The challenge

Monsoons are shifting winds that drive precipitation onto land and create distinct wet and dry seasons. The East Asian monsoon dominates North and South Korea, Japan and large parts of China, enhanced by conditions over the world’s largest plateau – the Tibetan Plateau is often referred to the ‘Third Pole’ due to the amount of snow and ice locked up there.

What we don’t know is how the monsoon will be affected by a climate that’s warming rapidly. We need to better understand how it responds to geographic and climatic changes and assess how that adaptation might translate into future behaviour. To do that, we need to look back to a time when temperatures were as warm as it’s predicted to become.

What we're doing

We used to believe that the East Asian monsoon had been around for a long time – about 23 million years. But our research proves that it has been around for a very long time – a near-constant regional feature for over 145 million years. Its intensity has varied greatly over that timeframe. For example, as tectonic plates collided 50 million years ago and began forming the giant plateau and surrounding Himalayan mountains, the monsoon intensified. Five million years ago, super-monsoons raged across East Asia, bringing rainfall 30% stronger than that seen today.

In collaboration with institutions such as the Chinese Academy of Sciences, one facet of our project has been to reconstruct the monsoon’s behaviour across 145 million years. We’ve modelled the climate at approximately four-million-year intervals, varying atmospheric carbon dioxide concentrations for each period to gauge the effect on the monsoon.

How it helps

Our findings show that compared to historical variations in geography, the monsoon is relatively unaffected by significant shifts in CO₂ concentrations. While atmospheric carbon dioxide does have an impact, over geologic time scale it’s secondary in importance to changes in the region’s unique geography and topography.

These results allow us to have more confidence in climate models predicting the future of the monsoon because we’ve confirmed that the geological data aligns with the models’ predictions. So as the world prepares for a growing climate crisis, we have a better knowledge of how the East Asian monsoon might behave under a range of possible scenarios and how that will affect the people and ecosystems who rely on it.

Investigators

• Professor Paul Valdes (PI)
• Dr Alex Farnsworth
• Professor Rich Pancost
• Professor Dan Lunt
• Dr J.P. Mayser
• Dr Caitlyn Witkowski
• Dr Vittoria Lauretano
• Greg Tourte
• Professor Robert A. Spicer (Open University)
• Professor Su Tao (Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences)
• Professor Ding Lin (Institute of Tibetan Plateau Research, Chinese Academy of Sciences)