A low climate threshold for south Greenland Ice Sheet demise during the Late Pleistocene
A low climate threshold for south Greenland Ice Sheet demise during the Late Pleistocene
复制标题
晚更新世期间格陵兰岛南部冰盖消亡的气候阈值较低
DOI：
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发表时间：
2019
影响因子：
11.1
通讯作者：
H. F. Kleiven
中科院分区：
文献类型：
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作者：
Nil Irvalı;E. Galaasen;U. Ninnemann;Y. Rosenthal;A. Born;H. F. Kleiven
重要性了解过去气候变暖如何影响格陵兰岛有助于确定未来气候变暖将如何影响格陵兰岛。格陵兰岛冰盖（GIS）在最近的间冰期期间已经退缩，这表明在现代温度的几度范围内存在一个关键的生存阈值。定义此温度阈值需要记录导致GIS消亡的过去气候。利用微体化石温度重建，我们表明，目前的间冰期是异常温和的，所有4个以前的间冰期比现在格陵兰岛附近的温暖。过去温暖的强度和持续时间对冰盖都有重要影响。值得注意的是，本世纪可能会超过过去GIS衰变的临界温度阈值。超过这一阈值的时间长短将决定格陵兰的命运。格陵兰冰盖（GIS）在最近几十年中一直在加速失去质量。模型表明，可能的温度阈值在0.8至3.2摄氏度之间，超过该阈值，GIS的衰退将不可逆转。高于某一阈值的温暖持续时间也是地理信息系统生存的一个关键决定因素，这突出表明了海洋变暖的作用，因为其惯性会破坏温暖并引发长期反馈。这些反馈被触发的确切点仍然是模棱两可的。晚更新世间冰期提供了潜在的情况下，限制过去的GIS的一系列气候状态，包括条件比现在更温暖的反应的例子。然而，在这些时期，人们对格陵兰岛附近变暖的幅度和持续时间知之甚少。使用高分辨率的多代理表面海洋气候记录南格陵兰岛，我们表明，在过去的450万年前的4个间冰期都达到了比现在的气候条件更温暖，超过了GIS崩溃的模拟温度阈值，但不同的幅度和持续时间。在海洋同位素第11 c期（MIS 11 c; 394.7 ~ 424.2 ka），南部GIS的冰川完全消退发生在仅比现在略暖的气候条件下（0.5 ± 1.6 °C），这使得GIS主要消退的温度阈值处于模型估计的低端，并在本世纪的预测范围内。
Significance Understanding how warmer climates affected Greenland in the past helps in determining how future warming will impact it. The Greenland Ice Sheet (GIS) has retreated during recent interglacials, suggesting a critical survival threshold within a few degrees of modern temperatures. Defining this temperature threshold requires records of the past climates responsible for GIS demise. Using microfossil temperature reconstructions, we show that the current interglacial is unusually moderate and that all 4 previous interglacials were warmer than present near Greenland. Both magnitude and duration of past warmth were important influences on the ice sheet. Notably, the critical temperature threshold for past GIS decay will likely be surpassed this century. The duration for which this threshold is exceeded will determine Greenland’s fate. The Greenland Ice Sheet (GIS) has been losing mass at an accelerating rate over the recent decades. Models suggest a possible temperature threshold between 0.8 and 3.2 °C, beyond which GIS decline becomes irreversible. The duration of warmth above a given threshold is also a critical determinant for GIS survival, underlining the role of ocean warming, as its inertia prolongs warmth and triggers longer-term feedbacks. The exact point at which these feedbacks are triggered remains equivocal. Late Pleistocene interglacials provide potential case examples for constraining the past response of the GIS to a range of climate states, including conditions warmer than present. However, little is known about the magnitude and duration of warming near Greenland during these periods. Using high-resolution multiproxy surface ocean climate records off southern Greenland, we show that the previous 4 interglacials over the last ∼450 ka all reached warmer than present climate conditions and exceeded the modeled temperature threshold for GIS collapse but by different magnitudes and durations. Complete deglaciation of the southern GIS in Marine Isotope Stage 11c (MIS 11c; 394.7 to 424.2 ka) occurred under climates only slightly warmer than present (∼0.5 ± 1.6 °C), placing the temperature threshold for major GIS retreat in the lower end of model estimates and within projections for this century.