Week 8 - Climate Change Impacts on Glaciers, Permafrost, and Sea Ice

Do continental ice sheets cause more erosion or deposition?

Deposition

Temperature at which methane hydrates thaw

0-15°C

1. Time range of the Pleistocene 2. Maximum extent of ice during Pleistocene 3. What sea level was like during Pleistocene

1. 1.8 mya until almost present 2. 1/3 of total land area 3. Sea level was much lower

1. Ice extent and thickness in 1979 2. Ice extent and thickness in 2014 3. Effect on transportation

1. 17,000 km^3, 3m 2. 4,200 km^3, 1m 3. Ships can sometimes pass thru the arctic now

How is the myth used by climate science deniers (Antarctic sea ice is growing --> no climate change) an example of cherry picking?

Ignores difference between land (declining) and sea (growing) ice - ignores big picture

How are coastal soils more susceptible to erosion as permafrost thaws?

Permafrost acts like glue to protect land from storm waves and ice bumping into it

What is subsidence and what causes it in cold regions?

Permafrost thaws, water is squeezed to the surface, soil grains become more closely packed - ground settles. -buildings resting on permafrost can cause it to melt

Why melting glaciers in the Himalayas particularly problematic for humans

Threatens crop irrigation

Describe where brittle and ductile formation occurs with glaciers

Top 50m - brittle (lots of crevasses) Blow top 50 m - ductile

Indicators of permafrost w/ an active layer

Cryoturbation (patterns in ground) and drunken trees

Nature of a glacial river

D I R T Y

Which side of Antarctica is more sensitive to climate change?

West Antarctic ice sheet

Temperature at which seawater freezes

-1.9°C

1. Defining characteristic of mountain glaciers 2. How they vary depending on latitudes 3. Size range

1. Are on mtns 2. Closer to equator, are restricted to higher altitudes 3. A few km long, 100s of m thick

Nature of Antarctic sea ice 1. When it forms 2. When it melts

1. Between July and August - polar night 2. Melts between Dec and Feb (polar day)

Describe... 1. Ice domes 2. Ice saddles 3. Ice streams 4. Ice lobes ...of continental ice sheets

1. Highest elevation 2. Places on the ridge between domes 3. Ice flows down sides 4. Ice potrudes beyond general ice margins

1. What is net accumulation? 2. What is net ablation? 3. Boundary between net accumulation and net ablation is ____°C for ice sheets and ____°C for glaciers. 4. Mass balance is higher were there's ________

1. Ice gain 2. Ice loss 3. -10, 0 4. more precipitation

1. Does Mt. Kilimanjaro have glaciers? 2. Will they last until the rest of our lives?

1. It did, but now they're mostly open canyons 2. No

1. Nature of Antarctic sea ice 2. Nature of Arctic sea ice 3. Y

1. Melts+reforms annually (1m thick) 2. Can get 4-5 yrs old (4m thick oldest) 3. Landmasses constrain movement of Arctic sea ice

2 ways thawing permafrost affects global temperatures

1. Meltwater flowing into the Arctic ocean promotes Arctic melting 2. Thawed peat releases CH4 and CO2

1. Does salt in seawater also freeze w/ sea ice? 2. Describe brinicle formation

1. No 2. Sea ice forms over shallow H2O --> releases dense, cold, salty brine --> brine sinks and freezes H2O con contact --> ice stalactite --> When it touches the sea floor it freezes anything too slow to get out of its way

If both East and West Antarctic ice sheets melt, how much would sea level rise?

72 m

1. Defining characteristic of continental ice sheets 2. Size range

1. On continents 2. 100s to 1000s of km long, 1-4 km thick

1. What are marine ice sheets? 2. What is unique (or potentially problematic) about them?

1. Part of them is below sea level 2. Vulnerable to sea level change

Engineering solutions to building in regions of permafrost (2)

1. Raising structures from the ground (cold air can circulate under) 2. Building on top of crushed gravel

1. What is calving 2. How is it different from other ablation processes

1. Shedding of icebergs into H2O 2. Icebergs leave + go melt somewhere else

Problems that thawing permafrost causes 1. directly for ppl 2. has to do with arctic 3. has to do with storms and erosion

1. Sinkholes, deformed roads/railroads, settling buildings 2. Feeds north-flowing rivers --> increases Arctic melting 3. ^wave heights, ^storm size, ^erosion rates (1-2m/yr)

1. Max extent of Arctic sea ice (season) 2. Min extent of Arctic sea ice (season) 3. Y lag?

1. Spring 2. Autumn 3. Heating+cooling takes time

1. When permafrost thaws on a slope, what happens? 2. What is hte nature of the movement?

1. Thawed layer slides downslope over remaining permafrost 2. Relatively shallow - a few m deep

1. Where does ice flow fastest when looking @ an aerial view? 2. Where does ice flow fastest in a longitudinal cross-section? 3. Y

1. The middle 2. The top 3. Friction

1. How Antarctica is divided 2. % of Antarctica that is ice 3. % of Earth's total ice that's in Antarctica

1. West and East (transantarctic mountains) - East is the size of the US 2. 98 3. 85

How Antarctic sea ice can be growing if the climate is warming 1. Wind brings _____ to land and ______ 2. _____ easier to freeze 3. _____ snowfall 4. some areas have ____

1. cold, spreads it out 2. fresh meltwater 3. more 4. cooled

How much of land is currently covered by glaciers?

1/10 (and falling)

How long does it take for the crust to rebound from glacial isostasy?

1000s of yrs

Why methane shouldn't be overlooked, even at small quantities

20-25 more effective GHG than CO2

When summer ice is expected to disappear

2030

How much of continental ice sheets sit below the surface that would have existed before ice was present?

30%

Challenges of trying to capture methane from methane hydrtaes for human use

Concerns about undersea landslides that would release a LOT of CH4

How the West Antarctic ice sheet compares to the size of Greenland

Contains 18% more ice

Where are the two existing continental ice sheets?

Antarctica + Greenland

Where are the only two continental ice sheets?

Antarctica+Greenland

Where does a marine ice sheet exist in Antarctica?

Bottom of the western part of the Antarctic ice sheet

What is an iceberg?

Broke off ice from a glacier

"Beaver" in italiano

Castoro

Do alpine/mountian glaciers cause more erosion or deposition?

Erosion

Which type of glacieers flow more quickly?

Glaciers on a steeper slope (gravity)

What causes a glacial flood?

H2O builds up against a barrier and floats the glacier - devastating flood

3 possible conditions when considering the mass balance of a glacier

Inputs>outputs --> advancing glacier Inputs=outputs --> stationary glacier Inputs<outputs --> retreating glacier (inputs-accumulation; outputs-ablation)

Relative size of East Antarctic ice sheet relative to West Antarctic ice sheet

It's a whole lot bigger

What is an ice shelf?

Part of the glacier/sheet is floating on water

What causes a glacier to surge?

Lots of H2O below ice - acts as lubricant

How methane hydrates form

Methane formed from anaerobic decomposition got trapped in hydrates and locked away under da sea

Mass balance of ice sheets @ low elevations and why

Negative - ^temps=melting

When icebergs melt, do they contribute to sea level rise?

Nope

Why soils in cold reagions are organic rich

Organic material doesn't break down so great in cold soils

"Bear" in italiano

Orso

Where do ice shelves form?

Over shallow ocean embayments

Where the greatest amount of global warming occurs

Polar regions

Effect of permafrost thaw on the atmosphere

Releases CH4 and CO2

Describe why air temp can be vastly different above cold oceans depending on whether sea ice is present or not

Sea ice insulates sea - w/o ice, air is same temp as water; w/ ice, air is much colder

Where methane hydrates are found

Shallow sea floor near coasts that used to be life-covered land

How Alaska Pipeline was built so the permafrost wouldn't thaw?

Support poles for the above-ground pipeline contain liquid with a lOw boiling point - continually warms (takes heat from permafrost), vaporizes, cools, condenses (releases heat into atmosphere), and sinks back to the bottom of the pole.

What is the climate like at high elevations on the Greenland and Antarctic ice sheets? Why is this problematic when considering glaciers are retreating?

Suuuuper cold --> low precipitation. Means that glaciers have a hard time coming back.

How can one tlel by looking @ an aerial view of a glacier where the equilibrium line is?

Where the clean snow meets the dirty snow

Where do icefalls occur?

Where there's a dropoff in the bedrock - like where waterfalls occur

Effect of black carbon on glaciers

^albedo --> ^melting

What is permafrost?

permanently frozen ground

permafrost thaw/global warming feedback loop

warming --> permafrost melts --> releases GHGs --> more warming

Profile of ground, including vegetation, active layer (and what it does), and permafrost

🌳Veg🌼et🌲at🌷io🌴n🌻 __________________________________________ Active layer - thaws in summer ___________________________________________ Permafrost