A study reconstructs variation in the extent of Arctic Ocean sea-ice since the last ice age. Although the recent decline in Arctic sea-ice is well documented, the natural variability of sea-ice extent on the scale of hundreds to thousands of years is poorly understood. Anne de Vernal and colleagues analyzed sediment cores from the Lomonosov Ridge in the Arctic Ocean, representing several millennia of sedimentation. Radiocarbon dating and micropaleontological analysis showed variation in phytoplanktonic production and organic carbon flux indicative of the extent of sea-ice cover. In the western and central Lomonosov Ridge, perennial sea-ice has persisted throughout the present interglacial period, even during a middle Holocene warm period that peaked around 6,500 years ago. However, the southeastern part of the ridge near the Russian margin experienced sporadic seasonal ice-free conditions from the early Holocene until around 4,000 years ago. The authors report that sea-ice variability and responsiveness to global climate conditions is likely not uniform across the Arctic Ocean. According to the authors, seasonally ice-free conditions in the southeastern Arctic Ocean may be recurrent in warm climate periods and may be amplified by the effects of global warming.
Article #20-08996: "Natural variability of the Arctic Ocean sea ice during the present interglacial," by Anne de Vernal et al.
MEDIA CONTACT: Anne de Vernal, University of Quebec at Montreal, CANADA; tel: +33-670-10-5399; e-mail: devernal.anne@uqam.ca
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Proceedings of the National Academy of Sciences