Green buffers are generally better for protecting coastal communities than concrete defenses
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| Taylor Swift's mansion in Watch Hill and its seawall (EcoRI photo) |
The
Intergovernmental Panel on Climate Change’s latest report has
a new emphasis on “maladaptation”, when measures taken to adapt to the effects
of climate change cause more problems than they solve.
While
seawalls do protect coastal properties and beaches, they are expensive, damage
wildlife, mainly benefit the rich and encourage risky building near the coast.
Experts
around the world told Climate Home News that green buffers like mangroves are
generally a better way of dealing with sea level rise than hard infrastructure
like seawalls and levees, although they are not suitable for every location.
Melanie Bishop is an associate professor of marine ecology at Australia’s Macquarie University. “Hard engineering structures, such as seawalls, have historically been the primary approach to coastal hazard reduction,” she said.
“While
these structures have in many instances effectively protected coastal assets
from erosion and inundation, their use has come at considerable cost – not only
in economic terms, but also environmentally and socially.”
A
near-final version of the report summary, drafted by scientists and seen by Climate
Home News, said that “seawalls reduce impacts to people and assets in the
short-term but can result in lock-ins and increase exposure to climate risks in
the long-term”.
After
government representatives had their say during the approval plenary, this
criticism was softened and the advantages of seawalls emphasised. The caveat
“unless they are integrated into a long-term adaptive plan” was added into the
final version and the word “effectively” was added before “reduce”.
Seawalls
are also “inflexible and/or expensive to change,” the summary concluded.
Two
sources with knowledge of the talks told Climate Home that European countries
emphasised the benefits of nature-based solutions while India, China and small
island states argued that all adaptation options should be on the table.
Seawalls’
price tags have sparked debates around the world over what should be protected
and who should pay for it.
In
California, tech companies like Google and Facebook have bought billions
of dollars of properties next to San Francisco Bay. Due to sea level rise, the
area is vulnerable to flooding during a storm surge.
To
build a levee, Facebook will pay $7.8 million, while the nearby low-income
community of East Palo Alto is chipping in $5.5 million, 13% of its annual
budget.
Mark
Lubell is an environmental science professor at the University of California.
He told Climate Home: “There are equity and environmental justice issues.
Seawalls are expensive. Poor communities with people of color have a harder
time affording them, and poor communities in the Bay Area (and most parts of
the world) are more vulnerable to sea level rise.”
Due
to their cost, seawalls are less common in the developing world. Anoka
Abeyratne, director of Sri Lankan environmental consultancy Aayusha Global,
said most of Sri Lanka’s seawalls are “not the type of large scale ones used in
the US”.
She
added: “Most are rudimentary with just rocks held together with wire mesh.
These are used to save the sandy beaches from washing away.”
Unlike
the 36-page summary for policymakers, the full 3,675-page report is not subject
to line-by-line approval from governments.
It
highlights seawalls’ ecological as well as economic cost, saying they “reduce
the space available for coastal ecosystems”.
Walls
on beaches can block animals like turtles off from reaching parts of the beach.
According to the Sea Turtle Conservancy, turtles are forced to lay eggs nearer
the water where their eggs are more likely to be washed out to sea.
Nature-based
solutions like mangroves are a cheaper and greener way of blocking storm surges
as they suck in carbon and provide a habitat for wildlife. However, planting
mangroves is not always possible, particularly in urban areas.
Retreat
from the sea is also an option. The report notes that the Fijian coastal
community of Vunidogoloa collectively relocated to another site within their
customary land.
But
the report warns: “The availability of customary land for the new site was a
key factor of success in this relocation example, although this will not
guarantee success in every case as relocation may expose communities to new
risks.”
David
Smith is a Jamaican coastal engineer working for Smith Warner International. He
told Climate Home that, for many Caribbean and other small islands, there is
nowhere to retreat to.
In
Barbados, he said, all the businesses and homes are by the coast. “Once you go
into the mountains, they’re subject to landslides and much more difficult
conditions for construction”, he added.
Smith
said that many engineers are looking at combinations of green and grey
infrastructure like a seawall with a belt of mangroves in front of it.
The
community of Ebeye in the Marshall Islands has even less of an opportunity to
retreat than in Barbados.
Ebeye
is a strip of land around 300 metres wide with the Pacific Ocean on both sides.
The Green Climate Fund is contributing $25m towards building a $60m 1.5km-long
seawall.
Albon
Ishoda, the Marshall Islands ambassador to Fiji and the Pacific Islands, told
Climate Home that the IPCC report made valid criticisms of seawalls but that
there are no other options for many atoll communities.
“Many
times, people think we have options lined up,” he said. “The reality is we
don’t, unless some benefactors are able to commit hundreds of millions for some
hard adaptation that includes relocating people and raising islands, then
perhaps seawalls will be the last option. Some of the places that national
efforts have mobilized to create sea walls are critical.”
He
added: “Sometimes, people think we can simply move inland. The fact is, as
atoll nations, many communities rely on underground aquifers for water. Once
that source of water is contaminated with salt water, plants and people will
struggle to find fresh water for drinking.”
