Sarah J. Doherty: How aerosols brighten clouds — and cool the planet

How aerosols brighten clouds — and cool the planet

Here's a conundrum: the same aerosol pollutants that harm human health also help cool the climate, says atmospheric scientist Sarah J. Doherty. Is there a way to clean up the air without warming the planet? Exploring the unintended consequences of reducing air pollution, she makes the case for a better understanding of marine cloud brightening — or intentionally adding sea salt aerosols to clouds over the ocean, which could reflect sunlight back into space and potentially reduce global warming.

Aerosols from human pollution, while deadly to millions each year, currently cool the planet by as much as a full degree Celsius. As efforts to improve air quality accelerate, the loss of these cooling particles could rapidly worsen global warming. Scientists are now exploring marine cloud brightening—adding sea salt aerosols to clouds over oceans—as a way to reflect sunlight without harmful pollution. This emerging research aims to balance urgent health needs with the realities of an overheating world.