Taking stock of our losses Earth's ice sheets are melting and sea levels are rising, so it behooves us to understand better which climate processes are responsible for how much of the mass loss. Smith et al. estimated grounded and floating ice mass change for the Greenland and Antarctic ice sheets from 2003 to 2019 using satellite laser altimetry data from NASA's ICESat and ICESat-2 satellites. They show how changing ice flow, melting, and precipitation affect different regions of ice and estimate that grounded-ice loss averaged close to 320 gigatons per year over that period and contributed 14 millimeters to sea level rise. Science, this issue p. 1239 Satellite laser altimetry shows the extent of ice sheet mass loss since 2003. Quantifying changes in Earth’s ice sheets and identifying the climate drivers are central to improving sea level projections. We provide unified estimates of grounded and floating ice mass change from 2003 to 2019 using NASA’s Ice, Cloud and land Elevation Satellite (ICESat) and ICESat-2 satellite laser altimetry. Our data reveal patterns likely linked to competing climate processes: Ice loss from coastal Greenland (increased surface melt), Antarctic ice shelves (increased ocean melting), and Greenland and Antarctic outlet glaciers (dynamic response to ocean melting) was partially compensated by mass gains over ice sheet interiors (increased snow accumulation). Losses outpaced gains, with grounded-ice loss from Greenland (200 billion tonnes per year) and Antarctica (118 billion tonnes per year) contributing 14 millimeters to sea level. Mass lost from West Antarctica’s ice shelves accounted for more than 30% of that region’s total.

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普遍存在的冰盖质量损失反映了相互竞争的海洋和大气过程

评估我们的损失 地球冰盖正在融化，海平面正在上升，因此我们有必要更好地了解哪些气候过程造成了多少质量损失。史密斯等人。使用来自 NASA 的 ICESat 和 ICESat-2 卫星的卫星激光测高数据，估计了 2003 年至 2019 年格陵兰岛和南极冰盖的接地和浮冰质量变化。他们展示了变化的冰流、融化和降水如何影响冰的不同区域，并估计在此期间，地面冰损失平均每年接近 320 吉吨，并导致海平面上升 14 毫米。科学，这个问题 p。1239 卫星激光测高显示自 2003 年以来冰盖质量损失的程度。量化地球冰盖的变化并确定气候驱动因素是改善海平面预测的核心。我们使用 NASA 的冰、云和陆地高程卫星 (ICESat) 和 ICESat-2 卫星激光测高仪对 2003 年至 2019 年的地面和浮冰质量变化进行统一估计。我们的数据揭示了可能与竞争性气候过程相关的模式：格陵兰沿海（地表融化增加）、南极冰架（海洋融化增加）以及格陵兰和南极出口冰川（对海洋融化的动态响应）的冰损失被质量增加部分补偿在冰盖内部（积雪增加）。损失超过收益，格陵兰岛（每年 2000 亿吨）和南极洲（每年 1180 亿吨）的陆冰损失对海平面造成了 14 毫米的影响。