The Biden administration has an opportunity — and a responsibility — to help save the coastal ecosystems that protect us.
America’s coastal saltwater wetlands
are on a course toward functional extinction in the coming decades. 
Photo by Will Collette
Their demise will come at the hands of steadily accelerating sea-level rise and relentless coastal development.
As these wetlands disappear, they will take
with them habitat, storm buffering and carbon sequestration benefits of
tremendous value.
Fortunately, there is still time to change course.
A determined and coordinated effort by local, state and federal
governments — led by the Biden administration — could dramatically increase the
number of saltwater wetlands that survive and go a long way to maintaining
their ecological and societal benefits into the future.
Saltwater Wetlands: To Know Them Is to Love Them
The most recent estimate of
the extent of saltwater wetlands along the American coast, published in 2009,
found some 6.4 million acres with about half occurring along the Gulf of
Mexico. This is a mere remnant of their historic extent and a decline of some
95,000 acres from the previous assessment in 2004, largely in the Gulf of
Mexico. Ominously, the rate of loss increased by 35% from the prior five-year
reporting period.
The remaining saltwater wetlands
still provide an impressive array of
ecological services and benefits to society. Often termed “the most productive ecosystems
on Earth” they are nursery grounds for fisheries and provide
habitat for birds, mammals and other wildlife.
Wetlands also protect communities
from storm surges and flooding. Along the Atlantic and Gulf coasts the
protective value of wetlands is estimated to be about $1.8 million per
square kilometer annually. On top of all that, saltwater wetlands help fight
global warming by storing carbon at a rate that is about two to four times greater than that
observed in mature tropical forests.
The Saltwater Wetland Extinction Scenario
Rising sea level and steady coastal
urbanization pose an existential threat to saltwater wetlands.
The National Oceanic and Atmospheric
Administration predicts that sea level along much of the American coast
is likely to rise by
2 to 4 feet, and may rise by as much as 8 feet, by 2100. And seas will continue
to rise in the centuries to come, with an “intermediate” estimate of more than
9 feet by 2200.
The rising seas will eventually
drown all the saltwater wetlands that now exist, converting them to open water.
Some wetlands will survive in place for a time if seas rise slowly enough. But
the rate of sea-level rise is accelerating rapidly and
other factors, such as land subsidence,
will shift the balance in favor of rising seas in the years ahead.
For most saltwater wetlands,
survival will require landward migration. This is possible where geography does
not present obstacles, such as steep slopes, and where human development has
not already staked a claim. There is no national assessment of the feasibility
of saltwater wetland migration, but several studies of smaller geographic areas
present a bleak picture.
On the Pacific coast, some 83% of
wetlands are projected to become open water by 2110 and “migration of most
wetlands was constrained by coastal development or steep topography,” according
to a 2018 study in Science
Advances. Along the Gulf of Mexico, estimated conversion
of wetlands to open water varies for each state, with rates from 24 to 37% by
2060.
The outlook for saltwater wetland
survival darkens further when one considers new coastal development occupying
dry land that might otherwise become a new wetland. Population in the 100-year
coastal floodplain is expected to almost double by 2060, significantly
expanding the coastal development footprint.
And the rising sea levels that drive
wetlands inland will also prompt people to defend the land they are on, often
with seawalls, bulkheads or levees. Some 14% of the coast is already armored by
this infrastructure and, if the current rate of armoring continues, that
percentage is expected to double by 2100.
Finally, wetlands that are able to
migrate will need years to provide the same degree of ecosystem services they
did originally. A study of over
600 restored wetlands worldwide found that biological structure and
biogeochemical functioning “remained on average 26% and 23% lower,
respectively, than in reference sites” even a century after restoration, which
means that even the wetlands to do survive won’t provide the same benefits.
Envisioning a Strategy for Saving Saltwater Wetlands
What can be done to help saltwater
wetlands survive the one-two punch of a changing climate and coastal
development?
A critical step is to admit we have
a problem and agree that we need a national response strategy. A national
strategy should define a goal for saltwater wetlands protection (e.g., a net
increase in acreage nationally and by state) and charge a federal agency (e.g.,
NOAA) with leading the effort.
The heart of a new strategy needs to
be carefully planned for landward migration of saltwater wetlands and
deployment of new authority and resources toward that end. This key objective
is widely supported in
the academic literature and the work to address it must engage local, state and
federal agencies.
Since it’s been more than a decade since the last published assessment of the United States’ coastal wetlands, existing saltwater wetlands need to be mapped anew. Then their varying rates of natural change should be assessed and the feasibility of landward migration evaluated. Evaluation of migration should include obstacles, such as natural features, and both existing and likely future development.
Coastal places that
are not wetlands today but are well suited to become wetlands as sea level
rises, should be identified. All this information should be used to develop
place-specific plans to protect and preserve the land that wetlands will need
to migrate inland on a priority basis.
While that work is going on, we’ll also need to focus on dampening the rate of population growth right along the coast. This will be essential to leave space for successful landward migration of saltwater wetlands.
State and local government have diverse tools,
including land-use plans and regulations, to apply to this challenge, but the
federal government needs to help. For example, FEMA should stop issuing federal
flood insurance for new development in coastal floodplains.
Another critical tool is expanded authority to restrict new coastal armoring projects that would prevent landward migration of saltwater wetlands. Eight states have implemented total or partial bans on coastal armoring, but efficacy and enforcement vary. All states should adopt and enforce such bans.
These projects also require permits from
the Army Corps of Engineers and existing requirements should be revised to give
stronger preference for “living shorelines” that
replace traditional structures with designs using biological and natural
materials.
In some places, regulation will not be enough and acquisition of real estate will be necessary. Some states have land-acquisition programs that consider sea-level rise. For example, Maryland identifies “coastal lands with the highest potential to aid in adaptation if sea level rises a meter per century” and uses the assessment in making conservation investments.
People in the San Francisco Bay area voted for Measure AA to
provide local funds for wetlands protection in the face of sea-level rise.
These programs and some others are a foothold but more states need to follow
this example.
Federal agencies need to support
these state initiatives by expanding modest existing federal programs that
protect coastal wetlands to include purchasing land for prospective wetlands
and removing buildings and other structures where needed.
Saving saltwater wetlands will
require that Congress, federal agencies, states and local governments
collaborate to agree on the strategy and then approve the new tools and funding
needed to carry it forward. This will require years of effort, but the start of
a new Congress and a new administration is an auspicious time to begin this
important work.
Jeff
Peterson is a retired senior policy advisor at the Environmental
Protection Agency and the author of A
New Coast: Strategies for Responding to Devastating Storms and Rising Seas.
https://islandpress.org/books/new-coast
