It describes changes in the state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes inside the Earth, forces from outside (e.g. variations in sunlight intensity) or, more recently, human activities. Ice ages are prominent examples.
Climate change is any significant long-term change in the expected patterns of average weather of a region (or the whole Earth) over a significant period of time. Climate change is about abnormal variations to the climate, and the effects of these variations on other parts of the Earth. Examples include melting of the ice caps at the South Pole and North Pole. These changes may take tens, hundreds or perhaps millions of years.
In recent usage, especially in the context of environmental policy, climate change usually refers to changes in modern climate (see global warming).
- Edwards, Paul Geoffrey; Miller, Clark A. (2001). Changing the atmosphere: expert knowledge and environmental governance. Cambridge MA: MIT Press. ISBN 0-262-63219-5
- McKibben, Bill (2011). The global warming reader. New York, N.Y.: OR Books. ISBN 978-1-935928-36-2
- Ruddiman W.F. (2003). "The anthropogenic greenhouse era began thousands of years ago". Climate Change 61 (3): 261–293. 
- Ruddiman, William F. (2005). Plows, plagues, and petroleum: how humans took control of climate. Princeton N.J: Princeton University Press. ISBN 0-691-13398-0
- Schelling, Thomas C. 2002. "Greenhouse Effect". Concise Encyclopedia of Economics (1st). Ed. David R. Henderson (ed.). Library of Economics and Liberty. OCLC 317650570, 50016270 and 163149563