Description

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Context

India has warmed at a slower rate (~0.6°C since 1950s) compared to the rest of the Northern Hemisphere (~1.2°C).

At first glance this appears positive but scientists caution that it represents a paradoxical and dangerous climate trend primarily driven by aerosol pollution.

Key Concepts

Term	Explanation
Aerosols	Fine particulate matter suspended in the air; can be reflective like sulphates or absorbing like black carbon.
Cooling Effect of Aerosols	Reflect sunlight or absorb radiation in upper atmosphere, reducing heat reaching Earth's surface.
Ground-Level Ozone	Harmful pollutant formed by reaction between sunlight and nitrogen oxides or VOCs.
PM2.5	Particulate matter smaller than 2.5 microns; deeply penetrates lungs and bloodstream.

Causes of Slower Warming in India

Aerosol Pollution

India has high levels of aerosols from fossil fuel burning, crop residue burning and industrial activities.

Aerosols

Reflect sunlight → Reduce surface temperature.

Absorb radiation (e.g., black carbon) → Warm upper atmosphere but cool surface.

Interact with clouds → Increase or reduce cloud cover, adding complexity.

COVID-19 Lockdown Anomaly

During 2020 lockdown:

25% reduction in particulate matter led to unexpected 2–4°C fall in night temperatures in Delhi.

Suggests aerosols may normally warm near-surface air while reducing sunlight.

Other Contributing Factors

Expanding irrigation → Increases local evapotranspiration contributing to surface cooling.

Stratosphere-troposphere interactions and monsoon variability may also play roles.

Lack of comprehensive India-specific data models adds uncertainty.

The Dangerous Trade-Off: Health vs Climate

Aerosol Benefits

Slows climate warming.

Shields surface from radiation.

Severe Health Hazards

Responsible for 1.5–2.1 million premature deaths annually in India.

Linked to:

Respiratory diseases

Cardiovascular issues

Complications in pregnancy

Strains public health infrastructure.

Warming Acceleration Risk

Cleaning air pollution may:

Reduce aerosol-induced cooling accelerating global warming.

Increase ground-level ozone harming health and crops.

Recent studies show synergistic effects of heat and air pollution raise mortality risk significantly.

Implications for Policy

Integrated Policy Framework

Need to synchronize air quality, climate change, energy, and development policies.

Avoid siloed solutions that improve one domain but worsen another.

Technology & Innovation

Promote:

Clean energy transitions

Emission-reducing industrial processes

Nature-based solutions e.g., afforestation, biofilters

Sources:

DOWNTOEARTH

PRACTICE QUESTION

Q. Despite experiencing a slower rate of warming, India faces a complex climate-health trade-off due to high aerosol pollution. Examine the reasons for this paradox and discuss its implications for environmental and public health policy. 250 words