Transcript Climate change, fires, and carbon aerosol over N. America

Climate change, fires, and carbon
aerosol over N. America
with preliminary detour to discuss GCAP
model development
(GCAP= Global change and air pollution)
GCAP phase 2: Daniel Jacob (PI), Loretta Mickley,
Shiliang Wu, Daewon Byun, David Rind, Joshua Fu, John
Seinfeld, David Streets, Moeko Yoshitomi, Havala Pye,
Hong Liao, Yum-Fat Lam (Nicky), Hyun Cheol, et al.
Landcover project: Loretta Mickley, Shiliang Wu, Jed
Kaplan, Daniel Jacob
Wildfire project: Jennifer Logan (PI), Dominick Spracklen,
Rynda Hudman, Loretta Mickley, Daewon Byun, David
Diner, Qinbin Li
GCAP Phase 2: How will global change affect U.S. air quality?
Focus is on both climate change + changes in precursor and POA
emissions.
past atmospheres
GISS general circulation model
1950 Spin-up
2000
changing greenhouse gases
2025
2050
Wu et al. 2007a, b, c
Pye et al., 2007
2100
MM5
Mesoscale
model
archive met fields
Precursor
emissions
from Streets
2075
GEOS-CHEM
Global chemistry model
archive
chemistry
archive
met fields
CMAQ
Regional
chemistry model
GCAP is now part of standard model. Please keep us in the loop if you use GISS met!!
Land cover variation of GCAP: How will climate change affect
future land cover? What are the chem-climate interactions of land
cover change?
GISS general circulation model
1950 Spin-up
2000
Apply19502100 met fields
+ CO2
veg
LPJ
type +
vegetation
LAI
model
changing greenhouse gases
2025
2050
2100
Recalculate
2000-2100
climate
Archive met fields
GEOS-CHEM
Global chemistry model
Anthro
emissions
2075
Ozone and aerosol
(including dust)
Chemistry fields +
land cover change
will be fed back
into GCM.
First results from link between GISS GCM + LPJ Land Cover model
collaboration with J. Kaplan
1995
2060
Tropical
evergreen
broadleaf
Boreal
evergreen
needleleaf
Increase in boreal evergreens
Large
increases in
grassland
Temperate
grasses
Fractional landcover for 3 vegetation types
EPA wildfire project: How will changing forest fire
frequency affect future air quality over the United States?
Area burned and temperature in
Canada over the last century
Observed trends in
temperature and area
burned over Canada
show large interannual
variability.
Most of the variability in
wildfire frequency is due
to year-to-year changes
in surface temperatures
and precipitation.
Gillet et al., 2004
What will happen next? Dominick Spracklen developed a fire
prediction tool to calculate area burned using GISS GCM
meteorological variables.
. . . 2050 and beyond
Wildfires have a large impact on summertime organic carbon
aerosol over western United States [Spracklen et al., 2007]
Total OC [mg/m3], mean over all IMPROVE sites
We derive interannually varying
wildfire emissions over the western
United States using observed areas
burned [Westerling et al., 2003].
We then apply these emissions to
GEOS-Chem.
Observed OC
Model OC, with
interannually
varying fires
Results show an improved match
between observed and modeled
organic aerosol concentrations,
compared to calculations with
climatological fires.
Model OC, with climatological fires
In high fire years, forest fire OC account for 50-60% of total particle
concentrations over the IMPROVE sites in the western United States.
Dominick’s Fire Prediction tool for the western U.S:
1) Regress observed met variables and drought indices against linear area burned
2) Choose best predictors for each ecosystem.
3) Archive these predictors from GISS GCM for future climate.
Regressions ‘explain’ 50-60% of
variability in annual area burned in
forest ecosystems.
Best predictors are often temperature
or Fuel Moisture Index.
May-Oct mean obs Drought Code
1980
1990
2000
Area burned / 106 Ha
Sample results for Pacific Northwest/Cascade Forests.
0.5
observations
R2=52%
model
May-Oct Area burned
0.25
1980
1990
2000
May-Oct mean obs Temperature
1980
1990
2000
Variation of GCAP model to predict climate change impacts on
forest fires and air quality
GISS general circulation model
1950 Spin-up
Area Burned
Regressions
Predict Area
Burned
2000
changing greenhouse gases (A1 scenario)
2025
2050
archive met fields
2100
Organic
carbon
aerosol from
wildfires.
GEOS-CHEM
Global chemistry model
archive
chemistry
Calculate
emissions
2075
Fields will be
fed back into
GISS GCM to
calculate
chem-climate
interactions.
Predicted mean biomass consumption by wildfires over the western
United States for 2045-2054 is 50% greater than for 1996-2004.
Annual total biomass consumed by forest fires, 1996-2055
Use stochastic placement of wildfires within ecosystem and
ecosystem specific fuel loads.
Plot shows standardized departures from the 1996-2055 mean.
Predicted changes to summertime (June-Aug) Organic Carbon
concentrations over the US from GCAP model
Current (1996-2000)
Future (2046-2050)
Largest
increases
over
Rockies and
Pacific
Northwest.
Future-current
Future / current
Dr. Hudman
will continue
this work with
full chemistry
GCAP model.
Summertime OC concentrations predicted to increase by ~30%
over western US.
Conclusions
• In western United States, interannual variability in summertime OC is
driven by variability in fires.
• Increased fires in western US since the mid 1980s has likely caused
increase in summertime OC concentrations.
• Regressions of annual area burned in western US capture 50-57% of
interannual variablity. Temperature and fuel moisture are best predictors.
• Using GISS GCM output, forest fire emissions of OC predicted to
increase by 50% by 2045-2055 (over 1995-2004) resulting in mean
summertime OC to increase by 30% over western United States.
Extra slides
Blueprint for model predicting forest fire area burned from met fields
[Flannigan et al., 2005; Spracken et al., 2007]
Observed daily
Temperature, Wind
speed, Rainfall, RH
Observed area burned
database (1o x 1o)
Canadian Fire
Weather Index
System
Aggregate area
burned to
ecosystem
Models uses stepwise linear regression
between meteorological/forest moisture
variables & area burned
Daily forest moisture
parameters
Linear stepwise
regression
Predictors of
Area Burned
Aggregated ecosystems (similar vegetation / climate)
12.8
151.6
6.7
105.8
4.8
51.8
17.5
25.4
3.6
11.6
4.5
9.8
Bailey (1994) classification
1980 – 2004 Totals
[Westerling et al., 2002]
Area Burned / 106 acres
Biomass consumed/ Tg
Over the western U.S., the
Pacific Northwest and
Rocky Mountain Forests
are the most important
regions for biomass
consumption in wildfires.
A1 scenario
1.8 oC
control
Rainfall / mm day-1
Temperature / oC
Trends in GISS western US mean July meteorological variables
GISS GCM predicts ~1.8 oC increase in July surface
temperatures over western United States.
How do these changes impact wildfires?
Trends in annual area burned for two regions, 1980-2055
observations
model
+50%
anomalous year
2045-2054
compared to
1995-2004
+90%
All ecosystems across the western US show increases in Area
Burned between ~5 and 90% due to increasing temperatures.
Predicted summertime Organic Carbon concentrations averaged across
western United States for present-day and future (2046-2050)
5 year mean
2047
2048
2049
2050
2.0
OC [mg/m3]
2046
+30%
+10%
1.5
1.0
About two-thirds of the predicted 30% increase in summertime
OC is due to increasing wildfire emissions. The rest is due to
change in climate and changes in monoterpene emissions.