| Summary: | Just before the onset of the Younger Dryas (YD) cold event, several stomatal proxy-based pCO 2 records have shown a sharp increase in atmospheric CO 2 concentration (pCO 2 ) of between ca 50 and 100 ppm, followed by a rapid decrease of similar or even larger magnitude. Here we compare one of these records, a high-resolution pCO 2 record from southern Sweden, with the IntCal13 record of radiocarbon (Δ 14 C). The two records show broadly synchronous fluctuations at the YD onset. Specifically, the IntCal13 record documents decreasing Δ 14 C just before the YD onset when pCO 2 peaks, consistent with a source of “old” CO 2 from the deep ocean. We propose that this fluctuation occurred due to a major ocean flushing event. The cause of the flushing event remains speculative but could be related to the hypothesis of the glacial ocean as a thermobaric capacitor. We confirm that the earth system can produce such large multi-decadal timescale fluctuations in pCO 2 through simulating an artificial ocean flushing event with the GENIE Earth System Model. We suggest that sharp transitions of pCO 2 may have remained undetected so far in ice cores due to inter-firn gas exchange and time-averaging. The stomatal proxy record is a powerful complement to the ice core records for the study of rapid climate change.
|
|---|