Brown University, Providence, RI, USA.
Nat Commun. 2021 Apr 13;12(1):2221. doi: 10.1038/s41467-021-22004-7.
Global climate models (GCMs) consistently underestimate the response of September Arctic sea-ice area (SIA) to warming. Modeled SIA losses are highly correlated to global mean temperature increases, making it challenging to gauge if improvements in modeled sea ice derive from improved sea-ice models or from improvements in forcing driven by other GCM components. I use a set of five large GCM ensembles, and CMIP6 simulations, to quantify GCM internal variability and variability between GCMs from 1979-2014, showing modern GCMs do not plausibly estimate the response of SIA to warming in all months. I identify the marginal ice zone fraction (MIZF) as a metric that is less correlated to warming, has a response plausibly simulated from January-September (but not October-December), and has highly variable future projections across GCMs. These qualities make MIZF useful for evaluating the impact of sea-ice model changes on past, present, and projected sea-ice state.
全球气候模式（GCMs）一直低估了 9 月北极海冰面积（SIA）对变暖的响应。模拟的 SIA 损失与全球平均温度升高高度相关，这使得很难判断模型中海冰的改进是来自于改进的海冰模型，还是来自于其他 GCM 组件驱动的强迫的改进。我使用了一组五个大型 GCM 集合和 CMIP6 模拟，来量化 1979-2014 年间 GCM 内部变异性和 GCM 之间的变异性，结果表明现代 GCM 不太可能在所有月份都合理估计 SIA 对变暖的响应。我确定了边缘冰区分数（MIZF）作为一个指标，它与变暖的相关性较低，从 1 月到 9 月（但不是 10 月到 12 月）的响应可以合理地模拟，并且在 GCM 之间具有高度可变的未来预测。这些特性使得 MIZF 对于评估海冰模型变化对过去、现在和预测海冰状态的影响很有用。
