Hydrological change in Southern Europe responding to increasing North Atlantic overturning during Greenland Stadial 1

Abstract

Greenland Stadial 1 (GS-1) was the last of a long series of severe cooling episodes in the Northern Hemisphere during the last glacial period. Numerous North Atlantic and European records reveal the intense environmental impact of that stadial, whose origin is attributed to an intense weakening of the Atlantic Meridional Overturning Circulation in response to freshening of the North Atlantic. Recent high-resolution studies of European lakes revealed a mid–GS-1 transition in the climatic regimes. The geographical extension of such atmospheric changes and their potential coupling with ocean dynamics still remains unclear. Here we use a subdecadally resolved stalagmite record from the Northern Iberian Peninsula to further investigate the timing and forcing of this transition. A solid interpretation of the environmental changes detected in this new, accurately dated, stalagmite record is based on a parallel cave monitoring exercise. This record reveals a gradual transition from dry to wet conditions starting at 12,500 y before 2000 A.D. in parallel to a progressive warming of the subtropical Atlantic Ocean. The observed atmospheric changes are proposed to be led by a progressive resumption of the North Atlantic convection and highlight the complex regional signature of GS-1, very distinctive from previous stadial events.

Abrupt climate changes during Termination III in Southern Europe

“…Several pollen sequences have demonstrated the synchrony of shifts to arid-adapted vegetation in the Iberian Peninsula and the marine cooling (23,24). A further proof for this tight AMOC-Iberia connection during T-I is provided by an accurately dated speleothem record from the southern Pyrenees which shows parallel changes in humidity and AMOC intensity along the Younger Dryas period (YD) (25).…”

Massive remobilization of permafrost carbon during post-glacial warming

“…After the cold and dry YD onset, the Northern Hemisphere experienced a second phase of the YD relatively more humid and warmer than the initial conditions. In Europe, this was associated with the resumption of North Atlantic overturning31. Ice cores from Greenland have recorded the period before the YD termination as a progressive decrease of the Asian dust concentration (Fig.…”

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].…”

“…Note that TKS is shown on a different y-axis to ease visual comparison. (C) Records from other parts of Western Europe (colour coded): SESO-Stalagmite SE09-6 from Seso Cave, Spain [113], PIN-Stalagmite Candela from El Pindal Cave, Spain [109,110], CHAU-Stalagmite Chau-stm6 from Chauvet Cave, France [67], VIL-Stalagmites Vil-stm9 and Vil-stm27 from Villars Cave, France [126,127], HAN-Stalagmite Han-9 from Han-sur-Lesse Cave, Belgium [85], BMS-Stalagmite BMS1 from Bue Marino Cave, Italy [65]. (D) Chronological uncertainty of the records: Speleothem U-Th ages are shown in colour coded dots.…”