title: Planktonic foraminifera of the California Current reflect 20th-century warming.
abstract: It is currently unclear whether observed pelagic ecosystem responses to ocean warming, such as a mid-1970s change in the eastern North Pacific, depart from typical ocean variability. We report variations in planktonic foraminifera from varved sediments off southern California spanning the past 1400 years. Increasing abundances of tropical/subtropical species throughout the 20th century reflect a warming trend superimposed on decadal-scale fluctuations. Decreasing abundances of temperate/subpolar species in the late 20th century indicate a deep, penetrative warming not observed in previous centuries. These results imply that 20th-century warming, apparently anthropogenic, has already affected lower trophic levels of the California Current.
authors.affiliation: Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA. dfield@mbari.org
authors.forename: David B
authors.initials: DB
authors.lastname: Field
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Baumgartner
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Charles
authors.forename: Vicente
authors.initials: V
authors.lastname: Ferreira-Bartrina
authors.forename: Mark D
authors.initials: MD
authors.lastname: Ohman
mesh_terms: D000818:Animals; D002140:California; D002980:Climate; D017753:Ecosystem; D004777:Environment; D056890:Eukaryota / Q000145:classification; D019015:Geologic Sediments; D017752:Greenhouse Effect; D011156:Population Density; D011157:Population Dynamics; D025341:Principal Component Analysis; D012621:Seasons; D013696:Temperature; D013997:Time Factors; D015048:Zooplankton / Q000145:classification