The climate system is typically described as consisting of five separate, yet interactive, parts, namely the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere. Each part is influenced by the sun, which affects evaporation, terrestrial radiation and other processes, and by the activities of human beings among other external factors.
The atmosphere is composed primarily of nitrogen (78 percent) and oxygen (21 percent), together with the inert gas argon and various other gases, known as trace gases, in minute quantities. Importantly, some of these gases, such as carbon dioxide, methane, nitrous oxide, ozone and water vapor, interact with the infrared radiation emitted by the Earth and contribute to the atmospheric heating phenomenon known as the "greenhouse effect." The composition of the atmosphere has changed during the history of the Earth and, according to the BBC, the level of carbon dioxide has increased by 40 percent since the Industrial Revolution.
The hydrosphere refers to all the liquid water on, beneath and surrounding the surface of the earth. It therefore includes oceans, rivers, lakes and water in the atmosphere. Oceans cover approximately 70 percent of the surface of the Earth and store not only large quantities of carbon dioxide, but also large quantities of energy.
The cryosphere refers to the frozen portions of the global, including the polar ice caps, the ice sheets of Greenland and Antarctica, glaciers and sea lake and river ice. The importance of the cryosphere in the climate system results from its role in driving deep ocean circulation currents, its high reflectivity of solar radiation and its low thermal conductivity.
The soil surface features (and vegetation at the land surface affect how much of the incoming solar radiation is reflected back into the atmosphere. Some of the incoming radiation evaporates water from the soil into the atmosphere -- a process that requires energy -- so the amount of water in the soil influences the temperature at the land surface.
The biosphere refers to the parts of the earth's surface and atmosphere inhabited by living things. Animal and plant life influences the consumption and production of greenhouse gases. Marine and terrestrial plants photosynthesize -- that is, create complex organic materials using carbon dioxide, water and inorganic salts as raw materials and sunlight as an energy source -- and therefore store, or "fix", large amounts of carbon dioxide.