Ice-albedo feedback
Encyclopedia
Ice-albedo feedback is a positive feedback
climate process where a change in the area of snow-covered land, ice caps, glaciers or sea ice
alters the albedo
. This change in albedo acts to reinforce the initial alteration in ice area. Cooling tends to increase ice
cover and hence the albedo, reducing the amount of solar energy absorbed and leading to more cooling. Conversely, warming tends to decrease ice cover and hence the albedo, increasing the amount of solar energy absorbed, leading to more warming.
The effect also applies on the small scale to snow-covered surfaces. A small amount of snow melt exposes darker ground which absorbs more radiation, leading to more snowmelt.
The effect has mostly been discussed in terms of the recent trend of declining Arctic sea ice
.
Internal feedback processes may also potentially occur, as land ice melts and causes eustatic sea level rise, and also potentially induces earthquakes as a result of isostatic rebound, which further acts to disrupt glaciers, ice shelves, etc.
Positive feedback
Positive feedback is a process in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system that responds to a perturbation in a way that reduces its effect is...
climate process where a change in the area of snow-covered land, ice caps, glaciers or sea ice
Sea ice
Sea ice is largely formed from seawater that freezes. Because the oceans consist of saltwater, this occurs below the freezing point of pure water, at about -1.8 °C ....
alters the albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
. This change in albedo acts to reinforce the initial alteration in ice area. Cooling tends to increase ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
cover and hence the albedo, reducing the amount of solar energy absorbed and leading to more cooling. Conversely, warming tends to decrease ice cover and hence the albedo, increasing the amount of solar energy absorbed, leading to more warming.
The effect also applies on the small scale to snow-covered surfaces. A small amount of snow melt exposes darker ground which absorbs more radiation, leading to more snowmelt.
The effect has mostly been discussed in terms of the recent trend of declining Arctic sea ice
Arctic shrinkage
Ongoing changes in the climate of the Arctic include rising temperatures, loss of sea ice, and melting of the Greenland ice sheet. Projections of sea ice loss suggest that the Arctic ocean will likely be free of summer sea ice sometime between 2060 and 2080, while another estimate puts this date at...
.
Internal feedback processes may also potentially occur, as land ice melts and causes eustatic sea level rise, and also potentially induces earthquakes as a result of isostatic rebound, which further acts to disrupt glaciers, ice shelves, etc.
See also
- Polar see-sawPolar see-sawThe Polar see-saw or Antarctic climate anomaly is the phenomenon that temperature changes in Antarctica are usually of the opposite sign to temperature changes elsewhere in the rest of the world....
describes an interesting variant on albedo and cooling.