文章标题：Twentieth-century contribution to sea-level rise from uncharted glaciers

文章作者：David Parkes & Ben Marzeion

DOI:https://doi.org/10.1038/s41586-018-0687-9

原文链接：https://www.nature.com/articles/s41586-018-0687-9

内容提要：二十世纪全球平均海平面上升（GMSLR）主要原因包括冰川和冰盖的质量损失、海水的热膨胀和陆地水储存的变化。然而，无论是基于观测还是基于气候模型的结果，这些贡献因子的估计总和往往不能达到观察到的GMSLR。目前冰川对GMSLR贡献的估计依赖于冰川库存数据的分析，而冰川库存数据则通过对最小冰川大小等级进行采样分析而得出。本研究表示，在1901~2015年期间，失踪和消失的冰川产生了大约16.7~48.0毫米的海平面当量（SLE）。由于区域分析和理论规模的关系，本文预计今天存在的那些小冰川就是缺失的冰川，但这些冰川没有在清单中体现出来。这些冰川为历史上的SLE贡献了大约12.3~42.7毫米。此外，那些存在于1901年但已于2015年消失的冰川、不能包含在现代全球冰川库存中，而这些消失的冰川对SLE的贡献估计在4.4~5.3毫米之间。未考虑这些未知的冰川可能是难以正确估算二十世纪GMSLR的一个重要原因：它们平均每年的SLE贡献约为0.17~0.53毫米，而1901~1990年期间的预算差异为每个GMSLR约0.5毫米。虽然未知的冰川在未来的海平面上升中起着微不足道的作用，且在1990年之后就不那么重要了，但这些发现意味着我们不需要通过一些未发现的物理过程来估算历史海平面变化。

论文摘要：Global-mean sea-level rise (GMSLR) during the twentieth century was primarily caused by glacier and ice-sheet mass loss, thermal expansion of ocean water and changes in terrestrial water storage1. Whether based on observations2 or results of climate models3,4, however, the sum of estimates of each of these contributions tends to fall short of the observed GMSLR. Current estimates of the glacier contribution to GMSLR rely on the analysis of glacier inventory data, which are known to undersample the smallest glacier size classes5,6. Here we show that from 1901 to 2015, missing and disappeared glaciers produced a sea-level equivalent (SLE) of approximately 16.7 to 48.0 millimetres. Missing glaciers are those small glaciers that we expect to exist today, owing to regional analyses and theoretical scaling relationships, but that are not represented in the inventories. These glaciers contributed approximately 12.3 to 42.7 millimetres to the historical SLE. Additionally, disappeared glaciers (those that existed in 1901 but had melted away by 2015, and that therefore cannot be included in modern global glacier inventories) made an estimated contribution of between 4.4 and 5.3 millimetres. Failure to consider these uncharted glaciers may be an important cause of difficulties in closing the GMSLR budget during the twentieth century: their contribution is on average between 0.17 and 0.53 millimetres of SLE per year, compared to a budget discrepancy of about 0.5 millimetres of GMSLR per year between 1901 and 1990. Although the uncharted glaciers will have a minimal role in sea-level rise in the future, and are less important after 1990, these findings imply that undiscovered physical processes are not required to close the historical sea-level budget.

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