A humpback whale splashing in the Northwest Atlantic Ocean off the coast of Massachusetts. (Photo: Tim Graham/Getty Images)

'Blue Carbon' Sinks: Can the Ocean Save the Planet?

The idea of ocean-based climate solutions is appealing, but the challenges are formidable.


Marine Technicians Margot Buchbinder and Luis Hernandez unlock a chain-link gate at Point Molate, a natural headland on San Francisco Bay, and drive to the water's edge along a degraded road, part of what was once a World War II Navy fuel depot. From here, they climb down concrete blocks and boulders in the fading light of dusk.

This comes down to three solutions: expanding offshore wind and other renewable ocean energy systems, greening global ports and shipping, and expanding Blue Carbon.

Wearing full wetsuits and booties, they shuffle through the mud and shallow water of low tide; the shuffling helps warn bat rays to get out of their way. Using a marine GPS finder, they quickly locate and retrieve a couple of remote sensors about the size of nine-volt batteries that measure the water's temperature and salinity around local eelgrass beds. Slogging back toward shore, they are backlit by the lights of an oil tanker docked at the local Chevron refinery's "Long Wharf."

The pair's work is part of research being conducted by San Francisco State University's Katharyn Boyer on the ecology and restoration of coastal habitats, including San Francisco Bay's approximately 3,000 acres of eelgrass. Eelgrass, a species of seagrass, along with kelp, coastal salt marshes, mangroves, and other marine plants and animals (including whales) have long been acknowledged as essential for ocean health. They are now also being recognized as "Blue Carbon" sinks--sequesterers of excess carbon dioxide in the atmosphere generated from the burning of fossil fuels and other sources.

"I suspect, but don't know yet, that natural eelgrass beds will have more carbon sequestration in the sediment than restored beds but restoration will also put you somewhere along that trajectory," says Boyer, whose team uses the historic eelgrass at Point Molate as a seedling bed for restoration elsewhere in the bay. "It's all part of the solution," she offers, "but we've got to deal with emissions or we don't solve the problem."

In promoting carbon dioxide removal--both "nature-based" and geo-engineered, as described in a recent National Academies of Sciences report --the United States, United Nations, and others are admitting failure.

Despite commitments by the world's leaders, the goal set forth in the 2015 Paris Agreement and the 2021 Glasgow Climate Pact , to limit global warming to 1.5 degrees Celsius above preindustrial levels (marking the difference between a dangerous climate shift and a catastrophic one), now appears unattainable unless carbon dioxide is also taken out of the atmosphere.

And so, in addition to efforts to reverse deforestation and shift global agriculture from being a carbon emitter to a carbon sink, an increased focus is being given to the 71 percent of the planet that is wet and salty.

The idea is to use ocean and coastal resources to reduce greenhouse gas emissions while also drawing down atmospheric carbon dioxide to safer levels. This comes down to three solutions: expanding offshore wind and other renewable ocean energy systems, greening global ports and shipping, and expanding Blue Carbon.

The most advanced of these strategies is "putting steel in the water," with the build-out of offshore wind projects. The European Union expects to generate at least sixty gigawatts of offshore wind by 2030. With the United States lagging far behind, the Biden Administration supports an ambitious plan to develop thirty gigawatts in U.S. waters by 2030 (enough to power more than ten million homes).

In Massachusetts, Democratic state Senator Marc Pacheco, a longtime climate leader, supports the Mayflower Wind and Commonwealth Wind projects, which will generate 1.6 gigawatts of power. He argues that these will not only help address climate change but also save state taxpayers lots of money, since solar and wind are now cheaper than oil and gas. A transmission cable for the project is even being built on the abandoned site of the state's last coal-fired power plant.

Other clean ocean energy sources not yet ready for commercial primetime include wave and tidal power and ocean thermal energy conversion, which uses the temperature differential between deep and surface water to generate power, as well as algae-based clean fuels.

Global shipping and port operations presently account for about 3 percent of global greenhouse gas emissions.

Plans for decarbonizing major ports began with environmental justice demands when low-income "fence line" communities of color gathered environmental activists and advocacy groups to sue the ports of Los Angeles and Long Beach, calling on them to reduce local air pollution from ships and trucks. Nominated to run the port of Los Angeles in 2005, marine biologist Geraldine Knatz showed that port air pollution and emissions could be economically reduced by more than 70 percent in six years. This led to a global initiative among fifty major ports to decarbonize.

Industry influence over the United Nations' International Maritime Organization via member countries has delayed a similar transition in the global commercial shipping fleet that includes more than 90,000 large vessels. Nonetheless, some industry players--including Soren Skou, chief executive officer of Maersk, one of the largest container ship companies--want to accelerate change with a carbon tax on freight and an eventual ban on fossil fuel-powered ships. Shipbuilders in South Korea and Europe have begun building "dual fuel" ships that can burn fossil fuel now but switch over to hydrogen, wood alcohol, green ammonia, or some other nongreenhouse gas emitter by the 2040s.

Activists such as Madeline Rose of the environmental group Pacific Environment want to expedite the process with mandatory rules to decarbonize shipping, starting in California, where the green ports movement began.

In Point Molate, the headland owned by the city of Richmond, the bay's most pristine and studied eelgrass beds are being threatened by runoff from a proposed private luxury housing development. The development is opposed by the majority of people in Richmond, a predominantly low-income community of color that (with this writer's involvement) is campaigning to protect the headland as a public park.

To the north of Point Molate and San Francisco Bay, more than 95 percent of the kelp forest has been lost since 2014 due to a multi-year marine heatwave and the die-off of sea stars, a key predator of urchins. This has caused an explosion of purple sea urchins that gobble up the surviving kelp. Both events are linked to climate change.

Global kelp forests are declining by 2 percent per year. Mangroves, which can sequester four times as much carbon as rainforests, declined by a third between 1980 and 2000, drained for development and threatened by rising seas.

Another source of Blue Carbon is large whales, which are making a comeback after centuries of slaughter. They have been found to sequester huge amounts of carbon before they die and sink to the bottom of the ocean. Also, their prodigious fecal plumes add nutrients to the water, generating algal blooms that then sequester even more carbon through photosynthesis before also sinking to the bottom, where the carbon may be locked away for thousands of years.

Besides protecting kelp forests and eelgrass meadows and expanding whale populations, some scientists have called for geo-engineering proposals, such as dumping shiploads of iron pellets into the ocean in the hope of generating algal blooms.

But Representative Jared Huffman, Democrat of California and chair of the House Natural Resources Subcommittee on Water, Oceans, and Wildlife, says he's "very skeptical of geo-engineering solutions in the ocean" due to the possibility of "unintended consequences." Instead, he's introduced the Blue Carbon Protection Act, which would commit hundreds of millions of dollars a year to identify, map, and protect "blue carbon areas of significance."

"It's an obvious first step," Huffman tells The Progressive . "Not all we need to do but a beginning."

The promise of ocean-based climate solutions is only as good as the survival rate of the ecosystems on which they depend.

Huffman laments the loss of the kelp forests in his district, which includes five Northern California coastal counties, and the resulting economic loss for fishing- and tourist-dependent communities.

"We have to regard this as a wake-up call that conditions like this can hit us suddenly and take away entire ecosystems," he warns. Last year, he introduced the Keeping Ecosystems Living and Productive (KELP) Act to provide federal research and recovery grants through the National Oceanic and Atmospheric Administration. And he hopes Congress could still pass parts of President Joe Biden's Build Back Better Act, which would commit $6 billion a year to coastal restoration plus $3 billion for the greening of ports. "We are one U.S. Senator away from putting it on the President's desk," Huffman says.

Meanwhile, a number of states--including Oregon , California , Louisiana , Maryland , New Jersey , and North Carolina --are developing their own Blue Carbon inventories to identify and protect coastal resources. Yet the promise of ocean-based climate solutions is only as good as the survival rate of the ecosystems on which they depend. And with warming, acidifying seas holding less dissolved oxygen and generating more marine heatwaves, dead zones, storms, and coastal flooding, it remains uncertain if restoration will outpace decimation.

Can the ocean, the crucible of life, help save the planet? The only thing certain is that it should never have come to this.

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