Reflectivity of ocean clouds drops as air pollution falls and global temperatures climb

by Clarence Oxford
Los Angeles CA (SPX) Nov 06, 2025

A recent study by University of Washington researchers explains that Earth is absorbing more heat than it did several decades ago, due to rapidly declining cloud reflectivity over ocean regions. Global warming has exceeded previous climate model projections, with observed temperatures in 2023 and 2024 surpassing expectations.

The study, published November 5 in Nature Communications, finds that reductions in air pollution have dimmed marine clouds, resulting in less sunlight being reflected back into space. Analyses of satellite data from 2003 to 2022 reveal clouds above the Northeastern Pacific and Atlantic Oceans became nearly 3 percent less reflective per decade. About 70 percent of this change is attributed to aerosol particles that influence both cloud composition and coverage.

Efforts to limit particulate pollution - mainly products of fossil fuel combustion - have lowered aerosol levels and will likely keep falling as clean energy increases. Scientists emphasize the importance of accurately modeling the relationships between aerosols, clouds, and solar heat to improve climate forecasts.

"This paper is a substantial contribution to the evidence that reductions in particulate air pollutants are contributing to accelerated warming," said Sarah Doherty, principal research scientist at the UW Cooperative Institute for Climate, Ocean and Ecosystem Studies.

Clouds lose brightness as aerosol concentrations drop. Smaller particles in the air help form clouds with many small, shiny droplets. Fewer aerosols mean bigger droplets that drop as precipitation sooner, shortening cloud lifespans and cloud cover.

"When you cut pollution, you're losing reflectivity and warming the system by allowing more solar radiation, or sunlight, to reach Earth," said lead author Knut von Salzen, UW senior research scientist of atmospheric and climate science.

Updating climate models to more accurately reflect aerosol formation and droplet size has led to improved projections of cloud reflectivity - a factor that critically affects future temperature forecasting.

"We may be underestimating warming trends because this connection is stronger than we knew," von Salzen said. "I think this increases the pressure on everyone to rethink climate mitigation and adaptation because warming is progressing faster than expected."

Researchers are also now investigating interventions to artificially brighten marine clouds - such as spraying seawater to increase cloud reflectivity - while stressing more research is needed on safety and risks. This recent work is expected to help improve global climate forecasts.

Research Report:Reduced aerosol pollution diminished cloud reflectivity over the North Atlantic and Northeast Pacific