Study finds clouds getting ‘brighter’ with pollutants won’t limit climate crisis

8 Apr 2020

Clouds over Antarctica. Image: C-CAPS

NUI Galway researchers have raised serious doubts about the claim that pollutants will make clouds ‘brighter’ and offset global warming.

A new study published by NUI Galway’s Centre for Climate and Air Pollution Studies (C-CAPS) has shone light on the impact of clouds on the climate crisis. Writing in Climate and Atmospheric Science, the researchers raised serious doubts about the belief that ‘cloud brightening’ with pollutants could limit the greenhouse effect.

The study looked into the role of sulphate in clouds, believed to be one of their most important elements. Clouds are known to play a key role in cooling our climate as they contain many droplets of condensed water on air particles, thereby reflecting sunlight.

Recent theories have suggested increased pollution serves as condensation points for cloud droplets, leading to more solar reflectance. For that reason, it has led some to believe that fossil fuel emissions and other air pollutions may offset global heating through cloud ‘brightening’.

However, this latest study found that the addition of a small of amount of sea salt can dampen the effect of cloud brightening as a result of increased sulphate in the atmosphere.

‘There’s only one pathway to solve this’

“The study backs up our previous thinking that sea salt will factor out other substances and cause competition between potential nuclei influencing cloud reflectance,” said Prof Colin O’Dowd, director of C-CAPS.

“This means that recent theories that increased sulphate production can decrease the impact of climate change need to be reconsidered. Science is clearly pointing to the fact that carbon-based human activity is hurting our environment and there’s only one pathway to solve this – less fossil fuel and no interference with nature.”

The study was funded by Science Foundation Ireland and the Spanish Ministry of Economy and Competitiveness, with the NUI Galway researchers conducting their research aboard the Spanish research vessel BIO Hesperides, circling Antarctica’s southern ocean.

The expedition originally set out to examine how the world’s atmosphere is functioning in a pollution-free environment, as the southern ocean has been deemed to be the ‘world’s cleanest laboratory’.

Lead author of the study, Dr Kirsten Fossum, added: “Clouds, particularly those overlying dark ocean surfaces, are the Earth’s key climate regulators, accounting for half of global reflectance.

“Pollution-induced changes to cloud reflectance represent the single biggest uncertainty in predicting future climate change.”

Colm Gorey was a senior journalist with Silicon Republic