New study on climatic variation in Himalayas 7,000 years ago will help assess future global warming trends – The Tribune India
Vijay Mohan
Chandigarh, March 3
It was not the Indian Summer Monsoon (ISM) but the Westerlies, which are permanent winds blowing in the middle latitudes, that defined the climatic variation and the evolution of landscape in the trans-Himalayan belt about 7,000 years ago, a new study has revealed.
“This is evident from the analysis of a huge detrital influx recorded at the lake bottom, indicating a glacial advancement in the region, particularly during the mid-Holocene thermal maxima,” a statement issued by the Ministry of Science and Technology read.
The findings will help characterise and assess the past climatic changes for a better assessment of regional and global factors impacting future glacier behaviour in the context of global warming, climate variability, and associated societal impacts.
The middle Holocene period, roughly from 7,000 to 5,000 years ago, is believed to be warmer than the present day. The Holocene thermal maximum was characterised by strong summer solar heating that substantially increased the summertime temperature relative to the pre-industrial climate.
Researchers found that the Westerlies and the ISM have had periodic shifts in defining the climatic variations of the north western Trans-Himalayas. The effect of the mid-Holocene warm period is evident at 6,040 years before present. The influence of the Westerlies gradually reduced 2,800 years ago, the study states.
The Himalayas is the most glaciated mountain region on earth outside the polar regions and lies between the ISM and mid-latitude Westerlies troughs. Glaciation in this region responds sensitively to changes in global climate.
According to the researchers, glacial fluctuations in the Himalayas significantly affect the hydrological balance of the Himalayan rivers and monsoon variability. Several glacial lakes are seen in the Ladakh Range, which could give an authentic picture of the entire region.
Scientists are of the view that since these lakes are located at an altitude of 5,000 metres and above and away from anthropogenic impact, these are an important archive to study the limnological characteristics and climatic variations.
A team from Birbal Sahni Institute of Palaeosciences under the aegis of the Department of Science and Technology, collected sediments from the lakes, compiled a high-resolution, multi-proxy climatic record from Ladakh, the cold desert of India, lying above the altitude of 3,000 metres in the Trans-Himalaya. The research has been published in the latest issue of Catena, an interdisciplinary journal focusing on geoecology and landscape evolution.
“This detailed study of the changing scenario in the region for the last 7,000 years analyses the relationship of the lake levels to the precipitation regimes active in the area and the detailed landscape evolution of the largest basin of the Ladakh Range, the Chang La-Tangtse basin, for the first time,” the statement said.
