LINKAGES AND SYNERGIES OF REGIONAL AND GLOBAL EMISSION

CONTROL

Workshop of the UN/ECE Task Force on Integrated Assessment Modelling

January 27-29, 2003

International Institute for Applied Systems Analysis

European Topic Centre on Air and Climate Change

Convention on Long-rangeTransboundary Air Pollution

Cooperative programme for monitoringand evaluation of the long-range transmission

of air pollutants in Europe

Questions

• What do we know about the linkages between air pollution and climate change?

• How important are these linkages?

• Which of these linkages could potentially influence rational policies to control emissions?

Sessions

1. Physical linkages through atmospheric chemistry

2. Physical linkages through environmental impacts

3. Concerns of national decision makers

4. Synergistic measures: Sectoral perspectives

5. Strategies to harness synergies

6. Economic instruments

7. Modelling approaches

Linkages through atmospheric chemistry

• Also air pollutants exert climate impacts • Radiative forcing (RF) of ozone and PM are

different in space and time from that of GHGs• Sulphates, nitrates and organic carbon have

cooling effect and can reduce precipitation• Black carbon has positive forcing• Ozone has strong positive RF, better understood

than that of aerosols• Methane influences RF and ozone• CC impacts on meteorology seem less relevant

for the next two decades

Linkages through environmental impacts

Numerous linkages exist, not all of them are yet fully understood.

• CC might reduce ecosystems sensitivity to acidification

• Increased N deposition increases C storage

• Air pollution weakens plant growth, reduces C storage

• Air pollution and CC affect biodiversity

Synergies of multi-objective strategies

• Simultaneous emission controls result in multiple benefits.

• Synergies may free resources.

• Existing trade-offs should be considered.

• Global CO2 stabilization will lead to lower SO2

emissions. Extent depends on how reduction is achieved.

• Synergies in agricultural sector important.

• Significant ancillary benefits demonstrated in many case studies

Strategic aspects

GHG emission trading schemes can have impacts on air pollution:

• C trading influences air pollution control costs

• C trading affects regional environmental impacts of air pollution. Ancillary (dis-)benefits should be considered.

• Effects of C trading are uncertain. This causes a problem for defining an air pollution baseline scenario.

Modelling the linkages

• Modelling requires bridging different temporal and spatial scales.

• Extension of multi-effect approach? Could offer a systematic tool for choosing multiple targets of different types.

• Models will have to address sustainable development and structural changes beyond cost-effectiveness.

• Keep models manageable!

The way forward

• Extension of RAINS towards greenhouse gas cost curves is underway to

– Help decision makers maximizing positive synergies and minimizing trade-offs, and

– Selecting most cost-effective measures in view of the objectives of both policy areas.

• Primary focus should be on scientific issues.

• Improved contacts between air pollution and climate change science communities necessary.