Declining lake ice in response to climate change can impact spending for local communities

change. Our findings reinforce the widespread loss of lake ice because of climate change, highlighting the decline of an important socio-economic resource. The value of lake ice activities Shorter periods of ice cover are likely related to a shorter window for activities (e.g., fishing season is shorter, fewer opportunities for events such as ice festivals or skating races) decreas- ing the possible revenue generated. In our 31 identified examples, we found that lake ice con- tributes over USD 2 billion in spending for local communities and economies that will decline in the coming decades. Our examples included lakes with a wide range of characteristics, sug- gesting even small lakes play an integral economic role in the communities they are situated in. For communities dependent on lake ice activities, the loss of millions in local spending can disrupt the economic stability of these regions. Shorter ice cover duration could result in event cancellations and a complete loss of revenue (i.e., 100% decline) for some activities that occur in specific time windows (e.g., winter festivals, sports competitions). For example, a skating race on Lake Ma¨laren in Sweden generated income for a remote Nordic region but was can- celled indefinitely in 2018 because of unpredictable ice conditions [3]. These communities will be forced to gamble running events at the risk of having no lake ice or unsafe ice that may not be thick enough to sustain human activities [5]. For events that continue, organizers may

incur higher costs. What has historically been decades of reliable revenue for communities near lakes will decline and become unreliable as climate change continues to shorten the dura- tion of ice cover. The specific economic examples provided are based on historical values in recent years but are by no means an exhaustive list. There are more examples of economic consequences of declining lake ice that have not been quantified, such as the value of ice roads for winter trans- portation [1], recreational activities (cross-country skiing, snowshoeing, skating) [52], and other winter festivals. For example, winter sports in the United States have been estimated to contribute USD 11.3 billion to the national economy [53], which includes downhill skiing and snowboarding, but also activities likely to require lake ice, such as backcountry skiing, snow- shoeing, and snowmobiling. These latter activities have been rapidly increasing in popularity, with backcountry skiing and snowshoeing equipment sales exceeding USD 50 million during the 2015–2016 winter [54]. Additionally, indirect costs include all the business-to-business related revenue, such as purchasing local goods and services, and induced effects include increasing wages and staff that further facilitate the local economy and generate revenue [55]. In the United States, every dollar spent directly on winter sports activities can generate an additional $1.55 from indirect and induced effects [53]. More importantly, although there could be instances of economic benefits associated with declining ice cover, it comes at the

cost of environmental degradation which cannot be economically quantified. Therefore, the spending associated with lake ice activities is significantly larger than the USD 2.04 billion we have collated. While this value cannot be easily extrapolated to represent a global value, our results present the initial steps in quantifying the direct and indirect monetary impacts of lake ice loss. With climate change causing the loss of lake ice, local communities may shift spending towards open-water activities. Instead of ice-based activities, individuals may choose to partici- pate in water recreational activities, such as boating, swimming, and open-water fishing. In these cases, income spending is not necessarily lost for the local communities because local businesses can reinvest their offerings to cater to the changing recreational preferences. For example, marinas and boat rental companies may see increased demand for their services that will consequently mitigate the loss of customer base from ice-activities for local hotels and PLOS ONE Financial loss of declining lake ice PLOS ONE | https://doi.org/10.1371/journal.pone.0299937 July 5, 2024 8 / 15