文章标题：Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming

文章作者：Luke D. Trusel, Sarah B. Das, Matthew B. Osman, Matthew J. Evans, Ben E. Smith, Xavier Fettweis, Joseph R. McConnell, Brice P. Y. Noël & Michiel R. van den Broeke

DOI:https://doi.org/10.1038/s41586-018-0752-4

原文链接：https://www.nature.com/articles/s41586-018-0752-4

内容提要：格陵兰冰盖（GrIS）是全球海平面上升的一个增长因素，近期冰质量减少主要受地表融水径流的影响。卫星观测揭示了GrIS表层融化程度的积极趋势，但在卫星时代之前，表层融水的可变性、强度和径流量仍然不确定。本文首次展示了一个连续的多世纪GrIS地表融化观观测记录，包括其强度和径流量。研究揭示最近GrIS表层融化的程度至少在过去350年中较为特殊。通过对中西部格陵兰冰芯的地层分析，研究证明渗透区冰芯中再冻结融化层的测量值可用于量化和重复重建过去的融化速率。本研究在格陵兰岛更广泛地展示了这些冰芯衍生的融化记录与模拟融化速率、卫星衍生融化持续时间之间显着的广泛空间相关性（P < 0.01），从而能够重建过去的冰盖表面融化强度和径流量。研究发现GrIS融化的增加紧随着19世纪中叶工业时代北极变暖的开始而出现，但GrIS融化的幅度最近才出现在自然变率的范围之外。由于表层融化对夏季气温升高的非线性响应，持续的大气变暖将导致GrIS径流和海平面上升的快速增加。

论文摘要：The Greenland ice sheet (GrIS) is a growing contributor to global sea-level rise1, with recent ice mass loss dominated by surface meltwater runoff2,3. Satellite observations reveal positive trends in GrIS surface melt extent4, but melt variability, intensity and runoff remain uncertain before the satellite era. Here we present the first continuous, multi-century and observationally constrained record of GrIS surface melt intensity and runoff, revealing that the magnitude of recent GrIS melting is exceptional over at least the last 350 years. We develop this record through stratigraphic analysis of central west Greenland ice cores, and demonstrate that measurements of refrozen melt layers in percolation zone ice cores can be used to quantifiably, and reproducibly, reconstruct past melt rates. We show significant (P < 0.01) and spatially extensive correlations between these ice-core-derived melt records and modelled melt rates5,6 and satellite-derived melt duration4 across Greenland more broadly, enabling the reconstruction of past ice-sheet-scale surface melt intensity and runoff. We find that the initiation of increases in GrIS melting closely follow the onset of industrial-era Arctic warming in the mid-1800s, but that the magnitude of GrIS melting has only recently emerged beyond the range of natural variability. Owing to a nonlinear response of surface melting to increasing summer air temperatures, continued atmospheric warming will lead to rapid increases in GrIS runoff and sea-level contributions.

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