These natural mechanisms include eccentricities in the earths orbit around the sun and about the earths own axis, variation in solar radiation, the earths natural carbon cycle, changes in oceanic currents and the position of the earths continents through geological time, and probably several other factors that I'm unfamiliar with. (realclimate.org)
Natural climate drivers include the energy from the sun; aerosols from periodic volcanic eruptions, dust, and salt spray; natural carbon cycle processes like termite mounds in Africa that emit methane, or tiny organisms in the ocean surface that take up carbon dioxide; and variation in snow and ice cover that change how much the Earth's surface reflects the sun's energy back into space (referred to as albedo). (ucsusa.org)
GeoCARB will provide important new measurements related to Earth's global natural carbon cycle, and will allow monitoring of vegetation health throughout North, Central and South America,» Michael Freilich, director of the Earth Science Division of NASA's Science Mission Directorate in Washington, said. (natureworldnews.com)