Eocene Hyperthermals Project

Science Center Objects

Sudden and extreme global warming events of the past are known as hyperthermals. The most intensely studied of these is the Paleocene-Eocene Thermal Maximum (PETM) that occurred about 56 million years ago. During the PETM, global temperatures rose by ~5°C, ocean acidification was widespread, floral and faunal communities were severely disrupted, and changing oceanic circulation and a disrupted carbon cycle caused mass extinctions. This project examines Eocene hyperthermals in terms of the response of critical ecosystems in shallow marine environments - ecosystems that provide the basis of many U.S. coastal economies dependent on the shellfish and seafood industries.

Scientists sit on ground with eocene hyperthermal core samples

Scientists sit on ground with Eocene hyperthermal core samples

(Credit: Marci Robinson, USGS. Public domain.)

Using sediment cores collected along the U.S. mid-Atlantic coast, we work with U.S. and international universities to document the response of past marine ecosystems to Eocene hyperthermals to better understand the challenges facing our coastal economies. We investigate past biotic patterns through examining microfossils and changes in marine temperature, salinity and acidity through geochemical analyses of fossil shells. The sediments themselves reveal changing coastal zone processes that respond to sea level and rainfall patterns. In this photo, USGS geologist Jean Self-Trail and graduate students from Penn State show off how the PETM can be seen in a sediment core from southern Maryland as older, darker fossiliferous sand gives way to younger, lighter clay void of any calcite due to acidic ocean water. Our data assist policy makers in coastal regions as they evaluate the potential consequences of the changes affecting the shallow shelf environment.