What We are currently at the end of a long inter-glacial period. Several studies assert that the current rate of greenhouse warming could potentially disrupt the climate system to such a point that it could prevent the return of a new glacial period. Studying such perturbations during the Cretaceous greenhouse may thus shed light on these questions that concern todays climate change. Why Major shifts in global climate (glaciations, greenhouse warming) affect the expression of orbital climate change (the pacemaker of climate over time scales of 20000 to 400000 years) but the reasons for such changes are not well-understood. In this project we will try to better constrain how such changes occurred in the Late Cretaceous by focusing on three distinct types of climatic perturbations: the Cretaceous-Paleogene boundary mass extinction, the coolhouse modes of the Maastrichtian, and some of the Cretaceous Oceanic Anoxic Events. How This research is gonna be achieved through the study of numerous cores and sections in Denmark, Sweden as well as from the South Atlantic. Two PhDs are involved, one in charge of the dating via biostratigraphy, and the other in charge of high-resolution geochemical studies.