Possible influences of tropical vegetation shift on the glacial-interglacial temperature changes

The feedback mechanism between climate and vegetation has attracted considerable attention, but there are large uncertainties about the influence of terrestrial vegetation on climate, especially in paleoclimate studies. Here, we reconstruct a quantitative temperature record from the Tianyang Maar Paleolake in tropical East Asia over the past 150 kyr, by using a state-of-the-art regression model and the expanded global branched glycerol dialkyl glycerol tetraethers database (n = 3614). The record shows a change amplitude of 4–5 °C during the glacial-interglacial cycles, about 1–2 °C higher than the sea surface temperature in the adjacent South China Sea. Temperature and pollen data from the same sediment core indicated the replacement of forest by savanna landscape along with relatively high insolation and CO₂ concentrations, probably caused two abnormal warm stages at 154–139 and 99–85 cal ka BP, by altering the surface evapotranspiration and roughness. Furthermore, the alternating occurrence of savanna replacing forest may have strengthened the precession signal (23 kyr) relative to the obliquity signal (41 kyr). Our study highlights the impacts of vegetation feedback on orbital-scale climate evolution and emphasizes the importance of reforestation in tropical regions with ongoing global warming.