Air pollution can amplify the negative effects of climate change, according to a new study

The impacts of air pollution on human health, economies and agriculture differ dramatically depending on where on the planet the pollutants are emitted, according to a new study that could give certain countries incentives to reduce emissions that cause climate change.

Led by the University of Texas at Austin and the University of California at San Diego, the study, published September 23 in science advances, is the first to simulate how aerosol pollution affects both climate and air quality in locations around the world.

Aerosols are small solid particles and liquid droplets that contribute to smog and are emitted by industrial factories, power plants, and vehicle exhaust pipes. They impact human health, agricultural and economic productivity in unique global patterns compared to carbon dioxide (CO_two) emissions, which are the focus of efforts to mitigate climate change.

Although CO_two and aerosols are often emitted at the same time during fuel combustion, the two substances behave differently in Earth’s atmosphere, said co-senior author Geeta Persad, an assistant professor in the UT Austin Jackson School of Geosciences.

“Carbon dioxide has the same impact on the climate no matter who emits it,” Persad said. “But for these aerosol pollutants, they tend to stay concentrated close to where they are emitted, so the effect they have on the climate system is very patchy and very dependent on where they come from.”

The researchers found that, depending on where they are emitted, aerosols can worsen the social costs of carbon (an estimate of the economic costs greenhouse gases have on society) by up to 66%. The scientists looked at eight key regions: Brazil, China, East Africa, Western Europe, India, Indonesia, the United States and South Africa.

“This research highlights how the harmful effects of our emissions are often underestimated,” said Jennifer Burney, co-senior author and Marshall Saunders Chancellor’s Endowed Chair in Global Climate Policy and Research in the UC San Diego School of Global Policy and Strategy. “CO_two It’s warming the planet, but it’s also emitted with a bunch of other compounds that directly affect people and plants and cause climate change in their own right.”

The work, which was supported by the National Science Foundation, represents a collaboration between Persad and Burney, who are physical scientists, and a group of economists and public health experts. Coauthors include Marshall Burke, Eran Bendavid, and Sam Heft-Neal of Stanford University and Jonathan Proctor of Harvard University.

Aerosols can directly affect human health and climate independent of CO_two. They are associated with negative health impacts when inhaled, and can affect climate by influencing temperature, precipitation patterns, and the amount of sunlight that reaches the Earth’s surface.

Study the influence of aerosols compared to CO_two, the team created a suite of climate simulations using version 1 of the Community Earth System Model developed by the National Center for Atmospheric Research. They ran simulations in which each of the eight regions produced identical aerosol emissions and mapped how temperature, precipitation and surface air quality were affected around the world. They then connected this data with known relationships between climate and air quality and infant mortality, crop productivity, and gross domestic product in the eight regions.

In a final step, they compared the total social costs of these aerosol-generated impacts with the social costs of co-emitted CO._two in each of the eight regions, and produced global maps of the combined effects of aerosols and CO_two. The researchers said the study is a big step forward from previous work, which only estimated the impacts of aerosols on air quality or did not consider their various global climate effects.

The result paints a varied and complicated picture. Emissions from some regions produce effects on climate and air quality that are two to more than 10 times stronger than in others and social costs that sometimes affect neighboring regions more than the region that produced the emissions. aerosol sprays. For example, in Europe, local broadcasts cause four times more child deaths outside Europe than inside.

But the researchers point out that aerosol emissions are always bad for both the emitter and the planet as a whole.

“While we could think of aerosols, which cool the climate, as having the upside of counteracting CO_two“Driven by global warming, when we look at all of these effects in combination, we find that no region experiences overall local benefits or generates overall global benefits through aerosol emission,” Persad said.

The researchers also said the findings create potentially new motivations for countries to cut emissions and worry about other countries cutting emissions. For example, the study found that adding aerosol costs to CO_two the costs could double China’s incentive to mitigate emissions. And it changes the impact of local emissions in Europe from a net local benefit to a net cost. The study also shows that some emerging economies, such as East African nations and India, might be motivated to collaborate in reducing emissions, as they are heavily affected by each other’s emissions.

The framework developed in this study can also be applied to maximize the societal benefits of current mitigation strategies that are being considered by policymakers. For example, the researchers applied it to the “fair share” approach laid out in the Paris Climate Agreement in which all countries target the same CO2 per capita._two emissions. They found that the approach, while beneficial for climate stability, does not improve mortality or crop impacts from the combination of aerosols and CO_two Emissions because it focuses mitigation on regions that already have fairly low aerosol impacts, such as the US and Europe.

“By expanding the social cost calculations to include the geographically resolved social impacts of co-emitted aerosols, we are showing that the incentive for individual countries to mitigate and to collaborate on mitigation is much greater than if we only think about greenhouse gases. Burney said. he said.