New insights into community-scale changes in shorefast sea ice from satellite remote sensing

Abstract:

Shorefast sea ice comprises a small fraction of global sea-ice cover yet has outsized importance for Arctic communities. Relatively little is known, however, about the dominant drivers of its breakup or how it will respond to climate warming. Here, we present results from an ongoing Navigating the New Arctic project that is investigating shorefast sea ice surrounding Arctic communities using novel remote sensing techniques. In the first stage of the project, we use near-daily MODIS satellite imagery to document the timing of shorefast ice breakup in 28 communities in northern Canada and western Greenland. We find that breakup timing is strongly correlated with springtime air temperature, but its sensitivity varies substantially among communities. When we combine these observations with climate model outputs, we estimate an annual reduction of 5-44 days in the length of the springtime shorefast ice season by 2100. Interestingly, we find it is the coldest and northernmost communities that are projected to experience the largest reductions in springtime ice season duration. However, while breakup timing is important, many community activities also depend on ice thickness and extent. Consequently, we are now using MODIS imagery to map maximum seasonal shorefast ice extent surrounding 50 Arctic communities and ICESat-2 data to constrain shorefast ice thickness in localized areas. Preliminary results suggest the largest changes in ice extent over the past 20 years have occurred in western Alaska and eastern Hudson Bay. Future work will integrate community knowledge into our remotely sensed research to further investigate drivers of shorefast ice growth, decline and breakup and how these processes in combination with natural, social and cultural drivers of change influence individual and collective futures.