Modulation of precession-forced Asian–African monsoon and arid climate variability by obliquity

Abstract

Precession and obliquity play vital roles in orbital-scale climate change. However, their combined effects remain poorly understood. In this study, we examine how obliquity modulates precession-driven climate responses across Asian–African monsoon and arid regions (AAMAR). Results demonstrate that under high obliquity, the minimum-precession-induced precipitation increase is weakened in the Asian–African monsoon regions but enhanced in the Asian–African arid regions. The changes in precipitation responses over Africa and West Asia are largely explained by an enhanced northward displacement of the regional Hadley circulation, which shifts the zone of precipitation increase northward from monsoon regions into adjacent northern arid regions. Additionally, intensified negative cloud-radiative feedback and adiabatic cooling under high obliquity contribute to attenuated Tibetan Plateau heating, further modulating hydroclimate responses over Asia. Overall, our findings reveal that obliquity modulates low-latitude climate sensitivity to precession and provide new insights into the spatially heterogeneous responses of the climate system to orbital forcing.