Abstract
Earth’s climatic evolution over the last 5 million years is primarily understood from the perspective of marine mechanisms, however, the role of terrestrial feedbacks remains largely unexplored. Here we reconstruct the last 5 million years of soil moisture variability in Central Asia using paleomagnetism data and isotope geochemistry of an 80 m-thick sedimentary succession at Charyn Canyon, Kazakhstan. We identify a long-term trend of increasing aridification throughout the period, along with shorter-term variability related to the interaction between mid-latitude westerlies and the Siberian high-pressure system. This record highlights the long-term contribution of mid-latitude Eurasian terrestrial systems to the modulation of moisture transfer into the Northern Hemisphere oceans and back onto land via westerly air flow. The response of Earth-surface dynamics to Plio-Pleistocene climatic change in Central Asia likely generated terrestrial feedbacks affecting ocean and atmospheric circulation. This missing terrestrial link elucidates the significance of land-water feedbacks for long-term global climate.
Highlights
Earth’s climatic evolution over the last 5 million years is primarily understood from the perspective of marine mechanisms, the role of terrestrial feedbacks remains largely unexplored
It is unlikely that continental regions were passive during this process; understanding the contribution of land−ocean-feedbacks is imperative in order to elucidate global climate feedback loops over the late Cenozoic
The Charyn Canyon sequence records long-term aridification in Arid Central Asia (ACA) (Supplementary Note 1). It comprises 13 m of distal alluvial fan, composed of gravels and silts which accumulated during the early Pliocene (Supplementary Fig. 2e), superposed by 24 m of alternating aeolian silts and alluvial sheetwash gravel deposits indicative of drier climates with short-lived wet pulses corresponding to the late Pliocene (Fig. 1b, Supplementary Fig. 2d)
Summary
Earth’s climatic evolution over the last 5 million years is primarily understood from the perspective of marine mechanisms, the role of terrestrial feedbacks remains largely unexplored. The response of Earth-surface dynamics to Plio-Pleistocene climatic change in Central Asia likely generated terrestrial feedbacks affecting ocean and atmospheric circulation. This missing terrestrial link elucidates the significance of land-water feedbacks for long-term global climate. The shoaling at 4.6 Ma of the Panama gateway[5,6] altered ocean dynamics by reduced mixing between Atlantic and Pacific waters, thereby strengthening Atlantic meridional overturning circulation[7] This process transported warmer near-surface waters to the North Atlantic via the Gulf Stream[5] and increased moisture supply to the high latitudes. Our record derives from an 80-m-thick sedimentary succession at Charyn Canyon located in the Ili Basin in southeast
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