Glaciers and Icesheets Flashcards
What is the definition of land cover
The observed biophysical cover on the Earths surface
Definition of land use
The arrangements, activity and inputs people undertake in a land cover type to produce, change or maintain it
land use change
alterations in the human purposes assigned to the land
Land cover change
shifts in the natural state of the biophysical environment
LGM
approx 21000-18000 years ago
sea levels were 130 metres lower
ice covered 25%
global temp 6 lower
HCO
approx 8000 years ago
rainfall 142% more than today
47% forest cover deserts decreased
Today
11% ice sheet cover
over 16 milliom km2 of cover
Where are icesheets/glaciers
Mountain glaciers can be found on all of the continents of the world with the exception of Australia. They exist typically at high elevations where the accumulation of snow out-paces the ablation–the loss of ice through melting or sublimation.
processes causing melt
natural processes increased temp 0.1 degree
human activity has increased temp by 1 degree
processes causing melt
Thermal expansion - 50%
Glacier and ice sheet ice loss - 42%
Sea water has .2 albedo reflects 20% of solar radiation
Ice has .8 albedo reflects 80% of solar radiation
more melt= more melt
Impacts
natural processes increased temp 0.1 degree
human activity has increased temp by 1 degree
sea level has risen 0.2 m in the last 17 years
Safe levels of CO2 are 350 ppm. CO2 at 410ppm
The levels of carbon dioxide are much higher at 410ppm but the effects of methane are 80% more potent than that of CO2.
CO2 long lasting (100’s to 1000’ of years)
Methane responsible for 16% of temp increase
Methane high impact (86 times more impact than CO2 over 20 years) but shorter lived (9 years)