In this article, "climate change" means a change in climate that persists over a sustained period of time.[14][15] The World Meteorological Organization defines this time period as 30 years.[14] Examples of climate change include increases in global surface temperature (global warming), changes in rainfall patterns, and changes in the frequency of extreme weather events. Changes in climate may be due to natural causes, e.g., changes in the sun's output, or due to human activities, e.g., changing the composition of the atmosphere.[16] Any human-induced changes in climate will occur against a background of natural climatic variations[16] and of variations in human activity such as population growth on shores or in arid areas which increase or decrease climate vulnerability.[17]
Also, the term "anthropogenic forcing" refers to the influence exerted on a habitat or chemical environment by humans, as opposed to a natural process.[18]