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Meltwater pulse 1B
Meltwater pulse 1B (MWP1b) is the name used by Quaternary geologists, paleoclimatologists, and oceanographers for a period of either rapid or just accelerated post-glacial sea level rise that occurred at the beginning of the Holocene and after the end of the Younger Dryas.〔 Meltwater pulse 1B is also known as catastrophic rise event 2 (CRE2) in the Caribbean Sea.〔 Other named, postglacial meltwater pulses are known most commonly as meltwater pulse 1A0 (meltwaterpulse19ka), meltwater pulse 1A, meltwater pulse 1C, meltwater pulse 1D, and meltwater pulse 2. It and these other periods of proposed rapid sea level rise are known as ''meltwater pulses'' because the inferred cause of them was the rapid release of meltwater into the oceans from the collapse of continental ice sheets.〔Cronin, T.M. (2012) ''Rapid sea-level rise.'' Quaternary Science Reviews. 56:11-30.〕
== Sea level ==
There is considerable unresolved disagreement over the significance, timing, magnitude, and even existence of meltwater pulse 1B. It was first recognized by Fairbanks in his coral reef studies in Barbados. From the analysis of data from cores of coral reefs surrounding Barbados, he concluded that during meltwater pulse 1B, sea level rose in about 500 years about 11,300 calendar years ago.〔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.〕
However, in 1996 and 2010, Bard and others published detailed analysis of data from cores from coral reefs surrounding Tahiti. They concluded that meltwater pulse 1B was, at best, just an acceleration of sea level rise at ~11,300 calendar years ago and it was, at worse, not statistically different from a constant rate sea level rise between 11,500 and 10,200 calendar years ago. They argued that meltwater pulse 1B was certainly not an abrupt jump in sea level, which they would considered to be a ''meltwater pulse''. They argue that the rise in sea level estimated by Fairbanks from cores is an artifact created by differential tectonic uplift between different sides of a tectonic structure lying between the two Barbados cores used to identify meltwater pulse 1B and calculate its magnitude.〔Bard, E., B. Hamelin, M. Arnold, L. Montaggioni, G. Cabioch, and others (1996) ''Deglacial sea-level record from Tahiti corals and the timing of global meltwater discharge.'' Nature. 382: 241-244.〕〔Bard, E., B. Hamelin, and D. Delanghe-Sabatier (2010) ''Deglacial Meltwater Pulse 1B and Younger Dryas Sea Levels Revisited with Boreholes at Tahiti.'' Science. 327:1235-1237.〕
Other differing estimates about the magnitude of meltwater pulse 1B have been published. In 2010, Standford and others found it to be "robustly expressed" as a multi-millennial interval of enhanced rates of sea-level rise between 11,500 and 8,800 calendar years ago with peak rates of rise of up to 25 mm/yr.〔Stanford, J.D., R. Hemingway, E.J. Rohling, P.G. Challenor, M. Medina-Elizalde, and A.J. Lester (2011) ''Sea-level probability for the last deglaciation: a statistical analysis of far-field records.'' Global and Planetary Change. 79:193–203.〕 In 2004, Liu and Milliman reexamined the original data from Barbados and Tahiti and reconsidered the mechanics and sedimentology of reef drowning by sea level rise. They concluded that meltwater pulse 1B occurred between 11,500 and 11,200 calendar years ago, a 300 calendar year interval, during which sea level rose from to , giving a mean annual rate of around 40mm/yr〔Liu, J.P., and J.D. Milliman (2004) ''Reconsidering Melt-water Pulses lA and lB: Global Impacts of Rapid Sea- level Rise.'' Journal of Ocean University of China. 3(2):183-190.〕 More recently, the estimated magnitude of meltwater pulse 1B has been revised downward to between and less than .〔Blanchon, P., and J. Shaw (1995) ''Reef drowning during the last deglaciation: Evidence for catastrophic sea-level rise and ice-sheet collapse.'' Geology. 23(1):4-8.〕〔Whitehouse, P.L., and S.L. Bradley (2013) ''Eustatic sea-level changes since the Last Glacial Maximum.'' In: Elias, S.A., ed., pp. 439-451. ''Encyclopedia of Quaternary Sciences'', 2nd Edition. Elsevier (Amsterdam).〕
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