Innovators who are working on ways to pull carbon dioxide out of the atmosphere to fight climate change are having a tough time lately.
Their biggest supporter, Microsoft, recently began that it is . To get a sense of how big of a deal this is, look at the numbers: The tech company alone has purchased approximately 80% of the . Its retrenchment is viewed as potentially to the sector.
However, there may be a bright spot for this industry, and it comes from an unexpected source: The U.S. Environmental Protection Agency quietly to grant a research permit under the to a Houston-based carbon removal startup.
The company, , aims to assess the potential to durably lock up greenhouse gases by harvesting plants that took in carbon dioxide on land and sinking them to the bottom of the ocean.
This approach is often called “,” or .
Ocean biomass sinking is one of several carbon removal approaches involving the ocean known as “.” Other marine approaches include to increase the uptake of carbon dioxide, seeding oceans with iron to stimulate the growth of phytoplankton , and to also take up carbon dioxide and sink it.
The Intergovernmental Panel on Climate Change, which compiles research on climate change from scientists around the world, calls carbon dioxide removal “” if the world hopes to keep rising temperatures in check and achieving the targets of the .
But is sinking biomass in the ocean the answer?
I am the of the at American University, and I have reviewed several of these projects. I see both pros and cons to ocean carbon removal techniques.
How ocean biomass sinking works
Carboniferous plans to carry out its field experiment in the Orca Basin off the coast of Louisiana. The basin is anoxic, meaning devoid of oxygen, and has a higher concentration of salt that most seawater. The EPA permit lets the company sink 20 burlap sacks to the bottom of the sea there to study what happens.
Globally, land vegetation, including trees and crops, sequesters . However, a large portion of this carbon is quickly released back into the atmosphere – – when the vegetation dies and decomposes, or is burned.
Ocean biomass sinking aims to lock up that carbon on the ocean floor in low-oxygen areas, where decomposition is much slower. Anaerobic processes, such as fermentation, . can also slow the rate of biomass decay.
The concerns
Two questions that arise are whether this approach would be effective at the scale needed and what risks it might pose to ocean ecosystems.
Recent studies have estimated that ocean biomass storage projects somewhere . That sounds like a lot, but humanity may need to remove from the atmosphere by the middle of the century and to meet global climate goals and avoid dangerously high temperatures.
A bigger concern is that substantially increasing organic matter in deep ocean environments might stimulate the growth of anaerobic bacteria, which , a potent greenhouse gas that could offset much of the benefits of this approach.
Proponents of ocean biomass storage counter that the would prevent any additional methane releases from ultimately escaping to the atmosphere. Further research is clearly required to know the risks.
Ocean biomass storage might also pose environmental and economic risks. As biomass descends in the water column, it has the potential to release particulates or organic matter, which could alter the activities of microbes as well as in the ocean . The zone is a busy region of . The result could harm and other species.
It’s also unclear how , such as bacteria, other microbes and fungi, might respond to the introduction of massive amounts of biomass.
And the introduction of large amounts of additional biomass in deep-ocean regions might attract , or their predators, in ecosystems that scientists know very little about. Those effects could be further exacerbated by decaying biomass reducing oxygen in seafloor environments and potentially increasing the release of .
Other ways to store carbon in the oceans
Carboniferous is not the only company focused on ocean biomass storage. is currently experimenting with burying waste plant matter from farms and cities , as well as beneath seabed sediments in the Mediterranean Sea . The company believes that it could sink annually by 2030.
Another Israeli company, , takes a very different approach. Instead of collecting biomass from terrestrial sources, to kill, and ultimately sink, toxic harmful algal blooms made up of cyanobacteria, also known as blue-green algae. This approach may also that can devastate aquatic environments by creating low-oxygen dead zones. And because algae sequester substantial amounts of carbon, the company claims that this approach could also .
The world’s oceans are by far Earth’s largest carbon sink, storing roughly and combined. This provides a compelling case to explore marine carbon removal options.
However, as is the case with all marine-based approaches, ocean biomass storage raises an array of questions that need to be resolved before the world can consider deploying it on a large scale. Carboniferous’ research program is one piece of this puzzle.
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