Milankovitch theory and monsoon

• Published in: Innovation (New York, NY) Vol. 3; no. 6; p. 100338
• Main Authors: Cheng, Hai, Li, Hanying, Sha, Lijuan, Sinha, Ashish, Shi, Zhengguo, Yin, Qiuzhen, Lu, Zhengyao, Zhao, Debo, Cai, Yanjun, Hu, Yongyun, Hao, Qingzhen, Tian, Jun, Kathayat, Gayatri, Dong, Xiyu, Zhao, Jingyao, Zhang, Haiwei
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 08-11-2022; Elsevier
• Subjects: Earth and Related Environmental Sciences; Geovetenskap och miljövetenskap; Natural Sciences; Naturvetenskap; Review
• ISSN: 2666-6758; 2666-6758
• DOI: 10.1016/j.xinn.2022.100338

The widely accepted “Milankovitch theory” explains insolation-induced waxing and waning of the ice sheets and their effect on the global climate on orbital timescales. In the past half century, however, the theory has often come under scrutiny, especially regarding its “100-ka problem.” Another drawback, but the one that has received less attention, is the “monsoon problem,” which pertains to the exclusion of monsoon dynamics in classic Milankovitch theory even though the monsoon prevails over the vast low-latitude (∼30° N to ∼30° S) region that covers half of the Earth’s surface and receives the bulk of solar radiation. In this review, we discuss the major issues with the current form of Milankovitch theory and the progress made at the research forefront. We suggest shifting the emphasis from the ultimate outcomes of the ice volume to the causal relationship between changes in northern high-latitude insolation and ice age termination events (or ice sheet melting rate) to help reconcile the classic “100-ka problem.” We discuss the discrepancies associated with the characterization of monsoon dynamics, particularly the so-called “sea-land precession-phase paradox” and the “Chinese 100-ka problem.” We suggest that many of these discrepancies are superficial and can be resolved by applying a holistic “monsoon system science” approach. Finally, we propose blending the conventional Kutzbach orbital monsoon hypothesis, which calls for summer insolation forcing of monsoons, with Milankovitch theory to formulate a combined “Milankovitch-Kutzbach hypothesis” that can potentially explain the dual nature of orbital hydrodynamics of the ice sheet and monsoon systems, as well as their interplays and respective relationships with the northern high-latitude insolation and inter-tropical insolation differential.
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•Orbital-scale climate variations of Earth are dictated by ice sheet and monsoon•Views of “monsoon system science” reinforce the Kutzbach monsoon hypothesis•A unified Milankovitch-Kutzbach hypothesis better explains the orbital dual nature