Based on the above passage, the following assumptions have been made: 1. Global warming has a bearing on the planet’s biological evolution. 2. Separation of land masses causes the release of huge quantities of carbon into the atmosphere. 3. Increased warming of Earth’s atmosphere can change the composition of its flora and fauna. 4. The present man-made global warming will finally lead to conditions similar to those that happened 56 million years ago. Which of the assumptions given above are valid?

Passage

Around 56 million years ago, the Atlantic Ocean had not fully opened and animals, perhaps including our primate ancestors, could walk from Asia to North America through Europe and across Greenland. Earth was warmer than it is today, but as the Palaeocene epoch gave way to the Eocene, it was about to get much warmer still — rapidly and radically. The cause was a massive geologically sudden release of carbon. During this period called Palaeocene — Eocene Thermal Maximum or PETM, the carbon injected into the atmosphere was roughly the amount that would be injected today if humans burned all the Earth’s reserves of coal, oil and natural gas. The PETM lasted for about 1,50,000 years, until the excess carbon was reabsorbed. It brought on drought, floods, insect plagues and a few extinctions. Life on Earth survived — indeed, it prospered — but it was drastically different.

Question

CSATMediumPrelims 2019Comprehension

Based on the above passage, the following assumptions have been made:

Global warming has a bearing on the planet’s biological evolution.
Separation of land masses causes the release of huge quantities of carbon into the atmosphere.
Increased warming of Earth’s atmosphere can change the composition of its flora and fauna.
The present man-made global warming will finally lead to conditions similar to those that happened 56 million years ago.

Which of the assumptions given above are valid?

Explanation

Statement 1 is correct. The passage describes how the PETM caused significant changes in Earth's environment, such as droughts, floods, and extinctions, which impacted life. It also states that "life on Earth survived — indeed, it prospered — but it was drastically different," implying evolutionary changes.

Statement 2 is incorrect. The passage does not establish any connection between the separation of land masses and the release of carbon. The described carbon release is attributed to a geologically sudden event, not land separation.

Statement 3 is correct. The passage notes that during the PETM, life on Earth was "drastically different," suggesting a change in the composition of flora and fauna due to increased warming.

Statement 4 is incorrect. The passage states that the amount of carbon released during the PETM was similar to what would happen if humans burned all fossil fuel reserves. However, it does not explicitly state that the conditions will become identical; this is speculative.