How Japan's ancient trees could tell the future
At his laboratory in a wooded grove in northern Kyoto, Takeshi Nakatsuka holds up a vacuum sealed bag. Inside, bobbing in a bath of brown water, is a glistening disk the size of a dinner plate and the color of rich gravy. This soggy circle is the remnants of a 2,800-3,000-year-old tree, recovered from a wetland – water included, so the spongy wood does not deform – in Japan’s Shimane Prefecture, just north of Hiroshima. Within this ancient trunk lie secrets that can help us prepare for the future.
Palaeoclimatologist Takeshi Nakatsuka is using information preserved inside ancient tree stumps to learn about Japan's climate in the past (Credit: Rachel Nuwer)
Nakatsuka, a palaeoclimatologist at Japan’s Research Institute for Humanity and Nature, along with a diverse team of 68 collaborators, has spent the last decade developing a novel method to reveal bygone precipitation patterns and interpret their effect on society. The results offer unprecedented insight into 2,600 years of Japanese rainfall patterns. By teasing out information locked inside the preserved wood of ancient forests, they are able to reveal just how much rain fell around the country over the past two and half millennia. It is an extraordinary record.
About every 400 years, the researchers found, the amount of rain falling on Japan would suddenly become extremely variable for a period. The nation would toggle between multi-decadal bouts of flood-inducing wetness and warmer, drier years that were favorable for rice cultivation. As the rains came and went, Japanese society prospered or suffered accordingly. [weiter]