Question

Long before man was a dominate species on Earth, there were shifts in Earth's climate. According to the data recorded in the graph seen here, we would assume that a major climatic shift on Earth, from tropical to frigid, occurred about 34 million years ago. We know there have been several ice ages on Earth. If such climatic shifts are naturally occurring and not the result of some catastrophic event like an asteroid impact, how can we explain them?

Answer 1

Natural global warming, interglacial periods and natural cooling, glacial periods, are considered to be initiated by Milankovitch cycles. These orbital and axial variations influence the long-term natural climatic cycles.

Answer 2

Before man became dominant species on Earth, the Earth has experienced many climate changes.

Step-by-step explanation:

Geological records shows that there were many changes in climate such as ice ages, hot conditions, oxygen devoid condition, acidic ocean, with massive extinction. These changes in climatic conditions were caused by orbital wobbles, fluctuation in solar radiations, and continents movements.

As the solar energy output is not constant at all times, it is one of the reasons for changes in climate. Besides, the earth's orbit around the sun is not circle but ellipse, hence the earth would appear to be warmer when the distance between the sun and earth is closer causing temperature changes. Another factor is rotation of the earth on its axis which is inclined at an angle. The angle changes with time causing certain periods to be with warmer summer and colder winters