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Publication - Dr William Roberts

    A new constraint on the size of Heinrich Events from an iceberg/sediment model


    Roberts, WHG, Valdes, PJ & Payne, AJ, 2014, ‘A new constraint on the size of Heinrich Events from an iceberg/sediment model’. Earth and Planetary Science Letters., pp. 1-9


    Heinrich Layers, anomalously thick layers of ice-borne sediment in the North Atlantic ocean, have long
    been associated with abrupt climate changes in glacial times. However, there is still no consensus on
    either the exact amount of ice needed to transport this sediment or how such a large volume of ice could
    be produced. Using an iceberg model that includes sediment, we simulate the delivery of sediment to the
    North Atlantic during such an event. Our model assumes that sediment is uniformly distributed within
    the ice with a concentration of 4%. Unlike sediment models which assume that the sediment lies in a
    single layer, this model can carry sediment all the way from the western to the eastern North Atlantic.
    We use a variety of different estimates for the total volume of ice released to model the sediment layer
    thickness and we show that to best fit the observations 60 × 104 km3 (with a plausible range of 30–120 ×
    104 km3 ) of ice needs to be released. This is equivalent to a 0.04 Sv (106 m3 s−1 , with a plausible range
    of 0.02–0.08 Sv) release of freshwater over the 500 yr of a typical Heinrich Event. This is a smaller flux
    of water than is required to show a significant impact on the global climate in most current “state of the
    art” GCMs.

    Full details in the University publications repository