Professor Liu Yu says tree rings are key to understanding and predicting climate change. For more than a decade, the deputy director of Chinese Academy of Sciences' Institute of Earth Environment in Xian has ventured into some of the wildest spots in the mid-eastern Tibetan Plateau region to collect samples and take measurements. Liu has run simulations on computers to determine annual temperatures in the region over the past 2,485 years. His research has yielded a particularly interesting, perhaps even shocking, finding: global warming may have stopped.
Where did you find trees more than 2,000 years old in a country with a long history of systematic logging?
I need luck to find a tree more than 100 years old in the lowlands. But on some mountains of the Tibetan Plateau, where the altitude reaches up to 4,000 metres, I have run into forest after forest of Qilian junipers that have remained undisturbed for thousands of years.
How does a tree survive in that kind of harsh environment for so long?
The Qilian juniper is one of the oldest surviving tree species on earth. In the high altitude of the eastern Tibetan Plateau, where poor soil, little rainfall and low temperatures make it impossible for other trees to survive, the juniper has perfectly adapted to the harsh environment by growing very slowly. We recently found one that is close to 2,000 years old, but less than 8 metres tall. In the study of tree rings, slow-growing trees provide information on variations in climate over a long period. Qilian junipers grow only in China.
Is the study of tree rings popular in China?