Hot topics increased poleward atmospheric latent heat transport during the latest Paleocene/earliest Eocene

Earth’s climate is warming as the rise in atmospheric CO₂ (p_CO2) contributes to increased radiative forcing. State-of-the-art models calculate a wide range in Earth’s climate sensitivity due to increasing p_CO2. Furthermore, the mechanism responsible for amplification of high latitude temperatures remains highly debated. However, the geological record provides the means to evaluate the consequences of extreme radiative forcing on Earth’s climate. Here we present clumped and oxygen isotope data of pedogenic siderites from the latest Paleocene/earliest Eocene (LPEE), 57-55 million years ago, when p_CO2 peaked between 1400 and 4000 ppm. Continental mean annual temperatures reached a scorching 41 °C in the Equatorial tropics, which became more evaporative. The hot tropical temperatures increased the transport of moisture and latent heat to the Arctic, raising summer temperatures there to 23 °C. Pedogenic siderite data from ancient greenhouse periods indicate that hot tropics can actively regulate polar amplification independent of paleo-geography.