Climate Change
Environment
The increasing temperature of the earth due to the greenhouse effect is known as climate change. It is causing extreme weather events, melting of polar ice, rising sea levels, and long-term changes in ecosystems.
Greenhouse Gases and the Greenhouse Effect
Greenhouse gases trap heat in the atmosphere. They allow sunlight to pass through but prevent heat from escaping. Without them, Earth’s average temperature would be -18°C instead of +15°C.
Major Greenhouse Gases
Water Vapour
• Most important greenhouse gas.
• Contributes nearly 60% of total warming.
• Its amount increases with rising temperature and decreases with cooling.
• Non‑condensable gases like CO2 actually drive long‑term warming, and water vapour amplifies it.
Carbon Dioxide (CO2)
• Produced by burning fossil fuels, solid waste, and biomass.
• Removed through photosynthesis.
• Main long‑term driver of global warming.
Methane (CH4)
• Emitted from wetlands, rice fields, cattle, coal mining, and natural gas.
• Has very high global warming potential compared to CO2.
Nitrous Oxide (N2O)
• Formed naturally by soil and ocean bacteria.
• Also released from fertilizers, combustion, and industrial activities.
Ozone (O3)
• Contributes about 10% of human‑induced warming.
• Exists naturally but is also formed by pollutants.
Fluorinated Gases
• Fully manmade, used as substitutes for CFCs.
• Released in small amounts but extremely high global warming potential.
Black Carbon
• Soot from diesel engines, biomass burning, and coal burning.
• A major cause of warming and health problems.
• Second most important contributor to climate change after CO2.
Brown Carbon
• Formed mainly from biomass burning and stubble burning.
• Absorbs blue light, giving the aerosol a brown color.
• Presence of hematite enhances absorption.
Global Warming Potential (GWP)
The effect of a gas depends on:
• Quantity in atmosphere
• Lifetime in atmosphere
• Heat‑trapping strength
Sustainable Development Goal 13 – Climate Action
Key targets:
• Increase resilience to climate‑related hazards.
• Integrate climate measures into national policies.
• Improve education and awareness on mitigation and adaptation.
• Mobilize USD 100 billion annually for developing countries.
• Build planning capacity in LDCs and SIDS.
Causes of Climate Change
Solar Irradiance
• Sun is Earth’s energy source, but its output has remained stable.
• If the sun were responsible for warming, all atmospheric layers would warm.
• Instead, upper layers are cooling while lower layers warm—proving greenhouse gas influence.
Sunspot Cycles
• Increased sunspots slightly warm the Earth, but cannot explain long‑term warming.
Climate Forcing
Factors that disturb global energy balance:
• Natural: Earth’s orbit changes, ocean circulation variations.
• Human‑made: Greenhouse gases, aerosols, albedo changes.
Impacts of Climate Change
Agriculture
• Reduced crop production.
• Increased livestock diseases.
• Indian indigenous breeds like Rathi and Tharparkar at risk.
• World Bank report: By 2040s, crop yields in India will drop greatly due to extreme heat.
• Childhood stunting expected to increase by 35% by 2050.
• Snowmelt‑dependent rivers like Ganga and Indus vulnerable.
Water Bodies
• Melting glaciers reducing freshwater and changing river flow.
• Hydrological cycle becoming more erratic.
• Sea level rise causing flooding, saltwater intrusion, and loss of mangroves and coral reefs.
• Increased water temperature decreases water quality.
Marine Ecosystems
• Higher temperatures and acidification harming corals and shell‑forming organisms.
• First climate‑change‑extinct mammal: Bramble Cay Melomy.
Mangroves
• Threatened by sea‑level rise and altered sediment supply.
• Loss affects coral reefs and seagrass beds.
Deserts
• Drylands becoming drier—Rajasthan, Haryana, Punjab.
• Flood‑triggered soil erosion causing desertification.
• Drought reduces soil moisture and groundwater recharge.
• Forest fires worsening degradation.
Mountain Ecosystems
• Biodiversity hotspots like the Himalayas under threat.
• Increasing fragmentation puts species like Snow Leopard at risk.
• Higher risk of Glacial Lake Outburst Floods (GLOFs).
Groundwater
• More droughts and floods disturb recharge.
• Saltwater intrusion in coastal aquifers due to sea‑level rise.
• Quality and availability severely affected.
Human Health
• Higher deaths from heat stress, malaria, and diarrheal diseases.
• Longer transmission windows for vector‑borne diseases like malaria and dengue.
• Floods increase water‑borne diseases.
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Subject: Environment
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