Recurring occurrence of Early Paleogene hyperthermals: a one-time climatic oddity or a characteristic feature of greenhouse climates?

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In the geologic record, abrupt warming events coupled to the release of large quantities of carbon to the ocean and atmosphere occur especially during the early Paleogene. These so-called hyperthermals have been shown to share many of the same key characteristics (e.g., rapid input of organic carbon, rapid warming) as the recent warming caused by anthropogenic carbon release. This makes them a prime target to study the mechanisms and effects of past warming events and therefore one of the only ways to test climate model predictions and how ecosystems cope with short-term but large CO2 emissions. Recent studies have demonstrated that the recurrent hyperthermal events of the early Paleogene are related to orbital forcing of the carbon cycle. Being an intrinsic part of Earth’s climate system and therefore the carbon cycle, past greenhouse climates should be governed by the same processes as the early Paleogene; arguing for the occurrence of recurrent hyperthermals during these intervals. So far, however, there are no reports about these recurrent hyperthermal events in the older geologic record and especially not from the Mesozoic greenhouse climate. The principal objective of this project is to test for the occurrence or absence of hyperthermal events in the Maastrichtian in order to obtain a mechanistic understanding of greenhouse climates. This objective will be reached through the generation of paleoclimate proxy records from two sites (North Atlantic IODP Site U1403 and Pacific ODP Site 1210) across a selected time interval of the Maastrichtian (67–68.5 Ma). Proxy records to be generated are based on benthic foraminiferal geochemistry (stable isotopes and Mg/Ca), XRF core scanning, and wt% CaCO3 analyses. Providing this information will allow detailed insight into the controlling mechanisms of greenhouse climates and therefore a test if the use of hyperthermal events as analogues to understand future climate warming and its implications is reasonable or not. Moreover, the data will allow a sophisticated comparison of the driving mechanisms behind hyperthermal events (if they indeed exist) during the greenhouse climates of the Maastrichtian (studied herein) and the early Paleogene.