First survey of Antarctic sub-ice shelf sediments reveals mid-Holocene ice shelf retreat

The retreat of five small Antarctic Peninsula ice shelves in the late 20th century has been related to regional (possibly anthropogenic) climate warming. We use the record of ice- rafted debris (IRD) in cores to show that the Prince Gustav Channel ice shelf also retreated in mid-Holocene time. Early and late Holocene-age sediments contain IRD derived entirely from local ice drainage basins, which fed the section of ice shelf covering each site. Core- top and mid-Holocene (5–2 ka) sediments include a wider variety of rock types, recording the drift of far-traveled icebergs, which implies seasonally open water at the sites. The period when the Prince Gustav ice shelf was absent corresponds to regional climate warming deduced from other paleoenvironmental records. We infer that the recent decay cannot be viewed as an unequivocal indicator of anthropogenic climate perturbation.