Antarctica/ Greenland Basic Flashcards
Introduction
Eq line
PMB
NMB
Temps rising
Region of
6x
- 2.5 (Tuner et al., 2005)
- 9oC (Morris and Vaughan, 2003)
Oscillation (van den Broeke and van Lipzig, 2004)
Pressure patterns
Measuring changes in climate
Ice core (Augustin et al, 2004)
Methane and carbon dioxide (Solomon et al., 2007).
Ice shelves are collapsing
Removal of ice shelf (Glasser and Scambos, 2008)
Meltwater on the surface (Glasser and Scambos, 2008)
Incursion of warm ocean currents (Viela et al., 2010)
Iceberg calving by hydrofracture (Sheperd et al., 2003)
Larsen Ice Shelf
Summer of 2002
Stable throughout the Holocene
Pine Island Glacier
Warmed from below
Interior
Primary driver Pritchard et al. (2012)
Troughs on the continental shelf
Glaciers are accelerating
Easier to float
Pritchard and Vaughan (2007)
Sea level is rising
3 mm per year (Solomon et al., 2007)
Impact of climate on glaciers
Small size and northerly latitude (Vaughn et al., 2003).
High snowfall but high melt (Pritchard and Vaughan, 2007)
It interrupts the Circumpolar Westerlies
Everything Antarctica
Introduction
The main difference between the East and West Antarctic Ice Sheets
Temperatures are rising:
Measuring changes in climate
Ice shelves are collapsing
Larsen Ice Shelf
Pine Island Glacier
Glaciers are thinning
Glaciers are accelerating
Sea level is rising
Impact of climate on glaciers
Measuring mass balance
The main difference between the East and West Antarctic Ice Sheets
The East Antarctic Ice Sheet (EAIS) has about 9 times the volume of the West Antarctic Ice Sheet (WAIS).
The EAIS has an average thickness of 2226m compared with the WAIS maximum of 1306m.
The EAIS reaches a higher elevation (over 4000m at Dome Argus) than the WAIS, and the EAIS reaches a maximum thickness of 4776m.
In contrast with the EAIS, the WAIS sits on bedrock that is mostly below sea level (lowest bed elevation of 2496m below sea level).
What are ice shelves?
These are areas where part of an ice sheet extends into the sea and floats because ice is less dense than water.
The lack of frictional resistance with bedrock causes the ice in ice shelves to move at a high velocity, up to 3km per year, and glacier ice is discharged to the sea as the edges of the ice shelf break off and float away as icebergs (a process termed ‘calving’).
What are significant parts of the Antarctic being lost?
The Ross Ice Shelf and the Ronne-Filchner Ice Shelf each cover an area larger than the British Isles. Smaller ice shelves along the Antarctic Peninsula are losing mass as a result of climate change
In addition to transporting ice, glaciers shape the land through erosion and deposition, ice streams are particularly important in this regard.
Glacial plucking and glacial abrasion they deepen and widen their valleys
As a major valley is widened, the spurs of tributary valleys become worn back to form truncated spurs.
Glacial erosion that is concentrated on two or more sides of an area of high relief leads to the formation of arêtes and pyramidal peaks.
Where is much of the glacial ice transported?
Since much of Antarctica’s glacier ice reaches the coastline and beyond, much of the material carried in Antarctic ice is taken to the sea and deposited as ice rafted debris.
However, moraines can be seen around the margins of glaciers that terminate inland, such as glaciers that terminate in the Dry Valleys.
GL Introduction
Surface mass balance (Box et al., 2006).
GL Effect of temperature (melt)
(Diamond, 1960).
At higher elevations, an increase in winter snow accumulation has partially offset the melt.
GL The individual basins response to heat is therefore likely to be characteristic of what?
(Sicart et al., 2008).
GL Effect of sea contact
(Rignot et al., 2008).
GL The mass balance of the polar ice sheets is affected by numerous factors, including…
Changes in precipitation and snowfall patterns
Summer melting of snow
Changes in ice sheet albedo
Changes in the extent of supraglacial lakes
Submarine melting of the floating ice shelves at the tongue of marine outlet glaciers (Wouters et al., 2015)
Icebergs breaking off of glaciers
Greenland is losing mass…
34 billion tonnes lost per year over the period 1992–2001 to 215 billion tonnes lost per year over the period 2002–2011.
In 2012, an exceptional loss estimated at more than 500 billion tonnes was recorded.
Atmospheric effects
Having said this,
(Fettweis et al., 2013)
Increased atmospheric moisture content, the effect of this being an increase in solid accumulation.
Everything Greenland
Introduction
Effect of temperature
Individual basins
Effect of sea contact
Mass balance of the polar ice sheets is affected by numerous factors
Greenland is losing mass…
Atmospheric effects
Having said this,
EVERYTHING
Introduction
The main difference between the East and West Antarctic Ice Sheets
Ice flow in East Antarctica
Climate in East Antarctica
Temperatures are rising
Measuring changes in climate
Ice shelves are collapsing
Larsen Ice Shelf
Pine Island Glacier
Glaciers are thinning
Glaciers are accelerating
Sea level is rising
Impact of climate on glaciers
Measuring mass balance
Introduction
Effect of temperature
Individual basins
Effect of sea contact
Mass balance of the polar ice sheets is affected by numerous factors
Greenland is losing mass…
Atmospheric effects
Having said this,
Ice flow in East Antarctica
The East Antarctic Ice Sheet has a complex configuration, with ice velocity being slow near the ice divide, but feeding out into a number of ice streams. Many of these ice streams end in ice shelves, floating glacier ice that is no longer in contact with the bed. Many of these ice shelves receive snow and ice in their own right, from freezing sea water below or from snow falling on them from above. One of the largest ice streams in East Antarctica is the Lambert Glacier System, which drains around 16% of the ice sheet by area 2.
Climate of the East Antarctic Ice Sheet
Although there has been rapid ice sheet thinning observed in West Antarctica and on the Antarctic Peninsula, so far, this has not been observed around East Antarctica 9.
In fact, parts of the East Antarctic Ice Sheet are thickening, especially deep in the interior, which contrasts strongly with the observed rapid thinning of the West Antarctic Ice Sheet
Some of the glaciers of the East Antarctic Ice Sheet are thinning and receding. These glaciers include Totten Glacier, the largest discharger of ice within the ice sheet
The East Antarctic Ice Sheet is currently cooling slightly 12, probably as a result of changes in the circumpolar vortex.
Some models predict that continued climate change will actually result in increased snowfall around East Antarctica.
