1256 difficult to characterize based on short monitoring periods. 4.3 Climate change, extremes and permafrost Climate change is expected to intensify many of the climatic drivers that affect dry stacking. IPCC AR6 scenarios (SSP1-2.6, SSP2-4.5 and SSP5-8.5) project increases in mean temperatures, changes in precipitation seasonality and more frequent extreme weather events in northern regions (IPCC, 2021–2023; SYKE, 2022). For dry-stacked tailings, this may translate into more intense winter and autumn precipitation, increased rain-on-snow events, higher and earlier meltwater peaks, and more frequent heavy rainfall episodes during the operational lifetime of a facility. In areas underlain by permafrost, warming temperatures and permafrost degradation may alter foundation conditions, drainage patterns and leakage pathways. Thawing of ice-rich layers can reduce bearing capacity and increase settlement, while changes in the active layer thickness affect seasonal moisture dynamics and frost action. These processes introduce additional uncertainty into long-term stability assessments, particularly for facilities designed under historical climatic conditions that may no longer be representative. 4.4 Modeling and knowledge gaps Despite growing interest in dry stacking under northern conditions, there are still significant gaps in the models and data available to support design and risk assessment. Coupled thermo–hydro–mechanical models that capture freezing and thawing processes in filtered tailings remain relatively immature, and their calibration is limited by the scarcity of long-term monitoring data from operating dry-stacked facilities in Arctic regions. Ongoing doctoral work aims to address some of these gaps by combining IPCC AR6 climate scenarios with hydrological modeling tools such as Amanzi-ATS to simulate the response of tailings structures to changing temperature and precipitation regimes, including extreme events and frost-related processes (Tuomela, 2022). Building on frameworks such as Tuomela’s frost susceptibility and leakage risk models, a new scoring system is being developed to evaluate the sensitivity of dry-stacked structures to basal leakage and climate-driven stresses. However, these approaches are still under development and have not yet been widely applied in operational decision-making, underlining the need for further research and validation. 5. POSSIBILITIES: CIRCULARITY, ENERGY AND WATER RECOVERY Beyond reducing water inventories and tailings-related risks, dry stacking can also act as an enabler for broader circular economy and low-carbon objectives. When filtered tailings are placed in a controlled, trafficable configuration, they become more accessible for future reprocessing, re-use in construction and more efficient closure solutions. In parallel, high rates of water recovery and the potential to integrate heat and renewable energy systems can improve the overall resource efficiency of the mine-to-mill chain. 5.1 Water and energy recovery opportunities Filtered tailings operations commonly return a large fraction of process water directly from thickeners and filters back to the plant. In practical terms, the value proposition of dry stacking lies in converting tailings dewatering from a disposal step into a measurable water-management function, where recovery efficiency, residual moisture and long-term free-water storage become decision variables rather than secondary outcomes. Compared with conventional slurry ponds, this reduces the need for make-up water, lowers pumping distances and helps decouple process reliability from local hydrological variability (Sahu et al., 2020). In cold and northern climates, where water management is complicated by snowmelt peaks, ice cover and changing precipitation regimes, high water-recovery efficiencies can significantly
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