海洋同位素階5a時期南歐地區的氣候震盪

Abstract

The orbital parameters during marine isotope stage (MIS) 5a, 85.8-76.0 thousand years ago (ka, before AD 1950), after an abrupt global temperature rise from MIS 5b, 95.0-85.8 ka, are similar with those during Holocene. However, it is still a controversial analogue for comparison of the climate fluctuations in MIS 5a and Holocene. In addition, lack of paleoclimate records with good age-control from MIS 5a hampers our understanding of regional climatic change and corresponding global links on centennial-to-millennial scales. Here, we present a 230Th-dated stalagmite δ18O-inferred precipitation time series during 83.7-80.2 ka from Observatoire Cave (43°44’N, 7°25’E), Monaco, southern Europe. The record shows a millennial-scale decreasing trend in precipitation from 83.7 to 82.5 ka punctured by an abrupt 200-year wet event at 82.7 ka and a rapid shift from aridity to wetness during 82.5-82.4 ka, followed by relatively stable conditions until 80.2 ka in southern Europe. This hydroclimatic variability is consistent with changes in seawater circulation in the Mediterranean during sapropel 3 and an ice rafted debris event in the Nordic Sea on multi-centennial-to-millennial scales. Consistent with published proxy records, the results reveal that southern Europe hydroclimate influenced water circulation in the Mediterranean, and a strong connection between mid-latitude and high-latitude climate systems. The indistinguishable differences between regional hydroclimate at the early stage MIS 5a and in Holocene imply a similar clime system in this two periods in southern Europe.