Climate change: the Lahaul-Spiti tree rings the alarm bells

LUCKNOW: Trees not only witness changes in the climate, but also record the pattern of change in their growth rings, and a 900-year-old cedar study by the Birbal Sahni Institute of Paleosciences (BSIP) has sounded the alarms

A team of four BSIP scientists, led by Krishna G Misra examined the cedars at an altitude of 3,200 meters in the district of Lahaul-Spiti to find that the frequency of severe droughts in the west Himalayas It was increasing, which is a clear indication of global climate change.

o Tree ring dating is a scientific method to track exactly when these growth rings formed. Its dating can provide data for dendroclimatology, the study of climate and atmospheric conditions during different periods of the history of wood.

The BSIP study showed that since the year 1100, there were six severe droughts (1554, 1626, 1705, 1785, 1971 and 2008) in the western Himalayan region. He revealed that compared to four severe droughts in 580 years (from 1437 to 2016), two had taken place in just 37 years (from 1971 to date).

The research paper, which was presented at the sixth Asian Dendrochronology Conference in progress at the Lucknow Institute, also found that, in terms of severity, the first three droughts were harder than the last three. In addition, the time gap between two subsequent droughts had been almost uniform until the 18th century. However, the time gap between the last two was low.

The gap between the first two droughts was 72 years; second and third 79; third and fourth 80; fourth and fifth 186; and fifth and sixth 37.

The findings, Misra said, show that droughts occurred due to climate change that caused poor rainfall in that year. But, more research is needed to find out if it was caused by global warming or some other phenomenon, he said.

Misra said they collected tree samples in 2017.

Each year a ring forms on the trunk of a tree and contains information about the weather of that particular year, he explained. Scientists will now collect the drought period and compare the same with the weather in other parts of India at that time.