**Executive Summary**
This document discusses new research revealing the combined influence of aerosols and water vapor on climate change, particularly in the Indo-Gangetic Plain (IGP) region. The study emphasizes the need to consider both aerosols and water vapor for reliable climate predictions, highlighting their interactions' significant impact on regional atmospheric dynamics. The research leverages data from AERONET sites across the IGP and employs radiative transfer simulations.
**Key Points / Main Content**
* **Research Focus:** The study analyzes the relationship between aerosol loading and water vapor radiative effects (WVRE) over the Indo-Gangetic Plain.
* **Key Finding:** Water vapor has a more significant impact on atmospheric heating than aerosols.
* **Aerosol-Water Vapor Interaction:** The radiative effects of water vapor are influenced by the presence of aerosols, and aerosol-water vapor interactions significantly modulate the radiation budget.
* **Clean Air Impact:** The effects of water vapor are more pronounced in cleaner air (with fewer aerosols), becoming more noticeable at the top of the atmosphere in the presence of aerosols.
* **Regional Significance:** The research underscores the major role of water vapor in influencing the climate over the Indo-Gangetic Plains.
* **Methodology:** The study used data from six AERONET sites and SBDART radiative transfer simulations.
* **Publication:** The research was published in the Atmospheric Research Journal.
**Impact Analysis**
**Stakeholder: Climate Scientists / Researchers**
* **Impact:** The findings refine the understanding of climate change implications, particularly in regions with significant aerosol and water vapor variability.
* **Action Required:** Incorporate the interactions between aerosols and water vapor into climate models for more accurate regional projections.
**Stakeholder: Policymakers / Government (Ministry of Science & Technology)**
* **Impact:** The research provides evidence to support climate mitigation and adaptation strategies in the Indo-Gangetic Plain region.
* **Action Required:** Consider the findings when developing policies related to air quality, water resource management, and climate resilience.
**Stakeholder: Residents of the Indo-Gangetic Plain (IGP) region**
* **Impact:** The research contributes to a better understanding of climate change impacts on the region, potentially informing public health and environmental planning.
* **Action Required:** Be informed about the effects of aerosols and water vapor on the local climate and support policies that address these factors.
Key Entities Referenced
Indo-Gangetic Plain (IGP): A region central to the study, characterized by high aerosol loading and water vapor content, influencing climate dynamics.
Aerosols: A key component in the research, studied for its interaction with water vapor and impact on radiative balance.
Water Vapor: A key component in the research, studied for its interaction with aerosols and impact on radiative balance.
Department of Science and Technology (DST): The ministry under which the research institutes operate.
Aryabhatta Research Institute of Observational Sciences (ARIES): One of the research institutes involved in the study.
Ministry of Science & Technology
Water vapor heats the atmosphere much more
than aerosols do: new study
प्रव तथ: 08 JAN 2026 11:15AM by PIB Delhi
New research has revealed the combined role of aerosols and water vapour in shaping the implications of
climate change, suggesting that for reliable climate implications and future projections, both aerosols and
water vapor should be considered, as their interactions can significantly impact regional atmospheric
dynamics and the Indian summer monsoon.
The radiative effects of aerosols and water vapour are crucial for understanding as well as predicting the
Earth’s radiation balance and hence climate dynamics, and play a pivotal role in the Earth’s radiation
balance, influencing global temperatures, weather patterns and climate stability. These radiative effects
provide insights on how aerosols, water vapour clouds, greenhouse gases influence the Earth’s radiation
balance by scattering and absorbing the incoming solar radiation and outgoing terrestrial radiation.
The Indo-Gangetic Plain (IGP) region is considered a global hotspot of aerosol loading, with high spatio-
temporal variability in aerosols and water vapor content, making accurate quantification of their climatic
response quite challenging and uncertain. To refine climate projections and assess the implications of
atmospheric composition changes on regional climate dynamics in and around IGP, it is important to
analyse the relationship between aerosol loading and WVRE.
Figure 1: Location of observational sites over the Indo-Gangetic Plain region (top left corner), radiative
forcing estimates due to aerosols (a) and water vapour, coupled with (b) and without aerosols (c), as well
as heating rate (d) in Kanpur for four intervals of single scattering albedo values (top right corner).Extinction Ångström exponent (EAE) vs EAE difference binned by PWV (in cm) for Kanpur (bottom left
corner) and scatter plot for EAE vs. AAE , shows the different aerosol types over Kanpur
440–870 440–870
(bottom right corner).
A study by Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital along with Indian
Institute of Astrophysics (IIA), Bengaluru, both autonomous research institute under the Department of
Science and Technology (DST), Government of India, and international collaborators, University of
Western Macedonia, Kozani, Greece and Soka University, Tokyo, Japan assessed the dependence of water
vapour radiative forcing on aerosol loading over the Indo-Gangetic Plain (IGP) region.
The researchers led by Dr. Umesh Chandra Dumka from ARIES and Dr. Shantikumar S. Ningombam
from IIA along with Dimitris G. Kaskaoutis, R.E.P. Sotiropoulou, and E. Tagaris from University of
Western Macedonia and Dr. Pradeep Khatri from Soka University leveraged data from six AERONET
(Aerosol Robotic Network, an international network of ground-based Sun Photometers which measure the
aerosol properties) sites across the IGP and employed radiative transfer simulations using the SBDART
(Santa Barbara DISORT Atmospheric Radiative Transfer) model.
Analysing the relationship between aerosol loading and water vapor radiative effects (WVRE) over the
densely populated and highly polluted Indo-Gangetic Plain (IGP) region with the help of this data they
found that water vapor has a greater impact on atmospheric heating than aerosols.
Fig 2: Climatology of aerosol properties and precipitable water vapour.
Their research published in Atmospheric Research Journal found that the radiative effects of water vapor
are strongly influenced by the presence of aerosols and that aerosol-water vapor interactions highly
modulate the radiation budget in the atmosphere, with the WVRE being much more intense in aerosol-free
atmospheres compared to aerosol-laden conditions.
These effects are stronger over both the Earth's surface and, in the atmosphere, when the air is clean (i.e.,
with fewer aerosols). When aerosols are present, the water vapor effect becomes more noticeable at the
top of the atmosphere highlighting a significant interrelation between aerosols and water vapour.The study also found that water vapor heats the atmosphere much more than aerosols do. This highlights
the major role of water vapor in influencing the climate over the Indo-Gangetic Plains. The results reveal a
strong dependence on both solar position and atmospheric variables related to aerosol absorption, thereby
unravelling the combined role of aerosols and water vapour in shaping climate implications.
Publication link: https://doi.org/10.1016/j.atmosres.2025.108343
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