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  • Five millennia of surface t...
    Fegyveresi, John M.; Alley, Richard B.; Fitzpatrick, Joan J.; Cuffey, Kurt M.; McConnell, Joseph R.; Voigt, Donald E.; Spencer, Matthew K.; Stevens, Nathan T.

    Paleoceanography, March 2016, 2016-03-00, 20160301, Letnik: 31, Številka: 3
    Journal Article

    Bubble number densities from the West Antarctic Ice Sheet (WAIS) Divide deep core in West Antarctica record relatively stable temperatures during the middle Holocene followed by late Holocene cooling. We measured bubble number density, shape, size, and arrangement on new samples of the main WAIS Divide deep core WDC06A from ~580 m to ~1600 depth. The bubble size, shape, and arrangement data confirm that the samples satisfy the requirements for temperature reconstructions. A small correction for cracks formed after core recovery allows extension of earlier work through the “brittle ice” zone, and a site‐specific calibration reduces uncertainties. Using an independently constructed accumulation rate history and a steady state bubble number density model, we determined a temperature reconstruction that agrees closely with other independent estimates, showing a stable middle Holocene, followed by a cooling of ~1.25°C in the late Holocene. Over the last ~5 millennia, accumulation has been higher during warmer times by ~12%°C−1, somewhat stronger than for thermodynamic control alone, suggesting dynamic processes. Key Points Bubble number density climate reconstruction was successfully extended for the WAIS Divide site Climate reconstruction agrees with independent estimates and reveals a late Holocene cooling Accumulation was higher during warmer times over the past ~5 millennia at the WAIS Divide site