1. Intercontinental and Hemispheric Scale Transport and the LRTAP Convention Terry J. Keating, Ph.D. Office of Air and Radiation U.S. Environmental Protection Agency

2. 1999 Gothenburg Protocol to Abate Acidification, Eutrophication, and Ground-Level Ozone Preamble –Recognized the potential for intercontinental transport Article 8: Research, Development, & Monitoring –Commits Parties to improve understanding of impact on hemispheric background and potential for intercontinental transport

3. A Series of Workshops Trans-Pacific, Seattle, July 2000 Trans-Atlantic and Arctic, New York, June 2001 ICAP Project I, North Carolina, Dec 2001 Hemispheric Air Pollution, Bad Breisig, Oct 2002 ICAP Project II, North Carolina, Oct 2004 Global Air Pollution, IIASA, Jan 2005

4. Key Scientific Questions Do we have the tools and data to quantify the source-receptor relationships of air pollutants (O 3, PM, Hg) between Asia, North America and Europe? What are the key uncertainties in these source-receptor relationships? What research activities could help reduce these uncertainties? How important are the links between these hemispheric air pollution problems and climate change for future air pollution policy? What are the roles of EMEP, EUROTRAC, IGAC, NARSTO, AMAP, European Commission Research Programs, etc. in pursuing these research activities?

5. Mechanisms of Transport Well-documented evidence for the intercontinental and hemispheric transport of ozone, particles, and their precursors, as well as mercury and persistent organic pollutants. Two mechanisms of intercontinental influence: –Increase in hemispheric burden of pollution –Discrete episodic flows of pollution For Asia to North America and North America to Europe, lifting into the free troposphere by deep convention or synoptic weather systems (e.g., warm conveyor belts) seem to be most important. For Europe to Asia, orographic lifting and transport in the boundary layer seem to most important. Conclusions

6. For ozone, the increase in hemispheric burden appears to have a greater effect than discrete intercontinental transport events. For aerosols and their precursors, episodic flows appear to be most important for intercontinental transport. For mercury, export into the free troposphere contributes to a hemispheric or global pool of elemental mercury. Mercury deposition patterns are more related to patterns of emissions and precipitation than to transport events. Mechanisms of Transport Conclusions

7. Need an integrated system of models capable of linking the local, regional, and hemispheric scales. Modeling of these transport pathways has resulted in a variety of highly uncertain estimates of source- receptor relationships that can be tabulated. These estimates alone are not sufficient to assess the impact of alternative control strategies. Modeling Source-Receptor Relationships Conclusions

8. Implications for the Future The emissions of ozone precursors have more than doubled since pre-industrial times. As a result the hemispheric burden of ozone has increased by 50% to 100% over pre-industrial levels. Observations suggest that local air pollution problems persist and the hemispheric burden is continuing to increase. Any further increase in Northern Hemispheric emissions will aggravate the exceedance of air quality objectives. For aerosols, the frequencies of large forest fires and dust storms are likely to change in the future in response to changes in climate, land use, and human intervention. Conclusions

9. Recommendations for Future Research Need a systematic approach to model evaluation, long-term monitoring, intensive observational studies, and emission inventory development. Highest priorities: –Global observing networks using surface “supersites”; satellite and ground-based remote sensors; and instrumented commercial passenger and research aircraft. –Emissions inventories, especially biogenics and historical trends. –Linked or nested models –Techniques to manage, analyse, and synthesize diverse types of information –Interdisciplinary communication and collaboration