With ecosystems increasingly squeezed by anthropogenic warming, even cleaning up pollution can cause problems.
In 2013, a huge marine heatwave known as the Blob hit the northeast Pacific Ocean. Temperatures soared to dangerous new highs, killing millions of marine animals and disrupting the broader ocean ecosystem in ways that have yet to—and may never—return to normal. Although the Blob officially ended in 2016, similar heatwaves have flared several times since. Scientists are still trying to unpack what exactly caused the Blob and its ilk, but a recent study highlights just how connected the global climate really is. This research, led by Hai Wang, an atmospheric scientist at the Ocean University of China, suggests environmental progress in China—aimed at clearing up the country’s substantial air pollution—inadvertently contributed to the extreme sea surface temperatures that cooked the Pacific coast from Alaska to California.
Since the early 2010s, China has tackled its aerosol emissions problem aggressively. Two decades ago, Chinese residents faced horrendous air quality, with concentrations of fine particulate matter (PM)—particles with a diameter smaller than 2.5 microns, known as PM 2.5—five to 10 times higher than the safe air quality guidelines published by the World Health Organization. These tiny particles, mainly produced by burning fossil fuels, irritate peoples’ throats and lungs, trigger asthma attacks, and drive up hospital admissions for cardiovascular issues. Extended exposure can increase the risk of stroke, heart disease, asthma, and lung cancer.
Between 2010 and 2017—and especially after 2013, when China adopted its new clean air action plan—the country’s PM 2.5 pollution level fell by 35 percent. But the waning toxic haze sparked a series of atmospheric changes in China and beyond.
Fine aerosol pollution increases cloud cover while also blocking and scattering heat from the sun.
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