Acoustic Thermometry of Ocean Climate: Marine Mammal Issues

After global warming became a concern in the mid-1950s, researchers proposed measuring deep ocean temperatures to reveal any significant trends in core ocean warming. Acoustic thermometry can detect changes in ocean temperature by receiving low-frequency sounds transmitted across an ocean basin because the speed of sound is proportional to water temperature. Acoustic Thermometry of Ocean Climate (ATOC) is an international program involving 11 institutions in seven nations. It is designed as a 30-month "proof-of-concept" project to provide data on possible global climate change, with funding provided by the U.S. Department of Defense. A Marine Mammal Research Program (MMRP) was established as part of ATOC to assess the effects of ATOC sound signals on marine mammals. The proposed ATOC sources will be located 15 kilometers off the coast of Kauai, Hawaii, and near the Pioneer Seamount in California. A debate has arisen over ATOC's impact on marine mammals versus the benefits of better global warming information derived from it. Among the concerns are questions regarding the effects of low-frequency sound on marine mammals, and the baseline data available on marine mammals near the proposed source locations. In response to concerns expressed by the public, environmentalists, scientists, and Congress, the National Marine Fisheries Service (NMFS) held a series of public hearings on the Marine Mammal Protection Act (MMPA) permit applications by Scripps Institution of Oceanography for ATOC. Consequently, ATOC was delayed until draft environmental impact statements could be prepared. The Office of Naval Research funded a National Research Council (NRC) investigation of current knowledge and research needs with respect to the effects of low-frequency sound on marine mammals. The NRC report, released in March 1994, concluded that the data were insufficient to determine the possible effects of low-frequency sound on marine mammals.

CRS Report for Congress. The original document contains color images.