GCAP Global Climate and Air Pollution: One of six projects funded by EPA-STAR to study effect of climate change on air

1. GCAP (Global Climate and Air Pollution): One of six projects funded by EPA-STAR to study effect of climate change on air quality. Collaborators: Harvard University: Daniel J. Jacob, Loretta J. Mickley, Shiliang Wu Argonne: David Streets Caltech: John Seinfeld, Hong Liao Goddard Institute for Space Studies: David Rind Univ. Tennessee: Joshua Fu

2. Blueprint for GCAP: 5 models working together to provide information on climate change impacts

3. GCAP progress : GISS model III developed, validated Linkages between models completed Present-day global chemistry model validated Present-day global ozone budget analyzed Future emissions of gas-phase precursors and PM developed Tracers of pollution meteorology implemented into GCM Transient simulation in progress Early results from GISS GCM II’ published

4. Implementing tracers of pollution into the GISS GCM

5. Early GCAP results: Effects of climate change on air quality over the Midwest and Northeast United States, using CO and BC tracers

6. Our approach: Look at daily mean concentrations averaged over specific regions for two 8-year intervals (1995-2002) and (2045-2052).

7. Frequency distributions for pollution tracers show higher extremes in 2050s compared to present-day.

8. How does depth of the boundary layer change with changing climate? We have just started a pilot study to explore this last issue. In this study, we include in the GISS GCM simple treatments of CO and black carbon tracers and conduct a transient climate simulation from 1950 to 2050 using the IPCC A1 scenario. We use CO as a relatively inert indicator for pollutant ventilation, and black carbon as the same but including the effect of precipitation – we assume that this BC is efficiently scavenged. We then compare concentration statistics of CO and black carbon for the present and future atmospheres. We are literally just starting to look at the results. Results are shown here for surface air in the northeast U.S. in summer. We see a higher frequency of high-CO and BC concentrations in the 2050 climate, indicating reduced ventilation – a fascinating result! In the western U.S. we see the opposite – a lesser frequency of pollution episodes. What is going on? We have just started a pilot study to explore this last issue. In this study, we include in the GISS GCM simple treatments of CO and black carbon tracers and conduct a transient climate simulation from 1950 to 2050 using the IPCC A1 scenario. We use CO as a relatively inert indicator for pollutant ventilation, and black carbon as the same but including the effect of precipitation – we assume that this BC is efficiently scavenged. We then compare concentration statistics of CO and black carbon for the present and future atmospheres. We are literally just starting to look at the results. Results are shown here for surface air in the northeast U.S. in summer. We see a higher frequency of high-CO and BC concentrations in the 2050 climate, indicating reduced ventilation – a fascinating result! In the western U.S. we see the opposite – a lesser frequency of pollution episodes. What is going on?

9. Evolution of a typical pollution episode over 6 days.Less frequent cold fronts across mid-latitudes in the future atmosphere increases duration and severity of pollution episodes.

10. Conclusions Over the Northeast and Midwest, reduced cyclone frequency in future climate increases duration and severity of summertime pollution episodes. Mean episode duration increases from 2 days to 3-4 days. GCMs can be a powerful tool to investigate responses of air quality to climate change.

11. GCAP progress : GISS model III developed, validated Linkages between model completed Present-day global chemistry model validated Present-day global ozone budget analyzed Future emissions of gas-phase precursors and PM developed Tracers of pollution meteorology implemented into GCM Transient simulation in progress Early results from GISS GCM II’ published

12. Extra slides

13. Climate change affects the meridional transport of energy in the model.

14. How do you translate our results into “ozone alert days”?