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Grant, Katharine M
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- PublicationRestrictedSea-level variability over five glacial cycles(2014-09-25)
; ; ; ; ; ; ; ; ; ; ; ;Grant, K. M.; The Australian National University ;Rohling, E. J.; The Australian National University ;Bronk Ramsey, C.; University of Oxford ;Cheng, H.; Xi’an Jiaotong University ;Edwards, R. L.; University of Minnesota ;Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Heslop, D.; The Australian National University ;Marra, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Roberts, A. P.; The Australian National University ;Tamisiea, M. E.; National Oceanography Centre, Liverpool ;Williams, F.; University of Southampton; ; ; ; ; ; ; ; ; ; Research on global ice-volume changes during Pleistocene glacial cycles is hindered by a lack of detailed sea-level records for time intervals older than the last interglacial. Here we present the first robustly dated, continuous and highly resolved records of Red Sea sea level and rates of sea-level change over the last 500,000 years, based on tight synchronization to an Asian monsoon record. We observe maximum ‘natural’ (pre-anthropogenic forcing) sea-level rise rates below 2m per century following periods with up to twice present-day ice volumes, and substantially higher rise rates for greater ice volumes. We also find that maximum sea-level rise rates were attained within 2 kyr of the onset of deglaciations, for 85% of such events. Finally, multivariate regressions of orbital parameters, sea-level and monsoon records suggest that major meltwater pulses account for millennial-scale variability and insolation-lagged responses in Asian monsoon records.296 73 - PublicationOpen AccessOrbital phasing of the Paleocene-Eocene Thermal Maximum(2022-10-04)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ;Paleocene-Eocene sedimentary archives record a series of global warming events called hyperthermals. These events occurred across a long-term increasing temperature trend and were associated with light carbon injections that produced carbon isotope excursions (CIEs). Early Eocene hyperthermals occurred close to both long (∼405 kyr) and short (∼100 kyr) eccentricity maxima. It has been proposed that under long-term global warming, orbital forcing of climate crossed a thermodynamic threshold that destabilized carbon reservoirs and produced Early Eocene hyperthermals. However, orbital control on triggering of the largest hyperthermal, the Paleocene-Eocene Thermal Maximum (PETM), remains unclear. Identification of the precise orbital phasing of the PETM has been hindered by extensive calcium carbonate (CaCO3) dissolution, which introduces uncertainty into PETM age models. Here, we report orbital signatures in marine sediments from Contessa Road (Italy), a western Tethyan section with reduced PETM CaCO3dissolution compared to other deep ocean sites. Orbitally controlled lysocline depth adjustments and orbital phasing of the PETM CIE onset close to both long and short eccentricity maxima are documented here. Precession-based age models from the well-resolved PETM section of Ocean Drilling Program (ODP) Site 1262 (South Atlantic) confirm these results and reveal that the PETM CIE onset was partially triggered by an orbitally controlled mechanism. Climate processes associated with orbital forcing of both long and short eccentricity maxima played an important role in triggering the carbon cycle perturbations of all Paleocene-Eocene CIE events.43 22