loretta j. mickley, harvard university shiliang wu, eric liebensperger, moeko yoshitomi, dominick...

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Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia Lin, David Streets Effects of Climate Change on U.S. Air Quality Projected trends in global temperature

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Page 1: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Loretta J. Mickley, Harvard University

Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field

Daniel Jacob, David Rind, Cynthia Lin, David Streets

Effects of Climate Change on U.S. Air Quality

Projected trends in global temperature

Page 2: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Probabilityof ozone exceedancevs. daily max. temperature

Day-to-day weather plays a large role in surface air quality (1).

Northeast

Ozone is strongly correlated with temperature in observations; this is due to (1) chemistry, (2) biogenic VOC emissions, (3) joint association with stagnation.

1988, hottest on record

Ave

rage

num

. of

day

s

Number of summer days with ozone exceedances (> 84ppb) over northeast U.S.

Lin et al., 2001

1992, coldest on record, due to Pinatubo eruption

Page 3: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Day-to-day weather plays a large role in surface air quality (2).

Stalled high pressure system increases ozone due to:

• increased biogenic emissions

• clear skies

• weak winds

• high temperatures.

cold frontEPA ozone levels

3 days later

Cold front pushes smog poleward and aloft on a warm conveyor belt.

cold front

L

L85-104 ppb 105-124 ppb

cyclone

Page 4: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Nitrogen oxide radicals; NOx = NO + NO2

combustion, soils, lightningMethanewetlands, livestock, natural gasNonmethane volatile organic compounds (NMVOCs)vegetation, combustion, industryCO (carbon monoxide)combustion, VOC oxidation

O3

O2h

O3

OH HO2

h, H2O

Deposition

NO

H2O2

CO, VOC

NO2

h

STRATOSPHERE

TROPOSPHERE

8-18 km

Troposphericozone

precursors

generally limiting

Chemistry of tropospheric ozone

What processes will climate change affect?

transport

Page 5: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

A decrease in cyclone frequency across mid-latitudes has been

observed (and calculated) for recent decades.

Observed trend in winter cyclone frequency over Northern Hemisphere.

McCabe et al., 2001

Calculated trend in summer cyclone frequency, from GISS 2x2.5 GCM, 23 layers

Climate models tend to predict decrease in mid-latitude cyclogenesis in future due to:• decrease in meridional temperature gradient • more efficient poleward transport of latent heat

Leibensperger et al., 2007

Page 6: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Ozone exceedances over eastern United States anti-correlate with cyclone frequency over Southern Canada/ Great Lakes region.

Correlation of 1980-2006 summertime ozone exceedances with cyclone number in the red and green boxes for each summer.

weak correlation

Stronganti-correlation

sample summertime storm tracks, 1979-81

NCEP/NCAR reanalysis

Page 7: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Cyclone trend works against improvements in emissions.

Number of summertime ozone exceedance days in Northeast dropped from 38 in 1980 to ~8 in 2006, but would have dropped to 0 in absence of cyclone trend.

Leibensperger et al., in prep.

Observed 1980-2006 trend in summertime cyclone number, 40-50 N

Number of O3 exceedances in Northeast

Interannual variability of cyclone frequency and ozone exceedance is highly anticorrelated (r = - 0.64).

Cyclone trend from NCEP/NCAR reanalysis would imply large effect on ozone trends.

Page 8: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Global change and air pollution (GCAP):Five models working together to provide information on climate

change impacts

Model for precursor emissions

archive met fields

GEOS-CHEM

Global chemistry model

CMAQ

Regional chemistry model

MM5 Mesoscale

model

archive chemistry

archive met fields

1950 2000 2025 2050 2075 2100

GISS general circulation model

Spin-up

changing greenhouse gases

Page 9: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Pollution episodes double in duration in 2050s due to decreasing frequency of cyclones ventilating the eastern U.S.

2045-2052

1995-2002

July - AugustGISS GCM simulations for 2050s vs. present-day climate. CO tracer: constant, present-day anthropogenic emissions+ sink of present-day OH fields.

Fewer cold front passages allow pollutants to build up.

Changes at high end of distribution due to 10-20% decrease in summertime cyclogenesis.

Mickley et al., 2004

Page 10: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

• Models agree that 2000-2050 climate change will decrease background ozone but increase surface ozone. We find an increase of 3-5 ppb over large regions.

• Most but not all models find maximum effect during pollution episodes (up to 10 ppb in ours) due to increased stagnation and higher temperatures.

• Most models find significant effects in Northeast/ Midwest.

• Many models disagree in Southeast partly due to different mechanisms for oxidation of biogenic isoprene (the dominant VOC precursor)

Wu et al., 2008

ppb

Increased water vapor sink

Higher temperatures, stagnation

2000-2050 A1 climate change increases summertime ozone.

Changes in summer 8-h avg. daily maximum ozone from 2000-2050 climate change

Page 11: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Effect of 2000-2050 climate change on pollution episodes.

Wu et al., 2008

Increased maximum temperatures during heat waves leads to increased ozone.

Amplification of temperatures at extreme due to • soil moisture feedbacks • 17% decreased cyclone frequency.

Cumulative probability (%)

Max

. 8-

hr-

avg

ozo

ne 2050s climate

99th percentile

Midwest

Dai

ly m

axim

um t

empe

ratu

re (

K)

Cumulative probability (%)

2050s

2000s

Maximum JJA temperatures Maximum JJA 8-h avg ozone

40% decrease in NOx2050s climate + NOx

2000s climate

Page 12: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

-1 -.5 0 .5 1correlationcoefficient R

GCAP modelpresent-day climate (3 years)

Correlations of daily max-8h-avg ozone with daily max temperature in Jun-Aug

Observations (1980-1998)

Yoshitomi et al., in progress

We can use ozone-temperature correlations as a test of model sensitivity to climate change, esp in Southeast US

Regions of strongest correlation in model and observations.

Page 13: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Most of the variability in wildfire frequency is due to year-to-year changes in surface temperatures and precipitation.

Forest fires in western US have big impact on particle concentrations and on surface ozone.

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 has developed a fire prediction tool to calculate future area burned using GISS GCM meteorological variables. . . . 2050 and beyond

Page 14: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Results show far: Future 2040-2050 biomass consumption by wildfires over the western United States is ~50% greater than for present-day.

Plot shows standardized departures from the 1996-2055 mean.

Annual total biomass consumed by forest fires, 1996-2055

Spracklen et al., in progress.

Rynda Hudman at Harvard is investigating effect of future forest fires on surface ozone concentrations.

Page 15: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Increased 2050s wildfire activity leads to 3-6 ppb increase in afternoon mean ozone in July over western U.S.

2051

[ppbv]

Biomass burning NOx emissions

2000

[Gg NO]

Mean of 5 ppbv enhancement due to fires a > 2 SD

Hudman et al., in progress

JJA surface ozone

Page 16: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

ConclusionsIn the 1980-2006 NCEP/NCAR record, we find a decline in cyclone frequency

of -0.15 cyclones/y, which may have limited the efficacy of air pollution regulations.

For 2050-2000 A1B climate change, we calculate a10-20% decline in cyclone frequency, lengthening pollution episodes over Midwest and Northeast.

Climate change is expected to degrade U.S. ozone air quality. The summer average daily max-8h ozone increases by 2-5 ppb over large areas due to 2000-2050 climate change with the IPCC A1B scenario. Largest effect is during pollution episodes, when ozone increases by as much as 10 ppb.

Summertime ozone concentrations are predicted to increase by 3-6 ppb over parts of western US due to increasing wildfire frequency in the 2050s.

Projected trends in global NOx emissions for a range of scenarios.

Page 17: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Extra slides

Page 18: Loretta J. Mickley, Harvard University Shiliang Wu, Eric Liebensperger, Moeko Yoshitomi, Dominick Spracklen, Brendan Field Daniel Jacob, David Rind, Cynthia

Why is ozone in the Southeast insensitive to climate change?

Isoprene has competing effects on ozone

Sensitivity test: Isoprene emissions +30% Δ(O3)

2000 2050 / 2000

Isoprene emissions

RO2 + NORONO2 (sink for NOx)

Isoprene + OH RO2 (OH sink)

Isoprene + O3 M (O3 sink)O3

RO + NO2 (O3 formation) O3

Wu et al., 2008