Deep Water Circulation
Early modeling studies by Peter Wyle and Clause Rooth in the 1960.s indicated that small perturbations in the fresh water balance in the high North Atlantic could modulate the production of North Atlantic Deep Water and possibly effect global climate. The pioneering carbon isotope studies on benthic foraminifera by Jean-Claude Duplessy and Nick Shackleton during the 1970.s hinted that North Atlantic Deep Water production rates varied dramatically during glacial-interglacial cycles. These results fueled a gold rush of speculations that NADW may be the mystery climate amplifier of the Milankovitch cycles. This sparked thirty years of NADW studies using an evolving arsenal of deep ocean circulation proxies. The picture is still confusing today but slowly there appears to be some concordance between the newer proxies although there remain stark differences in the details. We have worked on this problem for most of its evolution with five major foci. First we concentrated on statistically linking the North Atlantic surface water signal to the NADW signal. We then shifted to the Southern Ocean where we could unambiguously estimate the relative flux of NADW into the Southern Ocean. This obviated the chronic problem of falsely estimating NADW production changes by inadvertently measuring the migration of the Antarctic Bottom Water (AABW) and NADW mixing front that in many instances did not correspond to NADW production changes. Next we designed and built an automated stable isotope inlet system capable of analyzing single benthic foraminifera in order to continue working on many North Atlantic cores that were depleted in benthic foraminifera. We sorted out the significant fraction of the carbon isotope signal recorded in benthic foraminifera that was due to partial isotopic equilibration of seawater with the atmosphere in order to better understand the differences between the carbon isotope tracer and the Cd/Ca nutrient proxy. Using better-defined tracers from higher accumulation rate cores, we were able to estimate the changing fractions of southern source waters from the northern source waters including deep and intermediate waters.
Our current research uses radiocarbon measurements on 230Th/234U/238U dated deep-sea corals from the high North Atlantic in the Orphan Knoll region east of Newfoundland. In this region we can estimate the ventilation age of NADW arriving at Orphan Knoll during the last deglacial period. Along with our Canadian collaborators, we have proposed a research cruise in the coming year to sample deep-sea corals from 1700 meters to 4700 meters depth down the flanks of Orphan Knoll. In addition, recent work using the neodymium tracer of NADW may have broken the longstanding deadlock between the carbon isotope tracer and the Cd/Ca tracer history of the Southern Ocean.
- [PDF] Piotrowski, A.M., S.L. Goldstein, S.R. Hemming, and R.G. Fairbanks, 2005. Temporal relationships of carbon cycling and ocean circulation at glacial boundaries. Science, 307, 1933-1938.
- [PDF] Piotrowski, A.M., S.L. Goldstein, S.R. Hemming, and R.G. Fairbanks, 2004. Intensification of North Atlantic Deep Water through the last glacial termination. Earth & Planetary Science Letters, 225, 1-2, 205-220.
- [PDF] Lynch-Stieglitz, J.. A. van Geen, R.G. Fairbanks, 1996. Inter-ocean exchange of glacial North Atlantic Intermediate Water: evidence from subantarctic Cd/Ca and carbon isotope measurements, Paleoceanography, 11, 191-201.
- [PDF] Naqvi, W.A. and R.G. Fairbanks, 1996. A 27,000 year record of Red Sea outflow: implications for timing of post-glacial monsoon intensification, Geophy. Res. Lett., 23, 12, 1501-1504.
- [PDF] van Geen, A., R. G. Fairbanks, P. Dartnell, M. McGann, J.V. Gardner, and M. Kashgarian, 1996. Ventilation changes in the northeast Pacific during the last deglaciation. Paleoceanography, 11, 5, 519-528.
- [PDF] Charles, C.D., J. Lynch-Stieglitz, U.S. Ninnemann and R.G. Fairbanks, 1996. Climate connections between the hemispheres revealed by deep sea sediment core/ice core correlations, Earth and Planetary Science Letters 142:19-28.
- [PDF] Lynch-Stieglitz, J., T.F. Stocker, W.S. Broecker and R.G. Fairbanks, 1995. The influence of air-sea exchange on the isotopic composition of oceanic carbon: observations and modeling. Global Biogeochemical Cycles, 9, 4, 653-665.
- [PDF] Lynch-Stieglitz, J., R.G. Fairbanks and C.D. Charles, 1994. Glacial-interglacial history of Antarctic intermediate water: Relative strengths of Antarctic vs. Indian Ocean sources. Paleoceanography, 9, 1, 7-30.
- [PDF] Naqvi, W.A., C.D. Charles and R.G. Fairbanks, 1994. Carbon and oxygen isotopic records of benthic foraminifera from the Northeast Indian Ocean: implications on glacial-interglacial atmospheric CO2 changes. Earth & Planet. Lett., 121, 99-110.
- [PDF] Lynch-Stieglitz, J. and R.G. Fairbanks. 1994. A conservative tracer for glacial ocean circulation from carbon isotope and palaeo-nutrient measurements in benthic foraminifera. Nature, 369, 308-310.
- Charles, C.D., J.D. Wright and R.G. Fairbanks, 1993. Thermodynamic influences on the marine carbon isotope record. Paleoceanography, 8, 6, 691-698.
- deMenocal, P.B., D.W. Oppo, R.G. Fairbanks and W. L. Prell, 1992. A 1.2 Myr record of mid-depth δ13C variability in the North Atlantic: implications for climate change, ocean circulation, and atmospheric CO2. Paleoceanography, 7, 229-250.
- [PDF] Charles, C.D. and R. G. Fairbanks, 1992. Evidence from Southern Ocean sediments for the effect of North Atlantic deep-water flux on climate. Nature 355, 416-419.
- Wright, J.D., K.G. Miller, R.G. Fairbanks, 1991. Evolution of modern deepwater circulation: evidence from the late Miocene southern ocean. Paleoceanography, 6, 275-290.
- Charles, C.D. and R.G. Fairbanks, 1990. Glacial to interglacial changes in the isotopic gradients of Southern Ocean surface water. in: Geologic History of Polar Oceans: Arctic versus Antarctic, Bleil and Theide, eds., NATO ASI Series, 308, 519-538, Kluwer Academic Publishers, Boston, Mass.
- Oppo, D.W., R. G. Fairbanks, A.L. Gordon and N.J. Shackleton, 1990, Late Pleistocene Southern Ocean δ13C variability: North Atlantic Deep Water modulation of atmospheric CO2. Paleoceaonography, 5, 43-55.
- Oppo, D.W and R.G. Fairbanks, 1990. Atlantic Ocean thermohaline circulation of the last 150,000 years: relationship to climate and atmospheric CO2. Paleoceanography, 5, 277-288.
- Oppo, D.W. and R.G. Fairbanks, 1989. Carbon isotope composition of phosphate-free surface water of the past 22,000 years. Paleoceanography, 4, 333-351.
- Duplessy, J.C., N.J. Shackleton, R.G. Fairbanks, L. Labeyrie, and D. Oppo, 1988. Deep water source variations during the last climatic cycle and their impact on the global deep water circulation. Paleoceanography, 3, 343-360.
- [PDF] Oppo, D.W. and R.G. Fairbanks, 1987. Variability in the deep and intermediate water circulation of the Atlantic Ocean during the past 25,000 years: Northern Hemisphere modulation of the Southern Ocean. Earth and Planet. Sci. Letters., 86, 1-15.
- Miller, K.G., R.G. Fairbanks and E. Thomas, 1986. Benthic foraminiferal carbon isotopic records and the development of abyssal circulation in the eastern North Atlantic. In Ruddiman, W.F., Kidd, R.B., Thomas, E., et al.,Init. Repts. DSDP, 94: Washington (U.S. Govt. Printing Office), 981-996.
- Miller, K.G. and R.G. Fairbanks, 1985. Oligocene to Miocene global carbon isotope cycles and abyssal circulation changes. in: Natural Variations in Carbon Dioxide and the Carbon Cycle (E.T. Sundquist and W.S. Broecker, ed.) American Geophysical Union _Monograph 32, 469-486.
- [PDF] Mix, A.C. and R.G. Fairbanks, 1985. North Atlantic surface-ocean control of Pleistocene deep-ocean circulation. Earth and Planet. Science Lett., 73, 231-243.
- [PDF] Miller, K.G. and R.G. Fairbanks, 1983. Evidence for Oligocene-Middle Miocene abyssal circulation changes in the western North Atlantic. Nature, 306, 250-253.