Why is an excess of CO₂ in the atmosphere considered undesirable even though it is required by plants?
Although plants require CO₂ for photosynthesis, an excess of it in the atmosphere is undesirable because it disrupts the critical balance of the greenhouse effect. While some CO₂ is necessary to trap outgoing heat and keep the Earth warm enough to sustain life, excessive CO₂ intensifies this effect.
This intensification leads to global warming, which causes the melting of glaciers and Arctic sea ice, rising sea levels, and more extreme weather conditions. In India, it can result in more intense monsoons and threaten agriculture due to changing rainfall patterns.
If left unchecked, the enhanced greenhouse effect from excess CO₂ could make the Earth uninhabitable, similar to the uncontrolled greenhouse effect on Venus.
Explanation
The textbook context highlights that while CO2 is required by plants and is necessary in certain amounts to keep the Earth warm, an excess disrupts this balance. Excess CO2 intensifies the greenhouse effect, leading to global warming, melting glaciers, rising sea levels, and extreme weather. It also notes that an uncontrolled greenhouse effect could make Earth uninhabitable, as seen on Venus.