Changing circulation patterns cause climate change. Some scientists hypthesize that climatic changes cause by uplift are critical to the development of ice ages. The uplift of the Himalayas and the Tibetian Plateau probably contributed to the initiation of the current cool period. Similar tectonic uplift appears to have been involved in the three other long, ice age intervals. A general reduction in amount of CO2 in the atmosphere may contribute to the development of ice ages.
Carbon dioxide is an important greenhouse gas.
Decreases in the amount of CO2 in the atmosphere may lead to global cooling. Many processes can cause a long-term decrease in the amount of CO2 in the atmosphere. These processes include many complex interactions among organisms, ocean currents, erosion, and volcanism. Also, many scientists are not sure the magnitude of past CO2 changes was large enough to initiate ice ages. Changes in the Earth's orbit The Earth's orbit varies through time.