Chennai: A groundbreaking international study led by the Indian Institute of Technology Madras (IIT Madras) has revealed the profound impact of human activity on cloud-forming aerosols and climate in India’s coastal regions.
The research challenges common beliefs about the role of organic aerosols and provides critical empirical data that could significantly reduce uncertainties in global climate models.
What is the significance of cloud-forming aerosols?
The tiny airborne particles are essential for cloud formation and precipitation and are a major source of uncertainty in climate change predictions.
The study’s findings, published in the prestigious American Chemical Society’s ES&T Air Journal, highlight the complex relationship between human-caused emissions and cloud-forming aerosols, known as ‘Cloud Condensation Nuclei’ (CCN).
A lockdown experiment
Conducted between March and July 2020 during the Covid-19 lockdown, the study presented a unique ‘natural experiment.’
Researchers observed a startling 80-250 per cent increase in CCN concentrations following the lockdown. This surge was attributed to more frequent ‘new particle formation’' (NPF) as human emissions slowly rebounded. This demonstrates how a cleaner atmosphere can become highly sensitive to new emissions, significantly altering aerosol-cloud interactions.
The research team, which included Prof. Sachin S Gunthe, Aishwarya Singh, and Prof. R Ravikrishna from IIT Madras, found that this surge in freshly formed particles was the direct cause of the CCN increase.
According to lead researcher Prof. Gunthe, their findings challenge existing models and propose new ways to understand how human activities shape climate patterns.
Rethinking organic aerosols
One of the study’s most significant findings is that anthropogenic organic matter was the dominant factor in the growth of these new particles.
This challenges the long-held belief that organic particles inhibit cloud formation.
The study found that while organic particles have a lower ability to attract water compared to inorganic particles, their sheer number can promote cloud formation in coastal areas.
“Our observations show that even particles we thought might hinder cloud growth can, under certain conditions, play a crucial role in creating clouds, ultimately influencing weather patterns and climate,” said Aishwarya Singh, a former IIT Madras student now at the Max Planck Institute for Chemistry.
The power of empirical data
The study underscores the vital importance of real-world measurements in climate science.
As Prof. Gunthe emphasised, “Measurements like ours, drawn from real-world conditions, offer clarity that computer-based models alone cannot achieve.” This empirical data provides the foundation for more accurate climate projections, which are essential for informing policy and environmental management.
Dr M Ravichandran, Secretary of the Ministry of Earth Sciences, who was not involved in the research, noted that the findings are ‘critical information for negotiating future atmospheric dynamics.’
The research team is optimistic that their insights will help climate scientists reassess their models and approach to studying the effects of aerosols on climate change, paving the way for more effective and sustainable climate solutions.