Q.Write an essay on green house gases and their impact on the environment.

Greenhouse gases trap outgoing infrared radiation in the atmosphere, and their rising concentration due to human activity is intensifying the natural greenhouse effect into anthropogenic global warming, with wide-ranging impacts on climate, ecosystems, and human society.

The greenhouse effect and major greenhouse gases

• Certain atmospheric gases allow incoming short-wave solar radiation to pass through but absorb and re-radiate outgoing long-wave infrared (heat) radiation from Earth's surface, keeping the planet warmer than it would otherwise be -- this natural greenhouse effect is essential for life.
• Main greenhouse gases and their sources:
  • Carbon dioxide (CO2) -- burning of fossil fuels (coal, petroleum, natural gas) and deforestation (which also removes a carbon sink).
  • Methane (CH4) -- anaerobic decomposition in paddy fields and wetlands, enteric fermentation in livestock (cattle), and landfill waste decomposition.
  • Nitrous oxide (N2O) -- use of nitrogenous fertilisers in agriculture and various industrial processes.
  • Chlorofluorocarbons (CFCs) -- refrigerants, aerosol propellants, and foam-blowing agents (also ozone-depleting).
  • Water vapour and tropospheric ozone also contribute to the greenhouse effect.

Impact on the environment

1. Global warming -- rising concentrations of these gases enhance heat trapping, raising Earth's average global temperature over time.
2. Climate change -- altered and less predictable rainfall patterns, and increased frequency/intensity of extreme weather events such as floods, droughts, heat waves, and cyclones.
3. Melting ice and sea-level rise -- warming accelerates the melting of polar ice caps and mountain glaciers, causing sea levels to rise and threatening coastal cities and low-lying islands with flooding and submergence.
4. Impact on agriculture -- shifting temperature and rainfall zones affect crop-growing regions and can reduce yields of major food crops, threatening food security. …