Climate models may have significantly miscalculated the effect of clouds in global warming, a new report revealed. This means future global temperatures could actually be worse than previously believed.
Researchers at Yale University examined a number of global climate projections, as well as satellite data. Studying the make-up of mixed-phase clouds, they found that clouds today actually hold more liquid, instead of ice.
Mixed-phase clouds typically consist of ice particles, liquid droplets, and water vapor. How is more liquid on clouds bad?
Clouds with more ice crystals are effective in reflecting sunlight than clouds with more liquid, acting as a shield to prevent too much light from the sun to reach the Earth. Researchers said the more ice there is in clouds, the less warming there will be on the surface of the Earth.
The findings, however, are opposite. What's more, current projections underestimate the amount of liquid in clouds, which then leads to under-reporting in climate sensitivity, researchers said.
"We saw that all of the models started with far too much ice," said Yale professor Trude Storelvmo, co-author of the study. When he and his team ran simulations that better matched satellite observations, they actually found more warming.
Climate sensitivity is a measure that estimates how the Earth's surface temperature responds to changes in atmospheric carbon dioxide.
The Intergovernmental Panel on Climate Change (IPCC) had projected in 2013 that climate sensitivity would be within a range of 2 to 4.7 degrees Celsius (35.6 to 40.46 degrees Fahrenheit).
But Yale researchers estimated the climate sensitivity to be much higher: 5 to 5.3 degrees Celsius (41 to 42.08 degrees Fahrenheit). Such an increase in surface temperature could have adverse implications worldwide.
Lead author and Yale graduate student Ivy Tan said the effect would be from rising sea levels to more extreme and frequent floods and droughts.
Meanwhile, Tan said insufficient data and the continuing confusion over the role of clouds lead to the misunderstanding in warning estimates. She said scientists need to better understand the feedback of liquid on clouds.
Co-study author Kevin Trenberth said the report is a fine first step in understanding the role of clouds in global warming, but not the last step in the matter.
Further studies should be done to ascertain how clouds are affected as changes in climate occur, he added.
The findings of the study are featured in the journal Science.
Photo : Daniel Spiess | Flickr