A scientific report co-authored by David B. Field using evidence collected as part of the California Current Ecosystem (CCE) Long-Term Ecological Research program was published in the 6 January 2006 issue of the journal Science.
The report suggests that, based the evidence from sediment cores collected from the seafloor off Southern California, the 20th century ocean warming was unprecedented in the previous 1400 years.
Field is a graduate student at the Scripps Institution of Oceanography at the University of California, San Diego, and collaborated in this study with Timothy R. Baumgartner and Vicente Ferreira-Bartrina of Centro de Investigación Científica y de Educación Superior de Ensenada, Mexico, and Christopher D. Charles of Scripps, and Mark D. Ohman, the CCE LTER principal investigator, also of Scripps.
You can read or download the PDF of the complete report here.