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

winter ice roads, which can affect the transportation of goods to remote communities [1, 2]; delay or cancel skating, ice-fishing, and other recreational tournaments [3]; alter hunting sea- sons for traditional foods for Indigenous communities, including whales, seals, and caribou [4]; and result in increased winter drownings in warmer winters with less stable ice cover [5]. The monetary value of ecosystem services is rarely quantified, leaving the costs of global envi- ronmental stressors largely unknown. This is especially important given the higher cost of inaction relative to climate change mitigation [6, 7]. In the few cases where costs have been estimated, the monetary values are significant, such as invasive species negatively affecting the global economy by 26.8 billion USD annually [8] or lake eutrophication expected to cost 81 trillion USD by 2050 [9]. Water resources have already begun to display evidence of an eco- nomic decline from climate change [10], highlighting the urgency of evaluating the financial value associated with freshwater ecosystems. Global warming caused by human-induced climate change is already having pronounced biophysical implications globally [11]. Many regions around the world have identified droughts or warming that exceeds long-term averages in climate monitoring [e.g., 12–14]. Winter is a rapidly warming season [15, 16] threatening the ice cover of freshwater lakes and the services they provide. Climate change is causing the widespread loss of lake ice including

shorter seasons [17], more frequent ice-free winters [18], and in extreme cases, the permanent loss of lake ice cover [19]. One of the first physical lake responses to climatic warming in many lakes is the loss of ice cover due to the tightly linked relationship between winter air tempera- ture and freshwater freezing [i.e., 20–22]. The loss of winter ice cover portends the loss of a northern cultural identity, which has social, cultural, and health values that cannot be quanti- fied [23]. As climate change reduces lake ice cover and duration, the spending generated from these winter activities is at risk of being lost. Although we have a good understanding of future lake ice patterns under climate change, the financial implications of lake ice declines have never been attributed. Here, we conducted the first exploration of the spending generated by lake ice and the potential declines anticipated from climate change. Using process-based numerical models of lake ice cover across the Northern Hemisphere until the end of the 21st century, we quantified changes in ice cover, ice duration, and revenue of lake ice activities to ask the following three questions: 1) How is the duration and cover of lake ice in the Northern Hemisphere expected to change over the coming decades?, 2) What is the estimated spending generated from lake ice?, and 3) What are the socio-economic implications of decreasing lake ice? The findings from this study will offer valuable insights for informing policies to support local communities

as they experience shifts in revenue from changes in lake ice duration. Methods Data acquisition We conducted a modelling study to forecast the effects of climate change on lake ice duration and quantify the financial implications for local communities. Lake ice projections used in this study were simulated using an ensemble of process-based lake models, which contributed to the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b) Lake Sector [24]. These models include the Community Land Model version 4.5 (CLM4.5) [25], the Arctic Lake Biogeochemistry Model (ALBM) [26, 27], SIMSTRAT-UoG [28], and LAKE [29]. Each lake model was driven by climate data from four General Circulation Models (GCMs) which contributed to phase 5 of the Coupled Model Intercomparison Project (CMIP5), GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR and MIROC5, after bias-adjustment to the EWEMBI reference dataset [30, 31]. These models are well documented and are a culmination PLOS ONE Financial loss of declining lake ice PLOS ONE | https://doi.org/10.1371/journal.pone.0299937 July 5, 2024 2 / 15 Award, and Natural Sciences Engineering and Research Council Discovery Grant to SS. RIW was supported by a UKRI Natural Environment Research Council (NERC) Independent Research Fellowship awarded to RIW [grant number NE/ T011246/1]. The funders provided support in the form of salaries for authors AF, MAI, and RIW, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of

these authors are articulated in the ‘author contributions’ section. Competing interests: The authors have declared that no competing interests exist.