Q.Explain how does greenhouse effect cause global warming.

Greenhouse Effect and Global Warming

The greenhouse effect is the natural warming of the Earth caused by certain atmospheric gases. Sunlight reaches the Earth's surface, which absorbs it and re-emits heat as infrared (long-wave) radiation. Greenhouse gases — chiefly carbon dioxide (CO₂) and methane (CH₄), along with water vapour, nitrous oxide (N₂O) and chlorofluorocarbons (CFCs) — absorb and trap this outgoing infrared radiation, preventing its escape to space and reheating the atmosphere.

Without this effect the Earth would be too cold for life; however, rising anthropogenic emissions intensify it, causing global warming — an increase in average global temperature.

Relative contribution to global warming (approximate): CO₂ ≈ 60%, methane ≈ 20%, CFCs ≈ 14%, and N₂O ≈ 6% (values vary between sources). Methane, though present in smaller amounts, is a far more potent greenhouse gas per molecule than CO₂.

Consequences include melting of polar ice, rising sea levels, and shifts in rainfall and agriculture. Mitigation involves cutting fossil-fuel use, reforestation and reducing emissions of these gases. …