Unit 3- Changing the Land Flashcards
Def land cover
The observed biophysical cover on the Earth’s surface, including natural biophysical features of ice, vegetation, water, bare rock and soil, and additions made by human activity such as agriculture, urban and industrial landscapes
Def land use
Characterized by the arrangements, inputs and activities people undertake in a certain land cover type to produce, change or maintain it.
8 types of land cover
-Cultivated or managed
- Natural and semi-natural vegetation
-Cultivated aquatic or regularly flooded areas
- Natural and semi-natural aquatic land cover or regularly flooded vegetation areas
- Artificial surfaces and associated areas
- Bare areas
-Artificial water bodies, snow and ice
- Natural water bodies, snow and ice
4 natural processes that change land cover
Climate change
Geophysical changes
Plant succession
Fires and pests
Impacts of climate change
-Rising temps by at least 1.5 degrees by the end of century
-Decreased snow and ice cover
-Rising sea levels
-Longer fire seasons
-More extreme weather e.g. droughts, floods, hurricans
-Desertification
-Losses to biodiversity and ag
Def. plant succession
The directional non-seasonal cumulative change in the types of plant species that occupy a given area through time. Involves the processes of colonization, establishment, and extinction which act upon the participating land species.
How do ice ages change land cover?
-More snow and ice
-Drier and cooler conditions> more desert and semi-desert areas
-Lower sea levels
Human activities changing land cover (3)
Population dynamics
Policies
Technologies
Population dynamics key points
-rapid growth in last 300 years
- land surfaces have become areas used for housing, production and recreation
- land cleared of nat vegetation for cropping and grazing
- rural to urban migration
What percentage of people live in urban areas?
50-55%
Technologies key points
- allows for rapid, large-scale chnages to land cover
- e.g. dam building, water diversion schemes
- creation of toxic and non-biodegradable substances
- machinery can clear large amounts of vegetation
- mineral-deficient soils can be made suitable
- hybrid or GMO plants can be made to withstand hostile environments
Policies key points
- economic policies influence market prices, imports, exports, wages and tax levels
- incentives can promote logging and development
- policies can protect existing land cover e.g. against deforest
- allocations and diversions of water
Cryosphere def.
The frozen water part of the Earth system.
6 main categories of glaciers and ice sheets
Sea ice
Land covered by glaciers
Land covered by ice sheets, including ice shelves
Land such as tundra covered by snow every winter
Land underlain by permafrost
Peri-glacial zones on the margins of ice-bound land
Tundra def.
Type of biome where tree growth is hindered by frigid temperatures and short growing seasons
Permafrost def.
Permanently frozen layer on or under Earth’s surface. It consists of soil, gravel or sand usually bound together by ice.
Peri-glacial zones
The periglacial environment is a cold climate, frequently marginal to the glacial environment, and is characteristically subject to intense cycles of freezing and thawing of superficial sediments.
Glacial retreat def.
The rate of ablation exceeds the rate of glacial accumulation
Terminus def
Where glacier ice starts to melt
Ablation def
The process of melting ice on a glacier
Glacier mass balance def.
The gain and loss of ice from the glacier system.
Glacier def
A body of ice formed on land and in motion, confined by terrain, usually valleys
Ice sheet def
Vast masses of ice that bury tracts of land beneath them and which are not confined to valleys.
Last glacial maximum def.
17000 to 21000 years ago, temperatures were 6 degrees cooler, most liquid water was held in ice caps, sea levels were 125m lower and there were land bridges between landmasses. Dry period
Holocene climatic optimum def.
Deglaciation following the LGM, a period between 9000 and 5000 years ago when global were warmer than today, the climate was wetter, sea-levels higher and coasts further inland.
4 Natural processes causing the melting of glaciers and ice sheets
Variations in solar energy
Ocean circulation changes
Volcanic activity
Plate tectonics
Variations in solar energy
Solar energy received by Earth is not constant. Earth is sometimes closer to the Sun and sometimes further away ( according to 3 independent cycles every 26000, 41000 and 100000 years) called the Milankovitch cycles
Ocean circulation changes
Changing ocean currents have an impact on the exchange of heat b/w oceans and atmosphere. Leads to a warming or cooling effect. e.g. ENSO system
Volcanic activity
Short-term impacts. Both warming and cooling can occur. Warming: pollutants settling on ice, decreasing albedo, trapping greenhouse gases in the atmosphere. Cooling: Less heat absorbed from atmosphere as sunlight is blocked.
Plate tectonics
Long-term impacts. Movement of continents change oceanic and atmospheric circulation patterns. Colliding plates can also form volcanoes and mountains e.g. Himalayas
Natural sources of CO2
Life
Ocean absorption and dissolution
Volcanic emissions