In:
Climate of the Past, Copernicus GmbH, Vol. 19, No. 6 ( 2023-06-13), p. 1153-1175
Abstract:
Abstract. Between 15 and 27 kyr b2k (thousands of years before 2000 CE) during the last
glacial, Greenland experienced a prolonged cold stadial phase, interrupted
by two short-lived warm interstadials. Greenland ice-core calcium data show
two periods, preceding the interstadials, of anomalously high atmospheric
dust loading, the origin of which is not well understood. At approximately
the same time as the Greenland dust peaks, the Chinese Hulu Cave speleothems
exhibit a climatic signal suggested to be a response to Heinrich Event 2, a
period of enhanced ice-rafted debris deposition in the North Atlantic. In
the climatic signal of Antarctic ice cores, moreover, a relative warming
occurs between 23 and 24.5 kyr b2k that is generally interpreted as a
counterpart to a cool climate phase in the Northern Hemisphere. Proposed
centennial-scale offsets between the polar ice-core timescales and the
speleothem timescale hamper the precise reconstruction of the global
sequence of these climatic events. Here, we examine two new 10Be
datasets from Greenland and Antarctic ice cores to test
the agreement between different timescales, by taking advantage of the
globally synchronous cosmogenic radionuclide production rates. Evidence of an event similar to the Maunder Solar Minimum is found in the
new 10Be datasets, supported by lower-resolution radionuclide data from Greenland and 14C in the Hulu Cave speleothem, representing a good synchronization candidate at around 22 kyr b2k. By matching the respective 10Be data, we determine the offset between the Greenland ice-core chronology, GICC05, and the Antarctic chronology for the West Antarctic Ice Sheet Divide ice core (WDC), WD2014, to be 125 ± 40 years. Furthermore, via radionuclide wiggle-matching, we determine the offset between the Hulu speleothem and ice-core timescales to be 375 years for GICC05 (75–625 years at 68 % confidence) and 225 years for WD2014 (−25–425 years at 68 % confidence). The rather wide uncertainties are intrinsic to the wiggle-matching algorithm and the limitations set by data resolution. The undercounting of annual layers in GICC05 inferred from the offset is hypothesized to have been caused by a combination of underdetected
annual layers, especially during periods with low winter precipitation, and
misinterpreted unusual patterns in the annual signal during the extremely
cold period often referred to as Heinrich Stadial 1.
Type of Medium:
Online Resource
ISSN:
1814-9332
DOI:
10.5194/cp-19-1153-2023
DOI:
10.5194/cp-19-1153-2023-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2023
detail.hit.zdb_id:
2217985-9
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