HR: 1330h
AN: PP52A-0956    [PDF]
TI: Decadal- to Centennial-scale Changes in the California Current from Isotopic Records of Multiple Species of Planktonic Foraminifera
AU: * Field, D B
EM: dbfield@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92093-0208 United States
AB: Decadal- to centennial-scale changes in ocean climate are a recognized component of the North Pacific climate system. Documenting the nature of these modes of variability is essential for understanding future changes in climate and determining whether observations of warming in recent decades lie within the range of natural variability. High-resolution records of decadal and centennial variability in ocean climate of the California Current are developed from planktonic foraminifera from laminated Santa Barbara Basin sediments. Isotopic records are developed from continuous five-year sampling intervals from the last 1800 years and from two-year sampling intervals within the last 100 years. Comparison of isotopic records to temperature records from the 20th century indicates that each species' record can be affected by changes in habitat depth. The changes in habitat depth follow expected species-specific responses to changes in hydrographic structure based on observations of vertical distributions from living foraminifera across the California Current. Isotopic records from multiple species with different vertical distributions are used to distinguish changes in habitat depth from changes in hydrographic structure of the water column. Large decadal thermal fluctuations are superimposed on lower frequency trends indicating a response to the Medieval Warm Period and the Little Ice Age. Although isotopic values of near-surface species are not unprecedented, the combined records of multiple species indicate that previous warm periods can be associated with different hydrographic conditions.
DE: 3030 Micropaleontology
DE: 3309 Climatology (1620)
DE: 4267 Paleoceanography
DE: 4870 Stable isotopes
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting