Local aerosols may have halved local surface warming over the past three decades.
Earth is warming due to man-made climate change, but some places are warming slower than others for less obvious reasons.
India is the most populated and one of the hottest countries on Earth. The region is frequently subjected to severe heatwaves in both the spring and summer, which eventually relent after the monsoon season. However, the Indian region is warming at a lower rate than other landmasses, including those in the tropics.
One potential factor that may limit global warming over this region is aerosols, or solid or liquid particles, in the atmosphere. These particles can be natural, like dust storms; volcanic ash or wildfire smoke, or man-made, like manufacturing or vehicle emissions. Both types of aerosols can decrease the amount of sunlight reaching the ground, decreasing warming in the shaded area.
To investigate the contribution of aerosols in diminished warming in and around India, a group of researchers from Vikram Sarabhai Space Centre in India performed an observational study to determine what effect, if any, aerosols and clouds had on warming over the region from 2001–2024.
The team published their paper, “Anomalous Weakening of the Surface Warming Trend over India: Role of Aerosols and Clouds,” on August 4 in the journal Ocean-Land-Atmosphere Research .
“Th[e]...cooling paradox [observed in and around India] has been linked primarily to increased aerosol loading and the lower climate sensitivity of the region. This study aims to quantify the contributions of aerosols and clouds to the reduced warming trend over India utilising both satellite and ground-based observations,” said Vijayakumar S. Nair, scientist in the Space Physics Laboratory at Vikram Sarabhai Space Centre and primary author of the research study.
Aerosol loading is the total concentration of fine solid or liquid particles in the atmosphere. Historically, satellite data has confirmed that increased aerosol loading and cloud cover decreases surface temperatures over affected areas, but this data has not yet been quantified over India in the past three decades.
Overall, the study found that the Indian region was subject to a significant amount of surface dimming due to increased aerosol loading and cloud cover during the study period.
“This enhanced dimming has resulted in significant surface cooling (-0.125°C per decade), with an absolute magnitude comparable to the observed warming trend (+0.138°C per decade). Thus, in the absence of surface dimming induced by aerosols and clouds, the surface warming trend over the Indian region would have been nearly twice as large during the recent decades,” said Nair.
The researchers also discovered that aerosol composition over India has changed over time, decreasing the cooling potential of the aerosols, despite increased aerosol loading overall. Cloud cover contributed to twice the cooling capacity of aerosols at 0.08°C per decade compared to 0.04°C per decade, respectively. Importantly, these effects contributed to some, but not all, of the decreased surface warming experienced in and around India in the past three decades.
This research study contributes significantly to the field’s understanding of aerosol and cloud effects on local climate change, but more work needs to be done as aerosol composition and quantity changes over time.
“The large uncertainty in aerosol-cloud interactions, coupled with lower climate sensitivity over the tropics, poses a major challenge for future climate projections, especially assessments of surface temperature trends due to aerosol mitigation aimed at improving air quality. Hence, reducing the uncertainties associated with aerosol-cloud interactions and thus future climate projections is the next priority,” said Nair.
Anas Ibnu Basheer from the Space Physics Laboratory at the Vikram Sarabhai Space Centre in Thiruvananthapuram, India and the Faculty of Marine Science at the Cochin University of Science and Technology in Ernakulam, India, and Akhila RS, Prijith SS, Mukunda M Gogoi and S Suresh Babu also from the Space Physics Laboratory at Vikram Sarabhai Space Centre also contributed to this research.
This study did not receive any specific funding.
Ocean-Land-Atmosphere Research
Observational study
Not applicable
Anomalous Weakening of the Surface Warming Trend over India: Role of Aerosols and Clouds
4-Aug-2026
No conflicts of interest to declare.