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

Mathew Koll Roxy, Kapoor Ritika, Pascal Terray, Raghu Murtugudde, Karumuri Ashok, B. N. Goswami

Research output: Contribution to journalArticlepeer-review

552 Scopus citations

Abstract

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.
Original languageEnglish (US)
JournalNature Communications
Volume6
DOIs
StatePublished - Jun 16 2015
Externally publishedYes

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • General Chemistry
  • General Physics and Astronomy

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