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Physical Geography 24-25 > Sea-level change > Flashcards

Sea-level change Flashcards

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1
Q

What is global mean sea level (GMSL)?

A

The average height of the ocean’s surface globally.

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2
Q

What is relative sea level (RSL)?

A

Sea level relative to land, affected by ocean level and land movement.

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3
Q

How much could the Antarctic and Greenland ice sheets raise sea level?

A

By about 70 meters.

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4
Q

What does a tide gauge measure?

A

Changes in sea level over time at specific locations.

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5
Q

What causes spring tides?

A

Alignment of the sun and moon’s gravitational pull.

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6
Q

What is the tidal range of a microtidal environment?

A

Less than 2 meters.

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7
Q

What are the components of RSL rise?

A

Land sinking, ocean level rising, or both.

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8
Q

Why is sea-level history location-dependent?

A

Because of local land movements and uneven water distribution.

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9
Q

What is glacio-eustasy?

A

Sea-level change due to growth or melt of ice sheets.

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10
Q

What is geoidal eustasy?

A

Redistribution of sea level due to gravity field changes.

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11
Q

What is isostasy?

A

Gravitational balance between the Earth’s crust and mantle.

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12
Q

What is glacial isostatic adjustment (GIA)?

A

Land uplift or subsidence following glaciation.

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13
Q

What are near-field GIA effects?

A

Areas directly beneath former ice sheets, showing uplift.

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14
Q

What are far-field GIA effects?

A

Areas far from ice sheets, experiencing different RSL trends.

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15
Q

What is a sea-level fingerprint?

A

Pattern of sea-level change caused by melting at specific ice sheets.

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16
Q

What is hydro-isostasy?

A

Sea-level change due to water loading on ocean basins.

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17
Q

What are tectonic causes of sea-level change?

A

Land uplift or subsidence from faulting and earthquakes.

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18
Q

What is a coseismic RSL change?

A

Immediate RSL change during an earthquake.

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19
Q

What is a post-seismic adjustment?

A

Land movement and sea-level change following an earthquake.

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20
Q

What is a meteotsunami?

A

Sea-level disturbance caused by atmospheric pressure changes.

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21
Q

What is a storm surge?

A

Abnormal water rise due to storm winds above predicted tide.

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22
Q

What is storm tide?

A

The total water level including storm surge and astronomical tide.

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23
Q

How can ocean currents affect sea level?

A

By redistributing water across the ocean basins.

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24
Q

What is the AMOC?

A

Atlantic Meridional Overturning Circulation, a major ocean current.

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25
What are high energy coasts?
Coasts exposed to strong wave and wind activity.
26
What determines wave energy?
Wind speed, duration, and fetch.
27
What are barrier islands?
Narrow coastal landforms protecting inland areas.
28
What are coastal dunes?
Sand formations created by wind in coastal areas.
29
What is a salt wedge estuary?
River-dominated estuary with limited mixing.
30
What is a partially mixed estuary?
Estuary with moderate tidal mixing and halocline.
31
What is a well-mixed estuary?
Homogeneous water column due to strong tidal influence.
32
What is a fjord-type estuary?
Deep estuary with a sill, leading to stratification.
33
What causes flocculation?
Mixing of fresh and saltwater encouraging sediment clumping.
34
What is the difference between tide- and wave-dominated estuaries?
Tide-dominated: sediment extends inland; wave-dominated: limited mixing.
35
What are saltmarshes?
Vegetated intertidal wetlands in mid-high latitudes.
36
What are mangroves?
Tropical intertidal forests in low energy coasts.
37
What happens if marsh accretion < sea-level rise?
The saltmarsh drowns.
38
What is the indicative meaning of a sea-level indicator?
Its relationship to known tidal levels.
39
What are sea-level proxies?
Indicators like corals, microfossils, and sediment types.
40
What is RWL?
Reference Water Level used in RSL reconstructions.
41
How is RSL calculated from cores?
RSL = Sample elevation - RWL.
42
What is radiocarbon dating used for?
Dating recent biological samples up to ~50,000 years.
43
What are errors in radiocarbon dating?
Contamination, old/young carbon, ocean reservoir effect.
44
What is luminescence dating?
Dating method using trapped energy in sediments.
45
What is a raised shoreline?
Old shoreline elevated above current sea level due to uplift.
46
What are coral microatolls?
Corals that grow up to the low tide limit, used as sea-level indicators.
47
What is a continuous core?
Long sediment record acting as a geologic tide gauge.
48
What is the IPCC?
Intergovernmental Panel on Climate Change.
49
What are RCPs?
Representative Concentration Pathways used to model future climate.
50
What is RCP8.5?
High emissions scenario with no peak in CO2 by 2100.
51
What is RCP2.6?
Low emissions scenario with CO2 peaking before 2100.
52
What are SSPs?
Shared Socioeconomic Pathways for climate modeling.
53
What are bottom-up sea-level projections?
Combine individual system responses to estimate sea-level rise.
54
What are top-down projections?
Use broad system metrics or empirical correlations.
55
What is the projected GMSL rise by 2100 (AR5)?
0.26 to 0.82 meters.
56
What is the rate of sea-level rise 1971–2010?
2.0 [1.7–2.3] mm/year.
57
What do semi-empirical models estimate?
SLR of 0.5–1.4 m by 2100 based on temp correlation.
58
How does 1°C temp rise affect SLR?
Estimated 3.4 mm/year increase.
59
What is the expert elicitation method?
Survey of experts to estimate future sea-level rise.
60
What are high-end estimates?
Worst-case sea-level rise projections.
61
What is coastal squeeze?
Loss of intertidal area due to fixed landward barriers.
62
What is the Last Interglacial sea level?
~6–9 meters above present.
63
What are key uncertainties in sea-level projections?
Ice sheet dynamics, emission pathways, regional variability.
64
Why do we need local sea-level projections?
Because global trends vary due to local land movement.
65
What are UKCP18 projections?
UK-specific climate change and sea-level scenarios.
66
What drives sea-level change?
Thermal expansion, melting ice, land water storage, tectonics.
67
What is dynamic topography?
Sea-level variation due to mantle convection and gravity.
68
What is post-seismic deformation?
Earth’s surface response after earthquake strain release.
69
What is a tsunami?
A large sea wave caused by an underwater earthquake or landslide.
70
How do earthquakes impact RSL?
Via sudden land uplift or subsidence.
71
What does 'usable science' refer to?
Science that informs risk management and adaptation.
72
How do sediment cores help in sea-level reconstructions?
They preserve stratigraphy linked to past sea levels.
73
What are tidal flats?
Flat, muddy or sandy areas exposed at low tide.
74
What is marsh succession?
Zonation of plant species in saltmarshes by inundation level.
75
What is the Roaring Forties?
Winds between 40–50°S that generate high wave energy.
76
How does wave energy affect coasts?
It shapes beaches, dunes, and barrier systems.
77
What is longshore drift?
Sediment movement along coast due to oblique wave angle.
78
What is a tombolo?
A sandbar connecting an island to the mainland.
79
What is a spit?
An extended beach ridge formed by longshore drift.
80
What is back-barrier environment?
Lagoon or marsh behind a barrier island.
81
What are estuarine circulation types?
Salt wedge, partially mixed, well mixed, fjord.
82
How does stratification form in estuaries?
Due to salinity differences between fresh and marine water.
83
What causes well-mixed estuaries?
Strong tidal flows overcoming river input.
84
What defines a fjord estuary?
Deep basin with sill, poor mixing.
85
What is flocculation?
Clay particles aggregating in brackish water.
86
How does wave-dominated sedimentation differ?
Central zone low energy, marine processes dominate.
87
What are geomorphic sea-level indicators?
Shore platforms, beach ridges, tidal notches.
88
Why is knowing indicator elevation important?
To quantify sea-level change accurately.
89
What limits radiocarbon dating?
It only works on materials <50,000 years old.
90
How does sea-level change affect marshes?
It can drown or expand them depending on sediment supply.
91
What is an ideal saltmarsh sedimentation model?
Sediment settles out as tidal velocity decreases over marsh.
92
Why are sea-level projections important?
To guide adaptation and coastal planning.
93
What is the current sea-level rise rate?
~3.3 mm/year (satellite data).
94
How can estuaries indicate past sea levels?
Via sediment records and microfossil zones.
95
What is the role of coral in sea-level records?
Corals grow within narrow tidal limits, indicating RSL.
96
What are sedimentary sea-level proxies?
Stratigraphy, microfossils, and sediment type.
97
Why is sea level variable?
Due to tides, atmospheric pressure, wind, and land motion.

Physical Geography 24-25 (5 decks)

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