climate

Climate is the average weather, or more rigorously, its statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. In the ocean, climate change is manifested as altered hydrologic conditions including temperature, oxygen, sea level, the carbonate system, and related changes in productivity, mixing and circulation.