Temperature Sensitivity of Leaf Wax <i>n</i> ‐Alkane Carbon Isotopes: Mechanisms and Implications for Terrestrial Paleoclimates

Abstract While climate signals encapsulated in the 13 C content of C 3 plants' leaf wax n ‐alkanes are largely tied to precipitation, they may also be sensitive to plant physiological responses to temperature. In this study, statistical analyses on a global data set of modern plants reveal a correlation between the 13 C discrimination for leaf waxes (relative to atmospheric CO 2 ) and mean annual temperature (MAT), with a partial correlation coefficient of 0.14 ± 0.04‰/°C. Metabolic modeling including isotopic fractionation for both scenarios indicates isoprenoid emission is a likely driver of the temperature sensitivity expressed in the global data set. Furthermore, we apply this modern calibration to constrain paleoclimates for selected North American plant wax data sets, and compare our results with other independent proxies.