Export 4 results:
Sort by: [ Author  (Asc)] Title Type Year
A B C D E [F] G H I J K L M N O P Q R S T U V W X Y Z   [Show ALL]
Fairbanks, RG, Evans MN, Rubenstone JL, Mortlock RA, Broad K, Moore MD, Charles CD.  1997.  Evaluating climate indices and their geochemical proxies measured in corals. Coral Reefs. 16:S93-S100.   10.1007/s003380050245   AbstractWebsite

Standard ocean/climate indices such as the Nino-3 sea surface temperature (SST) index, based on sparse instrumental data, and atmospheric indices such as the Southern Oscillation Index (SOI), may now be substituted and/or extended by coral-based indices. Several elements or their isotopes are incorporated in coral aragonitic skeletons at predictable concentrations, some of which are temperature or salinity dependent. The availability of century-old corals, at key oceanographic sites, permits the establishment of a network of proxy climate indices.

Fairbanks, R, Charles CD, Wright JD.  1992.  Origin of the global meltwater pulses. Four decades of radiocarbon: an interdisciplinary approach. ( Long A, Kra R, Eds.).:473-500., New York, NY: Springer-Verlag Abstract
Field, DB, Baumgartner TR, Charles CD, Ferreira-Bartrina V, Ohman MD.  2006.  Planktonic foraminifera of the California Current reflect 20th-century warming. Science. 311:63-66.   10.1126/science.1116220   AbstractWebsite

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.

Flores, JA, Marino M, Sierro FJ, Hodell DA, Charles CD.  2003.  Calcareous plankton dissolution pattern and coccolithophore assemblages during the last 600 kyr at ODP Site 1089 (Cape Basin, South Atlantic): paleoceanographic implications. Palaeogeography Palaeoclimatology Palaeoecology. 196:409-426.   10.1016/s0031-0182(03)00467-x   AbstractWebsite

Coccolithophore assemblages at ODP Site 1089 in the southern Cape Basin (similar to41degreesS) were used to reconstruct surface-water conditions for the late Quaternary (Marine Isotope Stages (MIS) 1-15) in a region of strong hydrographic gradients in the southeast Atlantic. Stratigraphic control was provided by oxygen isotope stratigraphy and calcareous nannofossil events that are thought to be synchronous over a broad range of latitudes. The greatest coccolith abundances occurred at glacial terminations and, to a lesser degree, during glacial stages. Conversely, coccolithophores were the least abundant during the transition between interglacial to glacial stages, when calcium carbonate dissolution was strong. With the exception of these intervals, coccolith preservation is moderate to good, allowing study of the assemblages. The total abundance of coccolithophores and calcium carbonate variations at Site 1089 result both from variations in dissolution and carbonate production. During terminations, for example, the greatest calcium carbonate concentrations occurred at the same time as a moderate-to-poor preservation of coccoliths and foraminifers. Carbonate production was relatively high during these intervals. However, during terminations IV and V. maxima in carbonate production in the ocean were linked to high-dissolution processes at Site 1089. This trend is not observed for terminations I, II and III [Hodell et al., Earth Planet. Sci. Lett. 192 (2001) 109-124]. The interval from MIS 9 to 13 is coincident with high abundances of highly calcified species such as Gephyrocapsa caribbeanica. Here we discuss the contribution of this ubiquitous species to the production of calcium carbonate and their paleoecological significance. Except for occasional coccolith-barren intervals during interglacial periods, subtropical coccolith species were present continuously at ODP Site 1089 during the late Pleistocene. This suggests that the Polar Front has been south of Site 1089 for the last 600 kyr. (C) 2003 Elsevier Science B.V. All rights reserved.