Blue carbon ecosystems have the power to protect fragile coastlines, but time is running out

 Serge Dedina and Tannia Frausto
Originally published in the San Diego Union Tribune.

The salt marshes and salt ponds of southern San Diego Bay are 450 miles north of the mangrove fringed Laguna San Ignacio, a gray whale birthing lagoon on the Pacific Coast of the Baja California Peninsula. While geographically separated, these coastal embayments are connected by a common biophysical trait that binds them together as the world searches for a way to address the growing climate crisis.

In addition to being part of a linked chain of saltwater refuges on the Pacific Flyway that provide habitat for black brant, Eastern Pacific green sea turtles and important fisheries resources, we now know that these aquatic habitats called “blue carbon ecosystems” not only help us adapt to climate change, but can help us mitigate it as well.

Aquatic habitats such as seagrasses (also known as eelgrass), salt marshes and mangroves, are vital economic and recreational assets, and their ecosystem services, or the ecological benefits they provide, are key to addressing the increasing impacts of climate change.

That is why agencies such as the U.S. Fish and Wildlife Service, Port of San Diego, City of Imperial Beach and the California Coastal Conservancy among others, are helping to protect and restore hundreds of acres of seagrass meadows, salt marsh wetlands and riparian habitat throughout the southern portion of San Diego Bay. These nature-based solutions to climate change are the most cost-effective ways we have to protect local neighborhoods, businesses and flood-vulnerable infrastructure from floodwaters associated with rising sea levels.

Likewise in Laguna San Ignacio, a pristine desert lagoon, fishing communities are being hammered by tropical storms and hurricanes. It is here that our team at WILDCOAST is working with the United Women of El Dátil, a group of pioneering women who are planting mangroves as a buffer against storms and to build up local fisheries.

“The mangroves are what protect us from hurricanes because we are very close to the estuary and the beach,” said Minerva Carrillo, who lives in a plywood casita on the edge of the lagoon in one of the most remote coastlines in Baja California.

Mangroves exhibit a remarkable ability to capture and retain substantial amounts of carbon, up to ten times more than a tropical rainforest. In Laguna San Ignacio mangroves contribute to storing 920,900 tons of carbon annually, equivalent to the emissions produced by the gasoline consumption of 751,403 vehicles in a year.

Mexico ranks fourth in the world in terms of mangrove coverage, with 2.2 million acres. Mexico’s most likely next president, Claudia Scheinbaum, earned a Ph.D. in energy engineering and carried out her doctoral research at Lawrence Berkeley National Laboratory. Hopefully, if elected, she would embrace addressing climate change and especially community-based mangrove conservation and restoration in a way that has eluded President Andrés Manuel López Obrador.

In California, greenhouse gasses sequestered by blue carbon ecosystems provide an additional incentive for agencies and coastal communities to invest in preserving and restoring these aquatic superheroes. In San Diego Bay, a study by the Port of San Diego found that, “The bay’s eelgrass beds currently contain 170,000 metric tons of carbon dioxide (CO2), which is equivalent to the same amount of CO2 emitted by more than 37,000 cars annually.”

With the North American Carbon World conference in San Francisco this week, from March 19 to 21, the issue of using carbon markets and government incentives to expand blue carbon ecosystems in California and Mexico to protect fragile coastlines, fisheries, endangered wildlife and our global climate, is more pressing than ever. The conference brings together the private sector, conservation organizations, community members, and government agencies from the U.S., Mexico, Canada and Central America.

In both California and Mexico, efforts to rewild our blue carbon ecosystems are coming from the ground up but need much more support from governments and carbon markets. “We started working with mangroves because they bring many benefits to our community,” said Carrillo, “But they benefit the entire world.”