Cryosphere References

• Anthropogenic influences are robustly detected in observed SCE decrease and GHG influence is robustly detected in separation from anthropogenic aerosol and natural forcings with important hydrological and ecological impacts

• SCE decrease shifts solar flux by changing albedo feedbacks and hydrological cycles

• There is a poleward amplification of SCE sensitivity due to warming air temperature through albedo feedbacks

• Most of the late spring SCE decrease over NH from 1970-2019 is attributable to GHG influence which identifies human contributions and GHG influence as separable from other forcing

Palik & Min, 2020

• Observation sites can be used to observe snow catchment areas, rates of snowfall and depth of snow deposits

• Drifting and blowing can be measured with snow drift meters, traps, optical drift meters and radioactive tracing

• Snow depth and SWE can be found using snow stakes, temperature profiles, albedo and free water content

• Areal extents of snow cover can be estimated by ground or air surveys using satellites with long term averages being scientifically important

• Full time observation stations can be installed as well as unmanned stations using remote and telemetry systems

UNESCO et al., 1970

• The area and duration of snow cover are decreasing at 2-4 days per decade in the Arctic which impacts terrestrial ecosystems as it shows a decrease in plant cover and productivity in the last 30 years

• Duration of snow cover is projected to decrease by an addition 10-20% from current levels by mid-century and cold-season precipitation increase by 30-50%

• The Arctic is warming faster than any other region on Earth with feedbacks such as changing albedo and water vapour increase in the atmosphere being important

• Projected changes see coastal areas have fastest and largest declines and this will have implications for food sources, vegetation, habitats, marine ecosystems, water cycling, ocean acidification and atmospheric cycling

Brown et al., 2017

• Climate models suggest rain will be the dominant form of precipitation in the Arctic by 2100 due to atmospheric warming

• Arctic precipitation rates increase much faster than the global rate of 2% per degree instead at 4.5% per degree

• This will impact hydrology, climatology and eco-locality as well as leading to enhanced permafrost melting and methane emissions

Bintanja & Andry, 2017

• There is an overall tendency to decrease in several metrics of snow extremes, particularly in North America and Eurasia due to global warming

• Anthropogenically forced changes in temperature and water vapour have the potential to have major impacts on snowfall as seen in data collected from station observations, remote sensing, satellite and in situ sources

• Snow cover extent, SWE and duration of snow cover see widespread decreases in western US, North America and the Arctic

• These downwards trends are due to a combination of natural and anthropogenic forcings

Kunkel et al., 2016

• Climate change threatens to disturb warm-season water demand by altering fractions of precipitation falling as snow and timing of snowmelt, this threatens food production in basins relying on snowmelt runoff

• This will be particularly important in high-mountain Asia, central Asia, western Russia, western US and southern Andes

• Basins most at risk see 40% of irrigation demand needing to be met by new alternative water supplies under RCP4, adaption of water management and agricultural systems will be critical

Qin et al., 2020

• The timing of spring snowmelt influences patterns of hibernation and reproduction in the population of free-living Arctic ground squirrels in northern Alaska

• Findings show that with late spring snowmelt and early autumn snow melt offspring density was lower before hibernation and the shortening of the active season will compromise juvenile recruitment

Sheriff et al., 2017

• Winter tourism is threatened due to the combined effect of decreasing natural snow amounts and suitable periods for snowmaking 

• 14-25% of ski lifts may be considered in a critical situation in the near future

• Under RCP8.5 there would no longer be any snow reliable ski resorts based on natural conditions in the French Alps of Pyrenees by 2100 with only 24 projected to remain reliable and all in the Alps

Spandre et al., 2019

• Over the last two decades NH snow cover has decreased in extent by 11.7% in June from 1967 to 2010 and did not increase in any month 

• Human influence has been detected in reductions with evidence showing that human influence is extremely likely the dominant cause of observed warming since the mid C20th

• It is very likely NH snow cover will decrease during the C21st due to surface temperature rising, this will decrease by 25% under RCP8.5

IPCC, 2013

• Over the last decades global warming has led to widespread shrinking of the cryosphere with a total loss of 2.5 million km^2 of snow cover in the Arctic from 1967-2018

• Feedbacks continue to amplify global warming and surface temperature increases in the Arctic

• This has impacted terrestrial and freshwater species, animals have had to shift their range, food and water security are negatively impacted with hunting, herding, fishing and gathering practices

• Arctic residents and Indigenous peoples have had to adjust timings of activities to resort to changes in seasonality , hydropower facilities also experience changes and high mountain aesthetic and cultural aspects have been negatively impacted

• Global scale declines in snow cover extent are projected to continue to 2050, under RCP8.5 Arctic spring snow cover will decrease by 50-90%

• Floods and rain-on-snow landslides are projected to occur in new locations and river runoff will change

• There will be further upslope migration by low-elevation species, fire and hydrology regimes will be impacted, human settlements will face increased hazard risks and high mountain recreation will be negatively impacted

IPCC, 2019

• Human influence is very likely to the main driver of the global retreat of glaciers since the 1990s and has been contributing to NH spring snow cover decline since 1950

• Changes in the climate system are becoming larger in direct relation to global warming and this will amplify permafrost thawing and loss of seasonal snow cover

• The global water cycle is intensifying with earlier onset of spring snowmelt and higher peak flows

• All regions are projected to experience further decreases in snow with largest chances at 2 degrees than 1.5 degrees warming

IPCC, 2021