Which one of the following atmospheric change takes place due to the greenhouse effect?

The greenhouse effect is the trapping of outgoing infrared radiation by gases such as CO2, water vapour, methane and nitrous oxide. Without it Earth would be about 33 degrees Celsius colder. The question asks which change takes place due to this effect, and the change that is directly linked to it is the rise in carbon dioxide concentration. Burning fossil fuels and deforestation have pushed CO2 from roughly 280 ppm in pre-industrial times to above 420 ppm now, which intensifies the trapping of heat.

• B (humidity): Water vapour does amplify warming, but it is a feedback that follows from higher temperature. It is not the primary atmospheric change the question is after.
• C (biological population): This is an ecological consequence, not an atmospheric change.
• D (wind speed): Warming may alter circulation patterns, but this is an uncertain, regional and secondary effect, not a direct change from the greenhouse effect.

The core concept is radiative forcing and the enhanced greenhouse effect. For Mains, connect this to the Paris Agreement (2015), India's NDC commitments and the net-zero 2070 target.

Trap: Aspirants pick B because humidity rises with warming. Ask whether the change is the direct cause or only a feedback.