Consider the following statements Statement 1: Climate change is influenced by both natural and anthropogenic factors.

Question

Consider the following statements:

Statement 1: Climate change is influenced by both natural and anthropogenic factors.

Statement 2: The Amazon rainforest is often referred to as the "lungs of the Earth".

Statement 3: Current extinction rates are comparable to historical background rates.

Statement 4: Urbanization can negatively impact local biodiversity. The correct statement/s is/are:

1. A. 1 and 3 only
2. B. 2 and 4
3. C. 3 only
4. D. 1, 2, and 4. (Correct answer)

Correct Answer

Option D — 1, 2, and 4.

Detailed Solution & Explanation

The correct answer is 1, 2, and 4.

Key Points

• Statement 1 is correct. Climate change is driven by both natural and anthropogenic factors — natural forcings include solar variability, volcanic eruptions and orbital (Milankovitch) cycles, while the anthropogenic forcings of the industrial era are fossil fuel combustion, land use change and industrial agriculture.
• Statement 2 is correct. The Amazon rainforest is commonly called the "lungs of the Earth", a description often paired with the claim that it supplies about 20% of the world's oxygen.
• Statement 3 is incorrect. Current extinction rates are not comparable to background rates — they are estimated to be 100 to 1,000 times higher, which is why the present is described as the sixth mass extinction.
• Statement 4 is correct. Urbanisation negatively affects local biodiversity through habitat loss and fragmentation, impervious surfaces, pollution, artificial light and noise, and the spread of a small set of urban-adapted generalist species at the expense of specialists.

Additional Information

• The "lungs of the Earth" phrase is a useful shorthand but scientifically loose. A mature rainforest is close to carbon and oxygen neutral — the oxygen released by photosynthesis is largely consumed again by respiration and decomposition within the same ecosystem. Most of the world's free oxygen comes from oceanic phytoplankton. The Amazon's real significance lies in the carbon it stores, its role in regional rainfall recycling through flying rivers, and its unmatched species richness.
• The Amazon spans nine countries, with about 60% in Brazil, and holds roughly 10% of known species. Deforestation has raised concern about an approaching tipping point beyond which parts of the forest shift to savannah.
• The five previous mass extinctions are the Ordovician-Silurian, Late Devonian, Permian-Triassic (the "Great Dying", with about 96% of marine species lost), Triassic-Jurassic and Cretaceous-Palaeogene, which ended the non-avian dinosaurs.
• The current drivers of biodiversity loss, in the order IPBES ranks them: land and sea use change, direct exploitation of organisms, climate change, pollution, and invasive alien species.
• The Milankovitch cycles — eccentricity (~100,000 years), axial tilt or obliquity (~41,000 years) and precession (~26,000 years) — govern the natural pacing of glacial and interglacial periods, and are the reason natural climate change operates on timescales orders of magnitude slower than the present warming.