December 13, 2023  – A new study by the Hebrew University of Jerusalem and Princeton University researchers further illuminates how minuscule pollution particles, known as aerosols, alter climate patterns. 

In the study, published in Nature Geoscience, Dr. Guy Dagan of the Hebrew University Fredy and Nadine Herrmann Institute of Earth Sciences and his research team focused on understanding the complex interactions between aerosols, clouds, and large-scale circulation. A fundamental hurdle lay in the mismatched scales: small clouds, (1–10 kilometers in size) vs. expansive climate patterns (over 1,000 kilometers), akin to fitting puzzle pieces from different sets. 

A schematic representation of the coupling between clouds and circulation in the tropics under clean conditions (top) and the response of this coupled system to an increase in air pollution concentration (bottom). It demonstrates that under polluted conditions the circulation becomes stronger, which intensifies the cloudiness that acts to cool the planet. 
A schematic representation of the coupling between clouds and circulation in the tropics under clean conditions (top) and the response of this coupled system to an increase in air pollution concentration (bottom). It demonstrates that under polluted conditions the circulation becomes stronger, which intensifies the cloudiness that acts to cool the planet.

The innovative approach employed by Dr. Dagan’s team involved sophisticated computer simulations capable of examining the minute details of the atmosphere while capturing the broader essence of the entire climate system. The team dissected a mechanism involving changes in the large-scale circulation due to air pollution. Their comparative analysis revealed a compelling revelation: the presence of aerosols triggers changes in large-scale circulation, which in turn substantially enhances the effective radiative forcing i.e., the effect of human activity on the climate system. 

“We also found that more aerosols stop rain in some areas which moves moisture to places where big clouds form that in turn release more heat into the air and cause stronger winds,” Dagan says. “Our study helps us understand better how aerosols and clouds affect the climate and the changes caused by aerosols from complex shifts in big weather patterns.”   

Researchers 

Guy Dagan1, Netta Yeheskel1 & Andrew I. L. Williams2 

Institutions 

1) Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University 

2) Program in Atmosphere and Ocean Sciences, Princeton