Evolution of vegetation and climate variability on the Tibetan Plateau over the past 1.74 million years

Abstract

The Tibetan Plateau exerts a major influence on Asian climate, but its long-term environmental history remains largely unknown. We present a detailed record of vegetation and climate changes over the past 1.74 million years in a lake sediment core from the Zoige Basin, eastern Tibetan Plateau. Results show three intervals with different orbital- and millennial-scale features superimposed on a stepwise long-term cooling trend. The interval of 1.74–1.54 million years ago is characterized by an insolation-dominated mode with strong ~20,000-year cyclicity and quasi-absent millennial-scale signal. The interval of 1.54–0.62 million years ago represents a transitional insolation-ice mode marked by ~20,000- and ~40,000-year cycles, with superimposed millennial-scale oscillations. The past 620,000 years are characterized by an ice-driven mode with 100,000-year cyclicity and less frequent millennial-scale variability. A pronounced transition occurred 620,000 years ago, as glacial cycles intensified. These new findings reveal how the interaction of low-latitude insolation and high-latitude ice-volume forcing shaped the evolution of the Tibetan Plateau climate.

Cenozoic topography, monsoons and biodiversity conservation within the Tibetan Region: An evolving story

“…These astronomical cycles are driven by the interplay of changes in precession (19 and 23 kyr cycles caused by rotational wander in the direction that Earth's spin axis points), obliquity (41 kyr and 1.2 Myr - changes in the angle of Earth's spin axis relative to the orbital plane) and eccentricity (100 kyr, 405 kyr and 2.4 myr cycles caused by changes in the shape of Earth's orbit around the Sun) ( Berger and Loutre, 1994 ; Berger et al., 2006 ; Hays et al., 1976 ; Leuschner and Sirocko, 2003 ), and such ‘orbital forcing’ has a direct impact on monsoon ( Leuschner and Sirocko, 2003 ) and vegetation dynamics ( Claussen et al., 2006 ; Tuenter et al., 2006 ). Orbital forcing famously acted as a ‘pacemaker’ for the waxing and waning of Quaternary ice sheets ( Hays et al., 1976 ), and there is evidence of its impact on the Tibetan environment over the past 1.74 million years ( Zhao et al., 2020 ).…”

Divergent Evolution of Glaciation Across High‐Mountain Asia During the Last Four Glacial‐Interglacial Cycles

“…To help develop orbital-scale glacial history for HMA, we first examine the large-scale climate change over HMA during the last four glacial-interglacial cycles. Driven by variations in Earth's orbit and atmospheric greenhouse gases (Figures 1a and 1b), the climate model generally reproduces the temperature variability recorded in ice cores (Thompson et al, 1997) and lake sediments (Zhao et al, 2020) on the Tibetan Plateau. The modeled peak warming/cooling broadly matches with the pollen-based temperature reconstruction and δ 18 O records in ice cores (Figures 1c-1e), given the uncertainty in chronology.…”

Sedimentary ancient DNA reveals a threat of warming-induced alpine habitat loss to Tibetan Plateau plant diversity

“…Glacier-extant and habitat area simulation. Several previous studies have shown that the climate at a millennial time scale on the eastern Tibetan Plateau is strongly impacted by monsoons, particularly the East Asian summer monsoon, which tracks changes in the westerlies and continental warming that are largely a function of mid-to high-latitude changes 55,56 . Thus, the past climate change in our study was inferred by the synthesized record of Northern Hemisphere (30°-90°N) temperature anomaly since the last deglaciation 57,58 .…”