Short-lived climate pollutants: a focus for hot air

Abstract

If political communities that profess a commitment to climate change are to stop their credibility going up in smoke in the face of decades of inaction, they might start by focusing on short-lived climate pollutants. The impact of these pollutants on health and global warming is evident, the technology to reduce them already available, and the effect of doing so would be rapidly rewarding. Unlike carbon dioxide and other long-lived greenhouse gases that linger in the atmosphere for hundreds to thousands of years with effects that will develop over decades, short-lived climate pollutants—such as black carbon (soot), tropospheric ozone, and methane—persist for only days to decades and their reduction could slow global warming within 10 years. A report published by WHO and the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants in October, 2015, Reducing global health risks through mitigation of short-lived climate pollutants, concludes that a reduction in emissions of these agents would affect health through changes in air pollution, effects on food security (from the impact of ozone and black carbon on weather and agricultural production), and indirectly through actions to reduce these pollutants, such as effects on people's diets and physical activity. Reductions in short-lived climate pollutants could save 3·5 million lives each year by 2030. Evidence for the adverse effects of air pollution on health has been compelling; policy-makers' responses have not. Significant associations are reported between cardiopulmonary disease and mortality and both short-term and long-term exposure to black carbon. Ozone has been associated with poor respiratory and cardiovascular health, central nervous system problems, reproductive concerns, and developmental effects, such as low birthweight. Yet each time the European Union (EU) creates policies to improve air quality, they revise or ignore earlier promises, setting unambitious targets for the short to medium term against nonbinding pledges for the distant future. Decisive action to reduce emissions will include making uncomfortable decisions. The agricultural industry, especially livestock farming, is responsible for 90% of ammonia emissions and 50% of methane production in Europe. Both climate change policies and fuel poverty have prompted an increase in the use of renewable energy sources, such as burning wood as a cheaper alternative to electricity or gas—so household biomass combustion has become a substantial source of air pollution in the EU. Fuel combustion in buildings and transport accounts for about 80% of anthropogenic black carbon emissions. The recent scandal surrounding Volkswagen highlights the problems of allowing powerful industrial groups to flout legislation—and the urgent need for greater scrutiny and stronger regulation, such as the Real Driving Emissions test. Reducing short-lived climate pollutants will be difficult, but can be done. California halved black carbon concentrations between 1989 and 2008 through smoke reduction standards, changes in transport and industry, and reductions in wood and waste burning. In August, 2015, the US Environmental Protection Agency unveiled its Clean Power Plan to reduce carbon emissions from power plants by 32% by 2030. The US has also led the way in air quality standards for fine particulate matter (PM2·5) in outdoor air while Europe has consistently dragged its feet—the European limit of 25 μg/m3 annually by 2015 is 2·5 times higher than WHO's recommendation of 10 μg/m3 and twice the USA standard of 12 μg/m3. The WHO report proposes four available, affordable interventions to reduce short-lived climate pollutants that will positively affect health: lower emissions and higher efficiency standards to reduce vehicle emissions; improvements in public transportation systems and pedestrian and cycle networks; provision of cleaner, more efficient alternatives to households that depend on biomass and solid fuels for heating and cooking; and reduction in methane emissions from livestock farming through strategies to increase consumption of plant-based foods. At the time of going to press, the EU Parliament is about to vote on recommendations from the National Emissions Ceilings Directive regarding mandatory emissions ceilings for 2025. An alarming last-minute amendment tabled by the European People's Party coalition proposes removal of all obligations to cut methane and reduction in limits for ammonia. In November, 2015, the UN Climate Change Conference, COP 21 or CMP 11, will meet in Paris. Bold steps to reduce short-lived climate pollutants at these meetings could provide leaders with the results to persuade their citizens of the merits and possibility of finally facing up to climate change.