An in-depth examination of cloud formations has led a team of researchers from the CERN Cloud experiment to reveal the processes that drive the formation and evolution of small atmospheric particles that exist free of the effects of pollution. Using this information will help scientists move forward on the path towards creating accurate models that predict climate change and increase our understanding of the processes that drive it.
Due to the reflective ability of clouds and aerosols - the tiny particles in the atmosphere that become the basis for cloud formation - scientists are looking to them in order to better understand their ability to protect Earth from sunlight by masking some of the warming caused by the greenhouse gases in the atmosphere. Furthering our understanding of this process is essential for crafting accurate climate predictions.
"The best estimate is that about one-third of the warming by greenhouse gas emissions is masked by this aerosol cooling, but the fraction could be as large as half and as little as almost nothing," said Neil Donahue of Carnegie Mellon University and co-author of the study.
Although clouds and aerosols are integral in the calculations that are a part of climate prediction models, understanding the relationships that they share with the atmosphere and climate is challenging.
The CERN CLOUD experiment team used a large chamber to mimic the atmosphere and examine the formation and growth of aerosol particles and the clouds that they become. The results reveal that new particles can stem from the oxidation of molecules originating from trees separate from sulfuric acid, which typically originates from fossil fuels. This provides experts a window into the production of particles in the absence of pollution.
"This softens the idea that there may be many more particles in the atmosphere today due to pollution than there were in 1750, and suggests that the pristine pre-industrial climate may have had whiter clouds than presently thought," Donahue said.
"Earth is already more than 0.8C than it was in the pre-industrial epoch, and this is with some masking by aerosol particles," he added. "As the pollution subsides, up to another 0.8C of hidden warming could emerge."
The findings were published in the May 25 issue of the journal Nature.
