Research published by pollution experts at NUI Galway has poured cold water on the effectiveness of so-called ’’cloud brightening’’ to tackle climate change.
Cloud brightening, a theory first put forward in 1990, suggests the manipulation of cloud cover by spraying water-based particles into clouds, thereby reflecting more sunlight back into space, and subsequently reducing radiation.
The mass geoengineering concept has gathered support in recent years, but the sheer scale and method of how it could be done have baffled experts.
Research published by NUI Galway’s Centre for Climate & Air Pollution Studies (C-CAPS) has now raised what it called "serious doubts of the likely impact of human-led interventions involving methods of cloud brightening to counteract climate change".
The new study, published in the Nature’s journal Climate and Atmospheric Science, finds one of the most important types of elements in clouds is thought to be sulphate.
Clouds, which are made of many droplets of condensed water on air particles, cool the climate by reflecting sunlight.
According to recent theories, more air pollution serves as condensation points for cloud droplets leading to more solar reflectance.
This has led many to believe that fossil fuel emissions and other air pollutions may offset global warming through cloud brightening.
The Galway study found the addition of a small amount of sea-salt can dampen the effect of clouds becoming brighter as a result of increased sulphate in the atmosphere.
Professor Colin O’Dowd, Director of C-CAPS and Established Chair of Atmospheric Physics, said: “The study backs up our previous thinking that sea-salt will factor out other substances and cause competition between potential nuclei influencing cloud reflectance.
"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.”
Researchers from NUI Galway joined the Spanish research vessel BIO Hesperides circling Antarctica’s Southern Ocean to examine how the world’s atmosphere is functioning in a pollution-free environment.
Lead researcher Dr Kirsten Fossum said: “Pollution-induced changes to cloud reflectance, represent the single biggest uncertainty in predicting future climate change.
"The large area covered and systematic evidence from the cruise to Antarctica provided the vast sample of clean air needed to conclusively support this study.”
The study was funded by Science Foundation Ireland and the Spanish Ministry of Economy and Competitiveness.