Sinking atoll islands Flashcards

1
Q

what is an Atoll?

A

An atoll is a ring-shaped coral reef, often surrounding a central lagoon, that forms around a submerged volcanic island in tropical ocean waters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why are atolls significant?

A

habitats for marine life
home to human populations and rich culture
offer insight into geological and biological processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

1st theory of atoll formation?

A

Land Subsidence Theory (Darwin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain Land Subsidence theory

A

coral reef begins to grow around edges of volcanic island in shallow water

volcanic island begins to sink due to subsidence
coral continues to grow upward creating a reef separated from the island by a lagoon

volcanic island becomes completely submerged below sea level

coral forms reef shaped ring with lagoon in the centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what evidence was found to support Darwin’s theory?

A

Data from deep drilling on coral atolls in the pacific ocean
as depths of corals increased age of corals also increased
fossil corals dated back 50 million years
found underlying volcanic rock (basalt)
shallow corals found at deep depths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

problem with Darwin’s theory?

A

Doesn’t consider rising sea levels or changes in sea levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Daly’s glacial control theory?

A

alternative explanation for atoll formation
emphasised role of glacial cycles and sea level changes during the ice ages in shaping atolls
model highlights how fluctuations in global sea levels caused by glaciation and deglaciation impact coral reef growth and atoll formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

step one in Daly glacial model atoll formation process

A

during ice age sea levels lowered
many coral reefs exposed to the air and growth stopped because corals cannot survive out of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

step 2 in Daly model

A

post glacial sea level rise glaciers melted and reef platforms were submerged underwater
coral start growing again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

step 3 Daly model

A

atoll forms
corals grow upward along the edges of the submerged reef platforms keeping pace with the rising sea levels
upward coral eventually form ring shaped structure with central lagoon in middle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the key driving force in Darwins theory?

A

tectonic activity leading to subsidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the key driving force in Dalys theory?

A

sea level fluctuations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

weakness of Daly glacial model?

A

no reference to subsidence doesn’t explain why atolls are located in clearly subsiding locations

Suggests this is unrelated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what does the Antecedent karst theory propose about atoll formation?

A

atolls form on pre-existing karst landscapes (limestone platforms) that were shaped by chemical weathering and erosion before coral reefs began to grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is a karst landscape?

A

a landscape formed by the chemical weathering of limestone through acidic water creating features like sinkholes, caves and depressions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does a karst landscape form the foundation of an atoll?

A

when sea levels rise the karst features are flooded providing base for coral reefs to grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what happens to the central depressions in a karst landscape?

A

they become the lagoons of the atoll as coral grows around the rims of the depressions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what role does sea level play in the antecedent karst theory?

A

at low sea levels during glacial periods allows karst landscapes to form

at high sea levels during interglacial periods - floods landscapes allow coral to form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the strengths of the antecedent karst theory?

A

explains atolls on non-volcanic limestone platforms
considers the role of sea level change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

weakness of this model?

A

is usefull in karst landscapes but is not a universal model for all atolls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

which theory suggests that atoll islands will dissapear?

A

Darwin Land subsidence theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

which theory suggests that atoll islands will survive?

A

Daly glacial model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what do humans struggle to do that prevents correct knowledge being spread about atolls?

A

conceive time beyond generational memory = struggle to understand historical processes and their temporal scales

24
Q

what theory does the media use to explain atolls and thus their sinking?

A

Darwins theory

25
Q

Kench et al (2018) - what was this study on

A

analysed shoreline changes in 101 islands within the Pacific atoll nation of Tuvalu over the past 4 decades

26
Q

what was the key finding of the Kench et al study?

A

the total area of Tuvalu has increased despite rising sea levels

27
Q

by what percentage has the total land area of tuvalu increase by?

A

2.9%

28
Q

what has the Kench et al study revealed about the nature of islands?

A

Islands are dynamic features that can adjust to the changing of sea levels and climatic conditions
counters the assumption that they are static landforms that will simply drown

29
Q

what 3 changes were observed in Tuvalus Islands?

A

1) only 1 island has been completely eroded
2) the total land area increased by 2.9% since 1971
3) the magnitude and direction of changes varied significantly between islands

30
Q

population of Tuvalu in 2023?

A

11,400

31
Q

why is land loss unlikely to force depopulation in Tuvalu?

A

the majority of islands are either expanding - suggests land loss is not major factor in driving population movement

32
Q

what factors influence shoreline shifts and island morphology?

A

wave processes - any transfer across reef surfaces, causing shoreline and sediment shifts

storm wave processes - influence erosion or accretion based on storm size and island material composition

sediment supply and wave energy- often mask sea level rise effects

33
Q

What is the role of population density in island stability? give example

A

Low population density correlates with greater island stability and resistance to erosion.

example - island Nunumaga (lowest pop density) more stable than urban island of Fogafale

34
Q

What is the impact of flawed adaptation narratives?

A

persistent narratives of loss (e.g., inevitable drowning of islands) undermine adaptive planning, leading to strategies that fail to embrace islands’ dynamic and resilient nature.

35
Q

what 3 adaptation strategies are suggested for atoll nations in Kench et al?

A

1) Internal migration - Relocate populations to stable islands within the nation, such as Nanumaga or Vaitupu.

2) Support long-term, planned relocations to reduce trauma and allow communities to remain in familiar environments.

3) Develop adaptive initiatives to address changes in land resources and sustainability challenges.

36
Q

What does the study recommend for atoll nations’ sovereignty and dignity?

A

Support the autonomy of atoll nations and the rights of their people to dignified lives, through adaptive measures that respect their traditions and choices.

37
Q

How do wave and sediment processes mask the effects of rising sea levels?

A

wave and sediment processes cause higher frequency and larger magnitude changes to island morphology obscuring the gradual impact of sea level rise in the geomorphic record

38
Q

Montreux et al (2023)

A

Climate change and migration from atolls
no evidence yet

39
Q

Climate change and migration from atolls
no evidence yet - study name
what is the author and date

A

Montreux et al (2023)

40
Q

What is the prevailing assumption about migration from atolls in the climate change literature?

A

the assumption is that outmigration is the only option for atoll residents
with little attention to the local adaptation options and what local people would like

41
Q

How has Tuvalu’s climate vulnerability perception affected foreign investment?

A

investors perceptions of Tuvalu’s climate vulnerability have made it difficult to secure foreign investment for projects like rainwater tanks despite strong local interest in adaptation

42
Q

What type of research frames migration as an inevitable response to climate change?

A

Non-empirical research (e.g., literature reviews, commentary) often frames migration as permanent, forced, and external,

43
Q

Is there empirical evidence linking climate change to migration from atolls?

A

no the Montreux et al study found that there is no evidence in academic literature that links climate change directly to migration from atoll communities

44
Q

What systemic strategy have islanders traditionally used to persist in atolls?

A

Interisland mobility has been a traditional strategy for managing resources and adapting to challenges in atoll environments.

45
Q

How does place attachment influence migration decisions in atoll communities?

A

place attachment often overrides relocation meaning remaining populations are not necessarily ‘trapped’ but instead choose to stay because of their strong connection to the land and culture

46
Q

what does the Montreux et al (2023) study highlight as research and resource gaps?

A

need greater focus on in situ adaptation and the policies and institutions required to support atoll communities in securing their future

47
Q

Where is Tuvalu?

A

made up of 9 atolls and reef islands making 4th smallest country in the world
In the pacific ocean between hawaii and australia

48
Q

The first climate refugees - paper name

who wrote and when?

A

Farbotoko et al (2012)

49
Q

What is uncertain about climate change effects on populations?

A

While climate change effects, such as sea-level rise, are almost certain, their impacts on populations are far less predictable.

50
Q

how is climate mobility often portrayed?

A

as the production of refugees - overlooks long histories of ordinary mobilities among affected populations

51
Q

What does the Tuvalu case highlight about migration and climate refugee narratives?

A

It juxtaposes migration as an everyday practice with global discourses framing Tuvaluans as disempowered climate refugees.

52
Q

how do global narratives of climate change affect vulnerable communities?

A

they can entrench vulnerable communities in inequitable power relations and redirect their fate out of their own hands

53
Q

What is detrimental about the “climate refugee” label?

A

It undermines community strength and resilience, framing Tuvaluans as helpless victims rather than emphasizing their agency and value.

54
Q

How are Tuvaluans portrayed in photojournalism and documentaries?

A

As disempowered, wading through floods, symbolizing a “crisis of nature” framed by outsiders rather than reflecting Tuvaluans’ own views.

55
Q

What does equitable climate governance require?

A

Greater openness to islanders’ emotions, values, mobilities, and spaces.