Princeton University researchers have 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 report 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 inaccuracies in accounting for the diurnal, or daily, cloud cycle did not seem to invalidate climate projections, but they did increase the margin of error for a crucial tool scientists use to understand how climate change will affect us.
“It’s important to get the right result for the right reason,” said corresponding author Amilcare Porporato, a professor of civil and environmental engineering and the Princeton 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.”
Porporato and first author Jun Yin, a postdoctoral research associate in civil and environmental engineering, found that not accurately capturing the daily cloud cycle has models showing the sun bombarding Earth with an extra one or two watts of 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,” Porporato said.
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Image via Jun Yin, Princeton University
