Reconciling Contrasting Marine and Terrestrial Responses of South Asian Summer Monsoon Reveal a Remote Control from South Africa

South Asian summer monsoon (SASM) delivers substantial rains to Indian subcontinent and drives upwelling in the Arabian Sea that sustains one of the world's most productive fisheries there. Both marine upwelling records and terrestrial rainfall records have been established as fundamental archives for reconstructing past SASM variability. However, the upwelling records vary in opposite direction to the terrestrial rainfall records on orbital timescale, leading to a long-standing paradox in the past monsoon variability. To understand this paradox, here we combine paleoclimate records with novel transient climate simulations that explicitly separate the effects of the Northern and Southern Hemisphere insolation forcing. Our results show that the SASM rainfall is governed by Northern Hemisphere (NH) insolation, whereas the Arabian Sea upwelling is dominated by Southern Hemisphere (SH) insolation. When boreal summer occurs at perihelion, insolation is strongly enhanced not only in the NH but also in the tropical-subtropical SH. The former enhances the SASM rainfall through Eurasian warming, while the latter weakens the Arabian Sea upwelling by inducing South African warming and subsequent atmospheric teleconnections. We reconcile the long-standing paradox, and more broadly, reveal that warming in South Africa could exert a significant and previously overlooked remote forcing on the SASM system.