Greenland temperatures may affect Indian rains
Temperatures in Greenland, a frigid island located to the northwest of Europe, may have an effect on India’s southwest monsoon and likely nullify the impact of El Nino, a climate cycle in the Pacific which affects rain in India.
This has been revealed in a new study, done by a group of institutes led by the Wadia Institute of Himalayan Geology (WIHG), Dehradun, based on 8000-year-old peat deposits in the Himalayas. The study analysed a 5.2m thick peat sequence – partially decayed vegetation – in Kedarnath. Comparing the peat with similarly old ice cores from Greenland, the 13-member team found that temperature in the world’s largest island, which is mostly covered in ice, influences India’s summer monsoon. Wetter rainfall events coincide with a warm Greenland, and a cooler Greenland resulted in less rainfall over the country, the study said.
Scientists not involved in the study said linking the monsoon to temperatures in Greenland supports the activities taken up Goa-based National Centre for Antarctic and Ocean Research to study the effect of melting Arctic on the Indian monsoon. “The findings show that all changes in Indian monsoon are not only due to increase in anthropogenic greenhouse gases, but also have major contribution from naturally occurring changes on the earth,” JV Ratnam, senior scientist, Japan Agency for Marine-Earth Science and Technology, who was not involved in the study, said. The peat was a chance discovery after a team of geologists found it exposed between two moraines – deposits of past glacial advances – after the 2013 deluge in Uttarakhand. Professor YP Sundriyal, HNB Garhwal University, Srinagar, who was member of the team got the peat dated using 14C-AMS technique.
“We have tried to establish that this forcing factor for the Indian summer monsoon is valid for at least past 8,000 years. What is new about this finding is that Indian summer monsoon gets strengthened when temperature in North Atlantic is warmer,” said Pradeep Srivastava, lead author, WIHG.
The team also found a correlation between temperatures in Greenland influencing the Indian monsoon during an El Nino year. El Nino is a weather phenomenon caused when warm water from the western Pacific Ocean flows east. If the Pacific warms up, the precipitation shifts in that direction, weakening monsoon currents and causing below-normal rainfall in other parts of the world, including India. “The [drought-inducing] impact of El Nino nullifies over India if Greenland is warm. But a cold Greenland during an El Nino year will lead to severe drought,” said Srivastava.
Researchers said the study finding is significant because Kedarnath, with its 8,000year-old history of climate, has helped in understanding past variability, past vegetation cover, glacial period, and interglacial Holocene period which co-relate with human evolution in India.
MUMBAI: