13. River Ice Processes and Changes Across the Northern Regions

River ice is critical for northern hydrology and ecosystems, such as the magnitude and timing of hydrologic extremes, i.e., low flows and floods. Historical data analyses and model studies clearly show widespread decreases in river ice thinness and duration due to climate warming across the northern regions. Reductions in river ice jam flooding may have major positive benefits for communities and infrastructure along the river margins, but could also alter the ecology of deltaic riparian and coastal marine ecosystems. The reduction in river and lake ice will influence transportation opportunities in remote regions. In situ observations are important to monitor the ongoing changes in river and lake ice features across the northern regions. Modeling and remote sensing tools are very useful to the understanding of ice processes, attributions of past changes, and projection of future ice conditions in a warming Arctic. More effort is necessary to combine observations, models, and remote sensing technology to investigate ice hydrology over the broader northern regions.