Climate change, basically, is a change in the statistical properties of the climate system when considered over long periods of time, regardless of cause. Accordingly, fluctuations over periods shorter than a few decades, such as El Nino, do not represent climate change.

  The term sometimes is used to refer specifically to climate change caused by human activity, as opposed to changes in climate that may have resulted as part of Earth’s natural processes. In this sense, especially in the context of environmental policy, the term climate changehas become synonymous with anthropogenic global warming. In scientific journals, global warming refers to surface temperature increases while climate changeincludes global warming and everything else that increasing greenhouse gas levels will affect. On the broadest scale, the rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and....