OA lecture 5 - Jasmine Flashcards

1
Q

define mean sealevel (MSL)

A

Mean sea level: is the average height of the sea over longer periods of time (usually a month or year)

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2
Q

what is filtered out in sea level change

A

Short-term variations in waves, tides & storm surges are filtered out

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3
Q

how much higher was the last interglacial

A

Last interglacial (125,000 years ago) sea level 5 m above that of today

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4
Q

when the sea level fells, where was water trapped? how far did the sea level fall?

A

The sea level fell to >100 m below today; water was trapped in ice sheets during the last ice age.

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5
Q

has the sea level changed much in the past 2000 years?

A

no- very little

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6
Q

recent changes in MSL how much- during late 19th and early 20th centuries

A

1.7mm/yr-1

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7
Q

recent changes in MSL how much- 20th century

A

1.7mm/yr-1

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8
Q

recent changes in MSL how much- 1993-2021

A

3.3mm/yr-1

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9
Q

identify vulnerable regions to mean sea level rise

A

Highest risk to changes in MSL are coastal zones with
dense populations
low elevations
appreciable rates of subsidence
and/or inadequate adaptive capacity

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10
Q

Rate of rise is not….

A

uniform

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11
Q

natural variability in SLR due to…

A

ENSO
ocean current

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12
Q

3 major contributors to MSL

A

Thermal expansion;
Glaciers;
Ice sheets (Greenland and Antarctica).

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13
Q

what is the natural process of Melting of glaciers and polar ice caps

A

Summer: Naturally melt back
Winter: Snow balances out the melting

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14
Q

what have rising temperature caused to the melting of glaciers and polar ice caps

A

Rising temperatures caused:
greater than average summer melting
reduced snowfall

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15
Q

what has been lost from Greenland + West Antarctica

A

Melting of small glaciers & polar ice caps projected MSLR ~ 0.5m

Melting of Greenland ice sheet projected MSLR ~ 7.2m

Melting of Antarctic ice sheet projected MSLR ~ 61m

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16
Q

what some impacts of MSLR

A

Effects: modifies propagation of tides & storm surges raises risks of extreme events
greater wave heights
greater wave driven run-up
Raised ground water levels
Salinised freshwater lens

17
Q

what happens upon impacts of MSLR on wetland migration

A

Potential for landward migration & coastal squeeze across Gulf of Mexico estuaries (1.0 m sea level rise scenario)
landward erosion of seaward edge, new marsh is created in a retreated way.
if seawall is present infront of used land- ie farm, but nothing is protecting natural slatmarsh.. as sea levels rise this saltamarsh becomes SQUEEZES

18
Q

Main contributors to SLR

A

thermal expansion, glacial melt and the melting of the Polar ice sheets.

19
Q

Main impacts of MSLR

A

coastal inundation, flooding, wetland migration or loss, coastal erosion, saltwater intrusion and rising ground water tables

20
Q

WHAT kind of management should be suggested for urban areas in coastal areas?

A

Adaptive management strategies for urban areas need to take into consideration both marine inundation and groundwater intrusion into their adaptive

21
Q

what does historical SLR look like?

A

Large variations in sea level in the geological past
Recent changes driven by climate change