The Astronomical Theory of Climate Change relates changes in the latitudinal distribution of solar radiation, due to changes in the Earth's orbital obliquity, eccentricity, and the precession of the equinoxes, to the growth and decay of continental ice sheets. The continental records of the waxing and waning of ice sheets is very incomplete but its corollary, the rise and fall of global sea level, can be reconstructed in great detail. Sea level is considered to be one of the fundamental measures of millennial scale climate change, not only because it is a proxy of global ice volume, but also because it changes the Earth's climate boundary conditions by periodically flooding or exposing the continental shelves and opening or restricting critical passages for ocean currents. Ocean volume changes also have a direct impact on the chemistry of seawater and the atmosphere. The locations, sizes, and shapes of the continental ice sheet have a profound effect on the Earth's climate system and energy balance. In some polar regions the oceans intermediate waters or deep water are conditioned by sea ice formation on continental shelves and these processes can be enhanced or eliminated depending upon global sea level height. Local release of glacial melt water can impact deep and coastal ocean circulation, sea ice production, and ecology and chemistry of seawater. Isostatic adjustments due to former ice sheets and sea level rise associated with the last deglaciation continue to the present day and lead to significant corrections to modern sea level estimates measured with the global array of tide gauges.
Our sea level research program is primarily based on 230Th/234U/238U, 231Pa/235U, 14C dating reef corals that can be tied to past sea level heights. Our most detailed sea level record comes from Barbados and nearby Caribbean islands were we take advantage of the simple coral depth zonation (simple compared to the Pacific) and the dominance of the reef crest species Acropora palmata in the shallowest five meters, thus providing a reliable sea level indicator. Our coring targets are drowned coral reefs that grew during the last glacial low-stand and during intervals of rising sea level. The reef record of falling sea level is poorly preserved because a thin veneer of Acropora palmata only sometimes marks the regressive phase of sea level. On occasion, sea level rise is too fast for coral reefs to keep up thereby drowning the reefs. These drowned reefs are indicated by submerged ridges that can be mapped offshore many tropical islands. Using multibeam surveys from our research ship the R/V Ewing or side-scan sonar from our reef survey vessel R/V Coral Surveyor, we have mapped and cored drowned reefs, coring several hundred meters below the sea floor in over 100 meters water depth. We have modified a commercial hydraulic wireline-coring rig and made a hydraulic heave compensator for our riser pipe for offshore coring in sea conditions up to 2-meter swells and in water depths up to 150 meters. The coring rig is capable of coring more than 1000 meters below the sea floor although we typically core only 100 meters below the sea floor before we complete our local objective. Numerous cores containing thick sequences of the reef crest coral Acropora palmata, marking intervals of sea level rise, are the basis for our sea level curve.
We continue our active field work with a scheduled offshore coring program set for late May in 2005 off the south coast of Barbados to core into isotope stage 3 interstadial reefs with expected ages between 30,000 and 65,000 years BP based on prior coring results. In addition, we have scheduled return field trips during June-July 2005 to the Island of Araki in Vanuatu for more coral collection and shallow coring of the uplifted reef sequence. Araki Island has the best-preserved uplifted reefs spanning the 30,000 to 65,000 time period and we continue to study, map, and sample the island with our Columbia University graduate and undergraduate students for radiocarbon calibration samples and sea level reconstructions.
Collaborative modeling efforts continue with our colleagues Dick Peltier and Andrew Bush. Although no single sea level record serves as a global record, the sea level record from Barbados comes very close according to model results by Peltier and others. We continue our close collaboration with Dick Peltier in order to best interpret our Barbados sea level record and help to prioritize our future sea level reconstructions. Multiple ice sheets of varying proportions contribute to the deglacial sea level rise and only through modeling efforts validated by field observations can we begin to reconstruct the history of the melting ice sheets.
Changes in the aerial extent of continental shelves have impacts on human migration routes, regional climate, and ocean chemistry. Of particular interest to us is the changing aerial extent of the Maritime Continent due to the periodic exposure and flooding of the expansive continental shelves in this region associated with rising and falling sea level. Some believe that the Earth's “thermostat” is located in this region through the interplay between evaporation from the “warm pool” and cloud albedo feedback. More than one quarter of the Earth's atmospheric water vapor is injected into the atmosphere via the Indonesian Low. Quinn was the first to speculate that changes in the size of the Maritime Continent due to varying sea level was responsible for changes in the behavior of ENSO.
- [PDF] Peltier, W.R. and R.G. Fairbanks, 2006. Global glacial ice volume and Last Glacial Maximum duration from an extended Barbados sea level record. Quaternary Science Reviews, 25, 3322-3337.
- [PDF] Stanford, Jennifer D.; Eelco J. Rohling, Sally E. Hunter, Andrew P. Roberts, Sune O. Rasmussen, Edouard Bard, Jerry McManus, and Richard G. Fairbanks, 2006. Timing of Meltwater Pulse 1a and climate responses to meltwater injections. Paleoceanography, 21, No. 4, PA4103.
- [PDF] Bush, A. B. G., and R. G. Fairbanks, 2003. Exposing the Sunda shelf: Tropical responses to eustatic sea level change, J. Geophys. Res., 108(D15), 4446, 3-1-3-10.
- Fairbanks, R.G., C.D. Charles and J.D. Wright, 1992. Origin of global meltwater pulses, in: Four Decades of Radiocarbon Studies, (Long and Kra, eds.) Springer, 473-500.
- Bard, E., R. G. Fairbanks and B. Hamelin, 1992. How accurate are the U-Th ages obtained by mass spectrometry on coral terraces. Proceeding of the Mallorca Workshop on Radiochronology.
- [PDF] Hamelin, B, E. Bard, A. Zindler, R.G. Fairbanks, 1991. 234U/238U mass spectrometry of corals: How accurate is the U-Th age of the last interglacial period? Earth & Planetary Science Letters, 106, 169-180.
- Miller, K.G., J.D. Wright and R. G. Fairbanks, 1991. Unlocking the ice house: Oligocene-Miocene oxygen isotopes, eustasy, and margin erosion. Jour. Geophy. Res., 96, 6829-6848.
- [PDF] Bard, E., R.G. Fairbanks, B. Hamelin, A. Zindler and C. Hoang, 1991. Uranium-234 anomalies in corals older than 150,000 yr. Geochim. Cosmochim. Acta 55, 2385-2390.
- [PDF] Bard, E., B. Hamelin, R.G. Fairbanks, 1990. U/Th ages obtained by mass spectrometry in corals from Barbados: sea level during the past 130,000 years. Nature, 346, 456-458.
- Bard, E, R.G. Fairbanks, M. Arnold, P. Maurice, J. Duprat, J. Moyes, J.C. Duplessy, 1989. Sea-level estimates during the last deglaciation based on O-18 and accelerator mass spectrometry C-14 ages measured in Globigerina bulloides. Quaternary Research, 31, 1-11.
- [PDF] Fairbanks , R.G., 1989. A 17,000 year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep ocean circulation. Nature, 342, 637-642.
- Miller, K.G., R.G. Fairbanks and G. Mountain, 1987. Cenozoic oxygen isotope synthesis, sea-level history, and continental margin erosion. Paleoceanography, 2, 1-20.
- [PDF] Dodge, R.E., R.G. Fairbanks and L.K. Benninger, 1983. Pleistocene sea levels from raised coral reefs of Haiti. Science, 219, 1423-1425.
- Bender, M.L., R.G. Fairbanks, F.W. Taylor, R.K. Matthews, J. Goddard and W.S. Broecker, 1979. Uranium-series dating of the Pleistocene reef tracts of Barbados, West Indies. Geol. Soc. America Bull., 90, 577-594.
- Fairbanks, R.G. and R.K. Matthews, 1978. The oxygen isotope stratigraphy of the Plesitocene reef tracts of Barbados, West Indies. Quaternary Research, 10 (1), 181-196.
- Fairbanks, R.G., Mountain, G.S. and J. Wright, 1991. Geologic record of sea-level and its relevance to global change forecasts. NSF Advisory Panel Report on Earth System History, 75-97.
- Fairbanks, R.G., 1988. Barbados Offshore Drilling Program. L-DGO Technical Report. L-DGO-88-2. 221pp.