Cleaner Clouds Slowing Global Heating, Study Finds
Get the Energy newsletter
Daily energy & climate — solar, EVs, oil, the policy fights and tech bets shaping the transition. Free.
- Researchers analyzing satellite observations of high clouds from 2008 to 2018 found that northern hemisphere clouds became less icy as atmospheric dust levels fell over that period.
- Weakening surface winds, attributed to climate change, have reduced the amount of dust whipped into the atmosphere over the last two decades, meaning fewer particles available to seed ice crystals.
- Liquid droplets reflect more sunlight than ice crystals, and the extra reflectivity from less icy clouds offsets roughly a quarter of the heating caused by other changes, including increased high cloud cover that traps more heat.
- Current climate models do not account for this previously unidentified effect, which researchers say may mean those models are slightly overestimating the projected rate of global heating.
- Southern hemisphere clouds showed no comparable shift because there is far less dust in the southern hemisphere atmosphere to begin with.
- The study, published in Geophysical Research Letters, frames the finding as no reason for complacency but suggests global warming may not proceed quite as fast as models currently predict.
Why it matters: Climate models that guide policy decisions may be slightly overestimating the pace of global heating because they don't capture how cleaner air is making clouds more reflective. The researchers stress this is no reason for complacency — the effect offsets only about a quarter of the warming driven by other changes like rising high cloud cover.
