New study finds that the extinction of vegetation during the Permian-Triassic mass extinction limited carbon absorption and led to a long-term increase in temperatures
The collapse of tropical forests during the worst mass extinction event in Earth's history was likely the main cause of the long period of warming that followed, according to new research by a research team from the University of Leeds and the China University of Earth Sciences in Wuhan, published on July 2, 2025 in the journal Nature Communications..
The Permian-Triassic mass extinction, also known as the "Great Dying," occurred about 252 million years ago and caused a huge loss of marine species as well as a significant decline in terrestrial flora and fauna. The prevailing assumption until now was that the event was caused by intense volcanic activity in the Siberian region – the "Siberian Traps" – which caused a sharp increase in the concentration of carbon dioxide in the atmosphere. But researchers have not been able to explain why extreme greenhouse conditions continued for about 5 million years afterward.
Now, new research provides a complementary explanation: The collapse of tropical forests—and especially their slow recovery—limited carbon sequestration, the process by which carbon dioxide is absorbed by plants and soil. The researchers analyzed fossil records and geological signatures from rock formations across China, creating maps of changes in vegetation productivity throughout the extinction.
The results indicate that the loss of vegetation significantly reduced carbon uptake, resulting in CO levels remaining2 high in the atmosphere for millions of years.
Dr. Zhen Xu from the University of Leeds, who led the study, explained: "This is the most severe warming event in Earth's history, and the only one in which the tropical forest biosphere completely collapsed. After years of fieldwork, analyses and simulations, we finally have the data to support our hypothesis."
The study highlights the danger of reaching tipping points in the Earth's climate system – situations where change exceeds the containment limit and leads to increased warming that cannot be easily stopped.
Professor Benjamin Mills of the University of Leeds, who led the climate simulations, warned:
"If today's tropical forests collapse due to current warming, the climate may continue to warm even if we stop emitting CO2"We will create a fundamental change in the carbon cycle – one that will only return to balance after geological periods of time."
The researchers also emphasize the importance of an interdisciplinary approach to studying the past in order to protect the future. Prof. Hongfu Yin and Prof. Jianxin Yu, who have accompanied the research since its inception in China, call for strengthening international collaborations and expanding the use of advanced models and paleontological databases.
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