Context : The Paradox of Air Pollution and Global Warming
- Air pollution control is essential for public health but could inadvertently accelerate global warming.
- Aerosols, a key component of air pollution, have a cooling effect by reflecting sunlight away from Earth.
- Rapid reduction of aerosols without simultaneous reduction in greenhouse gases could cause a short-term temperature spike.
Relevance : GS 3(Environment and Ecology)
Study Findings on Aerosol Reduction and Temperature Trends
- Regions that cleaned their air in the late 20th century witnessed increased warming trends over time.
- Areas with high aerosol pollution, especially in urban centers with lower human development indices, have experienced less warming due to the “masking effect” of pollution.
- The study warns that abrupt reductions in aerosols could trigger extreme heat events.
Greenhouse Gases vs. Aerosols: Contrasting Climate Effects
- Greenhouse Gases (GHGs): Long-lived (e.g., CO₂ persists for centuries), trap heat, contribute to global warming.
- Aerosols: Short-lived (persist for days to weeks), reflect solar radiation, cool the surface, but disrupt the water cycle.
- Greenhouse gases lead to persistent warming, while aerosols provide temporary cooling.
India’s Energy Dependency and Aerosol Emissions
- Coal-fired thermal power plants generate 70% of India’s electricity, releasing sulphur dioxide (SO₂).
- Sulphate aerosols (formed from SO₂ oxidation) make up 50-60% of India’s aerosol load, contributing to cooling effects.
- Industrialization has historically led to high aerosol emissions, influencing regional climate patterns.
The ‘Invisible Offset’ Effect of Aerosols
- Without aerosols, India’s warming could have been 2°C instead of 0.54°C between 1906-2005.
- Net cooling of 1.5°C from aerosols and land use changes offset greenhouse gas-induced warming.
- Climate projections suggest that aerosol reductions could lead to more rapid warming in India.
Aerosols and Monsoon Rainfall
- Aerosols have a complex relationship with precipitation—they can both enhance and suppress rainfall.
- Global aerosol cooling (~0.6°C) has been unevenly distributed, affecting Indian monsoon patterns.
- Increased aerosol emissions could further disrupt the hydrological cycle and monsoon variability.
Global Case Studies on Aerosol Reductions
- China’s aerosol reduction led to more extreme heatwaves in the Pacific and North America.
- Indian aerosol emissions may have both local and global impacts on climate patterns.
- The Indo-Gangetic Plain is particularly vulnerable due to high aerosol loads and climate sensitivity.
Need for Balanced Climate Policies
- Net-zero carbon emissions is not the ultimate solution; long-term adaptation strategies are crucial.
- Heat action plans must be strengthened, especially in cities like Delhi, Mumbai, and Bengaluru.
- Policymakers need to weigh trade-offs—air pollution control benefits public health but can intensify heat stress.
Future Climate Strategy for India
- Simultaneously reduce greenhouse gases and aerosols to manage warming risks.
- Improve heat action plans in highly polluted cities to mitigate heat stress.
- Integrate long-term adaptation policies for vulnerable regions like the Indo-Gangetic plains.
- Develop climate-resilient energy policies, transitioning from coal-based power to cleaner alternatives.
