The disappearing cryosphere: Impacts and ecosystem responses to rapid cryosphere loss

Background/Question/Methods

The Earth’s Cryosphere – ice in all its forms, including glaciers, sea, lake and river ice, snow, and permafrost – harbors 82% of the freshwater on the planet. The Cryosphere plays a critical role in the global heat budget, regulates global sea level, insulates soil from subfreezing air temperatures and most importantly, serves as a seasonally-rectified water supply for human consumption, irrigation, nutrient transport and cycling, freshwater resources, and waste disposal. Cryosphere loss imposes enormous threats to these ecosystem services and, in turn to the global economy. A one-meter sea level rise alone, projected over the 21^st century, represents an estimated economic impact of $1 Trillion (USD). The extent and rates of cryosphere loss are increasingly well-monitored and our ability to project future rates of geophysical decline is improving. However the ecological consequences and especially the nature, extent and economic impacts on human society and institutions are still poorly understood. 

Results/Conclusions

Nutrient (e.g. organic matter and inorganic nutrients) mobilization appears to follow seasonal cryosphere recession across systems, but with earlier snow or ice melt, the phasing or phenology of mobilization events and biological responses appear to be shifting in time. Nitrate pulses in streams follow snowmelt in temperate forests, but with earlier seasonal snow melt, plants may not be able to take advantage of newly-available nitrogen. Thinner snowpacks can result soil drying and tree root loss, leading to increased nitrate in streams that was not taken up by the missing roots.  In addition thinner snow pack results in habitat loss for some large mammals and changing grazing patterns for others.  Shrinking alpine glaciers and buried ice changes high alpine hydrology significantly and reduces habitat critical to some alpine fauna.  Sea ice loss has had contrasting effects on marine phytoplankton productivity along a north-south climate gradient off the west Antarctic Peninsula. Nearly all known climate-ecosystem feedbacks resulting from cryosphere loss are positive: warming and melting intensify and promote further warming and cryosphere loss. Identifying and modeling cryosphere feedbacks has become a closely-pursued research priority, stimulated by catastrophic Arctic sea ice loss and tundra melting. Responsible stewardship of our planet in the face of rapid cryosphere loss poses a grand challenge for ecologists to confront in the coming decade