Snow in the climate system

Using the ‘Can it? Has it? Will it?’ framework, this Review synthesizes current understanding on Eurasian snow–atmosphere coupling, outlining observational and modelling evidence for their dynamical connection and discussing possible changes in the future.

Snow albedo is impacted by the presence of light-absorbing particles, including black carbon and dust. This Review collates knowledge on the associated radiative forcing, discussing geographic variability, future impacts and challenges for reducing uncertainty.

This Perspective provides an overview of the snow–sea ice systems in the Arctic and Antarctic, offering insight on how current uncertainties can be reduced, and future challenges met, to improve understanding of polar climate change.

Extensive evidence reveals that Earth’s snow cover is declining, but our ability to monitor trends in mountain regions is limited. New satellite missions with robust snow water equivalent retrievals are needed to fill this gap.

Indigenous reindeer herding in the circumpolar North is threatened by multiple drivers of environmental and social changes that affect the sustainability of traditional family-based nomadic use of pastures. These impacts are exacerbated by indigenous peoples’ lack of voice in governance strategies, management and adaptation responses.

Piece by piece, scientists are gathering evidence of the growing threat of wet snow avalanches in a warmer world.

Winter snow conditions influence which plants grow where in the Arctic. Now, a modelling study built on observational data of plant occurrence and snow conditions suggests that declines in snow cover will result in the loss of plant species.

January 2018 was an unusually warm and wet month across the Western Alps, with widespread landslides at low elevations and massive snowfall higher up. This extreme month yields lessons for how mountain communities can prepare for a warmer future.

Global snow coverage has declined substantially with anthropogenic warming, impacting biological, socio-economic and physical systems. This issue includes a suite of Comments, Reviews, Perspectives and original research documenting the importance of snow in the climate system, and how this may change with continued warming.

Arctic biodiversity patterns will be highly dependent on the evolution of snow conditions, according to simulation results that integrate observations of vascular plants, mosses and lichens over a range of Arctic landscapes.

Observations from western North America and model simulations are used to understand how climate change will affect snowmelt. Snowmelt is found to be slower under climate change as earlier melt means there is less energy for high melt rates.

Increased surface temperatures are expected to cause less precipitation in the form of snow. The impact of decreased snowfall has previously been assumed to not influence streamflow significantly. This work applies a water-balance framework to catchments in the United States and finds a greater percentage of precipitation as snowfall is associated with greater mean streamflow.

Arctic precipitation is projected to increase and this study shows that rainfall will become the dominant phase of precipitation, with a decrease in snowfall across all seasons.

The impact of climate change on the water resources and hydrology of High Asia is uncertain. This work uses a cryospheric hydrological model to quantify the hydrology of five major rivers in the region and project future water availability. Runoff is expected to increase until at least 2050 due to an increase in precipitation in the upper catchment of four rivers and increased melt entering the fifth river.

Surface melt of the Greenland ice sheet is retained through storage in the surface porous ice. This study shows that successive melt events have caused the formation of near-surface ice layers, preventing this storage and increasing meltwater runoff.

The glaciers of the Antarctic Peninsula are experiencing faster melt because of increased temperatures; however, changes in precipitation may offset some of the future melt. This study looks at the relationship between glaciers and climate and finds a representative glacier is more sensitive to temperature change, rather than precipitation change. This indicates that precipitation increases are unlikely to counter the increased melt from warming.

The Arctic winter polar vortex has weakened in recent years: this study shows that there has also been a shift in the location of the vortex towards Eurasia. This is related to cryospheric changes, with implications for mid-latitude weather.

As the atmosphere warms it can hold more water so precipitation is expected to increase. This study uses palaeoclimate data and modelling results to investigate what this means for Antarctic mass balance and sea-level rise, as more snowfall will increase the water stored as ice on the continent.

In many regions, a warming climate may lead to large decreases in annual snowfall while having a much weaker effect on the intensities of the heaviest snowfall events — those that can be most disruptive to urban infrastructure.

Microbes on glacial snow and ice reduce albedo and increase melting. Field experiments show that nutrient and meltwater additions increase microbial abundance and that areas of microbe-covered snow generate increased snowmelt.

Mountain snowpack in the western United States has declined over the past three decades. Fyfeet al. show that this trend cannot be explained by natural variability alone and show that under a business-as-usual scenario a further loss of up to 60% in mountain snowpack is projected in the coming three decades.

The atmospheric response to subseasonal variability of Tibetan Plateau snow cover has been largely ignored. Here the authors show that the fast subseasonal variability of Tibetan Plateau snow cover is closely related to the subsequent East Asian atmospheric circulation at medium-range time scales.