What Do Global Climate Models Tell Us about Future Arctic Sea Ice Coverage Changes?

The prospect of an ice-free Arctic in our near future due to the rapid and accelerated Arctic sea ice decline has brought about the urgent need for reliable projections of the first ice-free Arctic summer year (FIASY). Together with up-to-date observations and characterizations of Arctic ice state, they are essential to business strategic planning, climate adaptation, and risk mitigation. In this study, the monthly Arctic sea ice extents from 12 global climate models are utilized to obtain projected FIASYs and their dependency on different emission scenarios, as well as to examine the nature of the ice retreat projections. The average value of model-projected FIASYs is 2054/2042, with a spread of 74/42 years for the medium/high emission scenarios, respectively. The earliest FIASY is projected to occur in year 2023, which may not be realistic, for both scenarios. The sensitivity of individual climate models to scenarios in projecting FIASYs is very model-dependent. The nature of model-projected Arctic sea ice coverage changes is shown to be primarily linear. FIASY values predicted by six commonly used statistical models that were curve-fitted with the first 30 years of climate projections (2006–2035), on other hand, show a preferred range of 2030–2040, with a distinct peak at 2034 for both scenarios, which is more comparable with those from previous studies.

由于北极海冰快速且加速减少，在不久的将来北极可能无冰，这迫切需要对首个北极夏季无冰年（FIASY）进行可靠预测。结合对北极冰情的最新观测和描述，它们对商业战略规划、气候适应和风险缓解至关重要。在这项研究中，利用12个全球气候模型的逐月北极海冰范围来获取预测的FIASY及其对不同排放情景的依赖性，并检验海冰消退预测的性质。模型预测的FIASY平均值为2054/2042年，中/高排放情景的时间跨度分别为74/42年。两种情景下，最早预测的FIASY都出现在2023年，但这可能不现实。各个气候模型在预测FIASY时对情景的敏感性因模型而异。模型预测的北极海冰覆盖变化性质主要呈线性。另一方面，用气候预测前30年（2006 - 2035年）曲线拟合的6个常用统计模型预测的FIASY值显示出2030 - 2040年的偏好范围，两种情景下在2034年都有一个明显峰值，这与先前研究更为相似。