a b s t r a c tSea ice is an important component of the Earth system with complex dynamics imperfectly documented from direct observations, which are primarily limited to the last 40 years. Whereas large amplitude variations of sea ice have been recorded, especially in the Arctic, with a strikingly fast decrease in recent years partly attributed to the impact of anthropogenic climate changes, little is known about the natural variability of the sea ice cover at multi-decadal to multi-millennial time scales. Hence, there is a need to establish longer sea ice time series to document the full range of sea ice variations under natural forcings. To do this, several approaches based on biogenic or geochemical proxies have been developed from marine, ice core and coastal records. The status of the sea ice proxies has been discussed by the Sea Ice Proxy (SIP) working group endorsed by PAGES during a rst workshop held at GEOTOP in Montréal. The present volume contains a set of papers addressing various sea ice proxies and their application to large scale sea ice reconstruction. Here we summarize the contents of the volume, including a table of various proxies available in marine sediments and ice cores, with their possibilities and limitations.

ABSTRACT. [ t is ge nerally accepted th a t fresh-wa ter flu xes du e to ice accre ti o n or melting p rofo undl y influence the formati o n o f An tarctic bottom water (AA B\V ). Thi s is investigated by means of a globa l, three-dim ensiona l ice ocea n model. Two model runs were co nducted. At th e hi gh so uth ern latitudes, the co ntrol ex periment ex hibits positive (i. e. toward s the ocean ) fr esh-water flu xes over the deep ocea n, a nd la rge negative fluxes over th e Anta rctic contin ental shelf, because of the intense ice-production ta king place in this region. Th e salinity of shelf water can increase in such a way th at deep-water form ati on is facilitated. Th e simulated net fresh-water flu x ove r the shelf has a n a nnual mean va lue of -1 m a I. T hi s flu x induces a transport of salt to bottom wa ters, which corres po nd s to a n increase o[their salinity es tim a ted to be a round 0.05 psu. In th e seco nd m odel run, the fresh-water Duxes due to ice melting or freez ing a re neglected, leading to a rearrangement of the water m asses. In particul a r, the AABW-form ation rate decreases, which all ows th e influence of North Atl antic deep water (NADW ) to increase. As NADW is warm er a nd saltier th an AABW, th e bottom-water sa lini ty a nd temperature become higher.

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