What is the gradual increase in the average temperature of the earth’s lower atmosphere called?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Global warming
Global warming is the gradual rise in the average temperature of the earth’s lower atmosphere. It is caused mainly by the build-up of greenhouse gases such as carbon dioxide and methane from burning fossil fuels and cutting forests.
Why the other options are incorrect
Option (1) Rainwater harvesting — Incorrect. Collecting and storing rainwater for later use or to recharge groundwater.
Option (2) Multi-level cropping — Incorrect. Growing crops of different heights together on the same plot to make full use of land and sunlight.
Option (4) Deforestation — Incorrect. The large-scale cutting of forests; it is one of the causes of global warming.