Community Environment

Sea Level Rise in San Diego: How Mission Bay’s Wetlands Help Us Adapt

Increasing development surrounding Kendall-Frost Marsh poses a risk to San Diego’s ability to adapt to rising sea levels.

Why the Kendall-Frost Marsh Must Be Protected

Adapted from Sketches Magazine article “Update: ReWild Mission Bay,” by LaTresa Pearson

As sea levels rise across the world, researchers are looking for natural solutions that help us adapt. Salt marshes like those in Mission Bay provide a key solution to sea level adaptation through water retention and erosion control. However, the increasing development surrounding the Kendall-Frost Marsh may pose a significant risk to San Diego’s ability to adapt to rising sea levels.

Key Takeaways

  • Salt marshes and other wetlands mitigate the impacts of rising sea levels, prevent erosion and flooding, and protect us from damage from coastal storms.
  • As climate change causes sea levels to rise, many coastal wetlands are under threat of “drowning.”
  • The Kendall-Frost Marsh in San Diego’s Mission Bay is threatened by rising sea levels and encroaching development. Wetland restoration and preservation projects like ReWild Mission Bay are crucial to ensuring these marshes continue to protect San Diego from the impacts of sea level rise in the future.

Coastal Wetlands and Rising Sea Levels

Coastal wetlands like the Kendall-Frost salt marsh provide critical ecosystem services to us. Creating a buffer between the land and the ocean, these ecosystems protect us from rising sea levels and coastal storms.

Coastal wetland sea level rise

How Salt Marshes Protect Against Sea Level Rise

Salt marshes, dense vegetation communities that are regularly flooded by tides, provide several important ecosystem services. The compact sediment and thick root structure of the soil create a strong protection against erosion, while the sediments and vegetation protect against excess flooding by absorbing high amounts of sea water.

In the case of coastal storms, salt marshes absorb the energy of waves before they hit land, significantly reducing damage from hurricanes and minimizing overflow into urban areas. Salt marshes also protect against sea level rise as they absorb water and accrete upward with rising levels, to a certain extent. 

As climate change worsens, we’re already seeing more coastal storms and higher sea levels, resulting in flooding and erosion. Despite salt marshes’ protective capacities, quickly rising sea levels can drown out salt marshes. Without our action and protection, we may lose these critical ecosystems.

Kendall-Frost Marsh - sea level rise san diego

Threats of Sea Level Rise in San Diego

Southern California, which was once composed of thriving coastal wetlands, has lost about 75% of its natural ecosystems to development, fragmentation from roads, and rising sea levels. Without intervention, sea level rise in San Diego could swallow the rest by 2110, with the greatest escalation occurring between 2050 and 2100, according to a study led by the U.S. Geological Survey that was published in Science Advances in February 2018. In natural circumstances, salt marshes can naturally keep pace with sea level rises through accretion, where sediment accumulates and the salt marsh slowly moves upward with the sea levels. Encroaching development, however, doesn’t give the marshes enough physical space to migrate to adjust to rising sea levels. At the current pace, sea levels will drown San Diego’s coastal wetlands if we don’t act now.

 In order to help wetlands keep up with sea level rise in San Diego – and work to prevent its impacts – we have to imagine how we can actively manage these sites. ReWild Mission Bay is doing just that.

A Struggling Salt Marsh

Rose Creek - coastal wetland sea level rise

Managed by UCSD and owned by the UC Natural Reserve System, the Kendall-Frost Marsh Reserve includes 21 of the 40 acres of salt marsh remaining in Mission Bay. The rest are part of the Northern Wildlife Preserve, which is owned by the City of San Diego.

Finding places along California’s coastline that will allow salt marshes to migrate naturally as sea level rises isn’t easy. In many cases, roads, buildings, and other urban development hug the coastline, preventing the marshes from moving beyond the reach of rising waters. “You can see right here at Kendall-Frost, it’s not like the marsh can just move inward because there’s a road,” Heather Henter, Executive Director of the UC Natural Reserve System for UCSD. “There’s Pacific Beach Drive. There are apartments. There’s the city. There’s nowhere for the marsh to go.” With current sea level rise predictions, much of the existing wetland habitat here at Kendall-Frost and the Northern Wildlife Preserve will be gone by 2100. That’s why it’s so critical to restore as many acres of wetlands as possible along both sides of Rose Creek. Restored wetlands on De Anza Point would have the greatest chance of surviving sea level rise, according to projections in the ReWild Mission Bay Feasibility Study. “Through our advocacy efforts, at the beginning of June we convinced our partners on the City of San Diego’s Climate Action Plan Review Committee to officially recommend to the City Council that wetland restoration get underway as soon as possible,” says Andrew Meyer, Director of Conservation for San Diego Audubon.

To restore and actively manage Mission Bay’s coastal wetlands in time for them to be resilient to sea level rise, as well as to reap the many benefits they provide, we need to move fast. According to the State Coastal Conservancy’s 2018 regional strategy for the Southern California Wetlands Recovery Project, wetlands restoration projects take between 20 to 40 years to plan and complete. “Because of the rapidly increasing rate in sea level rise in the second half of this century, wetland restoration should occur before 2030 in order to establish mature marshes that are more resilient to sea level rise; such efforts need to start immediately,” the document stresses.

Protecting San Diego’s coastal wetlands from sea level rise is important now more than ever. Learn how you can take action to protect the Kendall-Frost nature preserve.

Read the whole article in our Sketches Summer 2022 issue.

Photos courtesy of LaTresa Pearson and Greg Hoxsie

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