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

frozen (e.g., winter only), intermittently frozen (i.e., freeze-thaw cycles), or completely ice-free (Fig 1A). Our models suggest that currently there are over 1.5 million km2 of lake area that freezes annually with an average ice duration of 128 days (Fig 1B). We predict that by the end of the century, we will lose between 43,568 ± 2,012 km2 (mean 2070–2099 ± SE; RCP 2.6), 82,199 ± 2,587 km2 (RCP 6.0), and 176,796 ± 5,618 km2 (RCP 8.5) of lake ice cover (Fig 1B). We also predict that the duration of ice cover will decrease, on average, between 13.2 ± 0.3 days (mean 2070–2099 ± SE; RCP 2.6), 23.5 ± 0.5 days (RCP 6.0), and 43.2 ± 0.9 days (RCP 8.5) (Fig 1B). Local revenue from lake ice Lake ice is responsible for considerable spending on activities through multiple streams including winter festivals, car testing in winter conditions, ice fishing, and sports competitions (Fig 2, Table 1). Ice fishing is a commonly reported source generating money for local commu- nities adjacent to frozen lakes and is responsible for USD 1.30 billion of spending generated annually in our examples (Table 1). For example, Lake Winnipeg in Canada can generate as much as USD 350 million annually from ice fishing alone [43]. This spending includes direct spending by the anglers, but also indirect benefits to GDP, salaries to local residents, and tax revenue for the regional government [43]. Similarly, the Swedish town of Arjeplog is a popular test site for winter driving by automakers and generates USD 164 million annually [44]. With

Fig 1. Patterns of lake ice cover are changing throughout the Northern Hemisphere. Lakes can be categorized as having permanent ice cover, seasonal ice cover (e.g., during winter), intermittent ice cover with multiple freeze-thaw events, and permanently ice-free (Panel A). With warmer temperatures, lakes transition from permanent ice cover to seasonal ice cover, and from seasonal ice cover to permanently ice free. Under a modest increase in greenhouse gas emissions (i.e., RCP 2.6) the duration of lake ice will decline by approximately 10 days. However, if greenhouse gas emissions rise substantially (RCP 8.5), on average the duration of lake ice will decrease by more than 40 days (Panel B). Consequently, the area of lake ice will decline as some lakes transition to completely ice-free. Depending on the greenhouse gas emissions, we predict a loss of between 50,000 and 200,000 km2 of ice cover. Lines represent mean model fit and standard error band represents the uncertainty associated among the different GCMs and lake models used to estimate ice phenology. https://doi.org/10.1371/journal.pone.0299937.g001 PLOS ONE Financial loss of declining lake ice PLOS ONE | https://doi.org/10.1371/journal.pone.0299937 July 5, 2024 5 / 15