Monitoring ‘frozen commons’ with MODIS in Google Earth Engine

Snow, ice, and permafrost constitute ‘frozen commons,’ or common-pool resources that are collectively used and managed. This study examines the state and uses of snow and ice commons in two remote communities: Bayanzürkh in Khövsgöl Aimag, Mongolia, and McGrath, Alaska. Regional climate analyses indicate air temperatures warmed more than 2.2°C in both locales since the mid-twentieth century, compounding their similar accessibility challenges and dependence on natural resources. Warming affects transit timing and duration over snow and ice, impacting Mongolian herding and Alaskan subsistence hunting. Snow cover duration in both communities was calculated by classifying MODIS Snow Cover imagery utilizing the Google Earth Engine JavaScript API. Annual lake and river ice breakup timing and safe travel days were quantified from winter MODIS imagery from 2002 to 2023 for Lake Khövsgöl in Mongolia and the Kuskokwim River near McGrath, Alaska. Snow and ice duration did not significantly change over the 21 years examined. Relatively high map accuracies allowed discussion of interannual variability impacts on subsistence, transportation, and tourism. Daily snow and ice mapping in Google Earth Engine is a cost-effective and rapid method for quantifying environmental change impacting frozen commons, and therefore a tool for community decision-making and communication.