TY - JOUR
T1 - Giant boulders and Last Interglacial storm intensity in the North Atlantic
AU - Rovere, Alessio
AU - Casella, Elisa
AU - Harris, Daniel L.
AU - Lorscheid, Thomas
AU - Nandasena, Napayalage A.K.
AU - Dyer, Blake
AU - Sandstrom, Michael R.
AU - Stocchi, Paolo
AU - D’Andrea, William J.
AU - Raymo, Maureen E.
N1 - Funding Information:
ACKNOWLEDGMENTS. We acknowledge P. J. Hearty and J. Hansen for discussions on LIG “superstorms.” We acknowledge useful discussions during the workshops of Project 1603P (Modelling Paleo Processes, International Union for Quaternary Sciences, INQUA) and of the Paleo Constraints on Sea Level Rise (PALSEA) working group (Past Global Changes, PAGES/ INQUA). Sarah Dendy and Alexander Janßen are acknowledged for help in the data analysis process. This research has been done under the permits issued by the Bahamas Environment, Science & Technology Commission [G-258] and the Bahamas Civil Aviation Authority (BCAA). We thank the staff at the Gerace Research Centre (San Salvador Island, The Bahamas) for logistical support for this research, the BCAA staff for assistance with aerial permits applications, and the staff at the Eleuthera Tourist Office for information on modern analog boulders. Boundary conditions and topography used in this study were extracted from datasets by the National Oceanic and Atmospheric Administration (NOAA), the US Geological Survey (USGS), the National Aeronautics and Space Administration (NASA), the Australian Bureau of Meteorology, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), and the British Oceanographic Data Centre (BODC). The map in Fig. 1A was created using Esri ArcGIS basemaps and software (ArcMap). This research was financially supported by the Institutional Strategy of the University of Bremen, funded by the German Excellence Initiative (ABPZuK-03/2014); the Leibniz Centre for Tropical Marine Research (ZMT); National Science Foundation (NSF) Grant OCE-1202632 “PLIOMAX” and NSF GRFP Grant DGE-11-44155; and the World Surf League PURE through a grant from the Center for Climate and Life at the Lamont-Doherty Earth Observatory of Columbia University.
Publisher Copyright:
© 2017, National Academy of Sciences. All rights reserved.
PY - 2017/11/14
Y1 - 2017/11/14
N2 - As global climate warms and sea level rises, coastal areas will be subject to more frequent extreme flooding and hurricanes. Geologic evidence for extreme coastal storms during past warm periods has the potential to provide fundamental insights into their future intensity. Recent studies argue that during the Last Interglacial (MIS 5e, ∼128–116 ka) tropical and extratropical North Atlantic cyclones may have been more intense than at present, and may have produced waves larger than those observed historically. Such strong swells are inferred to have created a number of geologic features that can be observed today along the coastlines of Bermuda and the Bahamas. In this paper, we investigate the most iconic among these features: massive boulders atop a cliff in North Eleuthera, Bahamas. We combine geologic field surveys, wave models, and boulder transport equations to test the hypothesis that such boulders must have been emplaced by storms of greater-than-historical intensity. By contrast, our results suggest that with the higher relative sea level (RSL) estimated for the Bahamas during MIS 5e, boulders of this size could have been transported by waves generated by storms of historical intensity. Thus, while the megaboulders of Eleuthera cannot be used as geologic proof for past “superstorms,” they do show that with rising sea levels, cliffs and coastal barriers will be subject to significantly greater erosional energy, even without changes in storm intensity.
AB - As global climate warms and sea level rises, coastal areas will be subject to more frequent extreme flooding and hurricanes. Geologic evidence for extreme coastal storms during past warm periods has the potential to provide fundamental insights into their future intensity. Recent studies argue that during the Last Interglacial (MIS 5e, ∼128–116 ka) tropical and extratropical North Atlantic cyclones may have been more intense than at present, and may have produced waves larger than those observed historically. Such strong swells are inferred to have created a number of geologic features that can be observed today along the coastlines of Bermuda and the Bahamas. In this paper, we investigate the most iconic among these features: massive boulders atop a cliff in North Eleuthera, Bahamas. We combine geologic field surveys, wave models, and boulder transport equations to test the hypothesis that such boulders must have been emplaced by storms of greater-than-historical intensity. By contrast, our results suggest that with the higher relative sea level (RSL) estimated for the Bahamas during MIS 5e, boulders of this size could have been transported by waves generated by storms of historical intensity. Thus, while the megaboulders of Eleuthera cannot be used as geologic proof for past “superstorms,” they do show that with rising sea levels, cliffs and coastal barriers will be subject to significantly greater erosional energy, even without changes in storm intensity.
KW - Climate change
KW - Eemian
KW - Extreme waves
KW - Last Interglacial
KW - Superstorms
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U2 - 10.1073/pnas.1712433114
DO - 10.1073/pnas.1712433114
M3 - Article
C2 - 29087331
AN - SCOPUS:85033717522
SN - 0027-8424
VL - 114
SP - 12144
EP - 12149
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 46
ER -