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Effect of 2000-2050 global change on
ozone air quality in the United States
Shiliang Wu, Loretta Mickley,
Daniel
Jacob, Eric Leibensperger, David Rind
(GISS), David Streets (ANL)
Harvard University
Oct. 12, 2007
work supported by the EPA-STAR program
Models and future scenario
GISS GCM 3
GEOS-Chem
23 vertical layers extending to 85 km
detailed ozone-NOx-VOC-aerosol chemistry
Horizontal resolution of 4º x 5º
Anthropogenic emissions
(IPCC A1B scenario)
GHG
Radiative forcing
Climate Change
Natural
emissions
Air
pollutants
& their
precursors
Chemistry, transport,
deposition, etc
GCAP (Global Change and Air Pollution) model
Global changes in anthropogenic emissions
Trends of NOx emissions from fuel use (2050 / 2000)
(IPCC A1B scenario)
4
-40%
2
+90%
+300%
1.5
1.1
+800%
0.9
0.8
0.7
0.6
Global total NOx emissions: + 90%
0.5
A1B 2000-2050 changes in climate
Temperature: 2050 – 2000
Humidity: 2050 / 2000
Annual mean surface temperature +1.6 K
2000
2050
D
NOx-lightning, Tg N/yr
4.9
5.8
+18%
NOx - soil, Tg N/yr
6.1
6.6
+8%
Isoprene, Tg C/yr
430
537
+25%
Effects of 2000-2050 global change on tropospheric ozone
(annual zonal mean)
2000
2050 climate / 2000
+1.6%
2050 emission / 2000
+17%
2050 / 2000
+18%
Effects of 2000-2050 global change on tropospheric ozone
(annual surface afternoon mean)
2000
2050 emission – 2000
2050 climate – 2000
2050 – 2000
Policy relevant background (PRB) ozone (summer afternoon)
Effects of 2000-2050 global change on U.S. ozone air quality
Daily max 8h-avg ozone averaged over JJA (ppb)
2000
2050 emission – 2000
2050 climate – 2000
2050 – 2000
Increase of
summer max8h-avg ozone by
1-5 ppb in large
areas of U.S.
due to 20002050 climate
change.
Less effects in
western U.S.
because (1)
increase of
ozone from
intercontinental
transport and
(2) anthro.
emissions are
low there.
Changes in summertime air pollution meteorology due to climate change
Surface temperature (2050 – 2000)
Convective mass flux (2050 - 2000)
oC
1.0
0.8
0.6
0.5
-0.5
-1.0
-1.5
-2.0
[g/m2/s]
Mixing depth (2050 / 2000)
Soil moisture (2050 / 2000)
What’s more: decrease of cyclone frequency
1999-2001
2049-2051
Summertime cyclones decrease by 17% in the 2050 climate
Eric M. Leibensperger, Harvard
Cumulative probability distributions of max 8-hr ozone (JJA)
Midwest
Max. 8-hr-avg ozone
2000 conditions
2050 climate
2050 emissions
2050 climate & emis
Cumulative
probability
(%)
Cumulative
probability
(%)
Midwest
Northeast
Southeast
Northeast
median
99th
percentile
Cumulative probability (%)
Max. 8-hr-avg ozone
Max. 8-hr-avg ozone
climate change has more effect on the pollution events than on the means
Southeast
Cumulative probability (%)
Midwest
Cumulative probability (%)
Max. 8-hr-avg ozone
Daily maximum temperature (K)
Why climate change has the most effects on
pollution events?
2000s conditions
2050s climate
2050s emissions
2050s climate & emis
median
99th
percentile
Cumulative probability (%)
Mitigation of climate change penalty by reductions
in anthropogenic emissions
“climate change penalty” for ozone AQ = Δ[O3] from climate change
Change of summer 90th percentile max-8h O3 due to climate change
(a) 2000 emissions
(b) 2050 emissions
Reductions of anthropogenic emissions significantly mitigate the
“climate penalty” and can even turn it into a “climate benefit” in
the Southeast and Northwest.
Translating climate change penalty to emission control efforts
NOx emission - 40%
2000 conditions
(2050 climate)
NOx emission - 40%
(2000 climate)
NOx emissions - 50%
(2050 climate)
2000–2050 climate
change implies an
additional 25%
effort in NOx
emission controls
to achieve the
same ozone air
quality.
Conclusions
1.
Climate change is expected to worsen the U.S. ozone air quality; the summer
average daily max-8h ozone is projected to increase by 2-5 ppb over large areas
due to 2000-2050 climate change with the IPCC A1B scenario. Climate change has
most effects on air pollution episodes than on the means; it increases the 90th
percentile ozone by up to 10 ppb.
2.
The 2000-2050 changes in anthropogenic emissions of ozone precursors outside
of North America would increase the mean summer PRB ozone by 3-6 ppb in the
western United States, and by 2-3 ppb in the East.
3.
Factors causing worse ozone air quality associated with the future climate include:
higher temperature, less convection, lower mixing depth, higher natural emissions
as well as less frequent cyclones.
4.
Preliminary analysis suggests that the climate change penalty corresponds to a
need for some 10% further reductions in NOx emissions to meet our goals for clean
air.
5.
Emission reductions can greatly mitigate the “climate change penalty” for ozone
air quality, and can even turn it into a “climate benefit”.