Stability of the Larsen B ice shelf on the Antarctic Peninsula during the Holocene epoch

Abstract

The stability of the Antarctic ice shelves in a warming climate has long been discussed, and the recent collapse of a significant part, over 12,500 km2 in area, of the Larsen ice shelf off the Antarctic Peninsula has led to a refocus toward the implications of ice shelf decay for the stability of Antarctica's grounded ice. Some smaller Antarctic ice shelves have undergone periodic growth and decay over the past 11,000 yr (refs 7-11), but these ice shelves are at the climatic limit of ice shelf viability and are therefore expected to respond rapidly to natural climate variability at century to millennial scales. Here we use records of diatoms, detrital material and geochemical parameters from six marine sediment cores in the vicinity of the Larsen ice shelf to demonstrate that the recent collapse of the Larsen B ice shelf is unprecedented during the Holocene. We infer from our oxygen isotope measurements in planktonic foraminifera that the Larsen B ice shelf has been thinning throughout the Holocene, and we suggest that the recent prolonged period of warming in the Antarctic Peninsula region, in combination with the long-term thinning, has led to collapse of the ice shelf.

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

“…is in agreement with the MRE range of 750e1300 14 C years determined in other parts of the Southern Ocean (e.g. Gordon and Harkness, 1992;Harden et al, 1992;Berkman and Forman, 1996;Domack et al, 2005).…”

“…Our interpretations are largely consistent with published facies classifications from elsewhere on the Antarctic shelf (e.g. Kurtz and Anderson, 1979;Anderson et al, 1980;Wright and Anderson, 1982;Licht et al, 1996Licht et al, , 1998Licht et al, , 1999Domack et al, 1998Domack et al, , 1999Domack et al, , 2005Anderson, 1999;Pudsey and Evans, 2001;Wellner et al, 2001;Evans and Pudsey, 2002; We interpret muddy diamictons of the lower lithological unit, which are characterised by medium to high shear strength values, low CaCO 3 contents and only minor fluctuations in MS, water content, WBD and grain-size composition, as subglacial soft tills (ST) deposited at the base of the ice stream that had advanced through Belgica Trough (Table 2, Fig. 2).…”

“…(w10 mg) picked from 1 to 2 cm thick sediment slices, because these 14 C dates provide the most reliable radiocarbon ages (e.g. Domack et al, 2005;Heroy and Anderson, 2007;Rosenheim et al, 2008). All other 14 C ages were obtained by dating the acid-insoluble organic fraction (AIO) of bulk sediment samples (cf.…”

“…Bindschadler, 1998;Conway et al, 1999;Pudsey and Evans, 2001;Stone et al, 2003;Alley et al, 2005;Domack et al, 2005;Anderson, 2005, 2007;Bentley et al, 2006Bentley et al, , 2009Dowdeswell et al, 2008b;Johnson et al, 2008). Similarly, it is unclear if Antarctic deglaciation since the last glacial period has contributed to prominent global meltwater pulses (Clark et al, 2002;Licht, 2004;Peltier, 2005;Bassett et al, 2007).…”

On the origins of Earth rotation anomalies: New insights on the basis of both “paleogeodetic” data and Gravity Recovery and Climate Experiment (GRACE) data

“…An interesting and important characteristic of the ICE-5G (VM2) model is that the deglaciation of Antarctica is such that the continent is assumed not to lose mass until the onset of meltwater pulse 1b, a pulse defined by a period of rapidly increasing sea level recorded in the Barbados data set that occurs at the end of the Younger Dryas period. This aspect of the ICE-5G reconstruction has recently been confirmed by Domack et al [2005] and Leventer et al [2006], who have carefully dated the timing of the recommencement of marine shelf sedimentation that occurred as the Antarctic ice sheet pulled back from the shelf break in response to the rise in sea level that was driven by the melting of northern hemisphere land ice. The spatial distribution of continental ice sheet thickness as a function of time for the ICE-5G (VM2) v1.2 model is currently available to interested users at http://www.atmosp.physics.utoronto.ca/ $peltier/data.php…”