Structural similarity between Termination III and I

Abstract

The sequence of abrupt climate variability during Termination III (T-III) is still controversial due to the scarcity of well-dated and high-resolved paleoclimate records. Here, we present 230Th-dated stalagmite δ13C and δ18O data covering T-III from northern China for the first time, with an average resolution of ∼20 years. T-III was featured by two Weak Monsoon Intervals (WMIs), separated by a millennial-scale interstadial. The earlier and later WMI was labeled as Mystery Interval-III (MI-III) and Younger Dryas-III (YD-III), respectively, and the interstadial as Bølling-Allerød-III (BA-III). The transition of MI-III/BA-III, BA-III/YD-III and YD-III/PI (Penultimate Interglacial), constrained by lamination counting, lasted 52, 87 and 68 years, respectively. According to 230Th dating, the duration of the climate variability is 3253 ± 2835, 1373 ± 2294 and 1266 ± 2309 years, respectively. If the KLS-20 δ13C record was aligned to Sanbao cave record within chronology uncertainties, the best estimates of these durations are ∼2300, ∼2100 and ∼4000 years, respectively. Additionally, two significant centennial-scale climate rebounds within YD-III were identified in our records, comparable to the three short-lived climate excursions within YD observed in stalagmite BW-1 δ13C and δ18O records from the same cave and NGRIP δ18O record. The close coupling of abrupt climate oscillations during T-III and T-I highlights the structural similarity between the two deglaciations, both of which are characterized by multi-interruption of WMI. It is probably due to the relatively low amplitude and rate of northern summer insolation rise during T-III and T-I, compared with T-II and T-IV.