Sea-ice is frequently cited as a likely driver and propagator of abrupt climate change because of the rapid and far-reaching impact of its feedbacks. However, numerical climate models are still unable to adequately represent modern Antarctic sea-ice distribution and consistently underestimate the rate and magnitude of current Arctic sea-ice decline. The rapid reduction in the extent and volume of Arctic sea-ice makes it especially urgent to obtain longer time series that put recent events into context. To achieve this we are almost entirely reliant on proxy data from marine sediments & ice cores to provide evidence of past sea-ice cover.
Marine archives of Antarctic sea-ice suggest that some places, during the Holocene, experienced intervals when sea-ice was less than at present. The timing and extent of these intervals are still to be determined but have a clear relevance to understanding and predicting the future response of sea-ice to continued global warming over the coming decades.
In Antarctica, reconstructions of summer and winter sea-ice during the late glacial reveal very different seasonal responses over time. Maximum & minimum extents of summer and winter sea-ice are asynchronous and produce vast shifts in the area of ocean affected by the seasonal formation and melting of sea-ice, with broad implications for the timing and impact of different feedback mechanisms.