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**Oceanography > Polar Oceans & Sea Level Rise > Flashcards

Polar Oceans & Sea Level Rise Flashcards

1
Q

Real tides

A

Dynamoc theory of tides further explains the details of the tides on Earth
Observed tidal range is much greater (on average ~2m) than max predicted lunar + solar tide (79 cm)

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2
Q

Can the tide keep up with the forcing? No…

A

1) pesky continents in the way
2) even without that, there are wave speed issues
“shallow water wave speed” comapred to speed with which earth’s rotation sweeps you past the tidal bumps

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3
Q

Bay of Fundy

A

world’s largest tidal range
max tidal range of 17m due to amplification

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3
Q

Where is the excess heat from climate change going?

A

Mainly the ocean

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4
Q

Impacts of climate change on ocean

A

[pic]

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5
Q

What is sea level and how is it measured?

A
  • Elevation where the sea surface meets the land
  • Can be measured relative to a position fixed on land (i.e tide gauge) or measured by satellite (since 1933)
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6
Q

Ways to measure sea level

A
  • land-based tide gauges
  • satellite altimetry (measuring height)
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7
Q

Global mean sea level change

A

[]

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8
Q

Global sea level changes due to

A
  1. changes in mass of ocean (adding ice/water from land to ocean)
  2. changes in density of ocean (ocean warming)
  3. relative sea level also affected by: changes in land elevation & gravity field

1 & 2 are eustatic = worldwide change of sea level
3 is isostatic = changed in local elevation of land

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9
Q

Melting land ice

A
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10
Q

Types of ice

A
  • ice sheets & glaciers: grounded ice on land
  • ice shelves: floating extensions of glaciers
  • icebergs: calve from glaciers & ice shelves
  • sea ice: floating ice that froms from freezing seawater
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11
Q

Why doesn’t sea ice cause sea level rise?

A

when the ice melts it still takes up the same volume

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12
Q

Role of ice in earth system & climate

A

Sea ice:
- albedo feedbacks
- insulation between ocean & atmosphere (limiting heat, momentum transfer)
- deep water formation & global overturning circulation

Glaciers & ice sheets:
- sea level rise
- (potentially) deep water foramtion & global overturning circulation

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13
Q

Where is earth’s water?

A
  • vast majority in ocean
  • 2.5% freshwater majority glaciers and ice caps
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14
Q

Types of glacial systems

A

terms for glacier, ice cap, ice sheet

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15
Q

Large cause of sea level rise

A

Mass loss from glaciers and ice sheets

16
Q

How much would sea level rise if all of Greenland and Antarctica ice sheet & glaciers melted?

A

surface area of ocean = surface area of earth * 0.71
volume of melted ice / surface area of ocean = sea level change

17
Q

Sea level change since last ice age

A

sea level in the past can be determined by paleproxies, inclduing the depth of old coral reefs

18
Q

Past ice sheets during glacial periods

A

[pic]

19
Q

Meltwater Pulse 1

A

fastest sea level rise, 10-20 meters in <500 years

20
Q

What’s happening at the molecular level?

A
  • molecules vibrate and move faster in a fluid and therefore take up more space
  • somewhat analagous to the ideal gas law: PV = nRT
  • water is nearly incompressible
  • V proportional to T
21
Q

Links between

A
22
Q
A
  • warming of atmosphere & ocean drives mass loss from ice sheets
  • mass loss from ice sheets raises sea level & alters ocean circulation
23
Q

warm waters (from subtropical Atlantic) reach Greenland’s glaciers & drive melting

A
24
Q

Land elevation & gravity

A
  • contributes to relative sea level
  • isostatic equillibrium:
  • the ship is the lithosphere, water is the mantle, cargo us the great ice sheets
25
Q

Uplift and subsidence of land level - present day

A

[pic]

26
Q

Gravity field also changes when ice sheets grow or shrink

A

-greenland ice sheet shrinking
- sea level rise near antarctica

27
Q

Combined effects

A

Ups and downs
-ice sheets are so large that thier grvaity pulls water towards them
- when they melt this attration is lost, causing the sea level around them to fall

28
Q

Abrupt tectonic change

A
  • another cause of land-level change
  • between earthquakes: plates slide freely but at shallow depth they stick together and the overriding plate thickens
  • ## during earthquake: edge of overriding plate breaks free, springing upwards
29
Q

Projections: sea level rise in the future depends on human behavior

A

[pic]

30
Q

Breaking down the contributions to future change

A
  • ocean heat content
  • grenland ice sheet mass loss
  • antarctice ice sheet mass los
  • glacier mass loss
31
Q

How abnormal is the current rate of sea level rise?

A
32
Q

Impacts of sea level rise

A
  • flood risk in boston
  • US property losses projected to increase by the end of the century
  • erosion rates will drastically increase
33
Q

Adaptation strategies for sea level rise

A
  • protect
  • accomodate
  • retreat

**Oceanography (15 decks)

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