Freshwater ice, on both lakes and rivers, is an integral part of the hydrologic regimes of cold environments.  Moreover, it acts as a primary control of the ecology of related aquatic systems, affecting a suite of physical, geochemical and biological processes.  It is also important economically, through facilitation of important winter transport to remote locations and via generation of extreme hydrologic events, such as spring floods. Given projected changes in future climate, significant concern has been raised about related changes in freshwater ice. This manuscript reviews the status and trends in records of lake and river ice around the circumpolar North from traditional observations, remote sensing, and paleo-sources.  The temporal and spatial variability in trends are evaluated along with some of the approaches used to link them with climatic conditions. Of particular note are some of the rapid changes experienced in the timing of freeze-up and break-up for high-latitude lakes as compared to those at more southerly locations.   Also considered are the nature and implications of changes in future freshwater-ice regimes that will have cascading effects on cold-regions hydrology, and a suite of hydro-ecological conditions such as UV-radiation receipts, thermal conditions, lake stratification, habitat quality and availability, fisheries productivity, and contaminant pathways.  Overall, the duration and event timing of river and lake ice are proving to be useful indicators of climate change.  Considering the scope and significance of ice-cover changes on northern hydro-ecology, a recommendation is made to place more emphasis on long-term and spatially diverse monitoring of freshwater ice.