Linking global scale and European scale modelling: Hemispheric Transport of Air pollution Frank Dentener JRC Andre Zuber ENV Terry Keating US EPA and HTAP authors/contributors

Task Force Hemispheric Transport of Air Pollution (TF HTAP) Established in 2004 by UNECE Interim report 2007 HTAP Assessment report 2010 Mandate: Examine the transport of air pollution across the Northern Hemisphere, ozone and its precursors and PM and its components (including black carbon) Assess potential emission mitigation options available inside and outside 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 the Convention.

HTAP 2010 Report 4 volumes, 826 pages, 178 contributors Covers O3, PM, Hg, POPs Contents addresses: Conceptual Models Observed Spatial & Temporal Trends Emissions Inventories & Projections Global & Regional Modeling of Pollution Transport Impacts to Health, Ecosystems, & Climate Available electronically at www.htap.org Available in print on request The Task Force on Hemispheric Transport of Air Pollution under the LRTAP Convention has recently completed an assessment of the intercontinental transport of air pollution across the Northern Hemisphere. 178 experts from around the world contributed to the report, which comprises 4 volumes addressing ozone, fine particles, mercury, and persistent organic pollutants. The report is available electronically from the Task Force website, www.htap.org, and will be available soon in printed form. 3

Pathways of hemispheric pollution transport CO passive tracer Lower troposphere Mid-upper troposphere Figure A1-4. Pathways of intercontinental pollution transport in the Northern Hemisphere. Shading indicates the location of the total column of a passive anthropogenic CO tracer released over the Northern Hemisphere continents after 8-10 days of transport, and averaged over 15 years. Shown are transport pathways in summer (June, July, August) (upper panel), and winter (December, January, February) (lower panel). Gray arrows show transport in the lower troposphere (< 3 km) and black arrows show transport in the mid- and upper troposphere (> 3 km). Image reproduced from Chapter 1, Figure 2, page 6, of Stohl, A Flexpart, A. Stohl et al, 2004

MACE HEAD, WEST COAST IRELAND: change in O3 between 1989-1994 and 2006-2010 Change in global baseline O3? Change in meteorological conditions? Is this happening everywhere along the borders of Europe? How does this impact air quality in Europe? Courtesy D. Derwent, K. Law

Measurements at Mount Batchelor, US West Coast Several surface stations and satellite analysis show intercontinental transport Plume transport versus ‘diffusive’ background transport the magnitude and importance of these transports from combination of models and measurements

HTAP: Design of Multi-Model Experiments NA EU EA SA Source-Receptor Sensitivity Simulations: Base Year 2001 >20 global models Decrease emissions of precursors in each region by 20% Precursors emission include NOX, VOC, CO, NOX+VOC+CO, NOX+VOC+CO+PM Hg, POPs CH4 concentration One of the unique contributions of the Task Force has been the organization of a series of multi-model experiments to quantify intercontinental transport. More than 30 modeling groups from around the world have participated in one or more of these experiments. In the first phase of these experiments, the Task Force defined a set of sensitivity analyses, looking at 20% decreases in emissions from 4 continental regions that approximate North America, Europe, South Asia, and East Asia. These experiments demonstrated that pollution within any of the regions is most sensitive to changes in emission sources within that region. However, every region could also benefit significantly from emission controls outside the region. 7

HTAP policy relevant metric RELATIVE ANNUAL INTERCONTINENTAL RESPONSE R= annual average response to emission perturbation Under current conditions: if everywhere in the world the same emission reductions were applied, what would be in the EU the relative contribution of pollution from abroad?

RAIR for air pollution, climate and ecosystem metrics “Ecosystem Impacts”

Emissions: EDGAR-HTAP National and regional inventories, complemented with EDGAR global emissions Policy consistency Consistent high resolution emissions databaseTF HTAP base year calculations

HTAP reconstruction of regional ozone changes: period 1960-2000; attribution of drivers. NA EU EA SA Surface O3 change [ppbv] Source Receptor relationships from ca. 10 global models Global emissions trends of precursors (1960-2000) Reconstruction of the past O3 trends Source attribution O. Wild et al., ACPD, 2011

HTAP reconstruction of regional ozone changes: period 1960-2000; attribution of drivers. NA EU EA SA Surface O3 change [ppbv] Contribution to O3 change [ppbv]

HTAP reconstruction of O3 changes in EU: attribution of drivers. NA EU EA SA Annual average - large region Small reductions in O3 during 1980-2000, largest changes (6 ppbv) happened before. O3 reductions attributable to EU emissions partly compensated by increasing emissions elsewhere Important role for (global) CH4 30-50 % Total change Within EU Outside of EU Methane

HTAP reconstruction of O3 changes in EU: attribution of drivers. NA EU EA SA Annual average - large region Small reductions in O3 during 1980-2000, largest changes (6 ppbv) happened before. O3 reductions attributable to EU emissions partly compensated by increasing emissions elsewhere Important role for (global) CH4 30-50 % Taken together changes in O3 from outside EU and CH4 are larger than within EU (60-70 %) External O3 becomes more important when ‘local’ source are more regulated. More important at ‘lower’ concentrations Total change Within EU Outside of EU Methane

TF HTAP Future Directions Deliver Policy Relevant Information to the LRTAP Convention, Other Multi-Lateral Forums, and National Governments and EU Fraction of air pollution concentrations attributable to emission within region compared to extra-regional. Impacts on human health (Global Burden of Disease), ecosystems (WGE) and climate change (IPCC) Sensitivity to changes in specific sources (e.g. ships) Change of impacts and fractions under expected air pollution abatement efforts or climate change: scenarios and control options: focus on Black Carbon, Methane, Mercury e. Comparison of the availability, costs and impacts of additional emission abatement options across different regions Improve Our Scientific Understanding of Air Pollution at the Global to Hemispheric Scale Emissions: EDGAR HTAP Various source apportionment methods Linking of global and regional models Model-Observation Evaluation and Process Diagnosis Build a Common Understanding by Engaging Experts Inside and Outside the LRTAP Convention

EC ENV contract on Hemispheric Transport Model simulations in the frame of TF HTAP, but focus on EU and review Contractor: MetNo, IIASA, FZ Julich, assisted by JRC Timeframe: 11/2011-11/2013 Emission scenarios and control options Contribute to multi-model analysis and evaluation in TF HTAP Provide dedicated information on the impact of past and future changes in boundary conditions on EU Air Quality