Air pollution increases the financial damage of climate change by up to two-thirds, according to new research from the USA. The study revealed that in some cases, smog raises the social cost of carbon by as much as 66 percent.
The measurement is used to help governments determine the benefits of a proposed policy. It includes the effects on human health, economies and agriculture. Study lead author Dr. Geeta Persad, of the University of Texas at Austin, said: “Carbon dioxide has the same impact on climate no matter who emits it but for these aerosol pollutants, they tend to stay concentrated near where they are emitted, so the effect they have on the climate system is very patchy and very dependent on where they are coming from.”
The findings are based on simulations of aerosols across Western Europe, the US, Brazil, China, East Africa, India, Indonesia and South Africa. They are emitted from vehicle exhausts, factories and power plants.
The tiny solid particles and liquid droplets fuel smog. Co-lead author Professor Jennifer Burney, of the University of California, Davis, said: “This research highlights how the harmful effects of our emissions are generally underestimated. CO2 is making the planet warmer, but it also gets emitted with a bunch of other compounds that impact people and plants directly and cause climate changes in their own right.”
Aerosols have been linked to a host of illnesses including asthma, bronchitis and even cancer. When inhaled, they can leak into the bloodstream. This affects the workforce and causes great financial damage. Dr. Persad said: “While we might think about aerosols, which cool the climate, as having the silver lining of counteracting CO2-driven warming, when we look at all these effects in combination, we find that no region experiences overall local benefits or generates overall global benefits by emitting aerosols.”
The team used a computer model in which each of the eight regions produced identical aerosol emissions. They analyzed how temperature, precipitation and surface air quality were affected across the globe. The data was also connected with known relationships with infant mortality, crop productivity and gross domestic product. The researchers then compared the total societal costs of aerosol-driven impacts against those of co-emitted CO2 in each area to map the combined effects.
Previous work has either only estimated the air quality impacts of aerosols or didn’t consider their diverse global climate effects. Emissions from some regions produce climate and air quality effects that range from two to more than 10 times as strong as others. Social costs sometimes affect neighboring regions more than where the aerosols originate. For example, in Europe local emissions result in four times as many infant deaths outside as within. But they are always bad for both the emitter and the planet overall.
The findings, published in the journal Science Advances, create potentially new motivations for countries to cut emissions – and to care about others doing the same. Adding aerosol costs to CO2 costs could double China’s incentive to mitigate emissions, for instance. And it switches the impact of local emissions in Europe from a net local benefit to a cost. The study also shows emerging economies, like East African nations and India, might be motivated to collaborate on emission cuts since they are strongly impacted by each other.
The framework can also be applied to maximize societal benefits from current mitigation strategies being considered by policymakers. This includes the ‘fair-share’ approach laid out in the Paris Climate Agreement in which all countries target the same per-capita CO2 emissions. The researchers found the approach, while beneficial for climate stability, does not improve the mortality and crop impacts from combined aerosol and CO2 emissions.
It focuses on mitigation in regions that already have fairly low aerosol impacts, like the US and Europe. Prof Burney added: “By expanding societal cost calculations to include geographically resolved societal impacts of co-emitted aerosols, we are showing the incentive for individual countries to mitigate and collaborate on mitigation is much higher than if we only think about greenhouse gases.”
