Zhu Haifeng, 42, talks to trees and learns about our planet's past.
Zhu uses tree ages, rather than high-tech instruments, to study glacier changes that happened centuries ago on China's Qinghai-Tibet Plateau, sometimes known as "the Third Pole." Glaciers are silent, but trees can talk. The concentric rings in tree trunks are their language, Zhu says.
The rings can tell a tree's age, with one ring signifying each year, and the outside rings, near the bark, are the youngest. The rings also reflect climatic conditions of when they were formed. "Cold might result in a narrow ring, while a warm year might result in a wide one," Zhu says. "If a stone hits a tree, it will leave a scar in the rings."
Since 2009, the professor at the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences, has been looking for clues on the glacier forefields, the landscape formed by retreating glaciers. As a glacier melts, the glacier bed is released, and new tree species begin to grow. The oldest trees on such sites are used to calculate when it retreated.
Zhu calls himself a "tree talker". For him, reading tree rings is like developing a roll of camera film, which records the past and hides the glaciers' future.
"Glaciers and human destiny are closely linked. Predicting the glaciers' future is predicting our future," Zhu says. Every year, Zhu and his colleagues spend two months looking for trees on the cold, bleak terrain. They camp in the snowy mountains, battered by icy winds and gasping for breath in the thin air.