[Seaweed farming is being hyped as a major weapon in the fight
against climate change. But skeptics say the rush to build
industrial-scale operations risks unintended consequences. By Bridget
Huber, June 1, 2023 ]
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PORTSIDE CULTURE

CLIMATE SAVIOR OR ‘MONSANTO OF THE SEA’?  
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Bridget Huber
June 1, 2023
The Fern
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_ Seaweed farming is being hyped as a major weapon in the fight
against climate change. But skeptics say the rush to build
industrial-scale operations risks unintended consequences. By Bridget
Huber, June 1, 2023 _

A variety of seaweed harvested from the Gulf of Maine, including
sugar kelp, sea lettuce, dulse, bladderwrack, and Irish moss.,
Photography by Lauren Owens Lambert

 

Early on a cool spring morning, in far Downeast Maine, Severine von
Tscharner Welcome and her husband, Terran, scrambled along a point
jutting into Cobscook Bay. The Passamaquoddy people named the bay
Kapskuk after the immense tides and wild currents that make the water
seem to boil. These turbulent waters support a rich array of life,
including Atlantic salmon, sturgeon, and alewives, as well as many
edible species of seaweed.

Harvesting in a spot that’s accessible fewer than 20 days per year,
during negative tides, Welcome pulled a long strand of alaria, a
golden ruffled kelp, from the riffles. She piled vivid green sea
lettuce that tastes surprisingly like its earthbound namesake in a
plastic fish basket, and handed me a hank of fine red strands of
gracilaria algae to taste. It was slippery, al dente, and tasted a
little, but not unpleasantly, like blood.

In a more sheltered part of the bay, the Welcomes farm sugar kelp and
oysters. They sell the wild and cultivated seaweed dried, and use the
less delicious, more abundant kinds to fertilize the saltwater farm
they’re reviving nearby. For years, much of the seaweed harvest in
North America looked a lot like this: Smalltimers scrabbling on rocky
shores or drifting in little boats — often on both the economic and
geographic margins.

But the industry is at an inflection point. While the North American
seaweed industry remains tiny by global standards — 95 percent of
farmed seaweed comes from Asia — it is the fastest-growing type of
aquaculture in the United States. Fueling this rise is a surging
appetite for seaweed as a food and an ingredient, and the hope that it
could play an important role in mitigating climate change.

In recent years, seaweed has been put forth as what one writer called
a Swiss Army knife solution to climate change: able to absorb
atmospheric carbon, reduce cattle’s methane emissions, provide
feedstock for biofuels, and feed the world — no fertilizers, fresh
water, or even land required.

Now, a new crop of seaweed startups, many funded by venture capital
and tech industry players, is pouring millions into projects using
seaweed to mitigate climate change. They’re driven by a slew of
corporate net zero pledges — which are increasing demand for carbon
offsets — and the growing realization that reducing emissions
won’t be enough to keep global warming at or below 1.5 degrees
Celsius: carbon will also have to be removed from the atmosphere.

To play a significant role in stabilizing the climate, though, seaweed
farming would need to scale to a level larger than anything North
America has ever seen. Much of that expansion would likely be
offshore, since the amount of suitable coastline is limited, and
potential conflicts with inshore industries like fishing and shipping
abound. This nascent transformation — from small-scale, coastal
operations to a large, increasingly offshore industry — is raising a
host of scientific and ethical questions as well as worries about the
environmental and social effects of growing vast amounts of seaweed.

As climate change intensifies, people are “panicking,” said
Kristen Davis, a professor of civil and environmental engineering and
earth system science at University of California, Irvine. Added to
this sense of urgency is a culture clash between scientists and
environmentalists who favor a more precautionary approach and the tech
industry’s “fake it till you make it” ethos, she said. Davis is
part of a growing number of scientists, small-scale harvesters, and
environmental groups that caution that some of these new ventures are
rushing ahead before fundamental questions about how much kelp can
responsibly be farmed – and how much carbon it can actually
sequester — are answered.

“The clock is ticking,” Davis said, “and people just want to
move really fast.”

Many of these new companies imply that seaweed is going to save the
world, Welcome said. And they have a point — the ocean itself is by
far the Earth’s largest carbon sink.  Since the Industrial
Revolution, it has absorbed at least a quarter of humanity’s CO2
emissions. And wild seaweed forests already sequester huge amounts of
carbon. But if the world’s seaweed stocks aren’t expanded
carefully, critical ecosystems could be harmed or attention diverted
from known solutions like quitting fossil fuels and protecting and
restoring the oceans and forests.

“Seaweed is already saving the world,” Welcome said.

One of the bolder experiments to use seaweed as a climate change
solution is underway in Iceland, where millions of small buoys, made
with wood byproducts and limestone will be dropped into the ocean in
the coming months.

Running Tide, the Maine-based company behind the project, is working
on a system that will eventually sink buoys bearing long locks of
seaweed to the deep ocean floor where the carbon they hold will remain
sequestered for 800 years or more. Of course, it’s hard to pin down
this timeframe; nothing like this has ever been done before.

Still, Running Tide’s carbon removal plans got a big boost in March,
when the company announced a contract with Microsoft to take 12,000
tons of carbon dioxide equivalent out of the atmosphere over the next
two years.

Running Tide is one of several ventures looking to use seaweed to
remove carbon from the atmosphere. Others want to use kelp to reduce
emissions by replacing carbon-intensive materials like soy,
fertilizers, plastic, and petroleum with seaweed-derived versions.

This cohort includes the Climate Foundation, which plans to grow
massive floating kelp farms offshore in the Philippines and California
and sink the kelp to the seafloor to sequester carbon. The project won
a million-dollar prize from the Musk Foundation last year.
California-based Umaro Foods, funded by the Department of Energy’s
ARPA-E program, is working on seaweed bacon and also to develop
seaweed farming at “terrestrial farming scales in the deep ocean.”
Another, Marine Bioenergy Inc., also ARPA-E funded, plans to grow
massive lines of seaweed off the Pacific coast and use drones to move
them between the ocean surface, where light abounds, to depths where
there are more nutrients.

Running Tide, which operates on Portland’s fish pier, was founded by
Marty Odlin, an engineer and fourth-generation commercial fisherman.
The Gulf of Maine is warming at a faster rate than nearly any other
part of the ocean, and Odlin has seen the changes firsthand — fish
moving north to colder ocean, clam shells dissolving in acidifying
waters.

About 15 years ago, Odlin heard a talk from Klaus Lackner — the
physicist, now at Arizona State University, who popularized the idea
of removing carbon from the atmosphere. It clicked. “It was like,
‘Oh, this is right because there’s no way we’re going to get off
fossil fuels in the next 50 years,’” Odlin said in an interview.
“It’s just not going to happen. We’re going to have to pull it
down.”

A recent assessment from the Intergovernmental Panel on Climate Change
echoes this prescription. In addition to swiftly cutting emissions —
which is mandatory if we are to limit climate change — the panel
also estimates that we’ll need to remove and sequester about 10
gigatons of CO2 equivalent from the atmosphere annually by 2050, and
double that amount, annually, by the end of the century. Right now,
there are about 2,000 square kilometers’ worth of seaweed farms in
the world; to sequester a tenth of a gigaton of carbon annually would
require 73,000 square kilometers — equivalent to planting a nearly
half-kilometer-wide belt of seaweed farms along the entire U.S. coast,
according to a report from the National Academies of Sciences,
Engineering, and Medicine.

Running Tide plans to sell credits for the carbon it removes from the
atmosphere. While the company won’t disclose how much Microsoft is
paying, it is just one of several tech companies, including Shopify
and Stripe, that have paid for future carbon removal services in order
to help kick-start the company. The credits sell for roughly $250 per
ton, said Running Tide.

By way of comparison, Climeworks, which uses mechanical processes to
remove carbon dioxide from the atmosphere and store it in rock,
reportedly charges between $500 and $1,000 per ton of carbon dioxide
equivalent removed. Climeworks is currently capable of removing 4,000
tons of CO2 equivalent per year, though it plans to scale up
operations and remove millions of tons annually by 2030.

There’s a logic to the idea of using kelp to draw down carbon, and
it would be an elegant, nature-based solution if it works. Some
scientists call the Earth’s seaweed forests, which cover an
estimated 2 million square kilometers, a “Marine Amazonia” because
they absorb as much carbon as the planet’s largest rainforest. But
much of that sequestration is short-lived. When the seaweed is
harvested, eaten by animals or washes up on shore, its stored carbon
is released … back into the atmosphere.

Running Tide’s model, in theory at least, would take that
sequestered carbon and sink it to the ocean floor where, in cold and
dark conditions, it would remain for centuries — moving the carbon
from what is sometimes called the fast carbon cycle to the slow,
geologic cycle. But coming up with a credible accounting system for
this model is an enormous challenge. (Even much more straightforward
carbon sequestration projects, like forest offsets, are hard to
measure and verify and have been shown, in some cases, to amount to
little more than corporate greenwashing.)

In the last couple of years, Running Tide and other kelp-based
CO2-removal ventures have gotten heat for racing to sell credits
before the science of deep sequestration has proved out. The MIT
Technology Review published a pair of articles critical of the general
idea and of Running Tide specifically. In editorials and articles,
scientists also have raised questions about the wisdom, feasibility,
and ethics of sinking seaweed to the ocean floor.

“There is no need for another yet-to-be proven technology-driven
approach to climate change mitigation that is not based in sound
science and marketability and distracts from other, more effective
actions, like reducing reliance on fossil fuels,” a group of
scientists wrote in the journal Reviews in Fisheries Science &
Aquaculture last year.

Another editorial, coauthored by some of the field’s most prominent
scientists, argued that seaweed-sinking ventures were “surging past
even perfunctory evaluation of the environmental impacts and social
benefits.”

These concerns aren’t hypothetical. Costly attempts to develop
algae-based biofuels haven’t panned out. And there have been
disasters. In the 1970s, entrepreneurs introduced a species of seaweed
off Hawaii, intending to manufacture a food thickener. The business
failed, but the species thrived to the point of becoming invasive; it
has taken over coral reefs and now dominates entire bays. And disease
outbreaks have devastated large seaweed farms in Zanzibar, Indonesia,
and elsewhere.

If the industry doesn’t get things right this time around — if it
grows too fast, brings unintended consequences, or just fails to
deliver on its promises — it could undercut the small-scale,
sustainability-focused seaweed economy that people like Welcome have
been nurturing.

Welcome got her start building a movement of young farmers before
becoming enraptured by seaweed, “beings that haven’t been
corralled, that haven’t been weeded or bred or contained or plowed
up,” she said.

Welcome is excited about seaweed’s potential. In addition to
harvesting and farming it, she is developing a mycobuoy project with
mycologist Sue Van Hook that would help reduce the amount of plastic
used in aquaculture, and working with organic groups to address the
overharvesting of wild seaweed to make non-chemical fertilizers.

But she worries that the current rush to farm the ocean at larger
scale risks replicating many of the same problems of terrestrial
agriculture — consolidation, monoculture, a lack of local control,
environmental harm.

The point was echoed by Bren Smith, a commercial fisherman turned
ocean farmer in Long Island Sound who has helped seed dozens of oyster
and seaweed farms over the last decade through his nonprofit
GreenWave. When he started out, the sector was a “little
experimental petri-dish,” something easily ignored. Now, the
industry’s expanded so fast that it’s unrecognizable, he said. And
while that’s exciting in some ways, it’s also alarming. “Is this
going to be some vertically integrated industry with thousand-acre
farms owned by three guys who are getting all the benefits?” he
asked. “Is this going to be the Monsanto of the sea?”

Welcome is part of the Seaweed Commons, an affiliation of small-scale
harvesters and growers, scientists and environmentalists who have
banded together in response to the rapid expansion and transition in
the seaweed industry.

In a recent position paper, the group argued for a precautionary
approach, warning that the industry is evolving before adequate
regulations are in place and before the potential environmental and
social impacts of mass-scale seaweed farming are fully understood.
Without adequate safeguards, they wrote, “seaweed could become the
next boom and bust crop that was supposed to ‘save the world.’”

Perhaps the largest scientific unknown in this field is exactly how
much carbon seaweed can actually remove from the atmosphere — the
amount can vary depending on location and weather. It’s also not
clear how much farmed and wild seaweed winds up on the deep ocean
floor, as opposed to drifting elsewhere. And there are critical
questions about how growing large amounts of seaweed or sinking it to
the seafloor could affect marine ecosystems. Could large kelp
monocultures spread disease to wild seaweed populations? Could an
expansion of seaweed farming disrupt phytoplankton — and the marine
food web that depends on it — by outcompeting it for nutrients and
sunlight?

Seaweed is also much harder to grow in the deep ocean than in coastal
environments. Researchers, especially those involved with Department
of Energy-funded projects, are trying to figure out how to reliably
grow large amounts of seaweed offshore, but they are still a long way
off.

But as scale expands, so do potential risks. Kelp farms use rope, and
increasing the amount of it raises the risk of entanglement for
animals like whales and tortoises. And what happens when a near-shore
organism, like kelp, and its associated microbes, flora, and fauna are
transported to the deep ocean? Does it create novel, hybrid
ecosystems?

“As someone who is looking at the models, we can grow a lot if we
paved the ocean,” said Davis, the U.C. Irvine professor. “But we
are not going to do that because that would obviously have hugely
detrimental effects on ocean health.” The amounts of seaweed that
people are talking about aren’t realistic, at least not right now.

“It has to be a slower ramp,” she said. “And we have to allow
time for science to catch up.”

Odlin, Running Tide’s founder, said his team is using modeling and
sensors that answer many of these questions; it’s also working with
an independent scientific advisory board and has brought in the
auditing firm Deloitte to review its carbon accounting process ahead
of issuing credits. 

In April, Running Tide  published a lengthy document detailing how it
intends to remove carbon from the atmosphere and how it plans to
account for how much carbon it is removing. Davis, who reviewed the
white paper, said it wasn’t a bad start but that it “needs more
detailed explanations to be actionable.” The document doesn’t
answer the outstanding questions about the sustainability and
viability of using seaweed to sequester carbon, she said, but it does
lay out a general methodology for assessing it.

Odlin said he takes the critiques seriously, but rejects the idea that
the industry should wait until all scientific questions are answered.
The climate emergency is too urgent, he said. “It’s the fourth
quarter, we don’t have time to spend 15 to 30 years trying to answer
questions that can only really be answered by actually going out and
doing these things.”

Odlin favors operating on the best available science. There should be
enormous amounts of scientific research going forward, he said, both
in collaboration with his company and “in opposition” to it. But
given the fact that we know that the planet is warming, that the ocean
is acidifying due to the huge amount of carbon it’s absorbing, and
that ecosystems are already being disturbed, he said, it is unethical
not to act. “There’s a counterpoint to the precautionary
principle, and that’s the duty to intervene.”

Amid a flurry of scientific research into the best use of seaweed,
Davis was part of a team that recently modeled the costs and potential
climate benefits of seaweed — the best emissions mitigation bang for
the buck. Sinking seaweed to sequester carbon, the researchers found,
was much more expensive than using farmed seaweed to replace foods
with high emissions, like soy that’s linked with deforestation.

Still, no matter how seaweed was used, the researchers cited a litany
of potential challenges to farming it, including the high cost of
seaweed-based carbon removal, potential ecosystem disruption, and the
uncertainty about whether large markets for seaweed products exist.
“The outlook for a massive scale-up of seaweed climate benefits is
thus decidedly murky,” they wrote.

Nichole Price, a senior research scientist at Maine’s Bigelow
Laboratory for Ocean Sciences, who is studying several potential ways
to use seaweed to mitigate climate change, said the idea that there
are only two options — “sink it or use it”—may be
oversimplifying things. It might be possible to produce seaweed
products and get credible carbon credits if seaweed farms could gather
the parts of the plant they don’t use — the frayed and broken tips
of seaweed blades and the tough holdfasts—and deposit them near
shore, in areas best suited to sequestering carbon in sediments. This
strategy would allow scientists to monitor how much carbon is actually
being sequestered and any environmental impacts, which are difficult
if not impossible to measure on the ocean floor.

Price said that while there are still many unanswered questions about
seaweed and its potential as a climate solution, the science is
progressing fast and some of the critical knowledge gaps will be
filled within the next five years.

“The race isn’t really about which pathway is the best at this
point,” she said. “It’s which pathway is the fastest and least
expensive.” Asked whether that felt appropriate, she said, “I
think 20 years ago, we could have gone with the best. Right now, we
have to go with what’s the fastest.”

Correction: This story was amended to reflect new information from
Running Tide about their operations.

This article was produced in collaboration with National Geographic,
which ran a shorter version of the story. It may not be reproduced
without express permission from FERN. If you are interested in
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[email protected].

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