Changes in Tibetan Plateau latitude as an important factor for understanding East Asian climate since the Eocene: a modeling study

Previous climate modeling studies suggest that the surface uplift of the Himalaya-Tibetan plateau (TP) is a crucial parameter for the onset and intensification of the East Asian monsoon during the Cenozoic. Most of these studies have only considered the Himalaya-TP in its present location between 26° N and 40° N despite numerous recent geophysical studies that reconstruct the Himalaya-TP 10° or more of latitude to the south during the early Paleogene. We have designed a series of climate simulations to explore the sensitivity of East Asian climate to the latitude of the Himalaya-TP. Our simulations suggest that the East Asian climate strongly depends on the latitude of the Himalaya-TP. Surface uplift of a proto-Himalaya-TP in the subtropics intensifies aridity throughout inland Asia north of 40°N and enhances precipitation over East Asia. In contrast, the rise of a proto-Himalaya-TP in the tropics only slightly intensifies aridity in inland Asia north of 40°N, and slightly increases precipitation in East Asia. Importantly, this climate sensitivity to the latitudinal position of the Himalaya-TP is non-linear, particularly for precipitation across East Asia. The simulated precipitation patterns across East Asia are significantly different between our scenarios in which a proto-plateau is situated between 11° N and 25° N and between 20° N and 33° N, but they are similar when the plateau translates northward from between 20° N and 33° N to its modern position. Our simulations, when interpreted in the context of climate proxy data from Central Asia, support geophysically-based paleogeographic reconstructions in which the southern margin of a modern-elevation proto-Himalaya-TP was located at 20° N or further north in the Eocene.