EFFECT OF CLIMATE CHANGE ON AIR QUALITY

1
EFFECT OF CLIMATE CHANGE ON AIR QUALITY
Daniel J. Jacob
with Loretta J. Mickley, Shiliang Wu, Eric M.
Leibensperger, Moeko Yoshitomi
and funding from, EPA, EPRI
2
CHEMISTRY-CLIMATE INTERACTIONS
3
CHEMISTRY-CLIMATE INTERACTIONS
FORCING
D Climate
D Emissions

• Atmospheric
• chemistry

• Air pollution
• meteorology

D Surface air quality
4
AIR POLLUTION IN THE UNITED STATES
people in areas exceeding national ambient air
quality standards (NAAQS) in 2006
84 ppbv
15 mg m-3 (day), 65 (annual)
5
CHEMISTRY OF TROPOSPHERIC OZONE
O2
hn
O3
STRATOSPHERE
8-18 km
TROPOSPHERE
hn
NO2
NO
O3
hn, H2O
OH
HO2
H2O2
Deposition
CO, VOC
generally limiting
Nitrogen oxide radicals NOx NO
NO2 combustion, soils, lightning Methane wetlands,
livestock, natural gas Nonmethane volatile
organic compounds (NMVOCs) vegetation,
combustion, industry CO (carbon
monoxide) combustion, VOC oxidation
Tropospheric ozone precursors
6
PARTICULATE MATTER (PM, AEROSOLS) SOURCES AND
PROCESSES
ultra-fine (lt0.01 mm)
fine (0.01-1 mm)
cloud (1-100 mm)
precursor gases
oxidation
nucleation
cycling
coagulation
H2SO4
SO2
condensation
RCO
VOCs
coarse (1-10 mm)
scavenging
NOx
HNO3
NH3
carbonaceous combustion particles
combustion biosphere volcanoes
soil dust sea salt
agriculture biosphere
7
OBSERVED DEPENDENCE OF AIR QUALITY ON WEATHER
WARNS OF POTENTIALLY LARGE EFFECT OF CLIMATE
CHANGE
Interannual variability of exceedances of ozone
standard in Northeast U.S.
summer days with 8-hour ozone gt 84
ppbv, average for 257 northeast U.S. AIRS sites
1992, coldest on record (Pinatubo)
1988, hottest of record
Lin et al. AE 2001
Ozone is strongly correlated with temperature in
observations this is due to (1) chemistry, (2)
biogenic VOC emissions, (3) joint association
with stagnation
8
USE OZONE-TEMPERATURE CORRELATION TO ESTIMATE
EFFECT OF CLIMATE CHANGE ON AIR QUALITY
Probability of max 8-h O3 gt 84 ppbv vs. daily
max. temperature
Projected T change for northeast U.S. in
2000-2100 simulated with ensemble of GCMs for
different scenarios IPCC, 2007
Northeast Los Angeles Southeast
Lin et al. AE 2001
Probability of exceedance doubles
Probability
DT 3K
Temperature, K
By 2025, DT 1-3 K depending on model and
scenario use statistical approach at right to
infer increased probability of ozone exceedance
for a given region or city assume nothing else
changes. Effect is large!
9
IMPORTANCE OF MID-LATITUDES CYCLONES IN AIR
POLLUTION METEOROLOGY
Cold fronts from mid-latitude cyclones tracking
across southern Canada are the principal process
ventilating the U.S. Midwest and Northeast
Clean air sweeps behind cold front
10
INTERANNUAL CORRELATION BETWEEN CYCLONE FREQUENCY
AND OZONE AIR QUALITY STANDARD EXCEEDANCES,
1980-1998
observed summer cyclone tracks (NCEP/NCAR
reanalysis, NASA/GISS cyclone tracker)
Correlation coefficient (R) in four
reanalyses between ozone AQS exceedances/summer
and 40-50o N cyclones (green box)
-1 0.5 0 0.5 1
Leibensperger et al. , in prep.
11
CLIMATOLOGICAL DATA SHOW DECREASE IN FREQUENCY
OF MID-LATITUDE CYCLONES OVER PAST 50 YEARS
1000
Annual number of surface cyclones and
anticylones over North America
cyclones
500
Agee 1991
anticyclones
100
1980
1950
Cyclone frequency at 30o-60oN
McCabe et al. 2001
12
TREND IN SUMMERTIME CYCLONE FREQUENCY, 1950-2006
1980-2006 trend
cyclones/summer tracking through green box
Both NCEP/NCAR and the GISS GCM show a decreasing
trend starting in 1980 no trend is seen in a
control GCM simulation in radiative equilibrium
Leibensperger et al., in prep.
13
CYCLONE TREND FROM NCEP/NCAR REANALYSIS WOULD
IMPLY LARGE EFFECT ON OZONE TRENDS
80 ppb exceedance days in Northeast dropped
from 38 in 1980 to 19 in 1998, but would have
dropped to 5 in absence of cyclone trend
Observed 1980-1998 JJA trends in daily 40-50N
cyclones 80 ppb O3 AQS exceedances
Interannual variability in the two is highly
anticorrelated (r - 0.64)
Black observed AQS exceedances Red AQS
exceedances predicted from trend in cyclone
frequency Green AQS exceedances predicted in
absence of trend in cyclone frequency
AQS exceedances cyclones
Leibensperger et al., in prep.
1980 1985 1990 1995 2000
1980 1985 1990 1995 2000
14
BUT OTHER REANALYSES SHOW NO 1980-2005 TREND
THOUGH LARGE INTERANNUAL VARIABILITY
Leibensperger et al., in prep.
15
EPA-STAR GLOBAL CHANGE AND AIR POLLUTION (GCAP)
PROJECT
D.J. Jacob and L.J. Mickley (Harvard), J.H.
Seinfeld (Caltech), D. Rind (NASA/GISS), D.G.
Streets (ANL), J. Fu (U. Tenn.) , D. Byun (U.
Houston)
2000-2050 IPCC emission scenario
ozone-PM precursors
greenhouse gases
input meteorology
boundary conditions
GEOS-Chem global CTM
CMAQ regional CTM
GISS GCM 3
MM-5 RCM
input meteorology
boundary conditions
Applied to 2000-2050 global change simulations
with IPCC SRES A1 scenario compare 2050 climate
(GCM 2049-2051, 3-y averages) to 2000 (1999-2001)
16
2000-2050 PROJECTED EMISSION TRENDS
Global Global United States United States
2000 emissions change, 2000-2050 2000 emissions change, 2000-2050
NOx, Tg N y-1 Anthropogenic Lightning Soils (natural) 34 4.9 6.1 71 18 8 6.0 0.14 0.35 -39 21 11
NMVOCs, Tg C y-1 Anthropogenic Biogenic 46 610 150 23 9.3 40 -52 23
CO, Tg y-1 1020 25 87 -47
Methane, ppbv 1750 2400 (37)
SOx, Tg S y-1 Anthropogenic Natural 59 21 38 0 9 - - 80

• Global increase in anthropogenic emissions but
  large decreases in U.S.
• Climate-driven increases in natural NOx, NMVOC
  emissions

Wu et al. JGR, in press
17
EFFECT OF 2000-2050 CLIMATE CHANGE ON GLOBAL
TROPOSPHERIC OZONE
Tropospheric ozone in year 2000 (ppb)
2050/2000 ratio
Zonal annual mean concentrations

• Ozone increases in tropical upper troposphere
  because of increased lightning
• but decreases in background surface air because
  of higher water vapor

Wu et al., submitted
18
CHANGES IN SUMMER MEAN 8-h AVG. DAILY MAXIMUM
OZONE FROM 2000-2050 CLIMATE CHANGE (NO CHANGE
IN EMISSIONS)
Effect of changing climate

ppb

• Different models agree that 2000-2050 climate
  change will decrease background ozone but
  increase surface ozone in U.S. by generally 1-10
  ppb
• Most but not all models find maximum effect
  during pollution episodes (up to 10 ppb in ours)
• All models find significant effect in Northeast
  but disagree in other regions
• Differences in Southeast partly due to different
  mechanisms for oxidation of biogenic isoprene
  (the dominant VOC precursor)

Wu et al. JGR in press
19
2000-2050 DECREASE OF CYCLONE FREQUENCY
Summertime cyclone frequency decreases by 17 in
2050 climate (GISS GCM A1 scenario)
Wu et al. iJGR n press
20
OZONE-TEMPERATURE CORRELATION AS TEST OF MODEL
SENSITIVITY TO CLIMATE CHANGE
Correlate daily max-8h-avg ozone with daily max
temperature in Jun-Aug
GCAP/GEOS-Chem model present-day climate (3 years)
Observations (1980-1998)
Yoshitomi et al. in progress
21
COMPARING THE EFFECTS OF CHANGING CLIMATE AND
EMISSIONS ON SUMMER MEAN 8-h AVG. DAILY MAXIMUM
OZONE (2000-2050)
2000
2050 climate - 2000
2050 emissions 2000
2050 2000
Wu et al. in press
22
CLIMATE CHANGE PENALTY MEETING A GIVEN AIR
QUALITY GOALWILL REQUIRE GREATER EMISSION
REDUCTIONS IN FUTURE CLIMATE
NOx emission - 40 (2050 climate)
2000 conditions
NOx emission - 40 (2000 climate)
NOx emissions - 50 (2050 climate)
In this example, 20002050 climate change implies
an additional 25 reduction in NOx emissions
(from 40 to 50) to achieve the same ozone air
quality.
Wu et al. JGR in press
23
2000-2050 CHANGE OF ANNUAL MEAN PM2.5 (mg m-3)
Effect of climate change is small (at most 0.3 mg
m-3), in part because of compensating factors
but this doesnt include fires
2000
2050 climate - 2000
2050 emissions 2000
2050 - 2000
Shiliang Wu, Harvard
24
WILDFIRES A SIGNIFICANT PM2.5 SOURCE
Total carbonaceous (TC) aerosol averaged over
all contiguous U.S. IMPROVE sites
S. California fire plumes, Oct. 25 2004
100 IMPROVE sites nationwide

• Interannual variability in annual mean
  carbonaceous PM2.5. is largely determined by
  wildfires
• Open fires contribute about 25 of annual mean
  PM2.5 in the western U.S., 10 in the east
• Dominant contributions from western U.S. fires
  (in the west), Canadian fires (in the northeast),
  prescribed fires (in the southeast)

Park et al. AE 2007
25
INCREASING WILDFIRE FREQUENCY IN PAST DECADES
Westerling et al. 2006
Temperature and drought index can explain 50-60
of interannual variability in fires
Canadian fires Gillet et al., 2004
1920 1940 1960 1980 2000
26
INTERCONTINENTAL DUST INFLUENCE
April 16, 2001 Asian dust!
clear day
Glen Canyon, Arizona
Annual mean PM2.5 dust (mg m-3), 2001
Asia
Sahara
Fairlie et al. AE 2007
Most fine dust in the U.S. (except in southwest)
is of intercontinental origin