New Delhi: A groundbreaking study led by the Indian Institute of Technology Madras has revealed how rapidly and significantly human activities can impact cloud formation, a critical component of the global climate system. The research, which treated the nationwide COVID-19 lockdown in 2020 as a unique “natural experiment,” provides new evidence on the direct link between human-caused emissions and aerosol behavior.
Published in the ACS ES&T Air Journal, the study focused on the coastal regions of India between March and July 2020. Researchers found that as human emissions were curtailed during the lockdown and then slowly rebounded, the concentration of cloud-forming aerosols, known as “Cloud Condensation Nuclei” (CCN), surged by an astonishing 80% to 250%.
The study’s lead researcher, Professor Sachin S. Gunthe from IIT Madras’s Department of Civil Engineering, explained that this increase was driven by “new particle formation” (NPF), a process where atmospheric gases transform into aerosol particles. The research also found that organic matter from human sources was a dominant factor in the growth of these new particles. This finding challenges the conventional belief that organic particles inhibit cloud formation, suggesting that in large numbers, they can actually promote it.
The findings have significant implications for climate modeling and policymaking. The interaction between aerosols and clouds remains one of the biggest uncertainties in climate predictions. By demonstrating the direct and immediate impact of human activity on these processes, the study provides valuable, real-world data that can help refine climate forecasts.
“Our research reveals that anthropogenic emissions strongly influence aerosol behaviour, particularly in how they form clouds,” said Professor Gunthe. “These results challenge existing models and open new avenues for understanding how human activities shape climate patterns.”
The study underscores the sensitivity of a cleaner atmosphere to new emissions and highlights the urgent need for policymakers to use measured evidence to create more reliable data for climate planning. The unique circumstances of the COVID-19 lockdown offered a rare opportunity to directly observe these complex atmospheric interactions, providing a clear window into how human behavior directly affects the planet’s climate systems.