TY - JOUR
T1 - The 8200yr BP cold event in stable isotope records from the North Atlantic region
AU - Daley, Timothy J.
AU - Thomas, Elizabeth R.
AU - Holmes, Jonathan A.
AU - Street-Perrott, F. Alayne
AU - Chapman, Mark R.
AU - Tindall, Julia C.
AU - Valdes, Paul J.
AU - Loader, Neil J.
AU - Marshall, James D.
AU - Wolff, Eric W.
AU - Hopley, Philip J.
AU - Atkinson, Tim
AU - Barber, Keith E.
AU - Fisher, Elizabeth H.
AU - Robertson, Iain
AU - Hughes, Paul D. M.
AU - Roberts, C. Neil
PY - 2011/12
Y1 - 2011/12
N2 - An abrupt cold event ca. 8200 cal. yr BP, is believed to have been caused by the catastrophic release of ice-dammed meltwater from Lake Agassiz and associated disruption of the Atlantic Meridional Overturning Circulation (AMOC). Previous reviews have highlighted both the “ideal” nature of the 8200 yr event as a target for numerical model validation and the likely geographical restriction of the ensuing cold event to the circum-North Atlantic region but have cited a lack of sufficiently resolved palaeoclimatic records to test this hypothesis. We review the current set of high-resolution stable isotope records from multiple archives (lake, bog, marine and ice cores) in the North Atlantic region for the period 9200–7400 yr BP (present = AD 1950). The isotopic values of terrestrial records are closely linked to isotopic values of palaeoprecipitation. All sites provided evidence for at least one centennial-scale anomaly (beginning ~ 8500–8250 yr BP) that exceeded background variability. No evidence for spatial or temporal transgression of the isotope anomalies was identified, implying that a simultaneous climate signal was observed in the circum-North Atlantic region. Comparison with new simulations using the UK Hadley Centre model HadCM3, which was isotope-enabled to simulate changes in the stable isotope composition of precipitation and forced by freshwater input (“hosing”) of 5 Sverdrups (Sv) (0.005 km3/s), for 1 yr, indicated agreement with the observed decrease in the amplitude of the isotope anomaly with distance from the NW North Atlantic. The model-simulated duration of the event, however, was consistently shorter than that observed in palaeoclimatic records. A review of evidence for forcing additional to the catastrophic release of meltwater from Lake Agassiz (solar variability, sea-ice feedback and longer-term meltwater history) suggested that reduced solar output did not directly coincide with the 8200 yr event, but that a more complex history of meltwater discharges and sea-ice feedback may have conditioned the AMOC for sustained climatic impact.
AB - An abrupt cold event ca. 8200 cal. yr BP, is believed to have been caused by the catastrophic release of ice-dammed meltwater from Lake Agassiz and associated disruption of the Atlantic Meridional Overturning Circulation (AMOC). Previous reviews have highlighted both the “ideal” nature of the 8200 yr event as a target for numerical model validation and the likely geographical restriction of the ensuing cold event to the circum-North Atlantic region but have cited a lack of sufficiently resolved palaeoclimatic records to test this hypothesis. We review the current set of high-resolution stable isotope records from multiple archives (lake, bog, marine and ice cores) in the North Atlantic region for the period 9200–7400 yr BP (present = AD 1950). The isotopic values of terrestrial records are closely linked to isotopic values of palaeoprecipitation. All sites provided evidence for at least one centennial-scale anomaly (beginning ~ 8500–8250 yr BP) that exceeded background variability. No evidence for spatial or temporal transgression of the isotope anomalies was identified, implying that a simultaneous climate signal was observed in the circum-North Atlantic region. Comparison with new simulations using the UK Hadley Centre model HadCM3, which was isotope-enabled to simulate changes in the stable isotope composition of precipitation and forced by freshwater input (“hosing”) of 5 Sverdrups (Sv) (0.005 km3/s), for 1 yr, indicated agreement with the observed decrease in the amplitude of the isotope anomaly with distance from the NW North Atlantic. The model-simulated duration of the event, however, was consistently shorter than that observed in palaeoclimatic records. A review of evidence for forcing additional to the catastrophic release of meltwater from Lake Agassiz (solar variability, sea-ice feedback and longer-term meltwater history) suggested that reduced solar output did not directly coincide with the 8200 yr event, but that a more complex history of meltwater discharges and sea-ice feedback may have conditioned the AMOC for sustained climatic impact.
U2 - 10.1016/j.gloplacha.2011.03.006
DO - 10.1016/j.gloplacha.2011.03.006
M3 - Article
VL - 79
SP - 288
EP - 302
JO - Global and Planetary Change
JF - Global and Planetary Change
SN - 0921-8181
IS - 3-4
ER -
