The under-ice water temperature of Ngoring Lake has been rising based on in situ observations. We obtained results showing that strong downward shortwave radiation is the main meteorological factor, and precipitation, wind speed, downward longwave radiation, air temperature, ice albedo, and ice extinction coefficient have an impact on the range and rate of lake temperature rise. Once the ice breaks, the lake body releases more energy than other lakes, whose water temperature remains horizontal.

We examined changes in the dates of ice break-ups in three Finnish rivers since the 1700s. The analyses show that ice break-ups nowadays occur earlier in spring than in previous centuries. The changes are pronounced in the south, and both rivers had their first recorded years without a complete ice cover in the 21st century. These events occurred during exceptionally warm winters and show that climate extremes affect the river-ice regime in southwest Finland differently than in the north.

Using unique data, some dating back to the 18th century, we show a significant trend in shorter ice duration, later freeze, and earlier break-up dates across Sweden. In recent observations, the mean ice durations have decreased by 11–28 d and the chance of years with an extremely short ice cover duration (less than 50 d) have increased by 800 %. Results show that even a 1 °C increase in air temperatures can result in a decrease in ice duration in Sweden of around 8–23 d.

Thermal regimes of seasonally ice-covered lakes in an arid region like Central Asia are not well constrained despite the unique climate. We observed annual and seasonal dynamics of thermal stratification and energetics in a shallow arid-region lake. Strong penetrated solar radiation and high water-to-ice heat flux are the predominant components in water heat balance. The under-ice stratification and convection are jointly governed by the radiative penetration and salt rejection during freezing.

Glacial lakes impact societies as both resources and hazards. Lakes form, grow, and drain as glaciers thin and retreat, and understanding lake evolution is a critical first step in assessing their hazard potential. We map glacial lakes in Alaska between 1984 and 2019. Overall, lakes grew in number and area, though lakes with different damming material (ice, moraine, bedrock) behaved differently. Namely, ice-dammed lakes decreased in number and area, a trend lost if dam type is not considered.

The paper investigates the performance of altimetric satellite instruments to detect river ice onset and melting dates and to retrieve ice thickness of the Ob River. This is a first attempt to use satellite altimetry for monitoring ice in the challenging conditions restrained by the object size. A novel approach permitted elaboration of the spatiotemporal ice thickness product for the 400 km river reach. The potential of the product for prediction of ice road operation was demonstrated.

Giant ice rings are a beautiful and puzzling natural phenomenon. Our data show that ice rings are generated by lens-like warm eddies below the ice. We use multi-satellite data to analyse lake ice cover in the presence of eddies in April 2020 in southern Baikal. Unusual changes in ice colour may be explained by the competing influences of atmosphere above and the warm eddy below the ice. Tracking ice floes also helps to estimate eddy currents and their influence on the upper water layer.

This research proposes and tests new methods for the estimation of the surface roughness of newly formed river ice covers. The hypothesis sought to determine if surface ice roughness was indicative of the subsurface. Ice roughness has consequences for winter flow characteristics of rivers and can greatly impact river ice jams. Remotely piloted aircraft and photogrammetry were used, and good correlation was found between the observed surface ice roughness and estimated subsurface ice roughness.

Acoustic backscattering data from Peace River frazil events are interpreted to develop a quantitative model of interactions between ice particles in the water column and riverbed ice layers. Two generic behaviours, evident in observed time variability, are linked to differences in the relative stability of in situ anchor ice layers which develop at the beginning of each frazil interval and are determined by cooling rates. Changes in these layers are shown to control water column frazil content.

We study the creep and fracture behavior of 3 m × 6 m floating edge-cracked rectangular plates of warm columnar freshwater S2 ice under creep/cyclic-recovery loading and monotonic loading to fracture. Under the testing conditions, the ice response was elastic–viscoplastic; no significant viscoelasticity or major recovery was detected. There was no clear effect of the creep/cyclic loading on the fracture properties: failure load and crack opening displacements at crack growth initiation.

Observations from 1890 to 2020 of ice phenology for 101 Norwegian lakes were used to detect variation in ice phenology. The average date of ice break-up occurred later in spring with increasing elevation, latitude and longitude. The average date of freeze-up and the length of the ice-free period decreased with elevation and longitude. Lakes were completely frozen later recently in autumn. There is a significant trend for earlier break-up, later freeze-up and completely frozen lakes after 1991.

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.

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.