A LATE HOLOCENE LOW-FREQUENCY STORMINESS SIGNAL FROM AN INLAND SUBMARINE CAVE IN BERMUDA

Several lower-resolution (centennial-scale) climate archives from the North Atlantic region provide evidence for a persistent low-frequency (millennial-scale) ‘storminess signal’ at higher latitudes in the North Atlantic basin. During the late Holocene, this signal is concentrated during: (1) the Little Ice Age (150 to 600 cal yrs BP), (2) centered at ~1700 cal yrs BP, and (3) at ~3000 cal yrs BP. However, the specific meteorological driver (e.g., extratropical vs. tropical cyclones) and climatological forcing of this signal remain poorly understood. We will present evidence from Bermuda that this low-frequency storminess signal is also persistent in the subtropical North Atlantic region. In short, Walsingham Cavern is an inland submarine cave on the northeastern portion of Bermuda (on the isthmus between Harrington Sound and Castle Harbour) that has been accumulating marine-based sediment throughout the late Holocene. However, an increased flux of terrigenous and coarse-grained sediment into the cave through a subaerial opening occurs during the late Holocene ‘storminess intervals’. Given that this signal is now also observed in the North Atlantic subtropics at Bermuda, the role of both hurricanes and extratropical cyclones on this North Atlantic ‘storminess signal’ cannot yet be dismissed. However, a hurricane reconstruction from the southern shore of Bermuda is forthcoming that will help inform the meteorological drivers of this low-frequency signal.