Since 1990, forty-seven tropical depressions of hurricane intensity have developed on average each year mainly in the northern hemisphere. Among them, a half-dozen become major storms in the North Atlantic Ocean, another 10 are generated in the eastern Pacific Ocean, and as many as 22 take hold over the western Pacific Ocean, where they are called typhoons. Whereas the numbers have remained relatively static, evidence suggests that storm intensity is on the rise. Most such storms dissipate in the open oceans, but elsewhere coastal impact affects the physical geography of rocky shores, beaches, and river deltas, as well as the infrastructure associated with human habitation and commerce.

During the Pliocene warm period between 4.5 to 3.0 million years ago, the average global temperature was both higher than today and global sea level stood above today’s datum. These conditions may have contributed to permanent El Niño conditions across the Pacific Ocean having a spill-over effect on the Atlantic Ocean.

With few exceptions since 2015, each succeeding year through 2024 has recorded an increase in the average global temperature. Air temperature affects sea-surface temperature, which is the key factor triggering hurricanes / typhoons on a seasonal basis today. This course looks at the physical evidence for storm deposits of exceptional size from the Pliocene warm period and the last inter-glacial epoch roughly 125,000 years ago. In the northern hemisphere, such deposits are well studied along the shores of Mexico’s Gulf of California as well as islands such as the Azores in the North Atlantic. The physical dynamics of recent hurricanes are reviewed for further insight on where and how coastal impact is most expected as global climate change continues.

Markes E. Johnson is the Charles L. MacMillan Professor of Natural Science, Emeritus, at Williams College in Williamstown, Massachusetts, where he taught courses in historical geology, paleontology, and stratigraphy in the Geosciences Department over a 35-year career. His undergraduate education in geology concluded with a BA degree (1971) from the University of Iowa. His advanced training in paleoecology through the Department of Geophysical Sciences at the University of Chicago culminated with a PhD degree (1977). Since 1990, Prof. Johnson has made one or two annual trips to the Baja California peninsula and Mexico’s Gulf of California to study coastal deposits related to the Pliocene Warm Period and later Pleistocene epochs when sea level and global temperatures were higher than today. He is the author of three books on the region's geology and storm deposits (University of Arizona Press). Since 2009, he has remained active with studies regarding the Miocene to Pleistocene history of many North Atlantic islands, including those of the Cape Verde, Canary, Madeira, and Azores archipelagos.

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