EC-Earth Simulations Reveal Enhanced Inter-Hemispheric Thermal Contrast During the Last Interglacial Further Intensified the Indian Monsoon

Paleoclimate proxy data indicate a stronger Indian summer monsoon (ISM) during the Last Interglacial (LIG) than in the present day. This is largely attributed to orbital forcing induced high seasonal and latitudinal insolation anomalies in the Northern Hemisphere during LIG. According to the general circulation model EC-Earth3, the simulated ISM rainfall is increased by approximately 28% during the LIG compared to the pre-industrial period as a result of the orbital forcing and the amplified land-sea contrast due to both local and remote ocean feedbacks. Although the LIG is often portrayed as a potential analogue of future warmer climates, our study suggests that the enhanced inter-hemispheric thermal gradient during the LIG strengthened the ISM, in opposition to the observed weakening of ISM under present-day warming.

Automated summary

Paleoclimate proxy data and model simulations suggest that the Indian summer monsoon was stronger during the Last Interglacial period than in the present day, attributed to orbital forcing and intensified land-sea contrast. Our study indicates that the enhanced inter-hemispheric thermal gradient during the Last Interglacial strengthened the Indian summer monsoon, contrary to the observed weakening under present-day warming.