A new study reveals that changes in plant life played a crucial role in accelerating major climate shifts during the Late Miocene, a period that lasted from 11.6 to 5.3 million years ago.
During this time, Earth's climate transitioned from the warm conditions of the Middle Miocene to conditions more similar to those we experience today. This transformation turned forests into grasslands and forced animals such as horses and elephants to evolve tougher teeth to eat gritty plants. Meanwhile, predators like big cats adapted to hunting in open plains, permanently reshaping terrestrial ecosystems.
While previous studies pointed to declining carbon dioxide (CO₂) levels and tectonic movements as the main drivers of these changes, these factors alone were insufficient to fully explain the global climate transition. Now, a study led by Prof. ZHANG Ran from the Institute of Atmospheric Physics at the Chinese Academy of Sciences highlights how vegetation feedbacks-changes in plant cover that influence climate-intensified cooling in high northern latitudes and altered rainfall patterns in lower latitudes.
In the high northern latitudes, the vegetation was likely dense forest before cooling temperatures transformed it into grassland during the Late Miocene, a change that further accelerated global cooling.
The findings, published in Science Advances, demonstrate that vegetation changes amplified cooling by altering surface reflectivity (albedo) and influencing water vapor, clouds, and sea ice. In some regions, these effects were even more significant than the cooling caused by the decline in CO₂ alone.
By combining geological data and climate models, the study clarifies the distinct roles of CO₂, tectonic changes, and vegetation feedbacks in shaping the climate during the Late Miocene.
"This study helps us better understand the mechanisms behind the Late Miocene climate shift and emphasizes how vegetation feedbacks can influence global climate-both in the past and in the future," said Prof. ZHANG.
Unlike today's rapid, CO₂-driven warming, the Late Miocene was characterized by cooling and declining CO₂ levels. This study underscores the often-overlooked impact of plant life on climate systems, providing valuable insights for historical and future climate change research.
