Giant boulders and Last Interglacial storm intensity in the North Atlantic

Alessio Rovere, Elisa Casella, Daniel L. Harris, Thomas Lorscheid, Napayalage A.K. Nandasena, Blake Dyer, Michael R. Sandstrom, Paolo Stocchi, William J. D’Andrea, Maureen E. Raymo

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)12144-12149
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number46
DOIs
Publication statusPublished - Nov 14 2017
Externally publishedYes

Keywords

  • Climate change
  • Eemian
  • Extreme waves
  • Last Interglacial
  • Superstorms

ASJC Scopus subject areas

  • General

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