The follow-up to this experiment was the 1996–2006 Acoustic Thermometry of Ocean Climate (ATOC) project in the North Pacific Ocean. Both HIFT and ATOC engendered considerable public controversy concerning the possible effects of man-made sounds on marine mammals. In addition to the decade-long measurements obtained in the North Pacific, acoustic thermometry has been employed to measure temperature changes of the upper layers of the Arctic Ocean basins, which continues to be an area of active interest. Acoustic thermometry has also been used to determine changes to global-scale ocean temperatures using data from acoustic pulses traveling from Australia to Bermuda.