Toomey Michael R.

No Thumbnail Available
Last Name
Toomey
First Name
Michael R.
ORCID

Search Results

Now showing 1 - 14 of 14
  • Article
  • Article
    Climate forcing of unprecedented intense-hurricane activity in the last 2000 years
    (John Wiley & Sons, 2015-02-23) Donnelly, Jeffrey P. ; Hawkes, Andrea D. ; Lane, D. Philip ; MacDonald, Dana ; Shuman, Bryan N. ; Toomey, Michael R. ; van Hengstum, Peter J. ; Woodruff, Jonathan D.
    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.
  • Preprint
    Increased typhoon activity in the Pacific deep tropics driven by Little Ice Age circulation changes
    (Nature Research, 2020-11-16) Bramante, James F. ; Ford, Murray R. ; Kench, Paul S. ; Ashton, Andrew D. ; Toomey, Michael R. ; Sullivan, Richard M. ; Karnauskas, Kristopher B. ; Ummenhofer, Caroline C. ; Donnelly, Jeffrey P.
    The instrumental record reveals that tropical cyclone activity is sensitive to oceanic and atmospheric variability on inter-annual and decadal scales. However, our understanding of the influence of climate on tropical cyclone behaviour is restricted by the short historical record and the sparseness of prehistorical reconstructions, particularly in the western North Pacific, where coastal communities suffer loss of life and livelihood from typhoons annually. Here, to explore past regional typhoon dynamics, we reconstruct three millennia of deep tropical North Pacific cyclogenesis. Combined with existing records, our reconstruction demonstrates that low-baseline typhoon activity prior to 1350 ce was followed by an interval of frequent storms during the Little Ice Age. This pattern, concurrent with hydroclimate proxy variability, suggests a centennial-scale link between Pacific hydroclimate and tropical cyclone climatology. An ensemble of global climate models demonstrates a migration of the Pacific Walker circulation and variability in two Pacific climate modes during the Little Ice Age, which probably contributed to enhanced tropical cyclone activity in the tropical western North Pacific. In the next century, projected changes to the Pacific Walker circulation and expansion of the tropics will invert these Little Ice Age hydroclimate trends, potentially reducing typhoon activity in the deep tropical Pacific.
  • Article
    South Pacific hydrologic and cyclone variability during the last 3000 years
    (John Wiley & Sons, 2016-04-18) Toomey, Michael R. ; Donnelly, Jeffrey P. ; Tierney, Jessica E.
    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.
  • Thesis
    Quaternary morphology and paleoenvironmental records of carbonate islands
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2014-02) Toomey, Michael R.
    Here I use a simple numerical model of reef profile evolution to show that the presentday morphology of carbonate islands has developed largely in response to late Pleistocene sea level oscillations in addition to variable vertical motion and reef accretion rates. In particular, large amplitude ‘ice-house’ sea-level variability resulted in long lagoonal depositional hiatuses, producing the morphology characteristic of modern-day barrier reefs. Reactivation of carbonate factories, transport of coarse reef material and rapid infilling of shallow water accommodation space since deglaciation makes these unique sites for reconstructing Holocene climate. Integration of new tropical cyclone reconstructions from both backbarrier reef (central Pacific) and carbonate bank (the Bahamas) settings with existing storm archives suggests a coordinated pattern of cyclone activity across storm basins since the late Holocene. Seesawing of intense tropical cyclone activity between the western Pacific (~0-1000 yrs BP) and North Atlantic/Central Pacific (~1000-2500 yrs BP) appears closely tied with hydrographic patterns in the tropical Pacific and El Niño-like variability. Decoupling of North Atlantic (inactive) and South Pacific (active) tropical cyclone patterns during the mid-Holocene suggests precession driven changes in storm season insolation may constrain ocean-atmosphere thermal gradients and therefore cyclone potential intensity on orbital timescales.
  • Article
    The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin
    (Nature Publishing Group, 2016-02-24) van Hengstum, Peter J. ; Donnelly, Jeffrey P. ; Fall, Patricia L. ; Toomey, Michael R. ; Albury, Nancy A. ; Kakuk, Brian
    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.
  • Article
    Seismic evidence of glacial-age river incision into the Tahaa barrier reef, French Polynesia
    (Elsevier, 2016-04-13) Toomey, Michael R. ; Woodruff, Jonathan D. ; Donnelly, Jeffrey P. ; Ashton, Andrew D. ; Perron, J. Taylor
    Rivers have long been recognized for their ability to shape reef-bound volcanic islands. On the time-scale of glacial–interglacial sea-level cycles, fluvial incision of exposed barrier reef lagoons may compete with constructional coral growth to shape the coastal geomorphology of ocean islands. However, overprinting of Pleistocene landscapes by Holocene erosion or sedimentation has largely obscured the role lowstand river incision may have played in developing the deep lagoons typical of modern barrier reefs. Here we use high-resolution seismic imagery and core stratigraphy to examine how erosion and/or deposition by upland drainage networks has shaped coastal morphology on Tahaa, a barrier reef-bound island located along the Society Islands hotspot chain in French Polynesia. At Tahaa, we find that many channels, incised into the lagoon floor during Pleistocene sea-level lowstands, are located near the mouths of upstream terrestrial drainages. Steeper antecedent topography appears to have enhanced lowstand fluvial erosion along Tahaa's southwestern coast and maintained a deep pass. During highstands, upland drainages appear to contribute little sediment to refilling accommodation space in the lagoon. Rather, the flushing of fine carbonate sediment out of incised fluvial channels by storms and currents appears to have limited lagoonal infilling and further reinforced development of deep barrier reef lagoons during periods of highstand submersion.
  • Article
    Reconstructing 7000 years of North Atlantic hurricane variability using deep-sea sediment cores from the western Great Bahama Bank
    (John Wiley & Sons, 2013-03-14) Toomey, Michael R. ; Curry, William B. ; Donnelly, Jeffrey P. ; van Hengstum, Peter J.
    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.
  • Article
    Intense hurricane activity over the past 1500 years at South Andros Island, the Bahamas
    (American Geophysical Union, 2019-10-19) Wallace, Elizabeth J. ; Donnelly, Jeffrey P. ; van Hengstum, Peter J. ; Wiman, Charlotte ; Sullivan, Richard M. ; Winkler, Tyler S. ; D'Entremont, Nicole ; Toomey, Michael R. ; Albury, Nancy A.
    Hurricanes cause substantial loss of life and resources in coastal areas. Unfortunately, historical hurricane records are too short and incomplete to capture hurricane‐climate interactions on multi‐decadal and longer timescales. Coarse‐grained, hurricane‐induced deposits preserved in blue holes in the Caribbean can provide records of past hurricane activity extending back thousands of years. Here we present a high resolution record of intense hurricane events over the past 1500 years from a blue hole on South Andros Island on the Great Bahama Bank. This record is corroborated by shorter reconstructions from cores collected at two nearby blue holes. The record contains coarse‐grained event deposits attributable to known historical hurricane strikes within age uncertainties. Over the past 1500 years, South Andros shows evidence of four active periods of hurricane activity. None of these active intervals occurred in the past 163 years. We suggest that Intertropical Convergence Zone position modulates hurricane activity on the island based on a correlation with Cariaco Basin titanium concentrations. An anomalous gap in activity on South Andros Island in the early 13th century corresponds to a period of increased volcanism. The patterns of hurricane activity reconstructed from South Andros Island closely match those from the northeastern Gulf of Mexico but are anti‐phased with records from New England. We suggest that either changes in local environmental conditions (e.g., SSTs) or a northeastward shift in storm tracks can account for the increased activity in the western North Atlantic when the Gulf of Mexico and southeastern Caribbean are less active.
  • Preprint
    Increased hurricane frequency near Florida during Younger Dryas Atlantic Meridional Overturning Circulation slowdown
    ( 2017-10) Toomey, Michael R. ; Korty, Robert ; Donnelly, Jeffrey P. ; van Hengstum, Peter ; Curry, William B.
    The risk posed by intensification of North Atlantic hurricane activity remains controversial, in part due to a lack of available storm proxy records that extend beyond the relatively stable climates of the late Holocene. Here we present a record of storm-triggered turbidite deposition offshore the Dry Tortugas, south Florida, USA, that spans abrupt transitions in North Atlantic sea-surface temperature and Atlantic Meridional Overturning Circulation (AMOC) during the Younger Dryas (12.9–11.7 k.y. B.P.). Despite potentially hostile conditions for cyclogenesis in the tropical North Atlantic at this time, our record and numerical experiments suggest that strong hurricanes may have regularly impacted Florida. Less severe surface cooling at mid-latitudes (~20–40°N) than across much of the tropical North Atlantic (~10–20°N) in response to AMOC reduction may best explain strong hurricane activity during the Younger Dryas near the Dry Tortugas and, potentially, along the entire southeastern coast of the United States.
  • Article
    Late Cenozoic sea level and the rise of modern rimmed atolls
    (Elsevier, 2016-03-23) Toomey, Michael R. ; Ashton, Andrew D. ; Raymo, Maureen E. ; Perron, J. Taylor
    Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sea level over the past 8.5 million years. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~ 20 m/Myr) and our numerical modeling results suggest that low sea levels (50–125 m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sea level was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.
  • Article
    Historically unprecedented Northern Gulf of Mexico hurricane activity from 650 to 1250 CE
    (Nature Research, 2020-11-05) Rodysill, Jessica R. ; Donnelly, Jeffrey P. ; Sullivan, Richard M. ; Lane, D. Philip ; Toomey, Michael R. ; Woodruff, Jonathan D. ; Hawkes, Andrea D. ; MacDonald, Dana ; D'Entremont, Nicole ; McKeon, Kelly ; Wallace, Elizabeth J. ; van Hengstum, Peter J.
    Hurricane Michael (2018) was the first Category 5 storm on record to make landfall on the Florida panhandle since at least 1851 CE (Common Era), and it resulted in the loss of 59 lives and $25 billion in damages across the southeastern U.S. This event placed a spotlight on recent intense (exceeding Category 4 or 5 on the Saffir-Simpson Hurricane Wind Scale) hurricane landfalls, prompting questions about the natural range in variability of hurricane activity that the instrumental record is too short to address. Of particular interest is determining whether the frequency of recent intense hurricane landfalls in the northern Gulf of Mexico (GOM) is within or outside the natural range of intense hurricane activity prior to 1851 CE. In this study, we identify intense hurricane landfalls in northwest Florida during the past 2000 years based on coarse anomaly event detection from two coastal lacustrine sediment archives. We identified a historically unprecedented period of heightened storm activity common to four Florida panhandle localities from 650 to 1250 CE and a shift to a relatively quiescent storm climate in the GOM spanning the past six centuries. Our study provides long-term context for events like Hurricane Michael and suggests that the observational period 1851 CE to present may underrepresent the natural range in landfalling hurricane activity.
  • Article
    The mighty Susquehanna-extreme floods in Eastern North America during the past two millennia
    (American Geophysical Union, 2019-02-19) Toomey, Michael R. ; Cantwell, Meagan ; Colman, Steven ; Cronin, Thomas M. ; Donnelly, Jeffrey P. ; Giosan, Liviu ; Heil, Clifford W. ; Korty, Robert ; Marot, Marci ; Willard, D. A.
    The hazards posed by infrequent major floods to communities along the Susquehanna River and the ecological health of Chesapeake Bay remain largely unconstrained due to the short length of streamgage records. Here we develop a history of high‐flow events on the Susquehanna River during the late Holocene from flood deposits contained in MD99‐2209, a sediment core recovered in 26 m of water from Chesapeake Bay near Annapolis, Maryland, United States. We identify coarse‐grained deposits left by Hurricane Agnes (1972) and the Great Flood of 1936, as well as during three intervals that predate instrumental flood records (~1800–1500, 1300–1100, and 400–0 CE). Comparison to sedimentary proxy data (pollen and ostracode Mg/Ca ratios) from the same core site indicates that prehistoric flooding on the Susquehanna often accompanied cooler‐than‐usual winter/spring temperatures near Chesapeake Bay—typical of negative phases of the North Atlantic Oscillation and conditions thought to foster hurricane landfalls along the East Coast.
  • Dataset
    Increased typhoon activity in the Pacific deep tropics driven by Little Ice Age circulation changes
    (Woods Hole Oceanographic Institution, 2020-09-02) Bramante, James F. ; Ford, Murray R. ; Kench, Paul S. ; Ashton, Andrew D. ; Toomey, Michael R. ; Sullivan, Richard M. ; Karnauskas, Kristopher B. ; Ummenhofer, Caroline C. ; Donnelly, Jeffrey P.
    The instrumental record reveals that tropical cyclone activity is sensitive to oceanic and atmospheric variability on inter-annual and decadal scales. However, our understanding of climate’s influence on tropical cyclone behavior is restricted by the short historical record and sparse prehistorical reconstructions, particularly in the western North Pacific where coastal communities suffer loss of life and livelihood from typhoons annually. Here we reconstruct three millennia of deep tropical North Pacific cyclogenesis and compare with other records to explore past regional typhoon dynamics. These records demonstrate low baseline activity prior to 1350 C.E. followed by a rapid culmination in activity during the Little Ice Age. This pattern is concurrent with hydroclimate proxy variability, suggesting a centennial-scale link between Pacific hydroclimate and tropical cyclone climatology. Using an ensemble of global climate models, we demonstrate that migration of the Pacific Walker circulation and variability in two Pacific climate modes during the Little Ice Age contributed to enhanced tropical cyclone activity in the tropical western North Pacific. Changes to Walker Circulation and expansion of the tropics projected for the next century invert Little Ice Age hydroclimate trends, potentially reducing typhoon activity in the deep tropical Pacific.