A SECTORAL FOCUS ON ATOLL ADAPTATION · 2019-05-15 · Compounding impacts of climate change on...
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A SECTORAL FOCUS ON ATOLL ADAPTATION ATOLLS VS VOLCANIC ISLANDS, COMPOUNDING IMPACTS AND ADAPTATION TIMING GEOSCIENCE ENERGY AND MARITIME DIVISION
Transcript of A SECTORAL FOCUS ON ATOLL ADAPTATION · 2019-05-15 · Compounding impacts of climate change on...
A SECTORAL FOCUS ON ATOLL ADAPTATION ATOLLS VS VOLCANIC ISLANDS, COMPOUNDING IMPACTS AND ADAPTATION TIMING
GEOSCIENCE ENERGY AND MARITIME DIVISION
Fundamental differences between atolls and
volcanic islands
• A few million years…
https://www.researchgate.net/figure/Many-atolls-have-irregular-shapes-
with-one-or-more-large-arcuate-bight-like-structures_fig2_257143897https://oceanservice.noaa.gov/education/kits/corals/media/supp_coral04a.html
Fundamental differences between atolls and
volcanic islands
Ocean
Volcanic Islands All Islands
Nadarivatu hydro dam, Fiji
Devil's point wind farm, Vanuatu
Matatoa solar farm, Tonga
• A few million years…
• Energy resources
Fundamental differences between atolls and
volcanic islands
• A few million years…
• Energy resources
• Agricultural resources
AtollsAll Small Islands
Narrow
genetic basePests/disease
impacts
Limited
water supply
Poor soil
nutrients
Salt water
inundation
Atoll
communities
25litres
25litres
about
50 L/p/d
Pacific
neighbours
25litres
25litres
25litres
25litres
25litres
25litres
25litres
25litres
200 L/p/d and
more
25litres
25litres
25litres
25litres
15 litres
Minimum
“Sphere standard”
15 L/p/d
15 litres
Vastly different water use
Fundamental differences between atolls and
volcanic islands
Household
storage21,176 kL
6,373 kL
3,136 kL
1,467 kL
Government
storage
Community
storage
Commercial
storage
Other
Funafuti rainwater reserves
Vastly different water reserves
Fundamental differences between atolls and
volcanic islands
Monasavu Dam, Fiji: 133,000,000 kL
Available water source
distribution Funafuti
106L/p/dHousehold
RWH
storage
74%
5.3m3/p
(106 days supply)
Government and
communal RWH
storage 25%
Desalination 24L/p/d
1%
1.8m3/p(37 days supply)
Funafuti water supplies
Fundamental differences between atolls and
volcanic islands
Assume 50L/p/d
1m3 = 1000L
Groundwater
availability
49 - 77 L/p/d
sustainable extraction
long term
4.7m3/p
94 days supply
at 50L/p/d
Government
storage (airport)
Other (desal and HH
RWH unknown)
Majuro water suppliesAssume 50L/p/d
1m3 = 1000L
Available water source
distribution Majuro
Fundamental differences between atolls and
volcanic islands
Compounding impacts of climate change on
atoll sectors
“Atoll countries in the Pacific will be the first nations to face extinction as a result of global
warming. Rising sea levels could wipe them off the map in a matter of decades.”
Pres. Hilda Heine and Patrick Verkooijen; 10 April 2019; https://www.washingtonpost.com/opinions
The following
model uses
this scenario
IPCC = 66% certainty
NOAA = 90% certainty
Compounding impacts of climate change on
atoll sectors
Groundwater vulnerability
to inundation
Storlazzi et al., Sci. Adv. 2018;4: eaap9741 25 April 2018
Key Findings:
• Groundwater impacted only
where inundation occurs
• Groundwater recovers with
rainfall recharge
• Recovery of 2-6 years
dependent on recharge
scenario
• Extraction and the rainfall
recharge are the most critical
Inundation modelling under 4 different SLR projections, and 3 probability events:
20, 50, 100 yr RI. (72 scenarios reviewed)
Compounding impacts of climate change on
atoll sectors
Compounding impacts of climate change on
atoll sectors
It’s not just about sea level
rise…
Global
warming
Intense storm
wavesSea level rise
Higher air
temperaturesFrequent intense
droughts
More overwash
Less recharge
Greater
extraction
Maldives are island building: pumping sand from
surrounding atolls and depositing it on shallow
reefs fortified with walls 3m above sea level
(higher than the highest island at 2.5m ASL)
https://thatmaldivesblog.wordpress.com/2017/10/16/happy
-birthday-hulhumale-reclaimed-island-gallery/
https://www.newscientist.com/article/2125198-on-front-line-of-
climate-change-as-maldives-fights-rising-seas/
Atoll adaptation: timing is everything
http://time.com/4341510/south-
china-sea-artificial-islands/
Atoll adaptation: timing is everything
Island building can be
rapid…
Atoll adaptation: timing is everything
Island building can be
rapid…
Although not currently
in the Pacific
Pictures courtesy Peter Olivier Calibre Consulting
Repairing
breach ocean
side geotextile
bags Funafuti
Beach mining -
2016
Lagoon
clamshell
Tarawa-
2016
If SLR results loss of land
• freshwater lens lifts with rising sea level
• freshwater lens reduced,
• infrastructure impacted, water quality can be compromised
SLR results in loss of land
Sea level
New sea level gallery
Atoll adaptation: timing is everything
Groundwater adaptation to
land reclamation
New sea level gallery Land reclamation
Groundwater adaptation to
land reclamation
Reclamation with sand dredging, land area maintained or increased
• freshwater lens develops 15 years,
• size of freshwater lens retained
Atoll adaptation: timing is everything
Atoll adaptation: timing is everything
• Science can do more than
identify the problem.
• Future scenario or probabilistic
modelling allows us to make risk
informed decisions.
