Effect of global warming on the frequency and intensity of tropical cyclones: an Early Jurassic perspective

Anthropogenic warming is predicted to increase the frequency and intensity of tropical cyclones, leading to severe damage and loss of life. However, projections based on historical observations are limited due to the lack of longer-term and spatially-resolved data. Here, we use the Toarcian Oceanic Anoxic Event (T-OAE) as a case study to investigate the link between tropical cyclone patterns and climate change. The T-OAE is a well-studied example of intense global warming and environmental change in Earth's history, characterized by a 7°C increase in sea-surface temperature and the common occurrence of tropical cyclones recorded in sedimentary deposits.

We collected sedimentary outcrop data along a 60 km-long transect, comprising 10 detailed sections along the paleo continental shelf in the central High Atlas in Morocco. We used sedimentary characteristics such as grainsize, texture, sedimentary features, and ichnofossils to identify storm-generated strata in offshore to lower shoreface settings, and extract paleo-tropical cyclone parameters. To constrain the age model, we used a cyclostratigraphic approach based on magnetic susceptibility datasets. By comparing the results to pre- and post-T-OAE time intervals, we gained insights into the frequency and intensity of tropical cyclones during this event and how they may have been affected by climate warming.

Our study highlights the potential of outcrop data to extract past storminess characteristics and test current model predictions on tropical cyclone patterns. By improving our understanding of how climate change affects tropical cyclones, we can better prepare for and mitigate the damage caused by these extreme weather events.