C51D-04
Complex Relationship between Accumulation and Temperature in West Antarctica for the Past 31,000 Years

Friday, 18 December 2015: 08:45
3005 (Moscone West)
Tyler J Fudge1, Bradley R Markle1, Kurt M Cuffey2, Christo Buizert3, Kendrick Taylor4, Eric J. Steig1, Edwin D Waddington5, Howard Conway1 and Michelle R Koutnik6, (1)University of Washington Seattle Campus, Seattle, WA, United States, (2)University of California Berkeley, Berkeley, CA, United States, (3)Oregon State University, Corvallis, OR, United States, (4)Desert Research Institute Reno, Reno, NV, United States, (5)Applied Physics Laboratory University of Washington, Kenmore, WA, United States, (6)Univ Washington, Seattle, WA, United States
Abstract:
The contribution to sea level change from the Antarctic ice sheet depends on the balance between ice loss along the margin and snowfall in the interior. Studies of accumulation trends for the past few decades show large interannual variability, and present inconsistent relationships with site temperature. Here we investigate the relationship between accumulation and temperature on centennial to multi-millennial timescales for the past 31 ka using records from the WAIS Divide ice core (WDC) in central West Antarctica. WDC is unique in Antarctica because (1) the accumulation history is well-constrained by measured annual layer thicknesses and (2) the temperature history is derived from the stable isotope record that has been calibrated by the internal ice-sheet (borehole) temperature.

Considering the full 31ka record, the accumulation and temperature vary coherently on timescales longer than 2ka and we find that a 1˚C warming corresponds to a 5% increase in accumulation, in agreement with GCM simulations. However, the relationship is not temporally consistent. For the past 8 ka, accumulation and temperature are coherent to timescales as short as 300 years and the accumulation/temperature scaling is much larger, 17% per ˚C; in contrast, from 8ka to 15 ka, a period which includes three abrupt climate change events, there is no coherent relationship and the accumulation-temperature relationship is slightly anti-correlated.

A transient GCM simulation for the past 22 ka (TraCE) shows coherence at all timescales in central West Antarctica and a consistent ~5% increase per ˚C. Whether the data and model differences extend beyond central West Antarctica cannot be assessed. The varying relationship between temperature and accumulation at WAIS Divide indicate that atmospheric circulations patterns are critical to predicting future Antarctic accumulation and that climate models may not be fully capturing the dynamics, at least in central West Antarctica. Therefore, considerable uncertainty exists in the projected accumulation increase on the Antarctic ice sheet in a warming climate.

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