Ehleringer, J.R., and T.E. Cerling. 1995. Atmospheric CO2 and the ratio of intercellular to ambient CO2 levels in plants. Tree Physiol. 15:105-111.

Much attention is focused today on predicting how plants will respond to anticipated changes in climate, and in particular to increases in CO2 concentrations. Here we review the long-term global fluctuations in atmospheric CO2 concentration as a framework for understanding how current trends in atmospheric CO2 concentrations fit into a selective, evolutionary context. We then focus on an integrated approach for understanding how gas exchange metabolism responds to current climatic conditions, has responded to glacial-interglacial conditions, and how metabolism might respond to future changes in atmospheric CO2 concentration.