London, Jan. 22 (Reuters): Indian monsoons are a world away from cold spells in the North Atlantic but scientists said today a long-term link exists between the two which is a key to understanding global climate.
Researchers in India and the United States studied sediment samples from the Arabian Sea to build up a detailed record of the patterns of the Asian monsoon during the Holocene, a period of about 11,000 years from the end of the last glacial period to the present.
Their record shows that weak summer monsoons coincided with cold spells thousands of miles away in the North Atlantic.
“The link between North Atlantic climate and the Asian monsoon is a persistent aspect of global climate,” Anil Gupta, of the Indian Institute of Technology in Kharagpur, said in a report in the science journal Nature.
Gupta and his colleagues took samples from the floor of the Arabian Sea because the sediment provides a consistent, continuous record of the Asian monsoon, which influences changes in the amount of microscopic organisms in the water.
They identified seven different intervals of weak summer monsoon that are related to cold spells in the North Atlantic.
“The significance of our results lies in demonstrating a pattern of persistent variability in the monsoon throughout the Holocene that may be linked with episodic warming/cooling of the North Atlantic,” Gupta said.
Rainer Zahn, of the University of Barcelona, said the study reveals both the changes in the strength of the monsoon and its impact on global climate.
It is just one many factors that influence global climate, he added in a commentary in the journal.
“Understanding the history of monsoon and past dynamics is necessary for improving our knowledge of the monsoon system and how it may respond to changing global conditions,” he said.