Blue carbon, or the carbon captured by oceans and coastal ecosystems, may hold potential as an emissions offset, according to U.S. lawmakers.

Environmentalists have long recognized the need for forests as "carbon sinks" in the effort to combat climate change. Others turned to geoengineering, including nascent technologies such as direct air capture, to reverse greenhouse gas emissions.

"It's only recently that we've recognized the role that blue carbon can play," Richard Spinrad, administrator of the National Oceanic and Atmospheric Administration, or NOAA, told the House Select Committee on the Climate Crisis on June 9. Spinrad was one of two officials who testified at the hearing on ocean-based climate solutions.

Coastal ecosystems such as mangroves, tidal marshes and seagrass meadows absorb more carbon per unit area than terrestrial forests, according to the International Union for Conservation of Nature. A recent McKinsey & Co. report on blue carbon said oceans have absorbed 40% of human-made carbon emissions since 1850. But the potential of oceans to mitigate climate change is being undermined by habitat destruction, pollution and overfishing.

For that reason, much of the emphasis of blue carbon policy has been on preservation. "That means investing in low-cost, big-impact solutions, like safeguarding marine and coastal habitats through well-implemented marine protected areas," said U.S. Rep. Kathy Castor, D-Fla., chair of the select committee.

The bipartisan infrastructure law that U.S. President Joe Biden signed in 2021 allocated $492 million to the NOAA for coastal resilience and restoration grants and $150 million for improved observing systems to collect data on the coasts, oceans and Great Lakes.

Another $6 billion for coastal and marine habitat restoration included in the Build Back Better Act passed by the U.S. House of Representatives in December 2021 remains in limbo.

"We urge our Senate colleagues to include those investments as they finalize the reconciliation legislation," Castor said at the June 9 hearing.

Accounting shortfalls

Others look to more direct interventions, such as carbon credits. Article 6 of the Paris Agreement on climate change, ratified in 2021 at a U.N. conference in Glasgow, Scotland, allows member countries to pursue voluntary investment in carbon offsets to meet climate targets.

Where blue carbon fits into the voluntary carbon market framework is still hazy, according to the McKinsey report.

"Financing for blue-carbon solutions has been thin on the ground, reflecting insufficient revenue sources, commercial arrangements and project delivery," the McKinsey report said. The science of blue carbon, such as unit volume of carbon dioxide absorption, is "still in its infancy."

In 2021, Rep. Suzanne Bonamici, D-Ore., introduced the Blue Carbon for Our Planet Act, which would create a map of U.S. blue carbon ecosystems and examine their sequestration potential.

"You discussed how some countries are using blue carbon as a way of meeting their nationally determined contributions under the Paris climate accord," Bonamici said when questioning Spinrad. "What can NOAA do to help put the U.S. on the same path and how can blue carbon mapping help?"

Spinrad said the NOAA is working to collect this data through the Biden administration's National Capital Account. The initiative, launched on Earth Day, will "connect changes in nature with changes in economic performance" by taking inventory of the nation's natural resources, including those that serve as assets through their ability to offset emissions.

"NOAA will play a critical role," Spinrad said. "We are the environmental intelligence agency, so our efforts to assess and account for and also to protect the potential for the growth of blue carbon is going to be a major contribution that we make to that assessment."

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