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.

Precursor emissions from Streets

archive met fields

GEOS-CHEM

Global chemistry model

CMAQ

Regional chemistry model

1950 2000 2025 2050 2075 2100

GISS general circulation model

Spin-up

MM5 Mesoscale

model

archive chemistry

archive met fields

changing greenhouse gases

past atmospheres

GCAP is now part of standard model. Please keep us in the loop if you use GISS met!!

Wu et al. 2007a, b, c Pye et al., 2007

Land cover variation of GCAP: How will climate change affect future land cover? What are the chem-climate interactions of land

cover change?

Anthro emissions

Archive met fields

GEOS-CHEM

Global chemistry model

Ozone and aerosol (including dust)

Chemistry fields + land cover change will be fed back into GCM.

1950 2000 2025 2050 2075 2100

GISS general circulation model

Spin-up

changing greenhouse gases

LPJ vegetation model

Apply1950-2100 met fields + CO2

Recalculate 2000-2100 climate

veg type + LAI

First results from link between GISS GCM + LPJ Land Cover model

1995 2060

Tropical evergreen broadleaf

Boreal evergreen needleleaf

Temperate grasses

Large increases in grassland

Increase in boreal evergreens

Fractional landcover for 3 vegetation types

collaboration with J. Kaplan

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.

Area burned and temperature in Canada over the last century

Gillet et al., 2004

EPA wildfire project: How will changing forest fire frequency affect future air quality over the United States?

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

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.

Results show an improved match between observed and modeled organic aerosol concentrations, compared to calculations with climatological fires.

Total OC [g/m3], mean over all IMPROVE sites

Observed OC

Model OC, with interannually varying 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.

[Spracklen et al., 2007]

Dominick’s Fire Prediction tool for the western U.S: 1) Regress observed met variables and drought indices against linear area burned2) Choose best predictors for each ecosystem.3) Archive these predictors from GISS GCM for future climate.

May-Oct mean obs TemperatureMay-Oct mean obs Drought Code

R2=52%

Are

a b

urn

ed /

106

Ha

0.5

0.25

1980 20001990

1980 1990 2000 200019901980

observations

model Regressions ‘explain’ 50-60% of variability in annual area burned in forest ecosystems.

Best predictors are often temperature or Fuel Moisture Index.

Sample results for Pacific Northwest/Cascade Forests.

May-Oct Area burned

Variation of GCAP model to predict climate change impacts on forest fires and air quality

Calculate emissions

archive met fields

GEOS-CHEM

Global chemistry model

1950 2000 2025 2050 2075 2100

GISS general circulation model

Spin-up

archive chemistry

changing greenhouse gases (A1 scenario)

Predict Area Burned

Area Burned Regressions

Organic carbon aerosol from wildfires.

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.

Use stochastic placement of wildfires within ecosystem and ecosystem specific fuel loads.

Plot shows standardized departures from the 1996-2055 mean.

Annual total biomass consumed by forest fires, 1996-2055

Current (1996-2000) Future (2046-2050)

Future-current Future / current

Predicted changes to summertime (June-Aug) Organic Carbon concentrations over the US from GCAP model

Summertime OC concentrations predicted to increase by ~30% over western US.

Largest increases over Rockies and Pacific Northwest.

Dr. Hudman will continue this work with full chemistry GCAP model.

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]

Daily forest moisture parameters

Observed area burned database (1o x 1o)

Aggregate area burned to

ecosystem

Canadian Fire Weather Index

System

Predictors of Area Burned

Linear stepwise regression

Observed daily Temperature, Wind speed, Rainfall, RH

Models uses stepwise linear regression between meteorological/forest moisture variables & area burned

Aggregated ecosystems (similar vegetation / climate)

6.7105.8

17.525.4

3.611.6

12.8151.6 4.8

51.8

4.59.8

1980 – 2004 Totals [Westerling et al., 2002]Area Burned / 106 acresBiomass consumed/ Tg

Bailey (1994) classification

Over the western U.S., the Pacific Northwest and Rocky Mountain Forests are the most important regions for biomass consumption in wildfires.

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?

Te

mp

era

ture

/ oC

Ra

infa

ll / m

m d

ay-1

A1 scenario

control

1.8 oC

Trends in annual area burned for two regions, 1980-2055

All ecosystems across the western US show increases in Area Burned between ~5 and 90% due to increasing temperatures.

+50%

+90%

2045-2054 compared to 1995-2004

observations model

anomalous year

Predicted summertime Organic Carbon concentrations averaged across western United States for present-day and future (2046-2050)

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.

2046 2047 2048 2049 2050

1.0

2.0

1.5

5 year mean

OC

[m

g/m

3]

+30%

+10%