Coastal river deltas are landscapes at significant risk from sea level rise and sediment deprivation (Nienhuis et al., 2020;Syvitski et al., 2009). Arctic deltas are likely more vulnerable than their temperate counterparts due to the presence of thermokarst lakes in permafrost, which are sensitive to rapid Arctic warming (Emmerton et al., 2007;Walker, 1998). Pan-arctic thermokarst lake coverage is responding to warmer temperatures in complex ways, as temperature-driven ground ice loss drives lake growth through retrogressive thaw slumping along lake shorelines (Grosse et al., 2013) but also generates surface and subsurface hydrologic connectivity that can cause lake drainage (