Multi-proxy evidence for environmental perturbations during the Paleocene-Eocene Thermal Maximum record on the southern Tethyan shelf

Past episodes of extreme global warming, such as the Paleocene-Eocene Thermal Maximum (about 56 million years ago), were caused by the release of large amounts of carbon into the ocean-atmosphere systems; however, its environmental impacts varied greatly. To understand how shallow coastal seas responded, we studied shallow marine record from the southern Tethyan shelf in Egypt. By analyzing multiple geochemical indicators, such as organic carbon isotope reecord, total organic carbon (TOC) content, and elemental compositions, we reconstructed sequential environmental changes. We found that the onset of the PETM brought intense rainfall, accelerating silicate weathering. This washed large amounts of clays from the land into the Tethys Ocean. Subsequently, during the PETM main body, sustained suboxic to anoxic conditions, drove phosphorus recycling, fueled high productivity, and enhanced organic carbon burial. This process acted as a natural brake on global warming by pulling carbon out of the atmosphere and ocean. This study therefore highlights that subtropical shallow coastal seas can play a powerful role in capturing carbon during extreme warming events, a process that may be important to consider in the context of future climate change.