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Global climate change

Climate models likely underestimate cooling influence of daily clouds

By Brett Anderson, AccuWeather senior meteorologist
1/10/2018, 11:53:37 AM

Researchers from Princeton University have determined that climate models underestimate the cooling effect that clouds have on a daily basis, especially over land areas.

Climate models are a tool used by scientists to help project future climate conditions across the world.

The study found that climate models factor too much of the sun's daily heat, which likely results in warmer and drier model projections than what might actually occur.

The researchers analyzed satellite images from 1986-2005 to calculate average diurnal cycles of clouds in each season across the world. The researchers compared the averages that they came up with to those from 9 climate models used by climate scientists.

The good news is that these model inaccuracies did not seem to invalidate climate projections. However, they did increase the margin of error.

Key excerpts from the Princeton report...........

"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," said co-author Amilcare Porporato, a professor of civil and environmental engineering at the Princeton Environmental Institute.

"louds change during the day and from day to day. Climate models do a good job of capturing the average cloud coverage, said lead-author Jun Yin, but they miss important peaks in actual cloud coverage. These peaks can have a dramatic effect on daily conditions, such as in the early afternoon during the hottest part of the day.

"Climate scientists have the clouds, but they miss the timing," Porporato said. "There's a strong sensitivity between the daily cloud cycle and temperature. It's like a person putting on a blanket at night or using a parasol during the day. If you miss that, it makes a huge difference."

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Global climate change