Key points
- The Tibetan Plateau's elevation was the main driver behind the Asian monsoon's development and expansion
- Initially, weaker summer rains were confined to East Asia before spreading across South Asia as the plateau continued to rise
- Falling carbon dioxide levels later in the late Miocene influenced monsoon intensity, but tectonic uplift remained the dominant force.
Research from Monash University reveals the climate history behind Asia's summer monsoon – Earth's most influential climate system.
In a new study published in npj Climate and Atmospheric Science, an international team of researchers led by Monash University has uncovered the pivotal role of the Tibetan Plateau's uplift in shaping Asia's iconic summer monsoon.
The Asian monsoon supports nearly half of the planet's population and shapes ecosystems, agriculture and livelihoods across South and East Asia.
Using advanced climate modeling combined with geological evidence, researchers reconstructed how the monsoon system developed over the past 66 million years. The monsoon began as a weak seasonal pattern and is now an intense climate engine.
Dr Abhik Santra, Research Fellow in the School of Earth Atmosphere and Environment at Monash University, said despite the Asian monsoon being central to life across the region, its long-term history has been poorly understood.
"Our work helps fill this gap by showing how changes in Earth's topography, especially the rise of the Tibetan Plateau, reshaped atmospheric circulation and rainfall patterns over deep time," said Dr Santra.
When the Tibetan Plateau rose above approximately 3.5 km around 27-38 million years ago, it reshaped atmospheric patterns. Warm air over the plateau strengthened the upper-tropospheric temperature contrast, pushing the rainbelt northward and enhancing rainfall over the South and Southeast Asian regions.
Key findings of the research found:
- Initially, strong summer rains were confined to East Asia. But as uplift continued, the monsoon expanded into South Asia by the Oligocene, marking a major shift in regional climate.
- The collision of India with Eurasia influenced rainfall, but most of the monsoon's strength and spread stemmed from the elevated Tibetan Plateau.
- After the late Miocene (10-5 million years ago), falling atmospheric CO₂ began to further influence the monsoon's intensity, though uplift remained the dominant force.
This investigation into ancient climate conditions sheds light on how tectonic forces can fundamentally shape regional climates.
"Our research shows that tectonic forces, not just greenhouse gases, have shaped rainfall patterns for millions of years. Our findings highlight that the rise of the Tibetan Plateau wasn't just a geological event, but fundamentally reshaped Asia's climate and helped establish the monsoon system that billions of people rely on," said Dr Santra.
Understanding the deep history of the Asian monsoon helps scientists better interpret past climate records and improves confidence in future climate projections for a region home to billions of people. The findings also underscore the powerful influence of Earth's topographic features, like mountain ranges and plateaus, on global weather and climate systems.
While some past studies argue that the Himalayan uplift alone is sufficient to drive the Asian monsoon, this research indicates that a widely expanded elevated landmass, such as the Tibetan Plateau, is necessary to establish and sustain a robust Asian summer monsoon. The findings provide a new context for how climate systems evolve over geological time and offer a foundation for exploring how changes in climate drivers may impact monsoon behaviour in the future.
Read the research paper: https://doi.org/10.1038/s41612-025-01259-7
RESEARCHERS
Dr Abhik Santra, Research Fellow, School of Earth Atmosphere and Environment, Faculty of Science, Monash University, Professor Fabio Capitanio, School of Earth Atmosphere and Environment, Faculty of Science, Monash University and Professor Bhupendra Nath Goswami, Professor of Excellence, Gauhati University, India, Senior Research Associate Alexander Farnsworth, School of Geographical Sciences, University of Bristol, Bristol, UK, Professor Peter D. Clift, Department of Earth Sciences, University College London, London, UK, Professor Dietmar Dommenget, School of Earth Atmosphere and Environment, Faculty of Science, Monash University.
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