Question

What factors do scientists believe caused the predictable, long-term climate change cycles of the past?

Answer 1

Amount of incoming solar radiation that makes it to the Earth,s surface and strength of the natural greenhouse effect are two important factors.

Explanation:

Changes in Earth.s orbit changed the amount of solar radiation and plunged the earth into glacial periods. Volcanic eruptions of CO2 have boosted the natural greenhouse effect and thereby created global warming periods. The same is happening now that humans are pumping large amount of greenhouse gases into the atmosphere.