Glaciers as Natural Systems Flashcards
Give the inputs of a glacier
Snow Avalanche Water Rocks Fern lost in summer Snow that survived the melting Rock picked up from moving KE
Give some stores, processes and transfers of a glacier
Ice Rock Fern becomes compressed by new snow Accumulation of snow Erosion of landscape Transportation of ice
Give some outputs of. a glacier
Meltwater Evaporation Sublimation Rock debris Carving
Why can a glacier be considered as an open system
Because it contains both inputs of matter and energy, as well as outputs such as water and snow
Give the first step in the formation of a glacier
Snowfall - for a glacier to form, the annual accumulation of snow must be greater than the amount of melting each year.
Often occurs in shady hollows downwind of mountains
Give the 2nd step in the formation of a glacier
After a few days, the delicate snowflakes begin to break up.
This process is accelerated by snow melting at the surface, producing meltwater which percolates into the snowpack where it refreezes in colder, deeper layers
Give the 3rd step in the formation of a glacier
Gradually snowflakes are squashed by the weight of more snow falling on top and they change into small, round granules - after a year this = firn
Give the 4th step in the formation of a glacier
The weight of the overlying snow continues to squash grains together and squeezes the air out (diagenesis).
After 10-20 years, the firn becomes ice
However, this process can take 100s of years in Greenland or Antarctica where there is no surface melting and a very gradual build-up of snow
Give the final step in the formation of a glacier
The ice becomes thicker and then the ice starts to move down the slope due to the pull of gravity. When the ice starts to move downhill it’s known as a glacier
Give 3 positive feedback cycles in glaciers
Increased warming - Melting sea ice - Less albedo - More heat absorbed
Increased warming - Melting snow - More bare rock exposed - higher heat absorption
Increased warming - Melting of tundra surface and permafrost - Methane and CO2 released
Give a negative feedback cycle for glaciers
Warming temperatures - Expose more land - More plants can survive - More CO2 absorption - Cooler temperatures
What is the ablation zone
Output of the glacier - lower altitude and warmer climate encourages melting
In the ablation zone, the ratio of ice to rock debris in the glacier are greatly……………
Reduced
What is the equilibrium line
The point where both accumulation and ablation are equal
Give 4 types of cold environments and their location
Polar - High latitudes within Arctic and Antarctic circles
Glacial - Any location associated with active glaciers
Alpine - Mountain areas, Alps and North American Rockies
Periglacial - Mainly at the margins of glacial and polar environments such as Alaska, Northern Canada and Siberia
Give the climate conditions for polar
Worlds most extreme conditions, with temperatures falling as low as -50 to -60ºC
Very high wind speeds + low precipitation
Human activities severely restricted
No natural vegetation
Give the climate conditions for glacial
- Very cold winter temperatures and significant precipitation in the form of heavy winter snowfall, encouraging glacial growth
- More moderate summers encourage glacial flow
- Human activities = tourism like skiing
- Some limited alpine vegetation will exist on the fringes of glacial environments
Give the climate conditions for Alpine
- Heavy winter precipitation with very cold temperatures averaging -10ºC or less (dictated by high altitude)
- Wide annual temperature range owing to warm, sunny summers averaging 20ºC or more
- Human activities such as agriculture and tourism can thrive (ideal for HEP)
- Rich meadows, grasslands and trees (mostly coniferous)
Give the climate conditions for periglacial
- Cold temperatures maintain permanently frozen ground (permafrost) though not covered by ice
- Brief warm summers allow surface layers to thaw making soil conditions marshy
- Limited human activities
- Tundra vegetation comprises low growing plants and shrubs with few trees
Climate is never………
Stable
What is the name of our Ice age and what is an ice age
Quaternary Ice Age - began 2 million years ago
Ice ages are periods when there are ice sheets and glaciers present on Earth
Ice masses cover …% of the Earths land area today
10
85% of ice is contained in the Antarctic sheet
What was the last glacial period called
Devensian glacial - the maximum extent of glaciers occurred between 20,000 and 18,000 years ago when ice covered 30%
How low were sea levels in Devensian glacial
100m lower - no English Chanell
Give 3 long term climate change theories (Milankovitch)
Orbit
Tilt
Wobble
How does the Earth’s 95,000-year orbit affect climate change
The Earth’s orbit stretches from being nearly circular to an elliptical shape and back in a cycle of 90,000 years
Glacials occur when the orbit is almost circular and interglacials occur when ut is more elliptical
How does the Earth’s 42,000-year tilt affect climate change
The Earth’s axis varies from its plane of orbit between 21.5º and 24.5º. When the tilt increases, summers will be hotter and winters colder - leading to conditions favouring interglacials
How does the Earth’s 21,000-year-old wobble affect climate change
As the Earth slowly wobbles through space, its axis describes a circle once every 21,000 years
At present, the Earth is closest to the sun in the northern hemisphere’s winter and furthest away in the summer. This makes winters mild and summers cool - ideal conditions for glacials to develop.
Give the climate in cold environments
- Temperatures are close to or significantly colder than freezing
- Liquid water is limited to certain times of the year
- Snowfall varies - not much in polar regions but lots in coastal + mountainous environments
Give the soils in cold environments
Weathering is limited due to the lack of liquid water and vegetation - little organic matter + decomposers which only thrive in warm conditions
Soil development is therefore really slow and any that do develop will be very thin, acidic and waterlogged + frozen
Give the vegetation in cold environments
Vegetation requires soil to act as an anchor and to extract nutrients and minerals from
Many cold environments don’t have vegetation so there is no fertlie soil - mostly lichens on bare rock
How much of Antarctica is ice-free
0.4% - 90% of this is able to support soil
What are the soils like in Antarctica
Cold, desert soils with deep-set permafrost evident in lower layers
The surface layer is often strewn with boulders and gravel - created due to the extreme weathering process
How many native plants are there in Antarctica and what are they
2
Antarctic Hair Grass
Antarctic Pearlwort
Found in small groups near the shore of the West coast - temperatures there are milder with more precipitation
How have plants adapted to Antarctica
- Able to survive under a snow layer + photosynthesis in very cold environments
- Leaf size is often small to prevent moisture loss + have a fur-like covering
- Plants produce flowers which are cup-shaped to focus the sun’s rays to the centre to assist photosynthesis
