Culpepper Joshua, Huang Lei, Woolway R Iestyn, Sharma Sapna
Department of Biology, York University, Toronto, ON, Canada.
College of Resource Environment and Tourism, Capital Normal University, Beijing, China.
PLoS One. 2024 Dec 11;19(12):e0313994. doi: 10.1371/journal.pone.0313994. eCollection 2024.
Millions of people rely on lake ice for safe winter recreation. Warming air temperatures impact the phenology (timing of formation and breakup) and quality (ratio of black to white ice) of lake ice cover, both critical components of ice safety. Later formation and earlier breakup of lake ice lead to overall shorter periods of use. However, greater proportions of white ice may further inhibit safe ice use owing to its lower weight-bearing capacity. As ice cover duration decreases and ice quality changes in a warming world, the period of safe ice use will similarly diminish. We use a large ensemble modeling approach to predict ice safety throughout the winter period in the Northern Hemisphere. We used the Community Earth System Model Version 2 Large Ensemble (CESM2-LE) to calculate the period when ice first appears until it is of sufficient thickness for safe use, which depends on the ratio of black to white ice. We conducted this analysis for 2,379 to 2,829 ~1° by 1° grid cells throughout the Northern Hemisphere. We focus on the period between ice formation (≥ 2 cm) to a safe thickness for general human use (i.e., ≥10, ≥15, or ≥20 cm, depending on the ratio of black to white ice). We find that the transition period from unsafe to safe ice cover is growing longer, while the total duration of safe ice cover is getting shorter. The transition period of unsafe ice increases by 5.0 ± 3.7 days in a 4°C warmer world, assuming 100% black ice. Diminished ice quality further limits safe ice conditions. The unsafe transition period increases by an average of 19.8 ± 8.9 days and 8.8 ± 6.6 days for the ice formation and breakup periods, respectively in a 4°C warmer world assuming 100% white ice conditions. We show that although many lakes are forecasted to freeze, they will be unsafe to use for an average of 5 to 29 fewer days in a 4°C warmer world for 100% black and 100% white ice ratios, respectively. This wide range indicates that ice quality has a strong influence on ice safety. This work highlights the need to understand both lake ice phenology and quality to better assess safe lake ice use during the formation and melt periods.
数百万人依靠湖冰进行安全的冬季娱乐活动。气温上升会影响湖冰覆盖的物候（形成和消融的时间）和质量（黑冰与白冰的比例），而这两者都是冰安全的关键要素。湖冰形成时间推迟、消融时间提前，导致总体使用期缩短。然而，白冰比例增加可能因其较低的承重能力而进一步阻碍安全使用冰面。在气候变暖的情况下，随着冰覆盖持续时间减少和冰质量发生变化，安全使用冰面的时间也会相应减少。我们采用大型集合建模方法来预测北半球整个冬季的冰安全状况。我们使用社区地球系统模型第2版大型集合（CESM2 - LE）来计算从冰首次出现到其厚度达到安全使用标准的时间段，这取决于黑冰与白冰的比例。我们对北半球2379至2829个约1°×1°的网格单元进行了此项分析。我们关注的时间段是从冰形成（≥2厘米）到达到一般人类安全使用的厚度（即≥10厘米、≥15厘米或≥20厘米，具体取决于黑冰与白冰的比例）。我们发现，从不安全冰覆盖到安全冰覆盖的过渡期变长，而安全冰覆盖的总持续时间变短。假设100%为黑冰，在气温升高4°C的世界中，不安全冰的过渡期增加5.0±3.7天。冰质量下降进一步限制了安全冰面条件。假设100%为白冰条件，在气温升高4°C的世界中，冰形成期和消融期的不安全过渡期分别平均增加19.8±8.9天和8.8±6.6天。我们表明，尽管预计许多湖泊会结冰，但在气温升高4°C的世界中，对于100%黑冰和100%白冰比例的情况，湖泊不安全使用的平均天数分别减少5至29天。这个较大的范围表明冰质量对冰安全有很大影响。这项工作强调了需要了解湖冰物候和质量，以便更好地评估在冰形成和融化期间安全使用湖冰的情况。
