"Adaptation to sea level rise
on low coral islands:
Lessons from recent events."
Ocean and Coastal Management 168:
Pages 35 to 40, 2019
by Esteban, M.,
Jamero, M.L., Nurse, L.,
Yamamoto, L., Takagi, H., Thao, N.D.,
Mikami, T., Kench, P., Onuki, M.,
Nellas, A., Crichton, R., Valenzuela, V.P.,
Chadwick, C., Avelino, J.E., Tan, N.
and Shibayama, T.
Model-based predictions
of the future climate
have been 100% wrong
for the past 30+ years.
Actual global warming has been slow,
and beneficial, since humans began
adding a lot of CO2 to the air in 1940
-- an actual global warming rate since 1940
of only 1/4 of the warming rate predicted
by the average climate model.
It's really hard to imagine global warming
will melt large portions of polar ice sheets,
thereby raising sea levels by up to a meter,
or more, by 2100.
Because sea level rise, ongoing for 20,000
years so far, has been at a slow rate of
about six inches per century, with NO sign
of any acceleration since humans began
adding a lot of CO2 to the air in 1940.
Any sea level rise could eventually affect
low-lying coastal areas, and turn citizens
into "climate refugees".
Observational trends of sea level rise
over the past decade remain far below
those predicted by models.
The paper by Duvat (2019)***
reveals that the vast majority
of small islands surveyed to date
are stable, or gaining in area,
in response to the sea level rise
that has occurred over
the past few decades.
The new paper by
Esteban et al. (2019)
looks at future
sea level rise
in an innovative way.
Esteban et al. presented three case studies.
They study coastal areas with rapid
coastal subsidence ( the land sinking )
in populated areas, as proxies to understand
human responses to the same challenges
that would be caused by future sea level rise.
The land was sinking for geologic reasons
( tectonic / earthquake ), or man made
reasons ( groundwater extraction ).
The sixteen researchers
that authored this new study say:
"there have been fears that many
low-lying atoll islands around the world
could disappear as a consequence
of climate change and sea level rise,
leading to mass migration and
threatening the existence
of several island nations."
But humans have adapted
to coastal land sinking.
The authors wrote that:
"humans have an innate
and often underestimated
capacity to adapt to changes
in their environment."
( able to ) "adapt and arrive
at solutions even when confronted
with cases of rapid rises
in water levels"
to avoid becoming
'climate refugees'.
(1)
For the Tohoku coastline of Japan:
The area had an earthquake in 2011
that caused a 78-120 cm regional
lowering of the land.
As a result, much of the coastline
is "barely above mean sea level,
with large portions of it being flooded
at high tide."
The Japanese government had a
large public works program to build up
and "return the coastal areas to their
original levels or even increase them,
and ensuring that no ground was lost
to the sea."
Over 200 km of coastline was reclaimed
in a handful of years, demonstrating
to the authors that "adapting to the
much slower sea level rise that is
projected to take place in the course
of the 21st century is technically feasible
and possible."
(2)
For the Tubingon Islands, Philippines:
A large-magnitude earthquake caused
rapid and extreme land sinking, in excess
of one meter!
The result was inland flooding during
normal high tides.
2016 measurements showed the islands
"became completely inundated
during the highest tides of the year,
with median flood levels reaching
up to 20.5-43 cm, and partial flooding
taking place between 44 and 135 days
per year."
Most island citizens chose to stay
despite the flooding.
They rebuilt their homes
by elevating them
on coral rocks or stilts,
and also built small elevated
pathways across the islands
to maintain mobility
during high tides.
(3)
Jakarta, Indonesia:
Due to high ground water extraction
the land there has been subsiding
at a rate of 9.5 to 21.5 cm per year,
causing a large amount
of coastal area
to be below sea level,
with extensive flooding
in 2007 due to high tides.
The community built large dykes
to hold back seawater and has elevated
some port wharfs and other buildings.
In summary,
Esteban et al.
write that they:
"found no evidence that these areas
will be abandoned, and it seems that
many adaptation methods are possible
through modern engineering methods
or human ingenuity."
They conclude that "it is possible
for coastal and island populations
to adapt to rising sea levels,
given that even the highest sea-level rise
scenarios are projected to happen
at much slower rates than the
case studies outlined."
Projected sea level rise
model scenarios
are FAR ABOVE
the sea level rise
actually happening.
People have no logical reason
to expect "climate refugees"
from future sea level rise.
"Highlights":
"Lessons learnt from adaptation to land subsidence in different parts of the planet.
Evidence that it is unlikely that dense coastal settlements will be abandoned in the face of sea level rise.
Long-term perspective about adaptation strategies to sea level rise."
"Abstract"
"In the past two decades there have been fears that many low-lying atoll islands around the world could disappear as a consequence of climate change and sea level rise, leading to mass migration and threatening the existence of several island nations. Here we show how sea level rise does not inevitably lead to coastal areas becoming uninhabitable, and that humans have an innate and often underestimated capacity to adapt to changes in their environment. To do so we showcase three instances of human- and earthquake-induced land subsidence that have taken place in the 21st century, where the coastal/island areas are still inhabited despite the challenge of living with higher water levels: the Tohoku coastline following the 2011 Tohoku Earthquake Tsunami (subsidence ∼0.4–1.0 m), the present day situation of coastal areas in Jakarta due to ground water extraction (>5.0 m), and the islands of Tubigon, Bohol in central Philippines after the 2013 Bohol Earthquake (∼1.0 m). Humans are able to adapt and arrive at solutions even when confronted with cases of rapid rises in water levels, and thus it is likely that in the future vulnerable coastlines will be engineered and largely remain at present day locations, particularly in densely populated areas. If anything, around densely populated areas it is more likely that humans will continue to encroach on the sea rather than the reverse. We caution, however, that small islands are not homogeneous, and many are unlikely to respond to rising sea levels in the manner that atolls do (in fact, many might just resort to build at higher elevations). Where engineering and other adaptation responses become necessary, the financial and human resource requirements may well be beyond capacity of some small islands, which could lead to impoverishment and associated challenges in many communities."
"Highlights":
"Lessons learnt from adaptation to land subsidence in different parts of the planet.
Evidence that it is unlikely that dense coastal settlements will be abandoned in the face of sea level rise.
Long-term perspective about adaptation strategies to sea level rise."
"Abstract"
"In the past two decades there have been fears that many low-lying atoll islands around the world could disappear as a consequence of climate change and sea level rise, leading to mass migration and threatening the existence of several island nations. Here we show how sea level rise does not inevitably lead to coastal areas becoming uninhabitable, and that humans have an innate and often underestimated capacity to adapt to changes in their environment. To do so we showcase three instances of human- and earthquake-induced land subsidence that have taken place in the 21st century, where the coastal/island areas are still inhabited despite the challenge of living with higher water levels: the Tohoku coastline following the 2011 Tohoku Earthquake Tsunami (subsidence ∼0.4–1.0 m), the present day situation of coastal areas in Jakarta due to ground water extraction (>5.0 m), and the islands of Tubigon, Bohol in central Philippines after the 2013 Bohol Earthquake (∼1.0 m). Humans are able to adapt and arrive at solutions even when confronted with cases of rapid rises in water levels, and thus it is likely that in the future vulnerable coastlines will be engineered and largely remain at present day locations, particularly in densely populated areas. If anything, around densely populated areas it is more likely that humans will continue to encroach on the sea rather than the reverse. We caution, however, that small islands are not homogeneous, and many are unlikely to respond to rising sea levels in the manner that atolls do (in fact, many might just resort to build at higher elevations). Where engineering and other adaptation responses become necessary, the financial and human resource requirements may well be beyond capacity of some small islands, which could lead to impoverishment and associated challenges in many communities."
Reference:
*** Duvat, V.K.E. 2019.
A global assessment of atoll island
platform changes over the past decades.
WIREs Climate Change 10: e557.