Global Warming

Definition: Global warming refers to the increase in the Earth’s average surface temperature due to the accumulation of greenhouse gases (GHGs) such as CO₂, CH₄, and N₂O in the atmosphere.
It is one of the major components of climate change.

Causes of Global Warming

Natural Causes

• Volcanic eruptions: Release large amounts of ash, CO₂, and other gases that can temporarily warm or cool the atmosphere.
• Natural greenhouse effect: Naturally occurring greenhouse gases trap heat and maintain Earth’s temperature; variations can influence climate.
• Solar radiation fluctuations: Changes in sunspot activity or solar output slightly alter Earth’s climate over long periods.

Human (Anthropogenic) Causes

• Burning fossil fuels: Coal, petrol, and diesel used in power plants, industries, and vehicles release large quantities of CO₂—the main gas responsible for global warming.
• Deforestation: Cutting down forests reduces the number of trees that absorb CO₂, increasing its concentration in the atmosphere.
• Industrial emissions: Factories release CO₂, methane (CH₄), and fluorinated gases that greatly enhance the greenhouse effect.
• Agriculture: Livestock emit methane during digestion; fertilizers release nitrous oxide—both are powerful greenhouse gases.
• Urbanization and transport: Expanding cities, increased vehicles, and construction activities generate heat and emit greenhouse gases, intensifying warming.

Greenhouse Gases Responsible

• Carbon dioxide (CO₂): Produced mainly from burning fossil fuels and deforestation; largest contributor to global warming.
• Methane (CH₄): Released from livestock, rice fields, landfills, and natural gas leaks; traps heat more effectively than CO₂.
• Nitrous oxide (N₂O): Emitted from fertilizers, industrial processes, and combustion; very high heat-trapping capacity.
• Fluorinated gases: Synthetic industrial chemicals used in refrigeration and electronics; extremely powerful greenhouse gases.

Overall Effect: These gases trap heat in the atmosphere, causing the Enhanced Greenhouse Effect, which leads to global warming and climate change.

Effects of Global Warming

i) Environmental Effects

• Rising global temperatures: Overall increase in Earth’s average temperature.
• Melting glaciers & ice caps: Reduces freshwater storage and accelerates warming.
• Sea-level rise: Causes coastal flooding, erosion, and loss of habitat.
• Extreme weather events: More frequent heat waves, cyclones, floods, and droughts.
• Ocean acidification: CO₂ absorption by oceans harms coral reefs and marine species.
• Loss of biodiversity: Many species face extinction due to habitat change and climate stress.

ii) Agricultural Effects

• Lower crop yields due to heat stress and irregular rainfall.
• Shift in sowing/harvesting seasons, affecting crop planning.
• More pests and diseases thrive in warmer conditions.
• Livestock heat stress reduces milk production and health.
• Less irrigation water due to declining rivers and groundwater.

iii) Social & Economic Effects

• Food insecurity from reduced agricultural production.
• Climate refugees: Migration from drought- or flood-hit areas.
• Spread of diseases like malaria and dengue due to warmer temperatures.
• Damage to infrastructure (roads, buildings) from storms and floods.
• Higher economic costs for cooling, health care, irrigation, and disaster relief.

Solutions to Global Warming

i) Mitigation

• Shift to renewable energy (solar, wind, hydro)
• Increase energy efficiency and reduce fossil fuel use
• Afforestation and reforestation
• Reduce industrial and vehicle emissions
• Encourage 3Rs: Reduce, Reuse, Recycle
• Promote sustainable agriculture (organic, precision farming)

ii) Adaptation

• Develop heat-, drought-, and flood-resistant crops
• Improve water conservation and irrigation methods
• Strengthen disaster management systems
• Build climate-resilient infrastructure

International Measures

• Kyoto Protocol – legally binds developed nations to reduce emissions
• Paris Agreement (2015) – limit warming to below 2°C
• UNFCCC – global climate framework
• IPCC – provides scientific climate assessment reports

Acid Rain

1. Definition

Acid rain refers to rain, snow, fog, or dust that becomes acidic due to the presence of pollutants like sulfur dioxide (SO₂) and nitrogen oxides (NOx) in the atmosphere.
The pH of acid rain is typically below 5.6.

2. Causes of Acid Rain (In Brief)
3. Natural Causes

• Volcanic eruptions: Release sulfur dioxide (SO₂) and other acidic gases into the atmosphere.
• Lightning: Produces nitrogen oxides (NOx) naturally during thunderstorms, which can contribute to mild acid formation.

1. Human (Anthropogenic) Causes

• Burning fossil fuels: Coal, diesel, and furnace oil produce large amounts of SO₂ and NOx.
• Industrial emissions: Power plants, refineries, and smelters release SO₂ and NOx into the air.
• Vehicle exhaust: Automobiles emit NOx during fuel combustion.
• Manufacturing industries: Many industries release sulfur and nitrogen compounds into the atmosphere.

Formation of Acid Rain

These gases mix with atmospheric moisture and undergo chemical reactions to form:

• Sulfuric acid (H₂SO₄) from SO₂
• Nitic acid (HNO₃) from NOx

These acids return to the Earth’s surface through rain, snow, fog, or dust, leading to acid rain.

3. Types of Acid Deposition (In Brief)

• Wet Deposition

• Occurs when acidic pollutants dissolve in rain, snow, or fog.
• Includes acidic rain, snow, sleet, dew, and fog.
• Directly affects soil, plants, water bodies, and buildings.

• Dry Deposition

• Occurs when acidic particles and gases (SO₂, NOx) settle on buildings, plants, and the ground without precipitation.
• These pollutants later mix with water during rainfall and become acidic.

4. Effects of Acid Rain (In Brief)
5. Environmental Effects

• Soil becomes acidic, reducing fertility and harming beneficial microorganisms.
• Forest damage, especially in mountainous and high-altitude regions.
• Acidification of lakes and rivers, harming fish, amphibians, and aquatic ecosystems.
• Leaching of toxic metals like aluminium into water bodies, making water harmful for life.

1. Damage to Buildings and Materials

• Corrodes and weakens marble, limestone, metals, and painted surfaces.
• Causes discoloration of historical monuments, e.g., Taj Mahal (marble cancer) due to SO₂.

1. Agricultural Impacts

• Acidic soil reduces nutrient availability for plants.
• Crop productivity decreases if soil pH falls below optimum levels.

1. Human Health Impacts

• Pollutants that cause acid rain (SO₂ and NOx) irritate lungs and cause respiratory diseases.
• Worsens asthma, bronchitis, and other breathing problems.
• Acidified water can dissolve harmful metals, contaminating drinking water sources.

5. Control Measures (In Brief)
6. Technological Measures

• Scrubbers, electrostatic precipitators, and filters remove SO₂, NOx, and particulate pollutants from industrial emissions.
• Use of low-sulfur fuels (low-sulfur coal, cleaner diesel) and switch to clean energy sources (natural gas).
• Promotion of renewable energy like solar and wind reduces dependence on fossil fuels.

1. Regulatory Measures

• Strict emission standards for industries and vehicles reduce pollutant release.
• Implementation of vehicle pollution control measures such as catalytic converters, Bharat Stage norms, and emission testing.
• Continuous air quality monitoring by CPCB and SPCBs helps detect and regulate pollution hotspots.

1. Preventive Measures

• Reduce use of fossil fuels through conservation and efficiency.
• Encourage public transport, carpooling, and fuel-efficient vehicles to lower NOx emissions.
• Afforestation and tree planting help absorb atmospheric pollutants and improve air quality.

6. International Initiative

Convention on Long-Range Transboundary Air Pollution (LRTAP), 1979

• First international treaty to address air pollution across national borders.
• Aims to reduce SO₂ and NOx emissions that cause acid rain.
• Encourages cooperation, monitoring, and adoption of cleaner technologies among member countries.