4. Plate Tectonics

Plate tectonic movements can alter climate. Over millions of years as seas open and close, ocean currents may distribute heat differently. For example, when all the continents were joined as the supercontinent Pangaea, nearly all locations experienced a continental climate (i.e. the interior land mass gets very cold). When the continents are separated, heat can be more evenly distributed.

Plate movements may help trigger an ice age. When continents are located near the poles, ice can accumulate, which may increase albedo and lower global temperature. Low enough temperatures may start a global ice age. 

Large volcanic eruptions can lead to global cooling. Photo courtesy of NASA. 

Plate motions also trigger volcanic eruptions. Eruptions release carbon dioxide, dust, gas and ash into the air. Even ordinary eruptions have short-term cooling effects; massive eruptions can change the climate for many years. 

Source: USOE OER Resources. Retrieved from http://www.slcschools.org/departments/curriculum/science/documents/4-Earth-Science.pdf on August 28, 2013.