The late Quaternary palynological record of the northern Yangtze Delta: Implication for palaeoclimate change in East Asia

Abstract

Marine Isotope Stage (MIS) 3 is the latest interstadial period with unstable climate regimes that provides an indispensable key to better predict future climate change. However, paleoclimate reconstruction in the Yangtze Delta covering MIS 3 remains elusive due to limited archives with reliable age. Here, we derived a 53,000–year–long paleoclimate record from the northern Yangtze Delta, using luminescence age–based palynological data of a coastal sediment core (YZ07). The results show that the climate was relatively warm and wet during ∼53.0–37.5 ka, followed by a slightly cool but wetter condition between ∼37.5 ka and ∼33.2 ka. Afterwards, a cool and dry climate prevailed from ∼33.2 ka to ∼30.7 ka. Three cold events were identified around 48.0 ka, 39.0 ka and 31.0 ka, corresponding to the timings of Heinrich Event (HE 5), HE 4 and HE 3, respectively. From ∼30.7 ka to ∼11.5 ka, broadleaved forests and wetland herbs obviously contracted in the Yangtze Delta region, indicating cold and dry climate conditions. From the late Pleistocene to Holocene, the pollen variations in this core site were linked to coastal geomorphology under climate–induced sea–level changes. Besides, our findings suggest that the percentages of emergent vegetation in this work were negatively correlated with El Niño–Southern Oscillation (ENSO)–linked flood events during the Holocene. Overall, from mid–MIS 3 to MIS 2, the climate exhibits a ‘warm–cool–cold’ pattern in the Yangtze Delta, broadly concordant with other climate proxies in East Asian monsoon domain and beyond on suborbital or millennial timescales. We argue that the northern hemisphere summer insolation may be responsible for the paleoclimate variability and paleovegetation successions in the Yangtze Delta. However, the variability of precipitation in MIS 3 might be governed by interhemispheric insolation forcing, which accounts for a wetter climate phase occurring during late MIS 3 rather than mid–MIS 3.