Bowling Jade S, McMillan Malcolm, Leeson Amber A, Livingstone Stephen J, Sole Andrew J, Ng Felix S L, Karlsson Nanna B, Nienow Peter, Boxall Karla, Noël Brice, van den Broeke Michiel R, Slater Thomas, Maddalena Jennifer, Sandberg Sørensen Louise, Simonsen Sebastian B, Mouginot Jérémie, Millan Romain, Melling Laura, Taylor Liam, Humbert Angelika
Lancaster Environment Centre, Lancaster University, Lancaster, UK.
UK Centre for Polar Observation and Modelling, Lancaster University, Lancaster, UK.
Nat Geosci. 2025;18(8):740-746. doi: 10.1038/s41561-025-01746-9. Epub 2025 Jul 30.
As Earth's climate warms, surface melting of the Greenland Ice Sheet has intensified, increasing rates of sea-level rise. Observations and theory indicate that meltwater generated at the ice sheet surface can drain to its bed, where it flows relatively unhindered to the ocean. This understanding of water movement within and beneath ice sheets underpins the theoretical models that are used to make projections of ice sheet change. Here we present evidence of a destructive mode of meltwater drainage in Greenland. Using multiple satellite sources, we show that a 90-million-cubic-metre subglacial flood forced its way upwards from the bed, fracturing the ice sheet, and bursting through the surface. This phenomenon was triggered by the rapid drainage of a subglacial lake and occurred in a region where the ice bed was predicted to be frozen. The resulting flood caused a rapid deceleration of the downstream marine-terminating glacier. Our observations reveal a complex, bi-directional coupling between the ice sheet's surface and basal hydrological systems and demonstrate that extreme hydrological forcing may occur in regions of predicted cold-based ice. Such processes can impact the ice sheet's dynamics and structural integrity but are not currently considered in ice sheet models.
随着地球气候变暖，格陵兰冰盖的表面融化加剧，海平面上升速度加快。观测和理论表明，冰盖表面产生的融水可以排到冰床，在那里它相对不受阻碍地流向海洋。这种对冰盖内部和底部水运动的理解是用于预测冰盖变化的理论模型的基础。在此，我们展示了格陵兰融水排水的一种破坏模式的证据。利用多个卫星数据源，我们表明一次9000万立方米的冰下洪水从冰床向上涌起，使冰盖破裂，并冲破表面。这种现象是由一个冰下湖泊的快速排水引发的，且发生在预计冰床冻结的区域。由此产生的洪水导致下游海洋末端冰川迅速减速。我们的观测揭示了冰盖表面和底部水文系统之间复杂的双向耦合，并表明在预计为冷基冰的区域可能会出现极端水文强迫。这些过程会影响冰盖的动力学和结构完整性，但目前冰盖模型中并未考虑这些因素。
