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Hemispheric ozone and cooperation - Frank Dentener


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Hemispheric ozone and cooperation - Frank Dentener

  1. 1. Hemispheric Ozone and CooperationTerry J. Keating, Ph.D.U.S. EPACo-chair TF HTAPFrank Dentener, Ph.D.European Commission JRCCo-chair TF HTAPAir Science Policy Forum, Dublin, 15.04.2013
  2. 2. Why do we worry about hemispheric tropospheric ozone?•Ground-level ozone is one the most harmful air pollutants in Europe•Levels continue to exceed air quality thresholds (EEA, 2011)•New evidence of health impacts of ozone at lower levels•Ozone is also damaging crops and natural vegetation•Tropospheric ozone is an important climate forcer (ca. 0.4 Wm-2 )•Hemispheric ozone is changing.2
  3. 3. Lower troposphereMid-upper tropospherePathways of transport hemisphericair pollutionStohl et al, 20043
  4. 4. • Change in global baseline O3?• Changes were stronger in 1990sthan in 2000s• What is the role of changingglobal emissions and climate?• How does this impact air qualityin Europe?• Is this happening everywherealong the borders of Europe?Courtesy D. Derwent, K. Law, D ParrishWhat is causing the change in O3between 1989-1994 and 2006-2010?Ozone at Mace Head, Ireland4
  5. 5. IPCC AR5 courtesy O. Cooper, 2013Global baseline ozone changes between 1990sand 20105
  6. 6. • Established in 2004 by the UNECEConvention on Long-Range Transport AirPollution• Co-chaired by the European Commissionand the U.S. EPA• An expert group of scientists studyinghemispheric transport of air pollution• HTAP Phase 1: HTAP Assessment report2010• HTAP Phase 2: by 2015 targetedbriefings, reports and publicationsWhat is HTAP?
  7. 7. •Examine transport of air pollution across the NorthernHemisphere, including ozone (precursors) and PM and components(including black carbon), mercury, and persistent organicpollutants.•Assess potential emission mitigation options available inside andoutside the UNECE region•Assess their impacts on regional and global air quality,public health, ecosystems, near-term climate change•Collaboration with other groups both inside and outside theConventionMandate7
  8. 8. NAEUEASAHTAP (2010) Multi-Model ExperimentsSource-Receptor Sensitivity Simulations:•Base Year 2001•More than 30 global models from Europe, US and Asia•Decrease emissions of precursors in each region by 20%•Precursors emission combinations NOx, VOC, CO, CH4, Hg, POPs8
  9. 9. Total O3changeWithin EUOutside of EUMethaneHTAP reconstruction of O3 changes inEurope: attribution of drivers.NAEUEASA• Annual average - large region –global models• Largest O3 (6 ppb) decreases before 1980; smallreductions in O3 during 1980-2000• O3 reductions attributable to EU emissionscompensated by increasing emissions elsewhere• Important role for (global) CH4 30-50 %• Taken together changes in O3 from outsideEurope and CH4 are larger than within EU (60-70% of total)• External O3 becomes more important when‘local’ sources are more regulated.• Hemispheric transport more important at ‘lower’concentrationsWild et al, ACP, 20129
  10. 10. 10European annual regional mean O3 changes [ppb] for a rangeof future global air pollution scenariosWild et al, in prep. 2013SRES A2RCP 8.5RCP 2.6
  11. 11. 1. Emissions &Projections2. Source/Receptor &Source Apportionment 3. Model/Observation &Process Evaluation4. Impacts on Health,Ecosystems, & Climate 5. Impact of ClimateChange on Pollution6. Data Network & Analysis ToolsPolicy-RelevantScienceProducts&OutreachTF HTAP: Themes of Cooperative Activities 2012-2016
  12. 12. 12• An improved modeling system based on ensembles of regional andglobal models that reflect our current best knowledge on theintercontinental transport of air pollution and its impacts on health,ecosystems and climate under past-present and future conditions.• An evaluation of the potential for mitigation of large scale airpollution problems under future emission scenarios, consideringvarious alternatives at the country, regional and global level,anchored by a set of consistent and plausible benchmark scenariosdeveloped by IIASA and an understanding of possible changes inemission drivers.• Enhanced global scientific cooperation to develop models, methods,and measurements to improve our understanding of the role ofhemispheric air pollution and its impacts.Perspectives for TF HTAP Phase: 2015
  13. 13. 13• To better understand hemispheric O3 transport, long-term, highquality monitoring of O3 and related components at strategic(inflow) locations in Europe are indispensable.• Scientific assessments show that the contribution of hemispheric O3to local pollution is increasing.• Increasing hemispheric pollution necessitates greater and moreexpensive controls at the local or national level to achieve the sameair quality objectives and justifies efforts to cooperate on ahemispheric or global scale to reduce tropospheric ozone.• The issue is being addressed by UNECE CLRTAP- with full support ofthe EC and the US EPA, elsewhere the TF HTAP is an importantinstrument to raise awareness.• A portfolio of options is emerging- it is clear that emission reductionof CH4 (producing O3) is going to be very important- with links toco-benefits from climate policies.Take home messages