Summary

Earth’s climate is complex and dynamic, but is mainly influenced by the amount of solar radiation hitting Earth and the composition of the atmosphere.

Large changes in climate are controlled by the concentration of greenhouse gases (most importantly carbon dioxide).

Changes in Earth’s orbit around the sun cause changes in Earth’s climate that are superimposed on the larger signal driven by greenhouse gases.

Carbon dioxide is increasing at rates more than 100 times greater than at any time in the past 800,000 years. This time span is more than four times greater than the time span of the existence of Homo sapiens.

The concentration of carbon dioxide is now higher than at any time in human existence.

Paleontological evidence ties mass extinctions to periods of rapid environmental change because biology requires time to adapt.