Observations of changes in the properties of ocean waters have been restricted to surface1 or intermediate-depth waters2,3, because the detection of change in bottom water is extremely difficult owing to the small magnitude of the expected signals. Nevertheless, temporal changes in the properties of such deep waters across an ocean basin are of particular interest, as they can be used to constrain the transport of water at the bottom of the ocean and to detect changes in the global thermohaline circulation. Here we present a comparison of a trans-Pacific survey completed in 1985 (refs 4, 5) and its repetition in 1999 (ref. 6). We find that the deepest waters of the North Pacific Ocean have warmed significantly across the entire width of the ocean basin. Our observations imply that changes in water properties are now detectable in water masses that have long been insulated from heat exchange with the atmosphere.
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Levitus, S., Antonov, J. I., Boyer, T. P. & Stephens, C. Warming of the world ocean. Science 287, 2225–2229 (2000)
Wong, A. P., Bindoff, N. L. & Church, J. A. Large–scale freshening of intermediate waters in the Pacific and Indian Oceans. Nature 400, 440–443 (1999)
Roemmich, D. & Wunsch, C. Apparent changes in the climatic state of the deep North Atlantic Ocean. Nature 307, 447–450 (1984)
Talley, L. D., Martin, M., Salameh, P. & the Oceanographic Data Facility. Transpacific Section in the Subpolar Gyre (TPS47): Physical, Chemical, and CTD Data, R/V Thomas Thompson TT190, 4 August 1985–7 September 1985 1–246 (Ref. 88–9, Scripps Inst. Of Oceanography, La Jolla, CA, 1988)
Talley, L. D., Joyce, T. & deSzoeke, R. A. Trans-Pacific sections at 47°N and 152°W: distribution of properties. Deep-Sea Res. (Suppl.) 38, S63–S82 (1991)
Uchida, H., Fukasawa, M. & Freeland, H. J. WHP P01 Revisit Data Book 1–73 (Jamstec, Yokosuka, 2002)
Johnson, G. C., Rudnick, D. L. & Taft, B. A. Bottom water variability in the Samoa Passage. J. Mar. Res. 52, 177–195 (1994)
Sclater, J. G. & Parsons, B. Oceans and continents: similarities and differences in the mechanisms of heat loss. J. Geophys. Res. 85, 11535–11552 (1981)
Joyce, T. M., Warren, B. A. & Talley, L. D. The geothermal heating of the abyssal subarctic Pacific Ocean. Deep-Sea Res. 33, 1003–1005 (1986)
Mantyla, A. & Reid, J. L. Abyssal characteristics of the world ocean waters. Deep-Sea Res. 30, 805–833 (1983)
Johnson, G. C. & Orsi, A. H. Southwest Pacific water-mass exchanges between 1968/69 and 1990/91. J. Clim. 10, 306–316 (1997)
Gille, S. H. Warming of the southern ocean since the 1950s. Science 295, 1275–1277 (2002)
Preston-Thomas, H. The international temperature scale of 1990. Metrologia 27, 3–10 (1990)
Mantyla, A. W. Standard seawater comparison updated. J. Phys. Oceanogr. 17, 543–548 (1987)
Aoyama, M., Joyce, T., Kawano, T. & Takatsuki, Y. Standard seawater comparison up to P129. Deep-Sea Res. 49, 1103–1114 (2002)
Kawano, T., Takatsuki, Y., Imai, J. & Aoyama, M. Seawater and quality evaluation of the standard seawater supplied in a bottle. [In Japanese with English abstract]. J. Jpn Soc. Mar. Surv. Tech. 13, 11–18 (2001)
Reid, J. L. On the total geostrophic circulation of the Pacific Ocean: flow patterns, tracers and transports. Prog. Oceanogr. 39, 263–352 (1997)
We thank the officers and crew of the three research vessels (RV Kaiyo-maru of JFA, RV Mirai of JAMSTEC, and CCGS John P. Tully) and all technical assistants. The Canadian contribution was funded by the Strategic Science Fund of the Department of Fisheries and Oceans, and the Japanese contributions were funded by the Promotional Foundation for Science and Technology of the Science and Technology Agency of Japan (now known as the Ministry of Education, Culture, Sports, Science and Technology).
The authors declare that they have no competing financial interests.
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Fukasawa, M., Freeland, H., Perkin, R. et al. Bottom water warming in the North Pacific Ocean. Nature 427, 825–827 (2004). https://doi.org/10.1038/nature02337
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