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Air pollution and climate change tackling both problems in tandem

Published: 31 January 2003

Geneva, 31 January 2003 - Scientists and policy makers should no longer treat air pollution and climate change as distinct problems, because the two are very closely related. The recent Workshop on Linkages and Synergies of Regional and Global Emission Control, organized under the UNECE Convention on Long-range Transboundary Air Pollution by the International Institute for Applied Systems Analysis (IIASA), looked at the numerous links between these two policy areas. It concluded that these links are so important that they merit close cooperation.

Air pollution affects the regional and global climate both directly and indirectly. Ozone in the lower layers of the atmosphere contributes to global warming even more than some greenhouse gases included in the Kyoto Protocol, and particulate matter in the atmosphere also has important climate impacts. However, although black carbon, or soot particles, has a warming effect, other particles, for instance sulphates and nitrates, may cool the climate. The current high levels of sulphates and nitrates mask the effects of climate change to some degree. Through cuts in sulphur and nitrogen emissions necessary to protect human health and the environment the climate impacts of the greenhouse gases may actually show more quickly. On the other hand, measures to cut black carbon emissions, for instance from diesel combustion, will have double benefits, protecting both human health locally and also the climate regionally and worldwide.

Methane has a direct negative impact on climate (it is one of the Kyoto Protocol greenhouse gases) and it contributes to ground-level ozone levels. Methane emissions (mainly from agriculture, energy and waste management) have grown very rapidly since pre-industrial times. Cutting these emissions will reduce health- and ecosystem-damaging ozone levels and reduce the extent of climate change.

While indications of the climate impacts of increasing greenhouse gas concentrations can already be seen in the rise of mean temperatures and the increase in the numbers of extreme climate events (floods and droughts), most impacts are likely to happen over the next 50-100 years. Some gases, like carbon dioxide, stay in the atmosphere for a very long time, so measures to reduce emissions only start to show an effect after a few decades. In contrast, ozone, black carbon and methane can be controlled to show effects much sooner (10-20 years). Cutting these pollutants could help reduce some climate impacts while waiting for longer-term measures to pay off.

Besides such links between atmospheric effects, there is also a strong link between the sources of emissions. Energy production and transport are responsible for most CO2 emissions and much of the air pollution. Cutting energy consumption and car use will therefore have double benefits. Synergies can also be found in agriculture: cutting ammonia emissions could lead to an increase of some greenhouse gas emissions, but the same reduction levels can also be achieved by an integrated strategy that will even cut some of the greenhouse gases.

The UNECE Conventions Centre for Integrated Assessment Modelling, run by IIASA, estimates that the cost of reaching the 2010 air pollution objectives in the Conventions Gothenburg Protocol could be reduced by at least 5 billion if European countries cut CO2 emissions in line with the Kyoto Protocol (without CO2 trading). Similar results have been found for China or Mexico.

While closely related, air pollution and climate change have mostly been treated as separate problems. At the international level, efforts under the UNECE Convention on Long-range Transboundary Air Pollution have helped cut air pollution levels in Europe. Sulphur emissions are 60% lower than in 1980, nitrogen oxides are down by 25% compared to 1990 and other pollutants are also starting to decline. At the global scale the United Nations Framework Convention on Climate Change has brought together more than 180 countries to agree on measures to combat climate change. More needs to be done, both to bring air pollution down to safe levels and to cut greenhouse gas emissions to halt climate change.

Taking certain climate change measures will yield additional benefits through improved local and regional air quality. Certain air pollution abatement measures will also help protect the regional and global climate. Much, though not all, is known about such links, but systematic studies are lacking. The UNECE Conventions Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) has begun to integrate these links into its assessment so that measures to further cut air pollution will lead to win-win situations. It is also seeking cooperation with scientists of the Intergovernmental Panel on Climate Change to move this work forward.


For more information, please contact:

Henning Wuester

Environment and Human Settlements Division
United Nations Economic Commission for Europe (UNECE)
Palais des Nations, office 323
CH - 1211 Geneva 10, Switzerland

Phone: +41(0)22 917 23 63
Fax: +41(0)22 907 06 21
E-mail: henning.wuester@unece.org
Web site: http://www.unece.org/env/lrtap/

Ref: ECE/ENV/03/P02


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