Effect of 2000 2050 global change on ozone
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 A 1 B 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 A 1 B scenario) 4 - 40% 2 +90% +300% +800% 1. 5 1. 1 0. 9 0. 8 0. 7 0. 6 Global total NOx emissions: + 90% 0. 5
A 1 B 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 8 h-avg ozone averaged over JJA (ppb) 2000 2050 emission – 2000 2050 climate – 2000 2050 – 2000 Increase of summer max-8 h -avg ozone by 15 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) o. C Convective mass flux (2050 - 2000) 1. 0 0. 8 0. 6 0. 5 -1. 0 -1. 5 -2. 0 [g/m 2/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 (%) Midwest Northeast Southeast Northeast median 99 th percentile Cumulative probability (%) 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? 2000 s conditions 2050 s climate 2050 s emissions 2050 s climate & emis median 99 th percentile Cumulative probability (%)
Mitigation of climate change penalty by reductions in anthropogenic emissions “climate change penalty” for ozone AQ = Δ[O 3] from climate change Change of summer 90 th percentile max-8 h O 3 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-8 h ozone is projected to increase by 2 -5 ppb over large areas due to 2000 -2050 climate change with the IPCC A 1 B scenario. Climate change has most effects on air pollution episodes than on the means; it increases the 90 th 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”.
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