Abrupt climate changes during Termination III in Southern Europe

Abstract

The Late Quaternary glacial-interglacial transitions represent the highest amplitude climate changes over the last million years. Unraveling the sequence of events and feedbacks at Termination III (T-III), including potential abrupt climate reversals similar to those of the last Termination, has been particularly challenging due to the scarcity of well-dated records worldwide. Here, we present speleothem data from southern Europe covering the interval from 262.7 to 217.9 kyBP, including the transition from marine isotope stage (MIS) 8 to MIS 7e. High-resolution δ 13 C, δ 18 O, and Mg/Ca profiles reveal major millennial-scale changes in aridity manifested in changing water availability and vegetation productivity. uranium-thorium dates provide a solid chronology for two millennial-scale events (S8.1 and S8.2) which, compared with the last two terminations, has some common features with Heinrich 1 and Heinrich 2 in Termination I (T-I).terminations | stalagmite | stadial event | stable isotopes |

Oxygen Isotope Variability of Planktonic Foraminifera Provide Clues to Past Upper Ocean Seasonal Variability

“…The Glacial termination between Marine Isotope Stages 8 and 7, Termination III (T-III), occurs at a time of dissimilar orbital conditions from those of T-I with an~10-kyr lag between maximum obliquity and minimum precession. Of the Terminations of the past 450 kyr it is one that is distinctly muted (Cheng et al, 2009), being referred to as a "low-amplitude" termination (Lang & Wolff, 2011) that gives rise to the weak Interglacial MIS 7 that rapidly plunges back into Glacial conditions (Lang & Wolff, 2011;Pérez-Mejías et al, 2017). Such an interruption of interglacial conditions makes it similar to T-I, which is a Termination interrupted by stadial conditions, despite having dissimilar orbital parameters making it an interesting objective for paleoclimate research (Pérez-Mejías et al, 2017).…”

“…Of the Terminations of the past 450 kyr it is one that is distinctly muted (Cheng et al, 2009), being referred to as a "low-amplitude" termination (Lang & Wolff, 2011) that gives rise to the weak Interglacial MIS 7 that rapidly plunges back into Glacial conditions (Lang & Wolff, 2011;Pérez-Mejías et al, 2017). Such an interruption of interglacial conditions makes it similar to T-I, which is a Termination interrupted by stadial conditions, despite having dissimilar orbital parameters making it an interesting objective for paleoclimate research (Pérez-Mejías et al, 2017). Further similarities include the ice-rafting events during Glacial MIS 8 having detrital carbonate that has similar provenance, the Hudson Strait, as the Heinrich events of the last glacial unlike MIS 6 (Obrochta et al, 2014).…”

The Potential of Speleothems from Western Europe as Recorders of Regional Climate: A Critical Assessment of the SISAL Database

“…Moreover, changes in atmospheric circulation patterns can lead to shifts in moisture trajectories and seasonality of precipitation at a site (e.g., [157]). These effects have been recognised as partially influencing many of the records in SISAL_v1, mostly as second-order controls (e.g., Baschg [58], Ejulve [11,77], Grotta di Ernesto [44], Schafsloch [112], Schneckenloch [58,88], Seso [113]). The LGM portion of the composite record from Sieben Hengste (7H) Cave, is the only instance where δ 18 O spel was interpreted as principally reflecting changes between northerly and southerly moisture transport, informing on shifts in the meridional position of the North Atlantic storm track [114].…”

“…Overall, the paucity of records spanning beyond the LGM presents an opportunity for future studies to target speleothems covering previous time periods, especially given their often more precise U-Th chronologies at these time scales compared to ice cores and marine sediment records [11,178,179]. Climate variability over the last glacial and beyond remains poorly constrained and speleothems could provide detailed information from vast range of different environments (coastal, continental, high altitude/latitude, etc.…”

“…This is particularly pronounced at mid-latitude sites and over the Holocene, when ranges in δ 18 O spel are typically small (average standard deviation of Western European δ 18 O spel in SISAL_v1 is 0.36 ) and reflect only moderate climate shifts, as is apparent from other palaeoclimatic evidence (e.g., [9]). Over glacial-interglacial timescales, changes in the seasonality of precipitation and the spatial stationarity of climate patterns need to be considered as additional external drivers for variability in δ 18 O spel [10,11]. These, along with the fact that the signal-to-noise ratio with respect to underlying climatic variations of a given speleothem-based record depends on the local climate, geology, hydrology, and vegetation, underpins the importance of interpreting speleothem records in their specific context.…”