by  Dennis T. Avery, June 30, 2017 in WUWT

Carbon dioxide truly is “the gas of life.” The plants that feed us and wildlife can’t live without inhaling CO2, and then they exhale the oxygen that lets humans and animals keep breathing.

Our crop plants evolved about 400 million years ago, when CO2 in the atmosphere was about 5000 parts per million! Our evergreen trees and shrubs evolved about 360 million years ago, with CO2 levels at about 4,000 ppm. When our deciduous trees evolved about 160 million years ago, the CO2 level was about 2,200 ppm – still five times the current level.

See also here (in French)