Geologists study the Bighorn Basin to learn about global warming 55 million years ago Paleocene–Eocene Thermal Maximum Bighorn Basin Buckrail - Jackson Hole, news
Rough Gulch showing PETM sediments in the Bighorn Basin. (Dr. Scott Wing, Smithsonian National Museum of Natural History)

JACKSON HOLE, WYO – The next Geologists of Jackson Hole (GJH) lecture on Tuesday, May 15, will look at a magical basin, which may hold secrets and answers locked away in its lithified lore about how earth once plunged into a global warming period that makes modern times look like a deep freeze. Plants and soil guided the comeback. What have we learned since?

Gabriel Bowen, a highly respected earth scientist from the University of Utah, will present, “Carbon and Climate: Lessons from Wyoming’s past,” tomorrow at the Teton County Library Auditorium.

Professor Bowen will examine fossil soils (paleosols) that rest between the Paleocene and Eocene boundary of the Willwood formation, which is exposed in many places in the Bighorn Basin. His focus on these rocks is no accident, for here so much has already been learned about the hottest moment in the Paleogene, a roughly 150,000-year period of unbelievable warming called the Paleocene-Eocene thermal maximum, or PETM if you are cool in a GJH sort of way.

Abundant evidence now documents terrestrial ecosystem change during this 150,000-year PETM period of global climate warming. Data from Wyoming’s Bighorn Basin, where some of the best-studied deposits are found, point to ubiquitous warming, dramatic changes in seasonal precipitation, and reorganization of biological communities.

The PETM captivates the collective imagination of scientists because it speaks of global warming 55 million years ago on a scale that dwarfs anything we have seen since we arrived on the scene. CO2 levels were simply off the chart.

But the fossil soil sequences preserved in the Bighorn and other basins worldwide also reveal more subtle information on changing biogeochemical processes in these ancient ecosystems.

As climate and plant communities shifted, the ability of ancient soils to capture and store organic carbon collapsed. What drove these changes, when and how did these systems recover, and what was the impact on the Earth’s climate? This talk will explore the evidence suggesting that terrestrial ecosystems—plants and soils—played a major role in guiding our planet’s response to a ‘paleoclimate catastrophe’ and could amplify the impacts of human activities on our future.