for purposes of the Third Assessment Report, the IPCC defines it as an interactive system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the land surface, and the biosphere. The climate system continues to evolve over time, influenced by: its own internal dynamics, external forcings such as volcanic eruptions, solar variations, and human-induced forcings such as fossil fuel burning and land use change.
The interacting system comprising the atmosphere, hydrosphere (liquid water in lakes, rivers, seas, oceans), cryosphere (snow, ice, permafrost), land surface and biosphere (ecosystems and living organisms) which determines the earth's climate.