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Global warming: meaning, causes, consequences

Short answer

Global warming is the gradual rise in Earth's average temperature from enhanced greenhouse effect by CO2, CH4, N2O, CFCs. Causes: fossil fuel burning, deforestation, agriculture. Consequences: glacier melt, sea-level rise, extreme weather, crop failures, biodiversity loss, and spread of diseases.

What is meant by global warming? Give its causes and consequences.

Meaning

Global warming is the gradual rise of the average temperature of the earth's surface and lower atmosphere due to the increased concentration of greenhouse gases (CO₂, CH₄, N₂O, CFCs, water vapour, O₃). The rise has been about 1.1 °C since the pre-industrial era.

Causes

GasMain sources
CO₂ (about 60 % of the effect)Burning of coal, oil, wood; deforestation; cement industry
CH₄Paddy fields, cattle (rumination), landfills, natural gas leaks, wetlands
N₂ONitrogenous fertilisers, burning of biomass, nitric acid industry
CFCsRefrigerators, air conditioners, aerosols, foam
O₃ (troposphere)Photochemical reactions of vehicle exhaust (NOx + hydrocarbons)

The main human causes are the burning of fossil fuels, deforestation, agriculture (paddy and cattle) and use of fertilisers and CFCs.

Consequences

  • Melting of glaciers and polar ice, and rise of sea level (flooding of coastal regions, island nations). In Nepal, Himalayan glaciers are retreating and glacial lake outburst floods are a threat.
  • Changed rainfall patterns: more floods, droughts, storms and heat waves.
  • Loss of crop yield, food and water shortage; shifting of climatic zones.
  • Extinction of species and loss of biodiversity; coral bleaching.
  • Spread of diseases such as malaria and dengue to new areas.

✓ Answer checked by Claude Opus 5.5 (high effort)

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