Question

The main cause of the increase in the amount of CO₂ in Earth’s atmosphere over the past 150 years is

(A) increased worldwide primary production.

(B) increased worldwide standing crop.

(C) an increase in the amount of infrared radiation absorbed by the atmosphere.

(D) the burning of larger amounts of wood and fossil fuels.

Short answer

1. The option “increased worldwide primary production” is false.
2. The option “increased worldwide standing crop” is false.
3. The option “an increase in the amount of infrared radiation absorbed by the atmosphere” is false.
4. The option “the burning of larger amounts of wood and fossil fuels” is true.

Step-by-step solution

Atmospheric carbon dioxide

Human activities largely influence the concentration of atmospheric carbon dioxide.Since the Industrial Revolution, the atmosphere has experienced an increase in carbon dioxide by 48%.

Consequently, the greenhouse effect has increased, and climate change is inevitable.

Explanation of option ‘(A)’

Most green plants conduct primary production to produce their food. During this process, they use sunlight and atmospheric carbon dioxide. It implies that this process does not contribute to increasing atmospheric CO₂.

Thus, the worldwide primary production does not increase CO₂ in the Earth’s atmosphere.

Therefore, the given statement is false.

Explanation of option ‘(B)’

Increased standing crop implies a more significant number of plants and hence increased primary production. Consequently, there would be increased CO₂ consumption.

Thus, increased worldwide standing crop increases CO₂ consumption and is not the cause of its increase.

Therefore, the given statement is false.

Explanation of option ‘(C)’

Infrared radiation absorption by the atmosphere gets influenced by the atmospheric CO₂level. Increased absorption of radiation is not a cause but a result of increased CO₂levels.

Thus, increased infrared radiation absorption is a result of increased CO₂.

Therefore, the given statement is false.

Explanation of option ‘(D)’

Over the years, increased population resulted in increased energy demand and hence fossil fuels and wood. The product of the burning of wood and fossil fuels is CO₂.

Burning more of these resources produces more CO_2, and consequently, its levels increase in the atmosphere.

Thus, burning fossil fuels and woods has increased atmospheric CO₂.

Therefore, the given statement is true.