The gas released during anaerobic degradation of vegetation may lead to:

We need to identify the environmental consequence of gas released during anaerobic degradation of vegetation.

Anaerobic degradation means decomposition of organic matter (vegetation) in the absence of oxygen. This process is carried out by methanogenic bacteria. The primary gas released is methane ($$CH_4$$).

Methane is a greenhouse gas. Greenhouse gases trap infrared radiation emitted by the Earth's surface and prevent it from escaping into space. This leads to an increase in the average temperature of the Earth's atmosphere, a phenomenon known as global warming.

Methane is approximately 25 times more effective than carbon dioxide ($$CO_2$$) at trapping heat over a 100-year period. Therefore, even small amounts of methane can contribute significantly to global warming.

Additionally, methane in the atmosphere undergoes photochemical reactions that produce ground-level ozone and other secondary pollutants. Prolonged exposure to such pollutants has been associated with increased cancer risk in living organisms.

The other options do not correctly describe the primary effect of methane. Corrosion of metals is caused by electrochemical reactions, not methane. The ozone hole is caused by chlorofluorocarbons (CFCs), not methane. Acid rain is caused by $$SO_2$$ and $$NO_x$$ emissions, not methane.

Hence, the gas released during anaerobic degradation of vegetation may lead to global warming and cancer.

Hence, the correct answer is Option 3.