Nature can soften impacts of rising seas—if we let it

This story is part of a Long Beach Post multi-part series, “Close to Home: How climate change is shaping the future of Long Beach.” For the full series, click here.

By the end of the century, rising seas will force Long Beach to find ways to protect homes and businesses—or see some of them swallowed by the sea.

While seawalls, breakwaters and other barriers are already deployed up and down portions East Coast and West Coast, not all solutions are made of concrete and stone.

Some say the future of protecting California’s coasts, and the developments behind them, will include more natural solutions like restoring wetlands and other habitats so they can help slow storm surges and combat other effects of sea level rise.

“Habitats or ecosystems serve many many benefits, including physical protections in many cases,” said Evyan Sloane, a project manager for the State Coastal Conservancy.

“When you’re building a wetland or a dune or a beach on the coast you can provide a habitat for different species including endangered species, you can sometimes sequester (carbon dioxide), further fighting against what’s causing climate change, and you can sometimes protect against erosion.”

Sloane worked on a project in Seal Beach in which sediment was dredged and then transported to two sites where it was layered on top of existing salt marshes. The project was located within the Seal Beach National Wildlife Refuge just south of the Long Beach border.

https://lbpost.com/news/education/csulb-researchers-seal-beach-wildlife-refuge-sea-level/

It raised the level of the salt marsh by about 8.5 inches above grade, something that researchers said could not only improve the ecosystem, but also make it more resilient to rising seas.

The project was part of a series of case studies performed by Coastal Resiliency, a group that advocates for natural modifications to coastal areas and includes researchers from a number of organizations including the Nature Conservancy, the National Oceanic and Atmospheric Administration and the California Resources Agency.

Some of these solutions included building a living shoreline in the San Francisco Bay to reduce wave energy through the creation of oyster reefs and eelgrass beds. The project resulted in a 30 percent reduction in wave energy.

One project involved a form of managed retreat in which the coastal city of Ventura restored dunes in front of a parking lot that was being damaged by wave activity. The parking lot was also moved back, resulting in the beach being widened by about 60 feet.

Sloane is hopeful that these types of projects will be recognized more often in the future for their win-win potential.

“We could have a coastline that’s all seawalls and ocean and no habitat and no recreation and all the other benefits, or we can have wetlands that you can kayak in and see birds and go to the beach and lay your towel down on the sand,” Sloane said.

By the year 2100 sea levels are projected to rise by up to 6 feet.

Christine Whitcraft, director of Cal State Long Beach’s Environmental Science and Policy program, said that wetlands serve a vital role in combating rising seas.

They help clean and filter water as it runs from rivers and streams into the ocean and retain nutrients and soil that helps support plant and animal life. But they also have another unique quality when it comes to combating sea level rise.

“Wetlands, if we weren’t here surrounding them, actually have the ability to keep pace with sea level rise and they do that in two ways,” Whitcraft said. “One is by having mud be spread over them from the watershed which helps them get taller, or accrete. And the other way is to transition backward, to transition inland as the water rises.”

If they become completely submerged, Whitcraft said wetlands could lose some of their cleansing qualities when it comes to water and the air.

She says she’s an environmentalist but also a pragmatist and recognizes that the future of protecting the California coast will probably require a mixture of both human-made and natural solutions. But she added that natural formations have the ability to respond to sea level rise in ways that walls do not.

“When you have storms moving onto the coast or even just flooding, having vegetation, plants and soil that can absorb water helps slow down major storm surges and can actually protect communities behind more than just having a hardscape,” Whitcraft said.

Alison Spindler, a planner with the city’s Development Services department, said that the city is “putting everything on the table” when it comes to combating climate change and will focus its efforts regarding sea level rise where flooding is expected to hit first and most dramatically.

The city’s draft report on possible climate adaptation actions include options to expand sea walls but it also mentions more natural solutions.

The city could undertake a beach nourishment study to look at sand volumes needed to keep pace with sea level rise and to identify potential sources of sand to transplant onto the city’s coast.

It could also pursue building a living shoreline or transforming seasonal sand dunes to permanent ones with vegetation being installed to stabilize the sand against erosion.

“This is just a starting point,” Spindler said.

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Jason Ruiz covers City Hall and politics for the Long Beach Post.
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