Addressing the interlinkages between greenhouse gases, climate change and air quality
Air pollution and climate change are closely related. The main sources of CO2 emissions – the extraction and burning of fossil fuels – are not only key drivers of climate change, but also major sources of air pollutants. Furthermore, many air pollutants that are harmful to human health and ecosystems also contribute to climate change by affecting the amount of incoming sunlight that is reflected or absorbed by the atmosphere, with some pollutants warming and others cooling the Earth. These so-called short-lived climate-forcing pollutants (SLCPs) include methane, black carbon, ground-level ozone, and sulfate aerosols. They have significant impacts on the climate; black carbon and methane in particular are among the top contributors to global warming after CO2.
Air pollution is currently the leading environmental cause of premature death. According to the World Health Organization (WHO), approximately 7 million premature deaths annually are due to the effects of air pollution. Moreover, SLCPs adversely affect ecosystems, including agriculture. In Europe alone, annual crops losses due to ozone are worth several billion euros. Beyond these impacts on health and agriculture, SLCPs are responsible for roughly half of current global warming. Although all plans to minimise climate change depend critically on swift action to reduce CO2 emissions, internationally agreed climate targets may not be achievable without additional activities to mitigate SLCPs.
Addressing SLCPs: quick wins with many co-benefits
CO2 remains in the atmosphere for a hundred years or more, so its effects on the climate are long-lasting. SLCPs, by contrast, have much shorter atmospheric lifetimes. Many aerosol particles such as black carbon and pollutant gases such as ground-level ozone remain in the atmosphere for only several hours to a few weeks, while methane stays in the atmosphere for about a decade. Changes in the emissions of these shorter-lived gases and particles lead to relatively rapid changes in their atmospheric concentrations. Thus the benefits of mitigating SLCPs would materialise in a relatively short time, presenting an opportunity for quick, coordinated action to improve both air quality and the climate. Indeed, halving air pollution by 2040 could prevent up to 45 million premature deaths.
Understanding and identifying the sources of SLCPs and tailoring mitigation options to specific political, social and economic contexts are key challenges. Today, climate change and air quality are often addressed in separate policy arenas and at different levels. Climate change is typically addressed at international and national levels, for example, in the United Nations Framework Convention on Climate Change (UNFCCC), which focuses on the mitigation of CO2 in particular. SLCPs are partially addressed by the Montreal Protocol to the Vienna Convention for the Protection of the Ozone Layer and the Gotheburg Protocol to the Convention on Long-Range Transboundary Air Pollution. Furthermore, at local and regional levels, SLCP emissions are tackled by local air-quality action plans or international programs with a regional focus, for example, the Task Force on Hemispheric Transport of Air Pollution (HTAP). Recently, however, there have been increasing efforts to bridge the policy divide between air quality and climate change, for example, via the Climate and Clean Air Coalition (CCAC), which was created in 2012. The CCAC is a voluntary initiative under the United Nations Environment Programme (UNEP), in which the IASS is an active Non-State Partner currently serving on the CCAC Steering Committee.
IASS research on air quality and climate change
In this research area, the IASS is conducting the following activities:
- joint development, demonstration and assessment of SLCP mitigation measures with stakeholders from all parts of society
- field measurement campaigns and monitoring of air pollutants in cooperation with local stakeholders to better understand levels, sources, and impacts of air pollution
- targeted studies using computer models that link sources and concentrations of SLCPs and facilitate the assessment of mitigation options
- collaboration with decision-makers at the science-policy interface at national and international levels based on our scientific results and analyses, to support and inform initiatives to reduce SLCP emissions and make scientific findings accessible to non-specialist audiences
Our work is currently focused on Europe, in particular the Berlin-Brandenburg area, the Southern Himalayan region, especially Nepal, as well as the Eurasian Arctic. We also engage policy communities and stakeholders at local, regional and global levels.
Photo on front page: (c) istock; photo above article and illustration: (c) IASS