Joint proxy inversion of terrestrial climate proxies reveals spatial and temporal patterns in climate change over the Paleocene-Eocene Thermal Maximum (PETM)

Abstract:

The Paleocene-Eocene Thermal Maximum (PETM) was a rapid warming event ~56 Ma characterized by a ~4 ‰ global carbon isotope excursion (CIE) that reflects a large injection of isotopically light carbon into the ocean/atmosphere system. Quantitative terrestrial climate proxies across the PETM are limited and their interpretation often ambiguous, and clear spatial or temporal patterns in hydrologic change over the event have not emerged. Statistically based integration of information from multiple proxy types has potential to reduce the ambiguity of these reconstructions by leveraging the overlapping environmental sensitivity of different records. We combine multiple quantitative terrestrial climate proxies in a Bayesian Joint Proxy Inversion (JPI), which produces probability distributions of local and global environmental parameter time-series that are conditioned on multiple proxy records. The JPI leverages a recently published proxy model for carbon and oxygen isotope values of pedogenic carbonate and empirical calibrations for several other terrestrial proxies and considers both annual and seasonal changes in temperature and precipitation. Results of the JPI show considerable spatial heterogeneity in precipitation and seasonal temperature change over the PETM with only moderate increases in pCO₂.