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

the predictions of lake ice duration to decline by between 10.3% (RCP 2.6) and 33.7% (RCP 8.5), we could expect changes in spending habits that equate to millions each year, cumulating to billions by the end of the century. Socio-economic implications of decreasing lake ice The countries anticipated to have the greatest ice loss by the end of this century are the coun- tries currently with the largest GDP (Fig 3), who also tend to spend the most money on activi- ties that use lake ice (Fig 2 and Table 1). We found that the greater loss of lake ice per country correlated with increased greenhouse gas emissions (F137 = 13.5, p < 0.0001; Fig 3), and higher GDP (F131 = 22.6, p < 0.0001; Fig 3), regardless of greenhouse gas emission scenario (all p > 0.05). We also found that countries with the greatest area of ice loss are the most depen- dent on freshwater for commercial and residential purposes (F137 = 16.3, p < 0.001; Fig 3). Discussion Lake ice is a valuable resource that is expected to decline in the coming decades. Previous research has identified lake ice as threatened by climate change both through modelling [19, 45] and in situ observations [3, 17, 18, 46]. We estimated that in the Northern Hemisphere, lake ice will become on average shorter by 13–43 days and have between 44,000 and 177,000 less km2 of ice cover, contributing to shifts in spending by the end of the century. Lake ice is strongly dependent on winter air temperatures to freeze, where increases in mean air tempera- ture or extreme warm events can lead to shorter freeze durations [17, 47], intermittent ice

cover [45, 48], ice-free years [22, 49], or in the most extreme case, the permanent loss of ice cover [19]. Lakes that are large and shallow have been identified as the most vulnerable to lake ice loss from climate change because of the high surface area with the air, sensitivity to ice breakup from wind, and lower heat latency from less water volume [46, 50, 51]. Understanding the mechanisms through which lake ice is affected by climate change is particularly important to identify the specific lakes and associated activities that will be most impacted by climate Fig 2. Lake ice is an important resource globally. Across the Northern Hemisphere, ice covers freshwater lakes on average ~150 days per year and up to 365 days per year at higher latitudes. The monetary value of lake ice is diverse including fishing, industrial manufacturing, recreational activities, and winter festivals. Inset in the figure are some examples of the revenue ($USD) generated by activities dependent on lake ice. Ice cover duration values shown in the top panel are based on the average simulations across the lake-climate model ensemble during the contemporary period (1970–1999). Map was generated using the data from GADM (https://gadm.org/) under a CC BY license with permission from the GADM organization, original copyright 2018–2022. https://doi.org/10.1371/journal.pone.0299937.g002 PLOS ONE Financial loss of declining lake ice PLOS ONE | https://doi.org/10.1371/journal.pone.0299937 July 5, 2024 6 / 15