Glacier: A mass of land ice that flows downhill under gravity (through internal deformation and/or sliding at the base) and is constrained by internal stress and friction at the base and sides. A glacier is maintained by accumulation of snow at high altitudes, balanced by melting at low altitudes or discharge into the sea.
Ice core: A cylinder of ice drilled out of a glacier or ice sheet.
Ice cap: A dome shaped ice mass, usually covering a highland area, which is considerably smaller in extent than an ice sheet.
A mass of land ice that is sufficiently deep to cover most of the underlying bedrock topography, so that its shape is mainly determined by its dynamics (the flow of the ice as it deforms internally and/or slides at its base). An ice sheet flows outward from a high central ice plateau with a small average surface slope. The margins usually slope more steeply, and most ice is discharged through fast-flowing ice streams or outlet glaciers, in some cases into the sea or into ice shelves floating on the sea. There are only three large ice sheets in the modern world, one on Greenland and two on Antarctica, the East and West Antarctic Ice Sheets, divided by the Transantarctic Mountains. During glacial periods there were others.
Ice shelf: A floating slab of ice of considerable thickness extending from the coast (usually of great horizontal extent with a level or gently sloping surface), often filling embayments in the coastline of the ice sheets. Nearly all ice shelves are in Antarctica, where most of the ice discharged seaward flows into ice shelves.
Any form of ice found at sea that has originated from the freezing of seawater. Sea ice may be discontinuous pieces (ice floes) moved on the ocean surface by wind and currents (pack ice), or a motionless sheet attached to the coast (land-fast ice). Sea ice less than one year old is called first-year ice. Multi-year ice is sea ice that has survived at least one summer melt season.
Překlad „bilance hmoty na pevnině“ použitý ve Shrnutí pro veřejné činitele je sice kvantitativně v pořádku, ale nevystihuje podstatu procesu. Jde totiž o přírůstek nového sněhu na povrchu grónského ledového příkrovu mínus jeho ablaci, tj. tání a sublimaci. Viz citát ze článku na realclimate.org:
3. The contribution from the two major ice sheets is split into two parts. What is called surface mass balance refers simply to snowfall minus surface ablation (ablation is melting plus sublimation). This is computed from an ice sheet surface mass balance model, with the snowfall amounts and temperatures derived from a high-resolution atmospheric circulation model. This is not the same as the coupled models used for the IPCC temperature projections, so results from this model are scaled to mimic different coupled models and different climate scenarios. (A fine point: this surface mass balance does include some "slow" changes in ice flow, but this is a minor contribution.)