The Antarctic Peninsula is a region that has experienced very rapid warming over the last 50 years, and this has been attributed with the collapse of a number of ice shelves and accelerating glacier mass loss [1][2][3][4][5][6][7] . In contrast, warming has been comparatively modest over West Antarctica and significant changes have not been observed over most of East Antarctica 8-9 , suggesting that the ice core palaeoclimate records available from these areas may not be representative of the climate history of the Antarctic Peninsula. Here we present an ice core record from James Ross Island that provides the first complete Holocene temperature history for the Antarctic Peninsula. The Antarctic Peninsula experienced an early Holocene temperature optimum followed by a long interval from ~9,200 -2,500 years before present (yrBP; 1950AD) of stable temperatures similar to modern day levels. We find that the late Holocene development of ice shelves on the northeastern Antarctic Peninsula was coincident with pronounced cooling from 2,500 to 550 yrBP, which was part of a millennial-scale climate excursion with opposing anomalies on the east and west Antarctic Peninsula. Whilst warming of the northeastern Antarctic Peninsula began around 600 years ago, the rapid rate of warming over the last century is unusual in the context of natural climate variability over the last two millennia. The connection shown here between past temperature and ice shelf stability suggests that warming for several centuries had left ice shelves on the northeastern Antarctic Peninsula poised for collapse, and that continued warming to temperatures that now exceed the stable conditions that persisted here for most of the Holocene is likely to see ice shelf instability encroach further southward along the Antarctic Peninsula.The Antarctic Peninsula is currently one of the most rapidly warming regions on Earth (Fig. 1a) 1 .Historical observations since 1958 at Esperanza Station (Fig. 1b) 2), which plays a role in driving present day variability of the Antarctic Dipole 21 . Antarctic Dipole-like cooling of the Weddell Sea in the late Holocene, and the propagation of these ocean temperature and sea ice anomalies along the eastern Antarctic Peninsula by the Weddell Gyre, may have also aided the rapid establishment of ice shelves in this region during the late Holocene.Sustained warming at James Ross Island began approximately 600 years ago (Fig. 4a). Lake sediments from Beak Island in Prince Gustav Channel also indicate warming beginning at ~1410 AD 18 ,and together these records demonstrate the absence of a widespread Little Ice Age signal on the Antarctic Peninsula that was comparable to northern hemisphere climate 22 (Fig. 4a). The overall rate of pre-anthropogenic temperature rise at JRI from 1400 AD to 1850 AD equates to 0.22 ± 0.06 °C per century. However, there are times in this interval when warming occurred at a much faster rate.Using annual-resolution data, trends were calculated for the JRI temperature record since 2,000 yrBP over moving ...

Abstract. The recovery of a 1.5 million yr long ice core from Antarctica represents a keystone of our understanding of Quaternary climate, the progression of glaciation over this time period and the role of greenhouse gas cycles in this progression. Here we tackle the question of where such ice may still be found in the Antarctic ice sheet. We can show that such old ice is most likely to exist in the plateau area of the East Antarctic ice sheet (EAIS) without stratigraphic disturbance and should be able to be recovered after careful presite selection studies. Based on a simple ice and heat flow model and glaciological observations, we conclude that positions in the vicinity of major domes and saddle position on the East Antarctic Plateau will most likely have such old ice in store and represent the best study areas for dedicated reconnaissance studies in the near future. In contrast to previous ice core drill site selections, however, we strongly suggest significantly reduced ice thickness to avoid bottom melting. For example for the geothermal heat flux and accumulation conditions at Dome C, an ice thickness lower than but close to about 2500 m would be required to find 1.5 Myr old ice (i.e., more than 700 m less than at the current EPICA Dome C drill site). Within this constraint, the resolution of an Oldest-Ice record and the distance of such old ice to the bedrock should be maximized to avoid ice flow disturbances, Published by Copernicus Publications on behalf of the European Geosciences Union. H. Fischer et al.:Where to find 1.5 million yr old ice for the IPICS "Oldest-Ice" ice core for example, by finding locations with minimum geothermal heat flux. As the geothermal heat flux is largely unknown for the EAIS, this parameter has to be carefully determined beforehand. In addition, detailed bedrock topography and ice flow history has to be reconstructed for candidates of an Oldest-Ice ice coring site. Finally, we argue strongly for rapid access drilling before any full, deep ice coring activity commences to bring datable samples to the surface and to allow an age check of the oldest ice.