Short-lived pollutants such as ozone, methane and aerosols are key to fighting both climate change and air pollution, says the team behind an EU-funded study that assessed effective emission abatement strategies for these short-lived climate forcers. Such strategies could reduce increases in global temperatures by 0.22 C by 2050, the team believes.
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When it comes to fighting climate change, policies targeting the reduction of greenhouse gas emissions, specifically, CO2, have been the main focus of policy makers. While the burning of carbon-based fuels has rapidly increased its concentration in the atmosphere, leading to global warming, other, short-lived pollutants also have a detrimental effect on the atmosphere. According to the team behind a study recently published in the journal Atmospheric Chemistry and Physics, the fight against climate change should be a two-pronged attack, mitigating the effects of these short-lived pollutants while simultaneously improving air quality and climate change.
Researchers from the ECLIPSE project studied the impact of a range of short-lived gases and aerosols, and their precursors, on the environment. These included nitrogen oxides, volatile organic compounds, sulphate, and black carbon. Although these substances remain in the atmosphere for a shorter period than CO2, they are nonetheless damaging to the climate and air quality. Methane, for example, is the second biggest contributor to climate warming after CO2, and is also an ozone precursor: chemical reactions in the atmosphere involving methane produce ozone, a pollutant that presents significant health risks and is itself a strong greenhouse gas. On the other hand, aerosols like those formed from sulphur dioxide, released in volcanic emissions but also from coal-fired power plants, have a cooling effect on the climate. Current climate policy fails to consider these short-lived pollutants.
“There is no doubt that the most important factor causing climate warming is CO2 emissions and this must be the prime target of our climate policies. Yet, there is merit in not completely ignoring other climate forcers, which could affect the rate of warming, particularly over the next few decades,” says Andreas Stohl, the ECLIPSE project coordinator from the Norwegian Institute for Air Research. “And what is probably even more important: targeting these substances would lead to large improvements in global air quality.”
The long-term benefits of tackling short-lived pollutants
Several of the new mitigation measures that the project recommends involve the oil and gas industry. The loss of methane in oil production, along with the flaring of gas in remote areas – which produces black carbon and warms the atmosphere – are major polluters.
Preventing unintended leaks during the extraction of shale gas would diminish methane emissions, while ending the flaring of gas produced during oil extraction would lower emissions of black carbon. Stohl says: “There are also other important measures to reduce methane emissions from coal mining, municipal waste treatment and gas distribution, for example, as well as reducing black carbon emission through elimination of high-emitting vehicles, using cleaner biomass cooking and heating stoves, replacing kerosene wick lamps with LED lamps etc.”
Climate benefits from the implementation of these measures would include the reduction of global temperatures by about 0.22°C by 2050. The reduced warming in the Arctic would be close to half a degree, while in Southern Europe the measures would not only reduce temperatures but also increase rainfall by about 15 mm/year. “This could help to alleviate expected future drought and water shortages in the Mediterranean region,” says Stohl.
The research has received a positive response from the intergovernmental Arctic Council, which is made up of the eight countries in the Arctic, but it’s now up to policy makers to act on the findings.
What will the consequences be if the project’s recommendations aren’t adopted? “The climate will definitely warm,” warns Stohl, “that will happen anyway. Our measures are not a solution. But if the recommendations are taken up, the climate would warm less and air quality in Europe would improve much more than currently predicted, with improvements being felt in 2030 to 2040.”