The biosphere, also known as the ecosphere, is the worldwide sum of all ecosystems. It can also be termed the zone of life on Earth. The biosphere is virtually a closed system with regards to matter, with minimal inputs and outputs. With regards to energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 130 Terawatts per year. However it is a self-regulating system close to energetic equilibrium. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis or biogenesis, at least some 3.5 billion years ago.
