Drying of Indian subcontinent by rapid Indian Ocean warming and a weakening land-sea thermal gradient

There are large uncertainties looming over the status and fate of the South Asian summer monsoon, with several studies debating whether the monsoon is weakening or strengthening in a changing climate. Our analysis using multiple observed datasets demonstrates a significant weakening trend in summer...

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Bibliographic Details
Published in:Nature communications 2015-06, Vol.6 (1), p.7423-7423, Article 7423
Main Authors: Roxy, Mathew Koll, Ritika, Kapoor, Terray, Pascal, Murtugudde, Raghu, Ashok, Karumuri, Goswami, B. N.
Format: Article
Language:English
Subjects:
704/106/829
704/106/829/2737
Anthropogenic factors
Basins
Climate change
Drying
Foothills
Hadley circulation
Humanities and Social Sciences
Moisture availability
Monsoons
multidisciplinary
Ocean warming
Ocean, Atmosphere
Rainfall
Science
Science (multidisciplinary)
Sciences of the Universe
Summer
Temperature gradients
Tropical environments
Wind
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Summary:There are large uncertainties looming over the status and fate of the South Asian summer monsoon, with several studies debating whether the monsoon is weakening or strengthening in a changing climate. Our analysis using multiple observed datasets demonstrates a significant weakening trend in summer rainfall during 1901–2012 over the central-east and northern regions of India, along the Ganges-Brahmaputra-Meghna basins and the Himalayan foothills, where agriculture is still largely rain-fed. Earlier studies have suggested an increase in moisture availability and land-sea thermal gradient in the tropics due to anthropogenic warming, favouring an increase in tropical rainfall. Here we show that the land-sea thermal gradient over South Asia has been decreasing, due to rapid warming in the Indian Ocean and a relatively subdued warming over the subcontinent. Using long-term observations and coupled model experiments, we provide compelling evidence that the enhanced Indian Ocean warming potentially weakens the land-sea thermal contrast, dampens the summer monsoon Hadley circulation, and thereby reduces the rainfall over parts of South Asia. The response of the South Asian summer monsoon to climate change remains uncertain. Here, the authors combine observational datasets and model simulations and show that a warming Indian Ocean and weakened land-sea thermal gradient lead to significant rainfall weakening over the central Indian subcontinent.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms8423