ABSTRACT
There is negative feedback that stabilizes Earth’s temperature, mediated by life. Life has regulated the two main greenhouse gases, carbon dioxide and methane, and hence temperature, in a way favorable for life throughout life’s history. The sun is about 30% hotter today than when it originated 4.5 billion years ago. On the early Earth, when it was very cold due to very little heat from the sun, methanogens manufactured a great deal of methane, making the temperature favorable to the simple microbes that existed then. As the sun increased its heat, organisms, such as trees, phytoplankton, and salps removed large quantities of carbon from the air. Excessive carbon dioxide levels are deleterious to life for other reasons than climate. The burying of carbon by life could potentially cause a future problem because carbon in the biosphere could eventually dwindle to levels too low for most life to survive. However, life is conserving carbon and thus prolonging the time life will be able to thrive by a variety of mechanisms, even as it removes it from the system. Organisms regulate the amount of silicon in the biosphere and salt concentration of seawater.
