Svalbard glaciers re-advanced during the Pleistocene-Holocene transition

Despite warming regional conditions and our general understanding of the deglaciation, a variety of data suggest glaciers re-advanced on Svalbard during the Lateglacial-early Holocene (LGEH). We present the first well-dated end moraine formed during the LGEH in De Geerbukta, NE Spitsbergen. This landform was deposited by an outlet glacier re-advancing into a fjord extending 4.4km beyond the late Holocene (LH) maximum. Comparing the timing of the De Geerbukta glacier re-advance to a synthesis of existing data including four palaeoclimate records and 15 other proposed glacier advances from Svalbard does not suggest any clear synchronicity in glacial and climatic events. Furthermore, we introduce six additional locations where glacier moraines have been wave-washed or cut by postglacial raised marine shorelines, suggesting the landforms were deposited before or during high relative sea-level stands, thus exhibiting a similar LGEH age. Contrary to current understanding, our new evidence suggests that the LGEH glaciers were more dynamic, exhibited re-advances and extended well beyond the extensively studied LH glacial expansion. Given the widespread occurrence of the LGEH glacier deposits on Svalbard, we suggest that the culmination of the Neoglacial advances during the Little Ice Age does not mark the maximum extent of most Svalbard glaciers since deglaciation; it is just the most studied and most visible in the geological record.