Climate Change Global Warming

The ozone layer in the upper atmosphere is crucial for protecting life on Earth. It absorbs harmful ultraviolet (UV) radiation from the Sun, which could otherwise cause skin cancer, cataracts, and other health problems in humans and animals. So, ozone in the upper atmosphere is not harmful but rather protective.

The other statements are correct:

A: Most of the forests have been lost in tropical areas. This is true, as deforestation has been a significant issue in tropical rainforests.

B: Greenhouse effect is a natural phenomenon. This is correct; the greenhouse effect is a natural process that warms the Earth.

C: Eutrophication is a natural phenomenon in freshwater lakes. This is also correct; eutrophication, often caused by excess nutrients, is a natural process, though it can be exacerbated by human activity.

Step 1: Understanding Greenhouse Gases and Their Contribution
Greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and chlorofluorocarbons (CFCs) all contribute to global warming by trapping heat in the Earth's atmosphere. Their contributions to global warming differ in terms of their potency and abundance.

Step 2: The Contribution Breakdown
Based on scientific studies, the approximate contributions to global warming are:

• CO₂ (Carbon Dioxide): About 60% of the total contribution to global warming.
• CFCs (Chlorofluorocarbons): Approximately 14% of the total contribution, though they are much more potent than CO₂.
• Methane (CH₄): Contributes around 6% to 20%, being a potent greenhouse gas, especially in terms of heat retention.
• N₂O (Nitrous Oxide): Accounts for roughly 6% to 20%, with a significant warming potential but less than CO₂.

The correct answer is (B) : CFC-14%, CO₂-60%, Methane-20%, N₂O-6%.