from an article now running on scitechdaily.com
"Scientists Uncover Surprising Cloud Change That Slows Global Warming
BY MCGILL UNIVERSITYJANUARY 25, 2025
"Researchers at McGill University have found that changes in cloud patterns are having a slight cooling effect on global warming. Although greenhouse gases remain the primary driver of rising temperatures, a decrease in low-cloud cover over land is modestly reducing the amount of heat trapped near the Earth’s surface.
""We started this research to observationally verify the increase of greenhouse effect of the Earth atmosphere,” said Yi Huang, Associate Professor in McGill’s Department of Atmospheric and Oceanic Sciences who conceived a recent study published in Nature, “We indeed verified that, although to our surprise we also found an offsetting effect due to changes in clouds.”
Observational Evidence of Clouds’ Impact
""Without these cloud changes, the surface would warm even faster,” said Lei Liu, a graduate student in McGill’s Department of Atmospheric and Oceanic Sciences and the first author of this study.
"“This work offers observational truth about how clouds affect warming, which can be used to improve climate models and guide environmental policies,” said Liu.
"To discover this surprising effect, the team used the measurements of a key radiative instrument, the Atmospheric Emitted Radiance Interferometer (AERI), along with satellite data, climate models, and a technique called “optimal spectral fingerprinting” co-designed by Yi Huang and Lei Liu to isolate the effects of clouds from other atmospheric processes.
Understanding Longwave Radiation and Cloud Changes
"The researchers focused on longwave radiation, the heat energy Earth emits back into the atmosphere. Usually, clouds trap some of this heat and send it back to the ground. But as the climate warms, there are fewer low clouds in some areas, which means less heat is returned to the surface.
"McGill’s Atmospheric and Oceanic Department, which operates three AERI instruments in Montreal, looks to continue using their critical data for understanding regional climate dynamics and enhancing climate modeling, the researchers said."
Expand
