Cosmogenic-nuclide data from Antarctic nunataks can constrain past ice sheet instabilities
Cosmogenic-nuclide data from Antarctic nunataks can constrain past ice sheet instabilities
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DOI：
10.5194/tc-17-1623-2023
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发表时间：
2023-04
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影响因子：
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通讯作者：
A. Halberstadt;G. Balco;Hannah Buchband;P. Spector
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文献类型：
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作者：
A. Halberstadt;G. Balco;Hannah Buchband;P. Spector
摘要。我们应用来自南极洲无冰区的地质证据来评估冰盖对温暖气候响应的模式模拟。这一点很重要，因为这样的模拟被用来预测未来温暖气候下的冰盖行为，但是过去比现在小的冰盖的地质证据被埋在现在的冰盖下，因此通常无法用于模型基准。为此，我们利用了另一个可访问的地质数据集：内部火山喷发基岩表面的宇宙成因核素浓度。这些数据产生了数百万年期间冰厚的频率分布，这也可以通过冰盖模型来模拟。端元瞬态模式，参数化了强和弱的海洋冰盖不稳定过程和海洋温度强迫，模拟了温暖期大和小的海平面影响，还预测了冰厚的对比和不同的频率分布。我们确定了南极洲的区域，其中预测的频率分布揭示了端元冰盖行为的差异。然后，我们证明了来自西南极洲一个基岩站点的单一综合数据集足够详细，表明数据仅与弱海洋冰盖不稳定末端成员一致，但其他不太广泛的数据集是不充分的和/或模糊的。最后，我们强调了收集额外数据可以限制过去和未来对温暖气候响应幅度的地点。
Abstract. We apply geologic evidence from ice-free areas in Antarctica to evaluate model simulations of ice sheet response to warm climates. This is important because such simulations are used to predict ice sheet behaviour in future warm climates, but geologic evidence of smaller-than-present past ice sheets is buried under the present ice sheet and therefore generally unavailable for model benchmarking. We leverage an alternative accessible geologic dataset for this purpose: cosmogenic-nuclide concentrations in bedrock surfaces of interior nunataks. These data produce a frequency distribution of ice thickness over multimillion-year periods, which is also simulated by ice sheet modelling. End-member transient models, parameterized with strong and weak marine ice sheet instability processes and ocean temperature forcings, simulate large and small sea-level impacts during warm periods and also predict contrasting and distinct frequency distributions of ice thickness. We identify regions of Antarctica where predicted frequency distributions reveal differences in end-member ice sheet behaviour. We then demonstrate that a single comprehensive dataset from one bedrock site in West Antarctica is sufficiently detailed to show that the data are consistent only with a weak marine ice sheet instability end-member, but other less extensive datasets are insufficient and/or ambiguous. Finally, we highlight locations where collecting additional data could constrain the amplitude of past and therefore future response to warm climates.