Princeton researchers found that the climate models scientists use to project future conditions on our planet underestimate the cooling effect that clouds have on a daily — and even hourly — basis, particularly over land.

The researchers reported in the journal Nature Communications that models tend to factor in too much of the sun’s daily heat, which results in warmer, drier conditions than might actually occur.

The researchers found that not accurately capturing the daily cloud cycle in models has the Earth being bombarded with an extra one or two watts of solar energy per square meter. The increased carbon dioxide in the atmosphere since the start of the Industrial Age is estimated to produce an extra 3.7 watts of energy per square meter.

“The error here is half of that, so in that sense it becomes substantial,” said corresponding author Amilcare Porporato, the Thomas J. Wu '94 Professor of Civil and Environmental Engineering and professor of civil and environmental engineering and the High Meadows Environmental Institute.

“These errors can trickle down into other changes, such as projecting fewer and weaker storms. We hope that our results are useful for improving how clouds are modeled, which would improve the calibration of climate models and make the results much more reliable.”