IIT-M-led study reveals human impact on aerosol-cloud interactions

CHENNAI: An international study led by the Indian Institute of Technology Madras (IIT-M) has reported key findings on how human activities influence aerosols that play a central role in cloud formation and precipitation. Aerosol-cloud interactions remain one of the largest uncertainties in climate change projections.

The study, conducted between March and July 2020, analysed cloud condensation nuclei (CCN) along India’s coastal regions.

Results showed that CCN concentrations increased by 80 to 250% following the COVID-19 lockdown, mainly due to more frequent new particle formation as emissions began to rebound. The findings have been published in the ACS ES&T Air journal.

The research team was led by Professor Sachin S Gunthe, coordinator, Centre for Atmospheric and Climate Sciences, IIT-M, and included Aishwarya Singh, now a post-doctoral researcher at the Max Planck Institute for Chemistry, Professor R Ravikrishna of IIT-M, and other national and international collaborators.

According to IIT-M, the study challenges the assumption that organic aerosols inhibit cloud formation. It found that while organic particles are less efficient at attracting water than inorganic particles, their large numbers contributed significantly to CCN, thereby aiding cloud development in coastal regions.

Commenting on the work, M Ravichandran, secretary, Ministry of Earth Sciences, said, “Aerosol-cloud interactions are highly complex and the results highlight the extent to which human activities influence these processes. Empirical field data remains critical for improving computer-based climate simulations.”

Sachin S Gunthe noted that anthropogenic emissions strongly shape aerosol behaviour and that the observations provide essential data to refine climate models. Aishwarya Singh added, “The lockdown created a natural experiment that showed how sensitive a cleaner atmosphere can be to fresh emissions.”

The researchers stated that their findings would help reduce uncertainties in climate projections and support more informed approaches to environmental policy and management.