Q.What would have happened if the greenhouse gases were totally missing in the earth’s atmosphere? Discuss.

The greenhouse effect is a natural phenomenon: solar radiation reaching the earth is partly absorbed and re-radiated as infrared (heat) radiation; greenhouse gases (CO2, CH4, water vapour, N2O, O3, etc.) in the atmosphere absorb this outgoing infrared radiation and re-emit part of it back towards the earth's surface, trapping heat and keeping the planet warm enough to sustain liquid water and life.

If greenhouse gases were totally missing from the atmosphere:

• There would be no absorption/re-radiation of infrared heat back towards the surface — nearly all the heat radiated by the earth would simply escape into space.
• The earth's average surface temperature would drop drastically. Calculations based on the earth's energy balance suggest that without any greenhouse effect at all, the average surface temperature would be around −18°C (compared to the actual observed average of about +15°C) — a difference of roughly 33°C.
• At such low temperatures, water on the surface would largely freeze, oceans could turn to ice, and the conditions needed to sustain liquid water, a stable climate and most forms of life as we know them would not exist. …

Recall that greenhouse gases trap outgoing infrared radiation to keep earth warm; reasoning by removing this mechanism entirely implies almost all heat escapes to space, so temperature woul …

• Saying the earth would simply become 'a bit colder' without recognising the drastic magnitude of the temperature drop (tens of degrees).
• Confusing this with the opposite (excess greenhouse gas) scenario of global warming — the question asks about total absence, not excess. …