TY - JOUR T1 - The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin JF - Scientific Reports Y1 - 2016 A1 - van Hengstum, Peter J. A1 - Donnelly, Jeffrey P. A1 - Fall, Patricia L. A1 - Toomey, Michael R. A1 - Albury, Nancy A. A1 - Kakuk, Brian KW - Climate-change impacts KW - Forest ecology KW - Ocean sciences KW - Palaeoclimate AB - Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval. VL - 6 UR - http://www.nature.com/articles/srep21728http://www.nature.com/articles/srep21728.pdfhttp://www.nature.com/articles/srep21728.pdfhttp://www.nature.com/articles/srep21728 IS - 1 ER - TY - JOUR T1 - South Pacific hydrologic and cyclone variability during the last 3000 years JF - Paleoceanography Y1 - 2016 A1 - Toomey, Michael R. A1 - Donnelly, Jeffrey P. A1 - Tierney, Jessica E. AB - Major excursions in the position of the South Pacific Convergence Zone (SPCZ) and/or changes in its intensity are thought to drive tropical cyclone (TC) and precipitation variability across much of the central South Pacific. A lack of conventional sites typically used for multimillennial proxy reconstructions has limited efforts to extend observational rainfall/TC data sets and our ability to fully assess the risks posed to central Pacific islands by future changes in fresh water availability or the frequency of storm landfalls. Here we use the sedimentary record of Apu Bay, offshore the island of Tahaa, French Polynesia, to explore the relationship between SPCZ position/intensity and tropical cyclone overwash, resolved at decadal time scales, since 3200 years B.P. Changes in orbital precession and Pacific sea surface temperatures best explain evidence for a coordinated pattern of rainfall variability at Tahaa and across the Pacific over the late Holocene. Our companion record of tropical cyclone activity from Tahaa suggests major storm activity was higher between 2600-1500 years B.P., when decadal scale SPCZ variability may also have been stronger. A transition to lower storm frequency and a shift or expansion of the SPCZ toward French Polynesia around 1000 years B.P. may have prompted Polynesian migration into the central Pacific. VL - 31 UR - http://doi.wiley.com/10.1002/2015PA002870 IS - 4 ER - TY - JOUR T1 - Climate forcing of unprecedented intense-hurricane activity in the last 2000 years JF - EARTHS FUTURE Y1 - 2015 A1 - Donnelly, Jeffrey P. A1 - Hawkes, Andrea D. A1 - Lane, Philip A1 - MacDonald, Dana A1 - Shuman, Bryan N. A1 - Toomey, Michael R. A1 - van Hengstum, Peter J. A1 - Woodruff, Jonathan D. KW - Climate change KW - common era KW - Holocene KW - sea surface temperature KW - tropical cyclones AB - How climate controls hurricane variability has critical implications for society is not well understood. In part, our understanding is hampered by the short and incomplete observational hurricane record. Here we present a synthesis of intense-hurricane activity from the western North Atlantic over the past two millennia, which is supported by a new, exceptionally well-resolved record from Salt Pond, Massachusetts (USA). At Salt Pond, three coarse grained event beds deposited in the historical interval are consistent with severe hurricanes in 1991 (Bob), 1675, and 1635 C.E., and provide modern analogs for 32 other prehistoric event beds. Two intervals of heightened frequency of event bed deposition between 1400 and 1675 C.E. (10 events) and 150 and 1150 C.E. (23 events), represent the local expression of coherent regional patterns in intense-hurricane-induced event beds. Our synthesis indicates that much of the western North Atlantic appears to have been active between 250 and 1150 C.E., with high levels of activity persisting in the Caribbean and Gulf of Mexico until 1400 C.E. This interval was one with relatively warm sea surface temperatures (SSTs) in the main development region (MDR). A shift in activity to the North American east coast occurred ca. 1400 C.E., with more frequent severe hurricane strikes recorded from The Bahamas to New England between 1400 and 1675 C.E. A warm SST anomaly along the western North Atlantic, rather than within the MDR, likely contributed to the later active interval being restricted to the east coast. VL - 3 ER - TY - JOUR T1 - Reconstructing 7000 years of North Atlantic hurricane variability using deep-sea sediment cores from the western Great Bahama Bank JF - Paleoceanography Y1 - 2013 A1 - Toomey, Michael R. A1 - Curry, William B. A1 - Donnelly, Jeffrey P. A1 - van Hengstum, Peter J. AB - [1] Available overwash records from coastal barrier systems document significant variability in North Atlantic hurricane activity during the late Holocene. The same climate forcings that may have controlled cyclone activity over this interval (e.g., the West African Monsoon, El Niño–Southern Oscillation (ENSO)) show abrupt changes around 6000 yrs B.P., but most coastal sedimentary records do not span this time period. Establishing longer records is essential for understanding mid-Holocene patterns of storminess and their climatic drivers, which will lead to better forecasting of how climate change over the next century may affect tropical cyclone frequency and intensity. Storms are thought to be an important mechanism for transporting coarse sediment from shallow carbonate platforms to the deep-sea, and bank-edge sediments may offer an unexplored archive of long-term hurricane activity. Here, we develop this new approach, reconstructing more than 7000 years of North Atlantic hurricane variability using coarse-grained deposits in sediment cores from the leeward margin of the Great Bahama Bank. High energy event layers within the resulting archive are (1) broadly correlated throughout an offbank transect of multi-cores, (2) closely matched with historic hurricane events, and (3) synchronous with previous intervals of heightened North Atlantic hurricane activity in overwash reconstructions from Puerto Rico and elsewhere in the Bahamas. Lower storm frequency prior to 4400 yrs B.P. in our records suggests that precession and increased NH summer insolation may have greatly limited hurricane potential intensity, outweighing weakened ENSO and a stronger West African Monsoon—factors thought to be favorable for hurricane development. VL - 28 UR - http://doi.wiley.com/10.1002/palo.v28.1http://doi.wiley.com/10.1002/palo.20012https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fpalo.20012 IS - 1 ER - TY - JOUR T1 - Reconstructing mid-late Holocene cyclone variability in the Central Pacific using sedimentary records from Tahaa, French Polynesia JF - Quaternary Science Reviews Y1 - 2013 A1 - Toomey, Michael R. A1 - Donnelly, Jeffrey P. A1 - Woodruff, Jonathan D. KW - enso KW - Precession KW - South Pacific KW - tropical cyclones AB - We lack an understanding of the geographic and temporal controls on South Pacific cyclone activity. Overwash records from backbarrier salt marshes and coastal ponds have been used to reconstruct tropical cyclone strikes in the North Atlantic basin. However, these specific backbarrier environments are scarce in the South Pacific, with cyclone records limited primarily to the period of modern observation. This instrumental record suggests a correlation with the El Niño–Southern Oscillation (ENSO), but longer records are necessary to test this relationship over geologic timescales and explore other potential climate drivers of tropical cyclone variability. Deep lagoons behind coral reefs are widespread in the Pacific and provide an alternative setting for developing long-term sedimentary reconstructions of tropical cyclone occurrence. Coarse-grained event deposits within the sediments of a back-reef lagoon surrounding Tahaa reveal a 5000-year record of cyclone occurrences. Timing of recent high-energy deposits matches well with observed tropical cyclone strikes and indicates coarse deposits are storm derived. Longer records show tropical cyclone activity was higher from 5000 to 3800 and 2900 to 500 yrs BP. Comparison to records from the North Pacific (out-of-phase) and North Atlantic (in phase) suggests a coordinated pattern of storm activity across tropical cyclone basins over the mid-late Holocene. The changes in tropical cyclone activity we observe in the South Pacific and across other basins may be related to ENSO as well as precession driven changes in ocean-atmosphere thermal gradients. VL - 77 UR - http://linkinghub.elsevier.com/retrieve/pii/S0277379113002849http://api.elsevier.com/content/article/PII:S0277379113002849?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0277379113002849?httpAccept=text/plain ER - TY - JOUR T1 - Reconstructing mid-late Holocene cyclone variability in the Central Pacific using sedimentary records from Tahaa, French Polynesia JF - Quaternary Science Reviews Y1 - 2013 A1 - Toomey, Michael R. A1 - Donnelly, Jeffrey P. A1 - Woodruff, Jonathan D. AB - We lack an understanding of the geographic and temporal controls on South Pacific cyclone activity. Overwash records from backbarrier salt marshes and coastal ponds have been used to reconstruct tropical cyclone strikes in the North Atlantic basin. However, these specific backbarrier environments are scarce in the South Pacific, with cyclone records limited primarily to the period of modern observation. This instrumental record suggests a correlation with the El Niño–Southern Oscillation (ENSO), but longer records are necessary to test this relationship over geologic timescales and explore other potential climate drivers of tropical cyclone variability. Deep lagoons behind coral reefs are widespread in the Pacific and provide an alternative setting for developing long-term sedimentary reconstructions of tropical cyclone occurrence. Coarse-grained event deposits within the sediments of a back-reef lagoon surrounding Tahaa reveal a 5000-year record of cyclone occurrences. Timing of recent high-energy deposits matches well with observed tropical cyclone strikes and indicates coarse deposits are storm derived. Longer records show tropical cyclone activity was higher from 5000 to 3800 and 2900 to 500 yrs BP. Comparison to records from the North Pacific (out-of-phase) and North Atlantic (in phase) suggests a coordinated pattern of storm activity across tropical cyclone basins over the mid-late Holocene. The changes in tropical cyclone activity we observe in the South Pacific and across other basins may be related to ENSO as well as precession driven changes in ocean-atmosphere thermal gradients. VL - 77 UR - http://www.sciencedirect.com/science/article/pii/S0277379113002849 JO - Reconstructing mid-late Holocene cyclone variability in the Central Pacific using sedimentary records from Tahaa, French Polynesia ER -