Canadian Fire Weather Index Model
OBSERVED INCREASE IN WILDFIRE ACTIVITY OVER
NORTH AMERICA DUE TO CLIMATE CHANGE?
Area burned in Canada has
increased since the 1960s,
correlated with temp. increase.
5 year means
[Gillett et al., 2004]
Increased fire frequency over
western U.S. in recent decades
– related to warmer temp.,
earlier snow melt.
[Westerling et al., 2007]
PREDICTING THE IMPACT OF FUTURE CLIMATE CHANGE
ON WILDFIRE AND AIR QUALITY
1. DEVELOP RELATIONSHIPS BTWN CLIMATE AND ANNUAL AREA BURNED
OBSERVED AREA BURNED
OBS WEATHER & FUEL
MOISTURE/ FIRE SEVERITY
Yearly Area Burned = C1X1 + C2X2 + … + C0
Climate Model
2. CLIMATE MODEL OUTPUT
Output
PREDICT FUTURE AB
3. PRED. FUTURE AIR QUALITY
FUTURE AREA BURNED
Emissions
CHEMICAL TRANSPORT MODEL
I. WESTERN U.S. ECOREGIONS & MET USED IN
REGRESSION
Combine ecoregions of similar vegetation and topography
Use observed meteorology from surface weather stations (USFS)  FWI
(Spracklen et al., 2009)
WHERE ARE THE FIRES IN THE WESTERN U.S.?
Mean area burned (1º x 1º grid) in
1980-2004 (Westerling, UC Merced)
Mean fuel consumed
Large areas burned in CA and the southwest, but fuel burned is
greater in forest than in shrub ecosystems
The Pacific North West and Rocky Mountain Forests are most
important for biomass consumption and emissions.
(Spracklen et al., 2009)
PREDICTING WILDFIRE OVER THE WESTERN U.S.
R2 of Area Burned regressions
Area Burned (ha)
48%
52%
57%
37%
Area Burned (ha)
24%
49%
Regressions ‘capture’ 24 – 57%
of the interannual variability in
area burned over western US.
Temperature contributes 80-90%
of the regression in forested
regions.
Year
(Spracklen et al., 2009)
CHANGES IN MAY-SEPT TERMPERATURE (2000 – 2050)
GISS GCM3 A1B Scenario - CO2 concentrations reach 522ppm
Temperature
Predicted met Changes
Temp. +1-3ºC across West
Rainfall and RH increase slightly
Wind speed decreases slightly
(Spracklen et al., 2009)
PREDICTED INCREASE IN AREA BURNED
Pacific Northwest US
Observed area burned
Predicted area burned
78%
increase
Rocky Mountain Forests
175%
increase
Predicted area burned for 1995-2004 does not match observed areas
on a yearly basis, as it is based on GCM output, but 10 year mean is
(Spracklen et al., 2009)
the same.
PREDICTED INCREASE IN AREA BURNED
Pacific Northwest US
+ 1-3K
Rocky Mountain Forests
Predicted area burned for 1995-2004 does not match observed areas
on a yearly basis, as it is based on GCM output, but 10 year mean is
(Spracklen et al., 2009)
the same.
FUTURE WILDFIRE AND PARTICULATE AIR QUALITY
AB + FUEL
Change in wildfire biomass consumption
Emissions
Δbiomass consumption = + 90%
Change in surface OC aerosol (Jun-Aug)
Chemical
Transport
Model
Δsurface OC
aerosol = + 40%
Climate change projected to cause a 90% increase in biomass
consumed and 40% increase in OC concentrations by 2050.
(Spracklen et al., 2009)
FUTURE WILDFIRE AND PARTICULATE AIR QUALITY
Present day fires in
black, 1996-2000
Future fires in red,
2046-2050
OC increases by 40%, EC increases by 20% (not shown).
For OC, 75% of increase is from fire emissions, 25% from higher
biogenic emissions in a warmer climate.
(Spracklen et al., 2009)
PREDICTED JULY MEAN MAXIMUM 8-HR OZONE
perturbation from fires doubles
5 Years Future (2046-2050) vs. 5 Years Present (1996-2000)
Consistent with these results, recent observational estimates of regional
enhancements of 2 ppbv for each 1 million acres burned [Jaffe et al., 2008]
(Hudman et al., in prep)
SUMMARY WESTERN U.S.
•Regressions capture much of the variability in annual area
burned over the western U.S. (24-57%). Temperature is the key
predictor.
• 2050 climate change (A1B) is predicted to increase annual
mean area burned over western U.S. (+54%)  90% increase
in biomass consumed relative to the present-day driven by 1-3K
increase in temperature.
• Future fires drive a 40% increase in organic carbon aerosol
over the western US and a 1-3 ppbv enhancement (doubling fire
enhancement) in summertime afternoon ozone.
II. BOREAL ECOREGIONS & MET USED IN REGRESSION
Largest Area
Burned over Plain
regions
[French et al., 2003]
[Stocks et al., 1999]
[105 ha]
Combine ecoregions of similar vegetation and topography (12 ecoregions)
Alaska wx stations (USFS) & Canadian wx stations (CFS)
(Hudman et al., in prep)
SUMMER 2004: 500hPa GEOPOTENTIAL HEIGHT
Height of pressure level above mean sea level
Strong ridges are accompanied by warm and dry weather conditions at the sfc
+60
Jul 1 – Aug 15 2004
Anomaly
Strong Alaskan Ridge  record fires
(Hudman et al., in prep)
CANADIAN FIRE WEATHER INDEX MODEL
Drying
time
2/3 day
15 day
52 day
Severity Rating
Severity Rating is a combination of drought and fire spread potential
REGRESSIONS CAPTURE VARIABILITY IN REGIONS WITH LARGEST
AREA BURNED (15-62%)
ALASKA/CANADA SUMMARY: 2-3 predictors chosen per region
Most Common Predictors:
•Monthly/Seas. 500 mb GPH Anomaly (Max contributor 7/12 ecoregions)
•Max/Mon./Seasonal Severity Rating (Max contributor in 3/12 ecoregions)
More influenced by fire
suppression and human
caused fires
GPH was chosen over temperature (Hudman et al., in prep)
PREDICTING WILDFIRE OVER CANADA AND ALASKA
- - - national totals for Canada (not included in regression) + Alaska
Regressions capture 71% of the variability in Canada and Alaska
About as good a non-linear regression which use many more variables
(Hudman et al., in prep)
DOES RAIN OFFSET TEMPERATURE/GPH INCREASE?
GISS simulated May – August 2046-2055 vs. 1996-2005
June 500mb anomaly over Fairbanks, Alaska (1940 – 2006)
GISS Mean 1999-2008 : -14 m
2045-2054 : 5 m
[Fairbanks GPH Courtesy of Sharon Alder, BLM]
(Hudman et al., in prep)
DOES RAIN OFFSET TEMPERATURE INCREASE?
GISS simulated May – August 2046-2055 vs. 1996-2005
Rain
Seasonal Severity Rating
Dry spell length important…GISS suggests decreased dry spell length,
likely very model dependent
(Hudman et al., in prep)
MOST GCMS PREDICT INCREASED SUMMERTIME
PRECIPITATION
A1B 1980-1999 vs. 2080-2099
Predicted Summer ppt Change
# of models showing increased ppt
Dry spell length important…GISS suggests decreased dry spell length,
likely very model dependent
(IPCC, 2007, Ch 11)
PREDICTED CHANGE IN AREA BURNED
2000-2050 change in area burned
GPH
dominates
DSR
dominates
Combination
34% increase over Alaska, 8% (-34 to +118%) increase in
Canada. Large regional variability. Seems consistent with
recent study by Meg Krawchuck (UCB)
(Hudman et al., in prep)
PREDICTING FUTURE AIR QUALITY
• Distribute annual area burned by month ( ha/month)
• Randomly place AB w/in ecosystem into 1°x1° (based on
current fire size stats)
• Combine with fuel consumption which varies throughout
season based on fuel moisture + make assump. severity (kg
DM/ha)
• Combine with emission factors ( g species/kgDM)
• Assume 20% of emissions in FT (Maria Val Martin MISR work)
• Input into GEOS-Chem CTM (w/ GISS met)  future air quaity
(Hudman et al., in prep)
PRESENT DAY SURFACE OZONE ENHANCMENT JUL-AUG
Fires predicted to enhance 8-hr max ozone by 3-10 ppbv, 1-4 ppbv
reaching Midwest U.S.
(Hudman et al., in prep)
CHANGE IN SURFACE OZONE ENHANCMENT JUL-AUG
Doubling of enhancement over Alaska, 1-2ppbv increase over populated
Quebec cities and Midwest (20-40% increase)
A decrease of ozone toward the Arctic
(Hudman et al., in prep)
PERCENT CHANGE IN SURFACE OC/EC JUL-AUG
Preliminary Result
[%]
Transport of Black Carbon aerosol to the Arctic decreases by 40%
(Hudman et al., in prep)
FUTURE WORK
• Examine change in extreme events using current simulations and
Regional modeling (U. Houston)
• Implement plume rise model into GEOS-Chem (Maria Val Martin)
• Improve regressions of desert southwest using PDSI (Harvard)
• Update Canada/Alaska regressions LFDB when avail.
•Do an envelope study of GCM response to Canada/Alaska
regressions to look at variability in response (Harvard)
•Impacts of new understanding of NOx emission factors on ozone
response (Harvard, Anna Mebust UCB)
Thanks for your attention!
SUMMARY CANADA/ALASKA
•Regressions capture much of the variability in annual area burned over Alaska
(53-57%), and Canada (15-62%). Key predictors : 500 mb GPH anomaly &
severity rating.
• 2050 climate change (A1B) increases annual mean area burned: Alaska
(+34%) relative to the present-day, but unlike most previous studies little
change over Canada as a whole (8%), but varies regionally (-34 - + 118%) due
to increases in GCM precipitation vs. temperature (scenario/GCM dependent).
•Present day ozone enhancements due to wildfire 3-10 ppbv over Canada and
Alaska. Future fire increases range from -2 - +4 ppbv. Large decreases of BC
toward the Arctic.
1. WILDFIRE PREDICTION MODEL
Observed daily
Temperature, Wind
speed, RH, Rainfall,
Canadian Fire
Weather Index
System
Daily forest
moisture/fire danger
parameters
500hpa GPH anom.
(Canada/Alaska)
Area burned
database
Aggregate area
burned to
ecosystem
Stepwise linear regression
between meteorological/forest
moisture variables & area burned
[Flannigan et al. 2005]
Linear stepwise
regression
Predictors of
Area Burned
IMPLICATION OF RISING OZONE BACKGROUND
FOR MEETING AIR QUALITY STANDARDS
Europe AQS
(8-h avg.)
Europe AQS
(seasonal)
0
Preindustrial
ozone
background
20
40
U.S. AQS
(8-h avg.)
60
80
U.S. AQS
(1-h avg.)
100
120 ppb
Present-day ozone
background at
northern midlatitudes
EPA policy-relevant background (PRB) : U.S. surface ozone concentrations
that would be present in absence of North American anthropogenic emissions
PRB is not directly observable and must be estimated from global models
GEOS-Chem GLOBAL MODEL OF TROPOSPHERIC CHEMISTRY
http://www.as.harvard.edu/chemistry/trop/geos
• Driven by NASA/GEOS assimilated
meteorological data with 6-h temporal
resolution (3-h for surface quantities)
• Horizontal resolution of 1ox1o, 2ox2.5o, or
4ox5o; 48-72 levels in vertical
• Detailed ozone-NOx-VOC-PM chemical
mechanism
• Applied by over 30 research groups in U.S.
and elsewhere to a wide range of problems
in atmospheric chemistry
• Extensively evaluated with observations
for ozone and other species (~200 papers in
journal literature)
Mean Asian surface pollution
enhancement (GEOS-Chem)
Global Carbon Emissions
49% Africa
13% South America
11% equatorial Asia
9% boreal forests
6% Australia
Short-lived Pollutants Affect Climate and Air Quality
[IPCC, 2007]
Regulations of short-lived species that improve air quality and warm the planet (BC)
present a “win-win” situation, while regulations of short-lived species that reduce
cooling and improve air quality (SO2) present a “win-lose” situation.
ACCOUNTING FOR DRIZZLY GCM
-------- Corrected (GISS – 1.5 mm)
_____ Uncorrected
Frequency
Observations
GISS Present Day
GISS Future
Dryspell Length (days)
An increase from current conditions (red) is indicated by a PΔ greater than unity,
little or no change (yellow) is indicated by a PΔ around unit, and a decrease (green) is
indicated by a PΔ less than unity. Panels show the mean PΔ for the ensemble of ten
FIRENPP (A–C) and FIREnoNPP (D–F) sub-models. Climate projections include 2010–20
(A, D), 2040–2069 (B, E) and 2070–2099 (C, F).