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62 Cards in this Set
- Front
- Back
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The importance of ice
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1. Increases albedo so helps to decrease temperature.
2. Contains 97% of our fresh water 3. Challenges of building on frozen ground. 4. Amount of methane released as some of the glacial ice/permafrost melts. |
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. what are the Components of the cryosphere
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1. Continental ice sheets, ice shelves, caps, river and lake ice, and alpine glaciers
2. Sea ice 3. Permafrost |
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Interactions between the cryosphere and climate:
1. Global-scale: |
a. Changes in distribution and coverage of sea ice and snow cover affect albedo
b. Sea level is affected by growth/melting of continental ice. c. Melting of permafrost releases greenhouse gases. d. Formation of sea ice helps to generate NADW and AABW |
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Interactions between the cryosphere and climate:. Regional scales:
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a. Sea ice, permafrost, and mountain snow cover important to ecosystems.
b. Mountain snow cover and glacial ice important source of fresh water – e.g mountain snow cover contributes about 75% of fresh water to western USA. |
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why is the Cryosphere dynamic
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always changing. Throughout most of Earth’s history – no permanent ice and other times, Earth almost an ice ball.
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what is the Northern hemisphere snow cover
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1. Varies from about 2,000,000 km² to 4,000,000 km² in summer to 45,000,000 km² to 47,000,000 km² in winter.
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does Fresh, low density snow have a high or low albedo
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high albedo – 80 to 90%
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how does Snow cover affect temp
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cover helps to keep air temperature lower, but it keeps the ground beneath it warmer.
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. what is Permafrost
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1. Permanently frozen ground
2. Ground must be at or below 0ºC for 2 or more years. 3. Can have pockets of unfrozen ground – Talik 4. Heated from ground below and cooled from surface |
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– Talik
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pockets of unfrozen ground
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Permafrost temps
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change slowly – response to decadal and longer time spans
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what is the Active layer in permafrost
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upper portion that responds to seasonal variation in temps
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what do Temp measurements indicate in northern hemisphere
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temp of permafrost in northern hemisphere is warming.
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what is the IPCC
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predicts permafrost in NA is likely to decrease by 20-35% by middle of this century.
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thermokarst
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If permafrost has a high ice content, as pockets of ice melts, get depressions and small hills
Affects ecosystems and construction. |
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Pingos
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Hills with ice in the center. Frozen ground is forced up by underground water. Some are as old as 1000 years. Reach over 200 feet in height and 2000 feet in diameter. Also can affect construction and ecosystems.
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how much permafrost is present in . The Northern hemisphere
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22.79 million sq. km. of permafrost.
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where else does permafrost exist besides land
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, there is permafrost under the Arctic Ocean on the continental shelves.
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what is the Thickness of permafrost
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ranges from about 1 meter to 1000 meters.
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how big is Western Siberian permafrost
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1. An area the size of France and Germany combined (approximately 1 million sq. km.) in western Siberia is melting
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what happens as Western Siberian permafrost melts
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shallow lakes are formed on the surface.
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what is the problem if Western Siberian permafrost melts
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. The problem is there are peat bogs underneath the western Siberian permafrost.
a. The peat bogs formed around 11,000 years ago at the end of the last glacial maxima |
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Gas hydrates, or clathrates
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crystalline solids (ice) which form when water molecules form a cage-like structure around smaller guest molecules (e.g. methane). The methane in gas hydrates is usually generated by bacterial degradation of organic matter in low oxygen environments. Below the frozen clathrates, methane may occur as bubbles of free gas in the sediments (http://ethomas.web.wesleyan.edu/ees123/clathrate.htm
Permafrost, methane, and global warming |
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how much has Western Siberia has warmed in past 40 years
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average of 3C
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why has there been warming in the Western Siberia
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a. Warming is part anthropogenic, partially due to a natural cycle in the atmosphere called the “Arctic Oscillation”, and feedback mechanisms.
5. Similar melting is occurring in Alaska |
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how much methane does the western Siberian peat bog that is now being exposed have
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due to the melting of the permafrost contains 70 BILLION tonnes of methane!
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what ice age are we currently in?
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We are still in the Pleistocene ice age because we still have glacial ice, but that ice is melting, so we are in an “interglacial” period.
B. The Pleistocene epoch was from 1.8 MYA to 10,000 years ago. C. We are now in the Holocene which has been warmer than the Pleistocene, but again, we still have glacial ice. |
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how long has The Antarctic ice sheet has been around for
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approximately 15 million years, so it is older than the Pleistocene
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how is the The Antarctic ice sheet divided
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divided into the East and West Antarctic ice sheets.
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where does the western Antarctic ice sheet flow
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The western ice sheet flows mostly into the Ross and Weddell seas and forms ice shelves.
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how are Ice shelves attached
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partially attached to the bottom of the continental shelf and are partiallyfloating. If the air is warm and the water is also, the sea ice can melt at a rapid pace.
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what happens if Antarctic ice sheet continues to melt
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. If they continue to melt, the ice would eventually completely break off and would be free-floating.
5. Once this ice becomes free-floating, the ice that “feeds” the shelves can surge and very rapidly flow into the ocean. This could cause a rapid (a few hundred years) rise in sea level. |
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how fast is West Antarctica’s Biggest Glacier Melting compared to 17 years ago
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50% Faster Than 17 Years Ago…
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how much ice is The Pine Island glacier losing per year
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losing about 78 cubic kilometers (30 cubic miles) of ice per year
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. Since 1974 how much ice shelf has been broken off?
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about 5300 sq. miles of shelf ice have broken off 7 of the Antarctic ice sheets.
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how much has temperatures in the Antarctic risen since 1950
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about 4.5F.
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If the entire Antarctic ice sheet melted how much would sea level rise
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approximately 60-70 meters (approximately 200-230 feet).
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what do glaceier surges cause
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rise in sea level
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If the Greenland ice sheet melts, how much would sea level rise
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another 7 meters (about 23 feet).
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Glacial till
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unsorted (sorting refers to sorting rocks and sediments by size) sediments deposited directly by glaciers. Till has all sizes of rocks and sediments jumbled up together
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. Loess
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deposits of windblown glacial silt (“silt” refers to a very small particle of rock = 1/16 to 1/256mm in diameter). They can form very rich soils.
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4 MAIN Pleistocene ice advances and the interglacials in North America. From the oldest to the youngest
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1. Nebraskan
a. Aftonian interglacial 2. Kansan b. Yarmouth interglacial 3. Illinoian c. Sangmon (or Eemian) interglacial 4. Wisconsin |
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In the USA, continental glacial ice extended into the states of
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Kansas, Indiana/Kentucky border, Pennsylvania and New Jersey. Alpine glaciers were found as far south as the northern part of New Mexico
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. In the western USA
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the climate was more humid and pluvial (rain) lakes were common. The largest lake was Lake Bonneville in Utah.
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Glacial-Interglacial Oscillations
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Again, we will rely on O18 to O16 ratio of deep sea sediments as a temperature proxy.
B. The finer climate resolution produced by the sea floor sediments indicates that there were “dozens” of climate swings in the Pleistocene. |
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During glacials what was the average global temp and CO2 concentration
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about 10C and the CO2 concentrations were about 200ppm
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what occured During the interglacials
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continental ice is limited to Greenland and Antarctica; average global temps. are 15C and CO2 concentrations are about 280ppm. The last 10,000 years, the Holocene, is an interglacial
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Although the periodicity of the Pleistocene glaciations have been regular since 700,000 years ago, what were the cycles like before that
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cycles were shorter – approximately 40,000 years. Why? Your book relates these cycles to the Milankovitch orbits
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what did Milankovitch think continental glaciations were related to
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the amount of summer radiation in the high latitudes. High amounts = warmer summers and the winter snows can melt while low amounts would lead to less melting and ice accumulation.
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The optimal conditions for glaciation just considering the Milankovitch orbits are
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1. Low obliquity = low seasonal contrast
2. High eccentricity 3. Precession angle that places the Northern hemisphere summers at aphelion and minimized the amount of summertime insolation at high northern latitudes |
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Marine biological pump
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(photosynthetic conversion of CO2 to organic matter in the surface of the ocean, settling of organic matter and its decomposition at the bottom of the ocean.) If the pump is more efficient in doing this, CO2 levels will drop and vice versa.
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Why would the marine biological pump be more efficient?
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More nutrients in the ocean? Nutrients come from rivers or from biological processes and are primarily removed by sedimentation of organic material. So if biological pump was more efficient during glacial episodes, then either there were more nutrients being supplied by rivers or sedimentation rates were lower.
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what happened to Sea levels as glaciers grew
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Sea levels fell as glaciers grew exposing the continental shelves which are rich in nutrients and organic matter. Weathering of the sediments released phosphate to the rivers draining the shelves. There was an increase in phosphate in the oceans which increased marine productivity and a carbon export from the surface of the ocean and a drop in atmospheric CO2.
But problem with this. No evidence that there is an increase in phosphate content of oceans during glacials. |
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what does the growth of coral reefs cause
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add carbon dioxide to the atmosphere in the “short” run (for 10s of thousands of years only).
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what happens If ancient coral reefs are exposed to the atmosphere
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chemical weathering leads to their dissolution.
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how is Atmospheric carbon dioxide converted
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converted into bicarbonate which is carried by rivers into the oceans and it cools.
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what happens to coral reefs As glaciers melt
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sea level rises and drowns the coral reefs, but if the reefs can grow vertically and keep pace with the rise in sea level, CO2 will once again be released into the atmosphere and it warms
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Changes in terrestrial biomass
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1). More trees and other terrestrial plants, less CO2 and vice versa.
2). Cold climate – less terrestrial biomass, increase in CO2 and warming. |
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. During glaciation, the MSA (Methane sulfonic acid) content of the atmosphere over the Southern Ocean was
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much greater
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More cloud condensation nuclei =
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more clouds which COULD equal more albedo.
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. If marine algal production is increased what happens to MSA
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If marine algal production is increased, so does the production of MSA
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what type of water do marine phytoplankton “like
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colder waters
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