Dr. Jeff Masters ·

Above: Indian commuters drive amidst heavy smog along a busy road past the South Extension area of New Delhi on December 6, 2018. India suffers 1.1 million premature deaths due to air pollution each year, according to research published in March 2019. Image credit: XAVIER GALIANA/AFP/Getty Images.

If humans stopped emitting air pollution, an astonishing 5.6 million premature deaths per year due to global outdoor air pollution could be prevented, according to research published Monday. About 65% of these deaths are due to burning of fossil fuels, with the remainder due to such activities as biomass burning and agriculture. Eliminating human-caused air pollution would also significantly reduce drought in monsoon regions, but it would allow more sunlight to reach the surface, increasing Earth’s surface temperature by at least 0.36°C (0.65°F). Overall, the effects would be hugely beneficial.

The study, Effects of fossil fuel and total anthropogenic emission removal on public health and climate, was published in the journal Proceedings of the National Academy of Sciences (PNAS) by a team headed by atmospheric researcher Jos Lelieveld of the Max Planck Institute. The study built on their previous work, published on March 12, which found that the health burden of fine particulate matter (PM2.5) air pollution is much higher than has been previously assumed. They concluded that outdoor air pollution from PM2.5 and ozone causes 8.79 million premature deaths globally each year. Of that total, natural sources of outdoor air pollution accounted for 3.24 million deaths per year, and human-caused sources were 5.55 million per year. According to air pollution scientist Susan Anenberg of The George Washington University, who was not involved in the study, “these results of the new study are in line with previous research showing that the global burden of ambient PM2.5 on mortality could be substantially larger than previously thought, indicating about a doubling of the estimates currently reported by the Global Burden of Disease study.”

The researchers found that the top three nations for human-caused air pollution deaths were China (2.2 million per year), India (1.1 million per year), and the U.S. (230,000 per year). In the U.S., 84% of these deaths were attributed to the burning of fossil fuels. Globally, a premature air pollution death was found to occur on average 26.5 years earlier than it otherwise might have. In the U.S., where the mortality of children from air pollution is lower than the global average, a premature air pollution death takes an average of 12 years off a person’s life, according to Caiazzo et al., 2013.

The new study did not attempt to estimate the costs of air pollution to the economy. But a 2016 report by the World Bank—which used an older estimate of air pollution mortality approximately half as high—found that in 2013, the most recent year full data was available, exposure to outdoor and indoor air pollution cost the world’s economy $5.6 trillion (2019 dollars). These losses were highest in South Asia, East Asia and the Pacific: 7.4 - 7.5% of the regional gross domestic product (GDP). The report estimated that the U.S. suffered $520 billion in health-related damages from air pollution in 2013 (2.9% of the GDP).

Figure 1. Temperature changes at the surface from removing particulate air pollution emitted by fossil-fuel-burning. Stippling denotes areas where the temperature changes are not significant at the 95% confidence level. Image credit: Lelieveld et al., 2019, Effects of fossil fuel and total anthropogenic emission removal on public health and climate, Proceedings of the National Academy of Sciences (PNAS).

Eliminating human-caused air pollution allows at least 0.36°C of “hidden” global warming to occur

The researchers found that by eliminating fossil fuel burning, Earth’s surface temperature would rise by about 0.51°C (0.92°F), due to fewer air pollution particles reflecting sunlight back to space. The largest temperature impacts were found over North America and Northeast Asia--1.5 to 2°C of warming (Figure 1). By further removing all human emissions of air pollution—including biomass burning—a mean global temperature increase of 0.73°C would result, they found. However, if we simultaneously reduced human-caused methane, ozone, and hydrofluorocarbons in the atmosphere—three powerful short-lived greenhouse gases—this 0.73°C increase could be reduced to 0.36°C (1.2°C in the U.S.).

Most importantly, eliminating the burning of fossil fuels would stop the rapid build-up of carbon dioxide in the atmosphere—the main source of increasing global warming. In a press release that accompanied the paper, the authors wrote: “Therefore, cessation of air pollution would lead to a fast rise in global temperatures in the short term, and the Paris Agreement’s 1.5°C target would not be achievable. Nevertheless, it is still possible to limit warming to 2°."

Less air pollution equals less drought

Another huge benefit of emitting less air pollution would be less drought. In recent decades, India, northern China, Central America, West Africa, and the Sahel region of Africa have experienced a notable drying of the climate. Much of the precipitation that falls in these areas is from the summer monsoon. A monsoon depends upon the contrast in temperature between warmer land areas and cooler ocean areas to drive a large-scale atmospheric circulation that brings moisture-laden air from the ocean to the land. When high levels of PM2.5 air pollution exist over land areas, the monsoon is weakened, since the temperature contrast between land and sea is reduced by the sunlight reflected out to space over land areas.

The model used by Lelieveld and colleagues found that by removing all human-caused emissions of particulate air pollution, rainfall increased by 10 - 70% over densely populated regions in India, 10 - 30% over northern China, and by 10 - 40% over Central America, West Africa, and the drought-prone Sahel region of Africa. Such a significant increase in rainfall would save countless lives by increasing water and food security. Particulate pollution from burning of fossil fuels caused about half of these effects globally, while other human-caused emissions, including biomass burning, contributed the other half.

Less air pollution equals a reduction in extreme “stuck” jet stream patterns

An October 2018 paper by Mann et al. (my review here) found that there has been an increase in “stuck” summertime jet stream patterns of the kind that cause long-lasting and extreme weather conditions over large regions of the globe. Part of this increase in what they called Quasi-Resonant Amplification or “QRA” events has been because human-caused global warming is causing the Arctic to heat up at least twice as rapidly as the rest of the planet. However, if we eliminate emissions of PM2.5 air pollution, the mid-latitudes—where most of the pollution is emitted—will tend to warm up faster than they have been. This will alter the contrast in temperature between the poles and the equator, causing a slower increase in QRA events. QRA events have been responsible for many of the most expensive billion-dollar summertime weather disasters of the past few decades.

Indoor air pollution kills 3.6 million people per year

The study did not take into account that the introduction of clean household energy in low-income countries could substantially reduce excess deaths from indoor air pollution, estimated to be about 3.6 million per year. The phaseout of human-caused emissions is expected to be paralleled by a reduction of household air pollution from the introduction of clean “zero carbon” domestic energy sources. In total, the elimination of human-caused indoor and outdoor air pollution would save 9 million lives per year, the researchers estimated.

Conclusion

The study concluded: “The prospect of preventing millions of excess deaths attributable to air pollution, and restoring perturbations of the hydrologic cycle that have contributed to regional drying, with the cobenefit of limiting climate warming to below 2°C, is compelling and underscores the urgency of acting on global environmental change.”

Related Cat6 posts

Pollution Helps Kill 6.1 Million People Per Year, But Indoor Air Pollution is Decreasing, our May 2018 post.

New Research Finds Air Pollution is Far Deadlier than Previously Thought, our June 2017 post.

Air Pollution From Cars Affects Everyone: Why We Should Care, our May 2017 post.

Trump’s Executive Order a Serious Blow Against a Future Livable Climate, our March 2017 post.