The history of CO2

Upon arrival on Earth, the reduced carbon pool split into a series of compartments: core, mantle, crust, hydrosphere, atmosphere, biosphere.This distribution pattern is caused by the ability of carbon to adjust structurally to a wide range of pressure and temperature, and to form simple and complex molecules with oxygen, hydrogen and nitrogen. Transformation also involved oxidation of carbon to CO₂ which is mediated at depth by minerals, such as magnetite, and by water vapor above critical temperature. Guided by mineral-organic interactions, simple carbon compounds evolved in near surface environments towards physiologically interesting biochemicals. Life, as an autocatalytic system, is considered an outgrowth of such a development.This article discusses environmental parameters that control the CO₂ system, past and present. Mantle and crustal evolution is the dynamo recharging the CO₂ in sea and air; the present rate of CO₂ release from the magma is 0.05 × 10¹⁵ g C per year. Due to the enormous buffer capacity of the chemical system ocean, such rates are too small to seriously effect the level of CO₂ in our atmosphere. In the light of geological field data and stable isotope work, it is concluded that the CO₂ content in the atmosphere has remained fairly uniform since early Precambrian time; CO₂ should thus have had little impact on paleoclimate. In contrast, the massive discharge of man-made CO₂ into our atmosphere may have serious consequences for climate, environment and society in the years to come.