Hemispheric Ozone and Cooperation

Frank Dentener European Commission- JRC

Co-chair TF HTAP

Terry J. Keating, Ph.D. U.S. EPA

Co-chair TF HTAP

Frank Dentener, Ph.D. European Commission JRC

Co-chair TF HTAP

Air Science Policy Forum, Dublin, 15.04.2013

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.

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Lower troposphere

Mid-upper troposphere

Pathways of transport hemispheric air pollution

Stohl et al, 2004 3

•Change in global baseline O3?

•Changes were stronger in 1990s than in 2000s

•What is the role of changing global emissions and climate?

•How does this impact air quality in Europe?

• Is this happening everywhere along the borders of Europe?

Courtesy D. Derwent, K. Law, D Parrish

What is causing the change in O3 between 1989-1994 and 2006-2010?

Ozone at Mace Head, Ireland

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IPCC AR5 courtesy O. Cooper, 2013

Global baseline ozone changes between 1990s and 2010

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• Established in 2004 by the UNECE Convention on Long-Range Transport Air Pollution

• Co-chaired by the European Commission

and the U.S. EPA

• An expert group of scientists studying hemispheric transport of air pollution

• HTAP Phase 1: HTAP Assessment report 2010

• HTAP Phase 2: by 2015 targeted briefings, reports and publications

What is HTAP?

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www.htap.org

•Examine transport of air pollution across the Northern Hemisphere, including ozone (precursors) and PM and components (including black carbon), mercury, and persistent organic pollutants. •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

Mandate

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NA

EU

EA SA

HTAP (2010) Multi-Model Experiments

Source-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, POPs

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Total O3

change

Within EU

Outside of EU

Methane

HTAP reconstruction of O3 changes in Europe: attribution of drivers.

NA EU

EA SA

• Annual average - large region –global models

• Largest O3 (6 ppb) decreases before 1980; small

reductions in O3 during 1980-2000

• O3 reductions attributable to EU emissions

compensated by increasing emissions elsewhere

• Important role for (global) CH4 30-50 %

• Taken together changes in O3 from outside

Europe 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’

concentrations

Wild et al, ACP, 2012

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10

European annual regional mean O3 changes [ppb] for a range

of future global air pollution scenarios

Wild et al, in prep. 2013

SRES A2

RCP 8.5

RCP 2.6

1. Emissions & Projections

2. Source/Receptor & Source Apportionment 3. Model/Observation &

Process Evaluation

4. Impacts on Health, Ecosystems, & Climate 5. Impact of Climate

Change on Pollution

6. Data Network & Analysis Tools

Policy-R

ele

vant

Scie

nce

Pro

ducts

& O

utr

each

TF HTAP: Themes of Cooperative Activities 2012-2016

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• An improved modeling system based on ensembles of regional and global models that reflect our current best knowledge on the intercontinental 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 air

pollution problems under future emission scenarios, considering various alternatives at the country, regional and global level, anchored by a set of consistent and plausible benchmark scenarios developed by IIASA and an understanding of possible changes in emission drivers.

• Enhanced global scientific cooperation to develop models, methods, and measurements to improve our understanding of the role of hemispheric air pollution and its impacts.

Perspectives for TF HTAP Phase: 2015

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• To better understand hemispheric O3 transport, long-term, high quality monitoring of O3 and related components at strategic (inflow) locations in Europe are indispensable.

• Scientific assessments show that the contribution of hemispheric O3

to local pollution is increasing.

• Increasing hemispheric pollution necessitates greater and more expensive controls at the local or national level to achieve the same air quality objectives and justifies efforts to cooperate on a hemispheric or global scale to reduce tropospheric ozone.

• The issue is being addressed by UNECE CLRTAP- with full support of the EC and the US EPA, elsewhere the TF HTAP is an important instrument to raise awareness.

• A portfolio of options is emerging- it is clear that emission reduction

of CH4 (producing O3) is going to be very important- with links to co-benefits from climate policies.

Take home messages