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Effect of 2000-2050 global
change on U.S. ozone air quality
Shiliang Wu
Loretta J. Mickley
GCAP
Daniel J. Jacob
Eric M. Leibensperger
David Rind (NASA/GISS)
David G. Streets (ANL)
GEOS-Chem users’ meeting, 2007/04
work supported by the EPA-STAR program
Background - We are facing rapid global change
NOx emission from fossil fuel (Tg N / yr)
50
45
40
2050
IPCC
A1B
scenario
35
30
2000
25
20
15
10
2000
5
2050
0
U.S.
(-40%)
Global
(+90%)
IPCC [2007]
Models and future scenarios
GISS GCM III
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
Natural
emissions
Climate Change
2000
2050
change
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%
Air
pollutants
& their
precursors
Chemistry, transport,
deposition, etc
Effects of 2000-2050 global change on tropospheric ozone
(annual zonal mean)
+3%
+17%
+20%
Effects of 2000-2050 global change on U.S. ozone air quality
Daily max 8h-avg ozone averaged over JJA (ppb)
2000 conditions
2050 climate – 2000
Increase of
summer max8h-avg ozone by
1-5 ppb in large
areas of U.S.
due to 20002050 climate
change.
2050 emission – 2000
2050 – 2000
Less effects in
western U.S.
because (1)
anthro.
emissions there
are low (2)
increase of
ozone from
intercontinental
transport.
Factors causing worse O3 AQ with the future climate
Summer surface T. (2050 – 2000)
Mixing depth (2050 / 2000)
Convective mass flux (2050-2000)
What’s more: decrease of cyclone frequency
2000 climate
2050 climate
1999-2001
Eric M. Leibensperger, Harvard
2049-2051
Max. 8-hr-avg ozone
Climate change has most effects on pollution events
2000s condition
2050s climate
2050s emissions
2050s climate & emis
median
99th
percentile
Cumulative probability (%)
Mitigation of climate penalty by emission reductions
in ozone precursors
“climate change penalty” for ozone AQ = Δ[O3] from climate change
Change of summer average max-8h ozone 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
southeast and northwest U.S.
Conclusions
1.
Climate change is expected to worsen ozone air quality in the United
States; the summer average daily max-8h ozone is projected to increase
by 2-5 ppb over large areas due to the 2000-2050 climate change with the
IPCC A1B scenario. Climate change has more effects on air pollution
episodes than on the means; it tends to increase the 90th percentile
ozone
by 5-10 ppb.
2000–2050
global change would make fresh air
2.
Factors causing worse ozone air quality associated with the future
more
luxuryhigher
in the
Unitedless
States.
climate include:
temperature,
convection and lower mixing
depth, higher natural emissions as well as less frequent cyclones.
3.
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.
4.
Reductions of anthropogenic emissions can significantly mitigate the
“climate penalty” for ozone air quality, and even turn it into a “climate
benefit”.
5.
The 2000-2050 climate change would reduce the PRB ozone in the United
States by 1-3 ppb for most areas while the changes in global
anthropogenic emissions would increase the PRB ozone by 2-5 ppb.
Effects on annual mean afternoon surface O3