A DEEP-TIME PERSPECTIVE OF SEASONALITY AND EXTREME WEATHER EVENTS IN THE NORTHEAST USA

Paleoclimate reconstructions can offer empirical data for comparison with modelled scenarios of future climate under different emission pathways. The climate states of the Miocene and Eocene are often used as analogues for carbon pathways with 2–3°C or 4–5°C of global warming, respectively. Novel Miocene terrestrial paleoclimate reconstructions based on the climatic distribution of nearest living relatives of plant fossils reveal generally homogeneous climates on the eastern seaboard. Both reconstructed temperatures and precipitation in the Miocene of the northeastern USA were higher than modern, resembling the climate of the modern southeastern USA, which in turn shows a similar climate between the Miocene and today. Notably, precipitation seasonality in the northeast USA was much greater during the Miocene. In modern times at >35°N on the eastern seaboard, the driest to mean month precipitation (DMP/MMP) ratio is >0.7, but in the Miocene DMP/MMP was ~0.3–0.4. Such a precipitation contrast is similar to that of modern-day Florida. Independent proxies are needed to establish whether the northeast indeed had a Florida-style summer wet season. Regardless, our reconstructions of enhanced Miocene seasonality and moisture transport to the northeast USA provide empirical support for modeled future scenarios of contemporary climate change. These conditions provide the mechanisms for increased extreme weather events in the Miocene of the northeastern USA, such as extreme precipitation events, droughts, and wildfires. Despite the sparsity of direct proxy records for these natural disasters, we will discuss some of the existing evidence and potential moving forward.