As with reducing CO2 emissions, addressing aerosol pollution could contribute to global cooling and prevent more than one million annual premature deaths over a decade, a recent study estimates.
Carried out by researchers at the University of California San Diego in the US, the research -- published in the Earth's Future journal -- highlights the urgent need to take into account pollution from fine solid particles or liquid droplets suspended in the air, particularly those arising from burning fossil fuels like coal and diesel.
The study authors set out to explore the trade-offs that countries committed to the Paris Agreement would face if they took into account aerosol particles, while still meeting CO2-emission reduction targets. As the paper's first author, Pascal Polonik, explains: "Polluting particles, known as aerosols, are emitted in tandem with greenhouse gases but aren't accounted for."
Country by country, the research models the impact of aerosol reduction in all national economic sectors that cause emissions. For each country, the authors consider three scenarios. The first scenario focuses on temperatures by targeting industries that emit aerosols contributing the most to global warming. The second scenario focuses on air quality, targeting aerosol reductions in the sectors that emit the most solid particles. The third scenario considers equal reductions in emissions from all relevant economic sectors (industrial production, transport, housing, etc.).
On this basis, the authors consider that by 2030, these three scenarios could prevent up to one million premature deaths per year and decrease global temperature by similar amounts to those achieved through policies to reduce greenhouse gas emissions.
Surprisingly, the study found that the third scenario could prove counterproductive in certain places, potentially leading to more deaths and less cooling in regions such as Africa, China, the Middle East or South America. Indeed, the study authors point out that pollution reductions linked to each economic sector depend closely on the situation in each country.
For example, cutting emissions in the transport sector could save more lives in India, while cuts in the residential sector would produce more cooling.
"There is substantial variation between sectors and countries of these aerosol climate and health impacts, which illustrates that different countries may require different approaches even if pursuing identical policy objectives for climate or health optimization," the researchers explain.
According to Franco-British research published in April, air pollution from the burning of fossil fuels is estimated to have caused some 8.7 million premature deaths worldwide in 2018.