Terrestrial plant production and climate change

'The green leaf or, to be more precise, the microscopic green grain of chlorophyll, is the focus, the point in the world to which solar energy flows on one side while all the manifestations of life on earth take their source on the other side.' Kliment Arkadievich Timiryazev The conclusions of a century of plant physiology, speech at Moscow University, 12 January 1901.