New research reveals that shifts in plant life played a key role in speeding up major climate changes during the late Miocene, a period spanning 11.6 to 5.3 million years ago.

During this time, Earth’s climate shifted from the warm conditions of the middle Miocene to conditions closer to what we experience today, turning forests into grasslands and forcing animals like horses and elephants to evolve tougher teeth for eating gritty plants. At the same time, predators like big cats adapted to hunting in open plains, reshaping life on land forever.

So what caused this major climate shift?

Previous studies pointed to falling carbon dioxide (CO₂) levels and tectonic movements as the main drivers of these changes.

However, these factors alone couldn’t fully explain the global climate transition.

Now, a study led by Professor Ran Zhang from the Institute of Atmospheric Physics, Chinese Academy of Sciences, highlights how vegetation feedbacks—changes in plant cover that influence climate—intensified cooling in the northern high latitudes and altered rainfall patterns in lower latitudes.

The findings, published in Science Advances, show that vegetation changes amplified cooling by altering surface reflectivity (albedo) and interacting with water vapor, clouds, and sea ice. These effects were even stronger than those caused by CO₂ decline alone in some regions.

By combining geological data and climate models, the study clarifies the distinct roles of CO₂, tectonic changes, and vegetation feedbacks in shaping the late Miocene climate.

“This research helps us better understand the mechanisms behind the late Miocene climate shift and underscores how vegetation feedbacks can influence global climate—both in the past and in the future,” said Professor Zhang.

Unlike today’s rapid, CO₂-driven warming, the Late Miocene was marked by cooling and CO₂ decline.

The study highlights the often-overlooked impact of plant life on climate systems, offering insights for both historical and future climate change research.