Researchers have found that shifts in cloud patterns are helping to slightly reduce global warming. Even though greenhouse gas emissions continue to push up temperatures, a decrease in low cloud cover over land has led to a small decrease in the amount of heat trapped near the Earth’s surface.
Researchers have found that shifts in cloud patterns are helping to slightly reduce global warming. Even though greenhouse gas emissions continue to push up temperatures, a decrease in low cloud cover over land has led to a small decrease in the amount of heat trapped near the Earth’s surface.
“We initiated this study to confirm observationally the increase in the greenhouse effect in Earth’s atmosphere,” said Yi Huang, an Associate Professor in McGill’s Department of Atmospheric and Oceanic Sciences, who was involved in a recent study published in Nature. “We did confirm this, but to our surprise, we also uncovered a balancing effect caused by changes in clouds.”
“Without these cloud variations, the surface would see a quicker rise in temperature,” noted Lei Liu, a graduate student in McGill’s Department of Atmospheric and Oceanic Sciences and the main author of the study. “This research provides observational evidence on how clouds influence warming, which can help improve climate models and inform environmental policies,” Liu added.
To uncover this unexpected effect, the team utilized measurements from the Atmospheric Emitted Radiance Interferometer (AERI), a key radiative instrument, in conjunction with satellite data, climate models, and a method called “optimal spectral fingerprinting,” jointly developed by Yi Huang and Lei Liu to separate cloud effects from other atmospheric phenomena.
The researchers concentrated on longwave radiation, the heat energy that Earth radiates back into the atmosphere. Typically, clouds capture a portion of this heat and send it back down to the surface. However, as the climate becomes warmer, there are fewer low clouds in certain regions, resulting in less heat being returned to the ground.
McGill’s Department of Atmospheric and Oceanic Sciences, which operates three AERI instruments in Montreal, plans to continue utilizing this crucial data to enhance understanding of regional climate dynamics and improve climate modeling, according to the researchers.
“Our study highlights the importance of accurate, long-term climate observations,” remarked John Gyakum, a co-author and Professor in the Department of Atmospheric and Oceanic Sciences. “This is critical for comprehending how Earth responds to global warming and for making educated choices for the future.”
The researchers warned that their findings do not cast doubt on the reality of global warming.
“It’s akin to having a thermostat that makes minor adjustments,” the researchers clarified. “But even with this adjustment, the room continues to heat up.”
