AbstractThe thermohaline circulation of the global ocean is primarily driven by water mass formation in the northern and southern Atlantic Ocean and its adjacent seas. Lateral and vertical mixing in the northern North Atlantic generate the North Atlantic Deep Water which occupies the major part of the world oceans. The oceanic bottom layer is filled with Antarctic Bottom Water which is mainly formed in the Weddell Sea. Physical reasoning let us believe that sea ice generation as well as thermal interaction of the large ice shelves with Weddell Sea water may likewise initiate a sequence of processes to produce bottom water.In the framework of the still ongoing international Weddell Gyre Study preliminary estimates of the mass, heat and salt transports have been derived from measurements. These values agree by and large with results of model calculations which have been obtained under the prerequisite that sea ice effects are taken into account. The latter model simulations distinctly indicate that the annual sea ice cycle in the Weddell Sea leads to a remarkable enhancement of the Weddell Gyre circulation and of the Antarctic Circumpolar Current. Numerical model experiments show that the melting and freezing processes under the wide Filchner-Ronne Ice Shelf may create as much cold Ice Shelf Eater as to finally generate the major amount of the Antarctic Bottom Water.