Recent increase in surface-water stability during warming off California as recorded in marine sediments

Abstract

Research Article| November 01, 1999 Recent increase in surface-water stability during warming off California as recorded in marine sediments A. L. Weinheimer; A. L. Weinheimer 1Climate Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0224, USA Search for other works by this author on: GSW Google Scholar J. P. Kennett; J. P. Kennett 2Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar D. R. Cayan D. R. Cayan 1Climate Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0224, USA Search for other works by this author on: GSW Google Scholar Geology (1999) 27 (11): 1019–1022. https://doi.org/10.1130/0091-7613(1999)027<1019:RIISWS>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation A. L. Weinheimer, J. P. Kennett, D. R. Cayan; Recent increase in surface-water stability during warming off California as recorded in marine sediments. Geology 1999;; 27 (11): 1019–1022. doi: https://doi.org/10.1130/0091-7613(1999)027<1019:RIISWS>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Warming of surface waters in the California Current since the 1950s has coincided with a significant decline in zooplankton volume. This has been attributed to reduced upwelling of nutrient-rich waters caused by increased thermal stratification across the thermocline. Proxy microfossil evidence preserved in the Santa Barbara Basin suggests that stability increased early in the 1900s, intensified after the early 1940s, and became well established by 1960. Accumulation of upwelled radiolarians in the basin has steadily declined since 1900, while oxygen isotopes in surface-dwelling planktonic foraminifera reflect increasing surface temperatures. Comparison of the δ18O records between surface and thermocline-dwelling planktonic foraminifera reveals that the temperature difference between surface and thermocline water has increased during the twentieth century. Instrumental records of surface and thermocline temperatures, monitored since 1950, support these results. This evidence suggests that relaxation of North Pacific anticyclonic gyre circulation deepened isopycnics, causing onshore movement of warmer, less saline waters and reduced upwelling of cool, nutrient-rich waters. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.