Ancient Wyoming forests lost 60% of canopy in PETM, took over 100,000 years to rebound
A new study shows that during the Paleocene-Eocene Thermal Maximum forests in what is now Wyoming lost about 60% of their canopy and required more than 100,000 years to recover, a pace far slower than today’s rapid carbon emissions.
Researchers published in Science a reconstruction of ancient forests in southern Wyoming, revealing that the Paleocene-Eocene Thermal Maximum caused a rapid loss of about 60% of canopy cover as global temperatures rose up to 11 °F. By analyzing microscopic leaf cuticles and calibrating cell-shape data against modern leaf-area index measurements, they showed forests were at peak density just before the warming began. The ensuing canopy thinning persisted for more than 100,000 years, altering soil and river dynamics, until prolonged weathering drew down atmospheric carbon and allowed forests to regrow denser than before.
The authors note that today’s anthropogenic CO₂ emissions are roughly ten times faster than the natural increase during the PETM, suggesting modern forests could be pushed beyond physiological limits with recovery times far exceeding human lifespans. The study underscores the need to avoid crossing climate thresholds that could trigger prolonged ecosystem disruption.
Why it matters
It warns that rapid modern warming could push forests past points of recovery that take tens of thousands of years.
In this story
