Estimation of past atmospheric carbon dioxide levels using tree-ring cellulose

The researchers studied the Farquhar model for carbon isotopic discrimination (change in carbon isotopic composition from air CO2 to tree-ring cellulose) in C3 plants to trees growing in the field. Two new carbon isotope datasets from Himalayan conifers with published data from another eight sites across the world show disparate trends in the plot of carbon isotope discrimination versus atmospheric carbon dioxide concentration.

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