Some good news: The air we breathe has been getting cleaner.
Across the globe and for many years now, air quality has been improving thanks to regulations that have dramatically reduced the release of pollutants that are harmful to human health.
But there’s a catch. Some of the particulate matter in all that pollution was actually exerting a cooling effect on the climate by blocking solar radiation. In doing so, it was effectively preventing some of the global warming driven by the burning of fossil fuels.
Scientists are now taking a closer look at this trade-off and arriving at a sobering conclusion: As we clean up the air, we also seem to making global warming a bit worse.
Cleaner air means healthier people
Before we examine the trade-offs, let’s acknowledge the obvious: Less pollution is a good thing.
Particulate matter — stuff like soot and sulfates, much of which comes from burning fossil fuels but also from forest fires and other sources — contributes to more than 4 million early deaths per year, according to the World Health Organization. The tiny particles can become lodged in the lungs and even enter the bloodstream, causing problems in the heart and beyond.
“There is absolutely no doubt that we would be all better off in the short term if we didn’t have to breathe in as many dangerous aerosols,” said Daniele Visioni, an assistant professor at Cornell University who has studied the relationship between air pollution and climate change. “From a health perspective, it makes sense to reduce pollutants.”
The Clean Air Act has gone a long way toward improving air quality in the United States. A wide range of dangerous pollutants have fallen sharply since 1990, according to the Environmental Protection Agency.
More such regulations are on the way. This year, the Biden administration proposed tighter limits on fine particulate matter such as soot from smokestacks, power plants and other industrial activity. Those measures may help counteract the worsening air quality caused by wildfire smoke.
And other countries, including China, have also begun cracking down on pollution, leading to global improvements in air quality over the past decade.
Pollution that prevents warming
But as air pollution falls, so too does the concentration of that particulate matter that happened to be deflecting a not-inconsiderable amount of solar radiation.
One striking example is currently playing out on the high seas. In 2020, a new rule went into effect that sharply limited the amount of sulfur dioxide in shipping fuel. It substantially reduced air pollution, according to research by NASA.
Yet it appears that the reduction in particulate matter is also letting more solar radiation in, contributing to global warming. An analysis by Carbon Brief estimated that the regulations will be responsible for increasing global temperatures by .05 degrees Celsius by 2050.
That alone is not enough to explain the record high temperatures that have baked the globe this year. But scientists know it’s a factor, and every fraction of a degree counts. “We know that there’s an effect, but nobody has properly quantified it yet,” Visioni said.
This week, a team of scientists made public data indicating that the planet is heating up even faster than expected. Among the factors cited by the researchers, who published their findings in the journal Nature Climate Change: lower levels of air pollution.
As my colleague Ray Zhong wrote, “reducing air pollution in the coming years would remove the cooling influence by a larger amount — good for lungs, bad for global warming.”
Of course, there’s a simple solution that would reduce pollution and drastically curtail global warming: Stop burning fossil fuels. That would make the mitigating effect of particulate matter irrelevant.
“The main way in which we could remove these sulfate emissions would be by stopped burning coal,” Visioni said. “Getting rid of that would be a massive win for a thousand reasons.”
On Thursday morning, James Hansen, the pioneering climate scientist who first warned congress about global warming in 1988, presented additional new research that he said showed that the pace of warming was accelerating, and that the drastic reductions in particulate matter pollution were a cause.
“Humanity made a Faustian bargain by offsetting a substantial but uncertain fraction of greenhouse gas warming with aerosol cooling,” Hansen said in a webinar. “Now, as we want to reduce all the chronic health effects of aerosols, our first payment is due. The payment is acceleration of global warming.”
Water regulation in the U.S. is a mess
America’s stewardship of groundwater, one of it most precious resources, relies on a lax and outdated patchwork of state and local rules. In many places, oversight is all but nonexistent, a New York Times analysis has found.
The majority of states don’t know how many wells they have. Many have incomplete records or no records at all and don’t register the millions of household wells that dot the country.
Even states that do try to count wells or regulate groundwater use often have other problems. Some carve out exemptions for powerful industries like agriculture, one of the nation’s biggest users of groundwater. And every state relies to some extent on well owners self-reporting their water use, raising the risk of deception by users big and small.
Regulations in some states, including Oklahoma, are guided by a principle of letting users extract groundwater at rates that exceed an aquifer’s ability to recharge. Some hydrologists call it groundwater “mining.”
Nationwide, the jumble of regulations that The Times identified has fed an industry of lawyers and consultants who help big users follow the rules, and also, sometimes, to take advantage of them. “People are shopping around for where they can exploit groundwater,” said Reba Epler, a lawyer who works on water rights cases in Wyoming and New Mexico.
— Dionne Searcey and Delger Erdenesanaa
(Read the full story, part of our investigative project into the national groundwater crisis.)
Other climate news
The weather report: Ciarán lashes France and the U.K.
A storm that battered northwestern France overnight was lashing Britain on Thursday with heavy rains and strong winds that the country’s weather agency warned could pose a “danger to life.”
The storm, given the name Ciarán (pronounced kee-RAHN), pummeled France’s Atlantic coast with record-breaking winds (gusts of about 120 miles per hour were recorded in parts of Brittany) that left at least one person dead and some 1.2 million customers without power.
With the storm moving north, Britain’s weather agency issued an “amber warning,” its second-highest level of alert, for parts of southern England, saying that winds were expected to exceed 85 miles per hour in some areas. The Coastguard warned people to “stay away from the water’s edge,” and the Port of Dover temporarily suspended “all sailings” because of the adverse conditions.
In southwestern England, photos showed large waves crashing into the shore in Devon and downed trees blocking roads in Falmouth. The highway authorities in Kent, in southeastern England, said that numerous roads were closed because of fallen trees.