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The finding helps explain why recent warming<\/a> has outpaced many forecasts. It points to a simple driver with complex physics: fewer air particles mean dimmer clouds and more shortwave energy reaching the sea surface.<\/p>\n Fading clouds, warming seas<\/p>\n The study was led by Dr. Knut von Salzen, a senior research scientist at the University of Washington<\/a> (UW) whose work explores how tiny airborne particles and cloud microphysics shape Earth\u2019s heat balance. <\/p>\n Clouds play a major cooling role by reflecting sunlight back into space \u2013 a property known as albedo \u2013 the fraction of light a surface reflects. Low clouds over cooler oceans handle much of this job.<\/p>\n But satellite data now reveal a subtle shift. The cloud radiative effect \u2013 the net change in energy caused by clouds \u2013 has weakened as marine clouds brightened less and covered less area. <\/p>\n The team zeroed in on the Northeast Pacific and North Atlantic, where ocean temperatures have risen rapidly over the past two decades. <\/p>\n Measurements from NASA\u2019s CERES EBAF<\/a> dataset show a steady drop in reflected shortwave radiation in these regions.<\/p>\n Together, these basins cover roughly 14 percent of Earth\u2019s surface. Even a modest decline in cloud reflectivity can translate into a measurable boost in global warming.<\/p>\n Airborne aerosols<\/a>, tiny particles that seed cloud droplets, have declined as pollution controls tightened. With fewer particles, droplets grow larger, and clouds lose some brightness and tend to rain out sooner.<\/p>\n \u201cWe may be underestimating warming trends because this connection is stronger than we knew,\u201d said Dr. von Salzen.<\/p>\n Two classic processes put numbers to that story. The Twomey effect, more particles make clouds brighter, weakens as air gets cleaner. The Albrecht effect, fewer particles can shorten cloud lifetime, also grows in a cleaner atmosphere.<\/p>\n Many Earth system models have not fully captured the observed changes. The new simulations improved accuracy by refining how particles activate into droplets and how droplet size influences drizzle and cloud cover.<\/p>\n Those improvements allowed the model to reproduce both the magnitude and the geographic footprint of the reflectivity drop. They also linked most of the change to aerosol reductions rather than ocean temperature shifts alone.<\/p>\n Global aerosol<\/a> declines didn\u2019t happen by chance. Independent analyses show sharp drops in sulfur dioxide emissions from power plants in China during the 2010s, with similar pollution cuts seen across other nations.<\/p>\n Yet even as the air grew cleaner, heat-trapping gases continued to rise. Long-term measurements from NOAA\u2019s Mauna Loa Observatory show a steady increase in atmospheric carbon dioxide<\/a> from 2003 to 2022 \u2013 adding to the planet\u2019s overall heat gain.<\/p>\n That progress carries a trade-off. Lower particle pollution brings major health benefits but also reduces the number of cloud condensation nuclei (CCN<\/a>) \u2013 the microscopic seeds that water vapor condenses on to form droplets. With fewer particles, clouds become less reflective and dissipate more easily.<\/p>\n \u201cWe do not want to go back in time and take away the Clean Air Act<\/a>,\u201d said Sarah Doherty, senior research scientist at UW. \u201cBut we need to understand how cleaner air changes the planet\u2019s energy balance.\u201d<\/p>\n Risky climate shortcut<\/p>\n Satellite observations show a clear trend \u2013 fewer shiny droplets, larger droplet sizes, and faster drizzle. Together, those shifts make marine clouds less reflective and expose darker ocean surfaces to more sunlight. <\/p>\n The physics form a positive feedback loop: as oceans warm, low clouds thin, allowing even more shortwave radiation<\/a> to reach the surface and amplify the initial heating.<\/p>\n In response, some researchers are exploring marine cloud brightening (MCB) \u2013 a proposed method to restore reflectivity by spraying fine sea-salt particles into the air to seed brighter clouds. <\/p>\n The concept aims to mimic nature by using salt rather than industrial pollution, but the science is still evolving. <\/p>\n NOAA reviews highlight key unknowns, including how predictable and safe such interventions would be if tested on a large scale.<\/p>\n Short-term forecasts may soon need to factor in dimmer clouds in cleaner air. As aerosol emissions<\/a> continue to fall, the study points to a persistent push toward less reflective marine clouds over the North Atlantic and Northeast Pacific.<\/p>\n That insight doesn\u2019t change the urgency of cutting greenhouse gases. But it does refine climate projections by showing how cleaner air can unmask hidden warming once offset by pollution particles.<\/p>\n Scientists are now watching several key indicators. One is radiative forcing<\/a>, the energy imbalance that drives warming or cooling. In these ocean basins, reduced aerosols have boosted the sunlight absorbed at the surface, adding regional heat pressure. <\/p>\n Another is the cloud radiative effect, which tracks how much energy clouds reflect or trap. Long-term satellite records help distinguish short-lived variations from lasting changes linked to cleaner air and shifting policy.<\/p>\n The study is published in Nature Communications<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Earth\u2019s mirror is dimming over two of its largest ocean basins, and that lost shine is turning into…\n","protected":false},"author":2,"featured_media":278599,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47],"tags":[192,79],"class_list":{"0":"post-278598","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-environment","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/278598","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=278598"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/278598\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/278599"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=278598"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=278598"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=278598"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"Aerosol](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/11\/clean-air_aerosol-particles_cloud-reflectivity_graphic_UWashington_1s.webp.webp\")
<\/a>Aerosol particles form cloud droplets by attracting water vapor. Click image to enlarge. Credit: Knut von Salzen\/University of WashingtonCleaner air, fewer cloud droplets<\/p>\n![\"In](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/11\/clean-air_aerosol-particles_cloud-interaction_graphic_UWashington_1s.webp.webp\")
<\/a>In the absence of aerosols, each cloud droplet carries more water but with aerosols, that water is dispersed between more droplets, impacting how reflective the cloud is and how long it lasts for. Click image to enlarge. Credit: Robert Wood\/University of WashingtonClean air\u2019s hidden cost<\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/11\/clean-air_less-pollution_cloud-streaks-aerosols_NASA_1s.webp.webp\")
<\/a>The streaks in this satellite image are from ships, which emit sulfate aerosols that can be toxic to humans and the environment. Aerosols also make the clouds more reflective. Efforts to curb pollution have reduced the amount of sunlight Earth reflects and accelerated warming, a new University of Washington study shows. Click image to enlarge. Credit: NASACloud clues for future warming<\/p>\n