In an attempt to determine whether the temperature and salinity properties of Arctic Ocean waters above the Atlantic water temperature maximum are the result of heat transfer to sea-ice, dissolved Ar has been measured as a temperature tracer. Consistent with such a hypothesis, it is found that there is a transition from supersaturation of Ar in the upper waters to undersaturation below a depth of 275 m. Using the known dependence of the solubility of Ar on T and S, and assuming that the water was originally equilibrated with the atmosphere at 760 mm Hg, it has been calculated that ca. 0.6 ¿C of cooling can be attributed to transfer of heat to sea-ice. ¿ American Geophysical Union 1990