National Carbonaceous Aerosols Programme

The National Carbonaceous Aerosols Programme (NCAP) is a major scientific initiative launched by the Government of India to study the characteristics, sources, and impacts of carbonaceous aerosols—particularly black carbon (BC) and organic carbon (OC)—on the country’s air quality, climate, and ecosystems. The programme seeks to improve understanding of these pollutants, quantify their sources and distribution, and assess their influence on atmospheric processes, climate change, and human health.

Background

Carbonaceous aerosols are fine particles emitted mainly from the incomplete combustion of fossil fuels, biomass, and biofuels. They are a crucial component of atmospheric particulate matter and have both climatic and environmental consequences.

• Black Carbon (BC) strongly absorbs solar radiation, contributing to atmospheric warming and influencing monsoon patterns.
• Organic Carbon (OC) scatters sunlight and can either cool or warm the atmosphere, depending on its composition.
• Deposition of BC on snow and ice surfaces reduces reflectivity (albedo), accelerating melting of glaciers and snowpacks—particularly in the Himalayan region.

Given India’s high emission levels from multiple sources—such as household biomass burning, transportation, industrial activity, and agricultural residue burning—the need for a comprehensive scientific study on carbonaceous aerosols led to the establishment of the NCAP under the Ministry of Environment, Forest and Climate Change (MoEFCC).

Objectives

The NCAP was designed to generate integrated scientific data and improve policy-making by achieving the following objectives:

• Developing an emission inventory for black carbon and organic carbon from key sources like domestic fuel use, transport, agriculture, brick kilns, and industries.
• Understanding aerosol dynamics, including their atmospheric transformation, transport, and deposition processes.
• Assessing climatic impacts, including changes in radiative forcing, monsoon variability, and Himalayan glacier melt caused by carbonaceous aerosols.
• Evaluating air-quality and health effects of black carbon and related pollutants.
• Strengthening national capacity in aerosol observation, modelling, and forecasting.

Implementation Framework

The programme brings together multiple scientific and academic institutions across India, coordinated through a central research consortium. One of the key coordinating institutions is the Indian Institute of Technology Bombay (IIT Bombay), which manages the COALESCE initiative (Carbonaceous Aerosol Emissions, Source Apportionment and Climate Impacts).
Key components of implementation include:

• Establishment of a nationwide network of observation sites across urban, rural, and high-altitude regions to monitor black carbon and organic carbon concentrations.
• Deployment of advanced instrumentation to measure aerosol optical depth, particulate composition, meteorological parameters, and radiative fluxes.
• Field campaigns focused on major emission sectors, such as agricultural residue burning, brick kilns, and vehicular emissions, to determine accurate emission factors.
• Modelling studies integrating observation data with regional and global climate models to simulate aerosol transport, climate feedbacks, and future scenarios.

Major Findings

Research under the National Carbonaceous Aerosols Programme has produced significant insights into India’s aerosol environment:

• The Indo-Gangetic Plain has been identified as a hotspot of carbonaceous aerosol pollution, especially during the post-monsoon and winter seasons due to stubble burning and stagnant meteorological conditions.
• Agricultural residue burning, residential biofuel use, and diesel emissions are the dominant sources of black carbon in northern India.
• Carbonaceous aerosols exert a strong positive radiative forcing, leading to atmospheric warming and potential impacts on monsoon circulation and rainfall distribution.
• Deposition of black carbon on Himalayan glaciers has been shown to accelerate ice melt and influence water availability in the region.
• Improved regional models developed under NCAP now allow better simulation of aerosol-monsoon interactions and prediction of extreme climatic events.

Significance

The NCAP plays a vital role in India’s environmental and climate strategy for several reasons:

• It provides a scientific foundation for developing effective policies targeting short-lived climate pollutants (SLCPs) such as black carbon.
• The programme helps design mitigation strategies that yield both climate and health benefits, linking air-quality improvement with greenhouse gas reduction.
• NCAP strengthens research capacity in India through state-of-the-art observation networks, data systems, and training of young scientists.
• The knowledge generated supports India’s commitments under international frameworks like the United Nations Framework Convention on Climate Change (UNFCCC).

Challenges

Despite its achievements, the programme faces certain operational and scientific challenges:

• Limited data coverage: Remote and high-altitude regions still lack consistent long-term monitoring stations.
• Uncertainties in emission factors: Many small and informal sources (e.g., rural cooking stoves, open burning) remain inadequately characterised.
• Integration gaps: Discrepancies between observational data and model simulations require continuous refinement.
• Translation into policy: Bridging the gap between scientific findings and implementation of actionable policies remains a critical challenge.

Future Directions

To strengthen and expand its impact, NCAP aims to:

• Increase the spatial and temporal coverage of observation networks across India and neighbouring regions.
• Develop integrated climate–air quality models that can link local emissions to global climate impacts.
• Promote low-emission technologies in domestic, industrial, and agricultural sectors.
• Strengthen interdisciplinary collaboration between climate scientists, policymakers, and local communities.
• Build regional partnerships with other South Asian countries to address transboundary air pollution and black carbon transport.