Which one of the following best explains why the balance of carbon dioxide in the atmosphere is getting disturbed?

The correct option is

Burning of fuels such as coal and oil.

Explanation

Carbon dioxide (CO₂) is a variable gas in the atmosphere that plays a crucial role in the greenhouse effect. Under natural conditions, the global carbon cycle maintains a balance between the release of CO₂ (sources) and its absorption (sinks). However, recent anthropogenic activities have disrupted this equilibrium.

Analysis of Options:

• Increased respiration by the growing human population. is incorrect: Respiration by the human population is part of the short-term biological carbon cycle. The carbon released through respiration is derived from food sources (plants and animals), which originally fixed carbon from the atmosphere. Thus, it does not contribute to a net increase in atmospheric CO₂.
• Burning of fuels such as coal and oil. is correct: Fossil fuels (coal, oil, and natural gas) contain carbon that was sequestered in the lithosphere for millions of years. Burning these fuels releases this stored carbon back into the atmosphere rapidly. This addition overwhelms natural sinks, leading to a steady rise in atmospheric CO₂ concentration.
• Reduction in the number of animals releasing carbon dioxide. is incorrect: A reduction in animals would theoretically lower the biological release of CO₂, which does not explain the current phenomenon of rising CO₂ levels.
• Excessive absorption of carbon dioxide by oceans. is incorrect: Oceans function as a carbon sink, absorbing a significant portion of anthropogenic CO₂. While this absorption is increasing (causing ocean acidification), the oceans act to mitigate the rise of CO₂ in the atmosphere, not cause the disturbance.

Key Takeaway: The burning of fossil fuels is the primary cause of the increasing concentration of carbon dioxide in the atmosphere, as it releases long-stored carbon that disrupts the natural carbon cycle.