Uncertainty about sea-level rise is dominated by uncertainty about iceberg calving, mass loss from glaciers or ice sheets by fracturing. Review of the rapidly growing calving literature leads to a few overarching hypotheses. Almost all calving occurs near or just downglacier of a location where ice flows into an environment more favorable for calving, so the calving rate is controlled primarily by flow to the ice margin rather than by fracturing. Calving can be classified into five regimes, which tend to be persistent, predictable, and insensitive to small perturbations in flow velocity, ice characteristics, or environmental forcing; these regimes can be studied instrumentally. Sufficiently large perturbations may cause sometimes-rapid transitions between regimes or between calving and noncalving behavior, during which fracturing may control the rate of calving. Regime transitions underlie the largest uncertainties in sea-level rise projections, but with few, important exceptions, have not been observed instrumentally. This is especially true of the most important regime transitions for sea-level rise. Process-based models informed by studies of ongoing calving, and assimilation of deep-time paleoclimatic data, may help reduce uncertainties about regime transitions. Failure to include calving accurately in predictive models could lead to large underestimates of warming-induced sea-level rise. ▪Iceberg calving, the breakage of ice from glaciers and ice sheets, affects sea level and many other environmental issues.▪Modern rates of iceberg calving usually are controlled by the rate of ice flow past restraining points, not by the brittle calving processes.▪Calving can be classified into five regimes, which are persistent, predictable, and insensitive to small perturbations.▪Transitions between calving regimes are especially important, and with warming might cause faster sea-level rise than generally projected.

中文翻译：

---

冰山崩解：制度和过渡


海平面上升的不确定性主要由冰山崩解、冰川或冰盖破裂造成的质量损失的不确定性主导。对快速增长的产犊文献的回顾导致了一些总体假设。几乎所有的崩解都发生在冰流入更有利于崩解的环境的冰川附近或落冰川附近，因此崩解速度主要由流向冰缘的水流控制，而不是通过破裂来控制。崩解可分为五种状态，它们往往是持续的、可预测的，并且对流速、冰特性或环境强迫的小扰动不敏感;这些机制可以通过仪器进行研究。足够大的扰动有时可能导致状态之间或产犊和非产犊行为之间的快速转换，在此期间，破裂可能会控制产犊的速度。海平面上升预测中，制度更替是最大的不确定性的基础，但除了少数重要的例外，没有被工具性地观察到。对于海平面上升最重要的制度过渡尤其如此。基于过程的模型以正在进行的产犊研究和对深时古气候数据的同化为信息，可能有助于减少政权过渡的不确定性。如果预测模型中未能准确包括产犊，可能会导致对变暖引起的海平面上升的严重低估。▪冰山崩解，即冰川和冰盖上的冰破裂，影响海平面和许多其他环境问题。▪现代冰山崩解的速度通常由冰流通过限制点的速度控制，而不是由脆性崩解过程控制。▪崩解可分为五种状态，它们是持续的、可预测的和对小扰动不敏感的。▪产犊制度之间的过渡尤为重要，随着气候变暖，海平面上升的速度可能比通常预测的要快。