This paper investigates changes in the dates of ice freeze-up and breakup for 678 Northern Hemisphere lakes and rivers from 1931–2005. From 3510 time series, the results show that breakup dates have gradually occurred earlier through time, whilst freeze-up trends have tended to be significantly more variable. These data combined show that the number of annual open-water days has increased through time for most sites, with the magnitude of change at its largest in more recent years.

Thermokarst lakes are common on ice-rich permafrost. Many studies have shown that they are sources of methane to the atmosphere. Although they are usually covered by ice, little is known about what happens to methane in winter. We studied how much methane is contained in the ice of a thermokarst lake, a thermokarst lagoon and offshore. Methane concentrations differed strongly, depending on water body type. Microbes can also oxidize methane in ice and lower the concentrations during winter.

Anchor ice typically forms on riverbeds during freeze-up and can alter the river ice regime. Most of the knowledge on anchor ice mechanisms has been attributed to lab experiments. This study presents for the first time insights into anchor ice initiation, growth, and release in rivers using an underwater camera system. Three stages of growth and modes of release have been identified. These results will improve modelling capabilities in predicting the effect of anchor ice on river ice regimes.

The paper investigates a performance of altimetric satellite instrument to detect river ice onset and melting and to retrieve ice thickness of the Ob River. This is a first attempt to use the satellite altimetry for monitoring ice in the challenging conditions restraint by the object size. A novel approach permitted elaboration of spatio-temporal Ob River ice thickness product. The potential of the product for climate change monitoring and for prediction of ice road operation was demonstrated.

In the context of a ubiquitous increase in winter discharge in cold regions, our results show that icing formations can help overcome the lack of direct observations in these remote environments and provide new insights into winter runoff generation. The multi-technique approach used in this study provided important information about the water sources active during the winter season in the headwaters of glacierized catchments.

Using daily ice records of 156 hydrological stations across Songhua River Basin, we examined the spatial variability in the river ice phenology and river ice thickness from 2010 to 2015 and explored the role of snow depth and air temperature on the ice thickness. Snow cover correlated with ice thickness significantly and positively when the freshwater was completely frozen. Cumulative air temperature of freezing provides a better predictor than the air temperature for ice thickness modeling.

River and lake ice thickens at varying rates geographically and from year to year. We took a closer look at ice growth across a large geographic region experiencing rapid climate change, the State of Alaska, USA. Slower ice growth was most pronounced in northern Alaskan lakes over the last 60 years. Western and interior Alaska ice showed more variability in thickness and safe travel duration. This analysis provides a comprehensive evaluation of changing freshwater ice in Alaska.

A new automated method for microwave satellite assessment of lake ice conditions at 5 km resolution was developed for lakes in the Northern Hemisphere. The resulting ice record shows strong agreement with ground observations and alternative ice records. Higher latitude lakes reveal more widespread and larger trends toward shorter ice cover duration than lower latitude lakes. The new approach allows for rapid monitoring of lake ice cover changes, with accuracy suitable for global change studies.