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Ancient Warming Thinned Wyoming Forests
Coverage from Gizmodo, The Conversation, and others
Fossil evidence from Wyoming shows that forests during the Paleocene-Eocene Thermal Maximum initially benefited from elevated carbon dioxide but later lost about 60% of their leaf area as heat, drought, and altered precipitation intensified.
Forest structure and function remained impaired for tens of thousands of years, with full recovery estimated to require more than 100,000 years in some accounts. The findings suggest that rapid modern warming could overwhelm CO2 growth benefits and reduce forest carbon storage, although the ancient event is not a direct forecast of future regional impacts.
Heat and drought outweighed CO2 fertilization
The PETM evidence indicates that elevated CO2 initially supported forest growth, but intensified heat, drought, and altered precipitation ultimately overwhelmed that benefit. Wyoming’s Hanna Basin forests lost roughly 60% of their canopy or leaf area during the warming event.
Forest impairment persisted for millennia
Canopy cover remained about 35% below earlier levels for tens of thousands of years, while forest loss altered water movement and sediment transport. Some accounts estimate that full recovery took more than 100,000 years, making the disruption far longer than human planning horizons.
The new article reinforces the existing evidence that PETM warming caused major Wyoming forest loss and exceptionally slow recovery, adding only a minor detail about altered water movement and sediment transport.
Previously
Fossil evidence from Wyoming shows that forests during the Paleocene-Eocene Thermal Maximum initially benefited from elevated carbon dioxide but later lost about 60% of their leaf area as heat, drought, and altered precipitation intensified. Forest structure and function remained impaired for tens of thousands of years, with full recovery estimated to require more than 100,000 years in some accounts. The findings suggest that rapid modern warming could overwhelm CO2 growth benefits and reduce forest carbon storage, although the ancient event is not a direct forecast of future regional impacts.