Q.Discuss the causes and effects of global warming. What measures need to be taken to control global warming?

Causes of global warming

• Increase in greenhouse gases: carbon dioxide (from burning coal, petroleum and natural gas), methane (from paddy fields, livestock, landfills), chlorofluorocarbons/CFCs (from refrigerants and aerosols), nitrous oxide (from fertiliser use and combustion), and water vapour all absorb and re-radiate infrared (heat) radiation, trapping heat in the atmosphere — the natural "greenhouse effect" intensified by human activity.
• Deforestation: fewer trees means less CO2 is removed from the atmosphere by photosynthesis, so more of it accumulates.
• Industrialisation and transport: large-scale burning of fossil fuels for power generation, manufacturing and vehicles adds enormous quantities of CO2 and other gases.
• Agricultural practices: rice cultivation and cattle rearing release methane; use of nitrogenous fertilisers releases nitrous oxide.

Effects of global warming

• Melting of glaciers and polar ice caps, reducing freshwater reserves and altering river flows.
• Rise in sea level, threatening coastal cities and low-lying island nations with flooding and submergence.
• Changed precipitation patterns, causing more frequent droughts in some regions and floods in others.
• Increase in extreme weather events — heat waves, storms and cyclones.
• Impact on agriculture and food security due to shifting growing seasons and unpredictable weather.
• Threat to biodiversity — species unable to adapt or migrate fast enough face extinction; coral reefs suffer bleaching due to warmer, more acidic oceans.

Measures to control global warming

• Reduce fossil-fuel consumption by improving energy efficiency and adopting public transport, carpooling and cycling.
• Shift to renewable energy sources such as solar, wind and hydro power in place of coal and petroleum.
• Afforestation and reforestation to increase the carbon sink that absorbs atmospheric CO2.
• Curb deforestation and promote sustainable land use.
• Adopt cleaner agricultural practices to lower methane and nitrous oxide emissions.
• International cooperation through agreements (e.g., the Paris Agreement) that commit nations to emission-reduction targets.

Address the three parts explicitly and separately: causes (list the greenhouse gases and the human activities producing them), effects (physical, climatic and biological consequences), and control measures (energy, land-use and policy solutions) — do not blend cause and effect into one undifferentiated paragraph.

• Naming only CO2 and forgetting the other greenhouse gases (methane, CFCs, nitrous oxide, water vapour).
• Confusing global warming (rise in average temperature due to greenhouse gases) with ozone depletion (a separate stratospheric phenomenon caused mainly by CFCs) — they are related but distinct issues.
• Listing effects without linking them causally to the temperature rise (e.g., stating "sea level rises" without explaining it is due to glacier/ice-cap melting and thermal expansion of water).