What is it about?
Sea surface tempeatures in Indian Ocean had weakend the South Asian monsoon during the last warm period. The anthropogenic induced Indian Ocean warming may threaten the stability of the monsoon system in South Asia.
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Why is it important?
The South Asian monsoon, also known as Indian Summer Monsoon (ISM), is crucial for the food security and socioeconomic well-being of 25% of the world’s population. From a historical perspective, fluctuations in monsoon rainfall have been linked to the rise and fall of civilizations in the Indian subcontinent. Our study reports for the first time that the Indian Summer Monsoon during the last warm period was weakened by sustained high sea surface temperatures in the equatorial and tropical Indian Ocean. This implies, due to the current increasing sea surface temperatures in the Indian Ocean, Indian Summer Monsoon failures are likely to increase. This work can help to improve future climate model projections and highlights the importance of understanding controls of monsoonal rainfall under different climate conditions. Ocean warming on monsoon precipitation intensity needs to be re-evaluated in climate models.
Perspectives
When we did this research, the results were not what we expected. Our hypothesis was that the solar radiation would have played an more important role in monsoon rainfall intensity in South Asia. However, our results shows the opposite, namely, the higher solar intensity did not lead to increased rainfall. We had to look for alternative hypothesis to explain the why the rainfall was weaker during the last warmer period of our planet. This was a great experience because our result challenges the common assumption and have shield new insight into the importance of sea surface temperature's role in shaping monsoon rainfall dynamics.
Yiming Wang
Read the Original
This page is a summary of: Higher sea surface temperature in the Indian Ocean during the Last Interglacial weakened the South Asian monsoon, Proceedings of the National Academy of Sciences, March 2022, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2107720119.
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Resources
Higher sea surface temperature in the Indian Ocean during the Last Interglacial weakened the South Asian monsoon
original publication
Indian Ocean Warming Could Weaken Summer Monsoon Rainfall in South Asia
insitutional press release
Stable hydrogen (dD) and carbon isotope (d13C) values of sedimentary terrestrial leaf wax from sediment core GIK17286-1
Data archive
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