effect of climate change on u.s. air quality daniel j. jacob, harvard university global change in...
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EFFECT OF CLIMATE CHANGE EFFECT OF CLIMATE CHANGE ON U.S. AIR QUALITYON U.S. AIR QUALITY
Daniel J. Jacob, Harvard University
Global change inemissions
Change in U.S. air qualityChange in
climate
NOx emissions, 2020
GLOBAL CLIMATE CHANGE SINCE 1850GLOBAL CLIMATE CHANGE SINCE 1850
IPCC [2007]
IPCC PROJECTIONS OF FUTURE WARMING… IPCC PROJECTIONS OF FUTURE WARMING… AND EVALUATION OF PREVIOUS PROJECTIONSAND EVALUATION OF PREVIOUS PROJECTIONS
IPCC 1995IPCC 1990
IPCC 2007:
IPCC [2007]
Mean results from an ensemble of GCMs using the same greenhouse scenarios
PROJECTED WARMING OVER 21PROJECTED WARMING OVER 21stst CENTURY CENTURY
CO2 trend
Global temperaturetrend
CO2 = 500 ppm
The Eocene climate was warm, even at high latitudes:-palm trees flourished in Wyoming-crocodiles lived in the Arctic-Antarctica was a pine forest-deep ocean temperature was 12°C (today it is ~2°C)-sea level was at least 100 meters higher than today
EOCENE (55 to 36 million years ago): The last time EOCENE (55 to 36 million years ago): The last time in Earth history when atmospheric COin Earth history when atmospheric CO22 was above was above 500 ppm.500 ppm.
Present models cannot reproduce this warm climate – missing processes?Positive feedbacks could cause abrupt climate change but this is not well understood
OBSERVED DEPENDENCE OF AIR QUALITY ON WEATHER OBSERVED DEPENDENCE OF AIR QUALITY ON WEATHER WARNS OF POTENTIALLY LARGE EFFECT OF CLIMATE CHANGEWARNS OF POTENTIALLY LARGE EFFECT OF CLIMATE CHANGE
Interannual variability of exceedances of ozone NAAQS
# summer days with 8-hour O3 > 84 ppbv,average for 257 northeast U.S. AIRS sites
1988, hottest on record
Ozone is strongly correlated with temperature in observations (R2 ~ 0.5); reflects (1) chemistry, (2) biogenic VOC emissions, (3) association with stagnation
Lin et al. [2001]
USE OZONE-TEMPERATURE CORRELATION TO ESTIMATE USE OZONE-TEMPERATURE CORRELATION TO ESTIMATE EFFECT OF CLIMATE CHANGE ON AIR QUALITYEFFECT OF CLIMATE CHANGE ON AIR QUALITY
Probability of max 8-h O3 > 84 ppbvvs. daily max. temperature
-4
-2
0
2
4
6
8
10
1900 1950 2000 2050 2100
Sum
mer
Tem
pera
ture
Ano
mal
y (o
C)
CCSM 1 PCM 1CCSM 2 PCM 2CCSM 3 PCM 3CCSM 4 HadCM3ECHAM 1 GFDL 0ECHAM 2 GFDL 1ECHAM 3 GISS
Projected T change for northeast U.S. in 2000-2100 simulated with ensemble of GCMs for different scenarios [IPCC, 2007]
T = 3K
Pro
bab
ilit
y
Temperature, K
Probabilityof exceedancedoubles
By 2025, T = 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!
Loretta Mickley (Harvard) and Cynthia Lin (UC Davis)
Lin et al. [2001]
NortheastLos AngelesSoutheast
STATISTICAL METHOD TO PROJECT NAAQS EXCEEDANCESSTATISTICAL METHOD TO PROJECT NAAQS EXCEEDANCESFOR A GIVEN LOCATION OR REGION IN A FUTURE CLIMATEFOR A GIVEN LOCATION OR REGION IN A FUTURE CLIMATE
Apply ensemble of GCMs to simulate future climate
Apply subgrid variability to T from present-day climatology
Apply local or regional probability of NAAQS exceedance = f(T)
Obtain probability of NAAQS exceedance in future climate assuming constant emissions
Obtain daily max T for individual grid squares
Obtain daily max T for individual locations
APPLICATION TO PROJECT FUTURE EXCEEDANCES OF OZONE NAAQSAPPLICATION TO PROJECT FUTURE EXCEEDANCES OF OZONE NAAQSIN THE NORTHEAST UNITED STATESIN THE NORTHEAST UNITED STATES
Statistical method allows quick local assessment of the effect of climate change, but it has limitations:
• gives no insight into the coupled effect of changing emissions• some fraction of variance unresolved by statistical model• no good statistical relationships for PM developed so far
Loretta Mickley (Harvard) and Cynthia Lin (UC Davis)
Three IPCC(2007) GCMs,downscaled to capturelocal variability
Northeast U.S.
2010 2032 2055 2078 2100YEAR
Nu
mb
er o
f ex
ceed
ance
day
s
30
20
10
0
Average for the 257 AIRS sites of Lin et al. [2001]
EFFECT ON CLIMATE CHANGE ON BOUNDARY LAYER DEPTH EFFECT ON CLIMATE CHANGE ON BOUNDARY LAYER DEPTH
Projected A1 2000-2050 changes in surface T and mixing depth, GISS GCM 3
Change in surface temperature (K) Change in afternoon mixing depth (ratio)
Loretta J. Mickley and Shiliang Wu, Harvard
Response of boundary layer mixing to climate change is largely driven by local soil moisture; drying of Texas due to NE shift of Bermuda High
EFFECT OF CLIMATE CHANGE ON REGIONAL STAGNATIONEFFECT OF CLIMATE CHANGE ON REGIONAL STAGNATION
Pollution episodes double in duration in 2050 climate due to decreasing frequency of cyclones ventilating the eastern U.S; this decrease is an expected consequence of greenhouse warming.
GISS GCM 2’ simulations for 2050 vs. present-day climate using pollution tracers with constant emissions
Mickley et al. [2004]
2045-2052
1995-2002
summer
Mid-latitudes cyclones tracking across southern Canada are the main drivers of northern U.S. ventilation
Northeast U.S.CO pollution tracer
Clean airsweepsbehind cold front
Sunday night’s weather map
CLIMATOLOGICAL DATA CONFIRM DECREASE IN FREQUENCY CLIMATOLOGICAL DATA CONFIRM DECREASE IN FREQUENCY OF MID-LATITUDE CYCLONES OVER PAST 50 YEARSOF MID-LATITUDE CYCLONES OVER PAST 50 YEARS
Annual number of surface cyclones and anticylones over North America
Cyclone frequency at 30o-60oN
cyclones
anticyclones
1000
100
500
1950 1980
Agee [1991]
McCabe et al. [2001]
COMPREHENSIVE APPROACH FOR INVESTIGATING COMPREHENSIVE APPROACH FOR INVESTIGATING EFFECT OF CLIMATE CHANGE ON AIR QUALITYEFFECT OF CLIMATE CHANGE ON AIR QUALITY
Global climate model (GCM)
Global chemical transport model
(CTM)for ozone-PM
Regional climate model (RCM)
Regional CTM for ozone-PM
boundaryconditions
inputmeteorology
inputmeteorology
boundaryconditions
IPCCfuture emission
scenario
greenhousegases
ozone-PM precursors
Need to run many years to obtain sufficient statistics expensive!
internal EPA project (CIRAQ) and several STAR projects
GLOBAL CHANGE AND AIR POLLUTION (GCAP)GLOBAL CHANGE AND AIR POLLUTION (GCAP)
GISS GCM
GEOS-Chemglobal CTM
MM-5 RCM
CMAQregional CTM
boundaryconditions
inputmeteorology
inputmeteorology
boundaryconditions
IPCC emissionscenario
greenhousegases
ozone-PM precursors
Applied to 2000-2050 global change simulations with IPCC SRES A1 scenario
EPA-STAR 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 EMISSIONS OF OZONE PRECURSORS (A1)2000-2050 EMISSIONS OF OZONE PRECURSORS (A1)
Global 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%)
Shiliang Wu, Harvard
• Global increase in anthropogenic emissions but 40-50% decreases in U.S.!• Climate-driven increases in natural NOx, NMVOC emissions
CHANGES IN SUMMER MEAN 8-h AVG. DAILY MAXMUM OZONE CHANGES IN SUMMER MEAN 8-h AVG. DAILY MAXMUM OZONE FROM 2000-2050 CHANGES IN CLIMATE AND GLOBAL EMISSIONS FROM 2000-2050 CHANGES IN CLIMATE AND GLOBAL EMISSIONS
2050 emissions & 2000 climate) 2050 emissions & climate)
2000 conditions ( ppb) 2000 emissions & 2050 climate)
Shiliang Wu, Harvard
SENSITIVITY OF POLLUTION EPISODES TO GLOBAL CHANGESENSITIVITY OF POLLUTION EPISODES TO GLOBAL CHANGE
• In northeast and midwest, climate change effect reaches 10 ppbv for high-O3 events; longer and more frequent stagnation episodes• near-zero effect of climate change in southeast
Shiliang Wu, Harvard
Midwest
Southeast
NortheastMidwest
Southeast
NortheastMidwest
Southeast
Northeast
Cumulative probability (%)
Ma
x-8
h-a
vg
ozo
ne Present
Future climateFuture emissionsFuture climate & emis
Midwest
Cumulative probability (%)Cumulative probability (%)Cumulative probability (%)
Ma
x-8
h-a
vg
ozo
ne Present
Future climateFuture emissionsFuture climate & emis
Midwest
Cumulative probability (%)
Max-8h-
avg
ozo
ne
Northeast
Cumulative probability (%)
Max-8h-
avg
ozo
ne
Cumulative probability (%)
Max-8h-
avg
ozo
ne
Northeast
Cumulative probability (%)
Southeast
Ma
x-8
h-a
vg
ozo
ne
Cumulative probability (%)Cumulative probability (%)
Southeast
Ma
x-8
h-a
vg
ozo
ne
Summer probability distribution of daily 8-h max ozone
median90th
99th
CLIMATE CHANGE PENALTY CLIMATE CHANGE PENALTY AS ADDED REQUIREMENTS ON EMISSION REDUCTIONSAS ADDED REQUIREMENTS ON EMISSION REDUCTIONS
2000-2050 climate change means that we will need to reduce NOx emissions by 50% instead of 40% to achieve the same ozone air quality goals in the northeast
Shiliang Wu, Harvard
2000 climate- 40% U.S.NOx
emissions
2050 climate-50% NOx
emissions
2050 climate-60% NOx
emissions
OZONE CLIMATE CHANGE PENALTY WILL BE HIGHER OZONE CLIMATE CHANGE PENALTY WILL BE HIGHER IF WE DON’T REDUCE EMISSIONSIF WE DON’T REDUCE EMISSIONS
Change in mean 8-h daily max ozone (ppb) from 2000-2050 climate change
with 2000 emissions with 2050 emissions
Reducing U.S. anthropogenic emissions significantly mitigates the climate change penalty
Shiliang Wu, Harvard
EFFECT OF 2000-2050 CLIMATE CHANGE EFFECT OF 2000-2050 CLIMATE CHANGE ON POLICY-RELEVANT BACKGROUND (PRB) OZONEON POLICY-RELEVANT BACKGROUND (PRB) OZONE
2000 conditions: PRB ozone, ppb 2000 emissions & 2050 climate)
(2050 emissions & 2000 climate) (2050 emissions & climate)
2050 climate decreases PRB in subsiding regions, increases in upwelling regions2050 emissions increase PRB due to rising methane, Asian emissions
Shiliang Wu,Harvard
2000-2050 EMISSIONS OF PM2000-2050 EMISSIONS OF PM2.52.5 PRECURSORS (A1) PRECURSORS (A1)
Global United States
2000 emissions
% change,
2000-2050
2000 emissions % change,
2000-2050
SOx, Tg S y-1
Anthropogenic
Natural
59
21
+ 38%
0%
9
-
- 80%
NOx, Tg N y-1
Combustion
Lightning
Soils (natural)
34
4.9
6.1
+ 71%
+ 18%
+ 8%
6.0
0.14
0.35
- 39%
+21%
+11%
NH3, Tg N y-1
Anthropogenic
Natural
40
17
+ 43%
+ 0%
2.2
0.8
+ 40%
+ 0%
BC, Tg C y-1 7.9 - 27% 0.6 - 56%
OC, Tg C y-1
Combustion
Biogenic (SOA)
33 - 17% 1.5 - 34%
David Streets, ANL and Shiliang Wu, Harvard
EFFECT OF 2000-2050 GLOBAL CHANGE ON ANNUAL MEAN EFFECT OF 2000-2050 GLOBAL CHANGE ON ANNUAL MEAN SULFATE CONCENTRATIONS (SULFATE CONCENTRATIONS (g mg m-3-3))
2000 conditions: sulfate, g m-3 2000 emissions & 2050 climate)
(2050 emissions & 2000 climate) 2050 emissions & 2050 climate)
Shiliang Wu, Harvard
Climate change increases sulfate by up to 0.5 g m-3 in midwest (more stagnation), decreases sulfate in southeast (more precipitation)
EFFECT OF 2000-2050 GLOBAL CHANGE ON ANNUAL MEAN EFFECT OF 2000-2050 GLOBAL CHANGE ON ANNUAL MEAN ORGANIC CARBON (OC) AEROSOL CONCENTRATIONS (ORGANIC CARBON (OC) AEROSOL CONCENTRATIONS (g mg m-3-3))
Shiliang Wu, Harvard
Climate change effect is mainly through biogenic SOA and is smallbecause of compensating factors (higher biogenic VOCs, higher volatility)
2000 conditions: OC, g m-3 2000 emissions & 2050 climate)
(2050 emissions & 2000 climate) 2050 emissions & 2050 climate)
EFFECT OF 2000-2050 GLOBAL CHANGE ON ANNUAL EFFECT OF 2000-2050 GLOBAL CHANGE ON ANNUAL MEAN PMMEAN PM2.52.5 CONCENTRATIONS ( CONCENTRATIONS (g mg m-3-3))
Shiliang Wu, Harvard
2000 conditions: PM2.5, g m-3 2000 emissions & 2050 climate)
(2050 emissions & 2000 climate) 2050 emissions & 2050 climate)
Effect of climate change is small (at most 0.3 g m-3) – but this doesn’t accountfor change in wildfires…
WILDFIRES: A SIGNIFICANT PMWILDFIRES: A SIGNIFICANT PM2.52.5 SOURCE SOURCE
S. California fire plumes,Oct. 25 2004
Total carbonaceous (TC) aerosol averaged over all contiguous U.S. IMPROVE sites
~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. [2007]
INCREASING WILDFIRE FREQUENCY IN PAST DECADESINCREASING WILDFIRE FREQUENCY IN PAST DECADES
Westerling et al. [2006]
Canadian fires [Gillet et al., 2004]
1920 1940 1960 1980 2000
Temperature and drought indexcan explain 50-60% of interannual variability in fires
Dominick Spracklen, Harvard
EFFECT OF 2000-2050 CLIMATE CHANGE EFFECT OF 2000-2050 CLIMATE CHANGE ON WESTERN U.S. WILDFIRES ON WESTERN U.S. WILDFIRES
GISS GCM, IPCC A1 scenario, using fire frequency regression on T and drought
observed
Mean biomass burned per year is projected to increase by 50% in 2050, resulting in 10% increase in annual mean PM2.5
Dominick Spracklen, Harvard
CONCLUSIONSCONCLUSIONS
• Climate change over the next decades is likely to have a negative effect on ozone and PM U.S. air quality– effect is most pronounced during pollution episodes– probability of ozone NAAQS exceedances might double in some regions
by 2025 if emissions stay constant• Climate change for 2000-2050 is projected to increase mean summertime
ozone by 1-5 ppb (mean 8-h daily max) and up to 10 ppb (pollution episodes) – effect is largest in central and northeast, much weaker in southeast– Model results suggest that this will require an additional 10% decrease in
NOx emissions to meet ozone air quality goals in the northeast – the ‘climate change penalty’.
• Policy-relevant background (PRB) ozone is expected to increase by 1-5 ppb by 2050 (highest in the west) due to rising methane and non-U.S. emissions– climate change partly offsets this effect
• Effect of climate change on PM2.5 air quality may be relatively small because of canceling factors– but climate-driven increases in wildfires may be an important issue