Compared with today, the temperature on Earth during its first half- billion years was probably
A) considerably colder.
B) about the same as today.
C) considerably warmer.
D) about the same as today on average, but the diurnal fluctuations were much greater.

Question

Quizplus · Accepted Answer

During the Earth's first half-billion years, there were no plants to produce oxygen, and the atmosphere was primarily composed of methane, ammonia, and water vapor. This atmosphere would have trapped heat, leading to a greenhouse effect that made the temperature considerably warmer than it is today.

Compared with Today, the Temperature on Earth During Its First