Glaciers and Ice Sheets Flashcards
Cryosphere
the regions on Earth where snow freezes into snow or ice` make up 20% of Earth’s surface.
6 main categories of cryosphere
- 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
- periglacial zones on the margins of ice bound land
Last Glacial Maximum
17,000-21,000 years ago, temperatures were 6 degrees cooler, most liquid water was held in ice caps, sea levels were 125m lower + there were land bridges with land masses.
Holocene Climate Optimum
Deglaciation following the LGM a period between 9000 + 5000 yrs ago when global annual average temp was warmer than today. The climate was wetter; sea level higher + lasts further inland
Tundra
a type of biome where tree growth is hindered by frigid temperatures and short growing seasons.
Permafrost
a permanently frozen layer of the Earths surface. It consists of soil, gravel, and sand.
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 sediment.
Glacier
a body of ice formed on land and in motion, confined by terrain, most commonly valleys.
Ice Sheet
vast masses of ice that bury tracts of land beneath them and which are not confined to valleys (sometimes referred to as continental valleys.)
Accumulation
annual snowfall and ice which does not entirely melt in the summer months and builds up over time.
Terminus
Where glacier ice starts to melt
Ablation
the process of melting ice on a glacier
Cryonite
a grey to black coloured mineral composed of wind blown sediments such as soot, dust + soil - can accelerate melting (due to reducing the albedo -reflectiveness) and lead to the formation of moulins that can cause an ices sheet to melt from its base
Moulin
a vertical cylindrical shaft in the ice by which surface meltwater flows down from the surface to the base of the glacier
The current distribution of glaciers and ice sheets
- Every continent contains glaciers except Australia
- 217,175 glaciers covering approx. 726,800 square km
- Two major ice sheets= The Antarctic ice sheet and covers 9% of the land area on Earth and Greenland ice sheet
How has the spatial distribution of glaciers and ice sheets changed?
- The current distribution of glaciers and ice sheets is very different to how areas looked in the past
- Over the last 100 years land covered by ice has decreased dramatically as a result of global warming
What are the Natural Processes Causing Melting Glaciers + Ice Sheets
- Variations in solar energy
- Oceanic Circulation Changes
- Volcanic Activity
- Plate Tectonics
Human Activities causing melting glaciers and ice sheets
- Alteration of the composition of gases in the atmosphere
- Alteration of Landscapes
- Direct Addition of heat to the atmosphere
Variations in solar energy
- The solar energy received by the Earth is not constant. Regular long- term variation solar levels of solar radiation reaching Earth was thought of by Milankovitch- argued that the elliptical orbit of the Earth is subject to three independent cycles of change that alter the distance between the Earth and Sun every 26 000, 41 000, 100 000 years and consequently produce the planets natural climatic cycles of global glaciation and warming.
Oceanic Circulation changes
the direction of ocean currents has changed regularly in recent geological times and many continents have experienced changed climates as a result as they have an impact on the exchange of heat between oceans + the atmosphere. E.g. in the Pacific region El Nino and LA Nina have a significant impact o Australia’s climate.
Volcanic Activity
this can cause significant amounts of dust and gases to be injected into the atmosphere. This can lead to both heating and cooling events which can cause minor and short-term climate events. Masses of volcanic dust can lead to cooling when atmospheric dust reflects incoming solar radiation and the ejection of GHG can cause minor warming.
Plate Tectonics
The redistribution of land masses has long been caused by plate tectonics. This has led to LT impacts on the climate as the movement of continents change oceanic and atmospheric circulation patterns. This has also led to the formation of fold mountains like the Himalayas that are growing at a rate of 1cm per year.
Alteration of the composition of Gases in the atmosphere
- the greatest cause of global warming
- Industrialization has meant the increased injection of GHG like CO2, methane + fluorocarbons, nitrous oxides and ozone into the atmosphere
- UN has estimated that 60% of ghg emissions are from cities h/w only cover 2% of Earths surface
- Destruction and degradation of natural systems, like forests or swamps normally trap and reduce greenhouse gas emissions like c02 and methane
Alteration of Landscapes
- 2nd most important factor of global warming
- Considerable changes in solar radiation absorption (albedo) are created by the construction of hard surfaces in cities, the clearing of forests + other modifications to landscape causing the retention of heat – enhancing the greenhouse effect
Direct Addition of heat to the Atmosphere
- Burning fossil fuels for electricity prod, transportation, heating + cooling of residences and workplaces oven and household items = good example of activities that directly add heat to the atmosphere
- 2019-202 Aus bushfires produced huge amounts of ash that were blown across the Tasman Sea and deposited on New Zealands 300= glaciers which may have sped up melting by 20=30% in the 2019-20 summer
- Tourism estimated to be responsible for 5% of global ghg emissions as ice cover recedes in European alps winter sports enthusiasts are tending to move further afield to pursue snow sports increasing demand for fluing and increasing pressure on ski resorts enhancing ghg emissions
Moraine [depositional]
a large mass of material left behind by a moving glacier
eskers [depositional]
ridges made of sand and gravel deposited by glacial meltwater flowing through tunnels within and underneath glaciers
cirques [erosional]
bowl shaped ampitheatre like depressions the glaciers carve into mountains
arete
thin jagged crest that seperates two adjacent glaciers
national scale response increasing ag production
location?
date?
farming occuring mainly in south of island
implemented in early 2000s onwards
increasing ag production
reasons for implementation
increasing fertile land
increasing temp and growing seasons
imports to greenland is very expensive
aims of increasing ag production
be more self sufficient
be 50% reliant on food
decrease costs on imports
main features of increasing ag production
set up experimental farms to research which crops work in the new climate
use greenhouses to control harsh climate
SWOT of increasing ag prod
s - more food for local people + cheaper
reduction in GHG emmisions
decreased reliance on denmark
w- summer droughts mean irrigation needed
hard to transport due to lack of roads and ice
global paris climate agreement
background info
developed and signed in 2015 into force in 2016
aim to substantially reduce ghg emmisions to hold global temp increase well below 2 degrees
paris climate main feautures
legally binding international treaty
195 parties from the UN had agreed
have individual goals for each country of how to reduce ghg, make own commitments
each 5 yrs country has to submit updated national climate action plan
SWOT of paris climate agreement
S - sets diff goals for each country depending on current reliance of fossil fuels
includes 195 countries
w- many nations dont frequently meet goals
