Brad Ack understands why people are concerned about using nascent technology to sink billions of tons of carbon pollution into the oceans to address the climate crisis.
However, record levels of global warming are putting our planet and oceans at great risk, and aggressive, large-scale action is essential, says Ocean Visions, a nonprofit organization promoting ocean climate solutions. said Mr. Ack, CEO of .
“The ocean has huge potential to support and be part of the huge challenge we have in carbon removal,” Ack said. “The ocean is already the largest source of carbon cycling on Earth.”
Ack said that even if emissions from fossil fuel combustion are reduced to near zero by 2050, it will not be possible to cool the Earth system and overheated oceans or fully mitigate the occurrence of wildfires, droughts and floods. said it was not enough.
The United Nations Intergovernmental Panel on Climate Change (IPCC) has found that a range of carbon dioxide removal (CDR) strategies are needed to meet the international goal of limiting global warming to 1.5°C.
Carbon removal, also known as negative emissions strategies, includes natural solutions such as relying on forests, wetlands, and soil to capture and store carbon, as well as emerging solutions that extract carbon directly from the air and oceans for long-term storage. Includes technology implementation. .
Estimates suggest that between 5 billion and 16 billion tonnes of CO2 per year, or 16 GtCO2 (gigatons), will need to be removed by 2050, depending on emissions reduction rates and whether climate change targets are exceeded. Masu.
Ack emphasized that it’s not a matter of whether carbon removal is done, but where it is done.
The ocean is already the largest carbon sink on Earth, absorbing 30 percent of anthropogenic emissions and 90 percent of excess heat from greenhouse gases. The oceans, which can trap CO2 deep down for hundreds or even thousands of years, act as a storehouse for approximately 38 GtCO2 of this “blue carbon.”
The ocean sequesters CO2 in two ways. One is when microscopic marine organisms and plants absorb carbon, and the other is when carbon dioxide dissolves in the ocean.
Phytoplankton on the ocean surface pull in carbon and release oxygen during photosynthesis. They can be eaten by other animals or die and fall to the ocean floor where they become trapped in sediments.
Surface water also absorbs and dissolves carbon. The colder and less salty the water, the more dissolved carbon it can take up. Frigid water near the poles tends to absorb more CO2, which is denser and therefore sinks to the ocean floor, where it travels under pressure on deep ocean currents into ocean basins over longer periods of time.
Ack said there is growing interest in marine carbon dioxide removal (mCDR) solutions, which aim to scale up and speed up the ocean’s natural biological or chemical processes to capture and store CO2. It is said that there is.
Expanding natural blue carbon stocks by conserving and restoring marine ecosystems such as mangroves, eelgrass, and salt marshes, with synergistic benefits to biodiversity, is widely supported in the scientific community. and is underway around the world.
But researchers are divided, with some worried about the new strategy, which has not yet been tested on a large scale.
Proposals include significantly increasing production of seaweed like kelp, which absorbs carbon during photosynthesis, before sinking it into the deep ocean or turning it into climate-friendly seafood and bioplastics.
Another option is to pump surface water deep into the ocean, where it increases pressure and solubility, allowing it to store more carbon. Alternatively, they push nutrient-rich, cold water up from the depths to encourage plankton growth, which absorbs carbon before sinking into the deeper water when they die.
A related strategy is to fertilize the ocean with iron or nitrogen and trigger large plankton blooms.
Scraping carbon from the air, removing carbon from seawater, and filling the ocean with minerals such as basalt and carbonates increases the ocean’s alkalinity and ability to absorb carbon before injecting it into the deep ocean or ocean floor. It is also being studied to increase
Critics suggest that focusing on new methods will distract from urgent and fundamental emissions cuts and nature-based solutions that can be implemented now.
Many marine scientists affiliated with the Deep Sea Marine Management Initiative are also wary of using the deep sea as a potential waste site without a thorough understanding of the effects on ocean chemistry, food webs, and marine life. is calling.
Lisa Levin, a professor at the Scripps Institution of Oceanography at the University of California, San Diego, explains how manipulating the oceans to curb the climate crisis could threaten deep-sea ecosystems and their critical carbon cycle services. led a team research on
As seaweed rots on the ocean floor, oxygen is depleted and excess carbon dioxide is pumped into the deep ocean, potentially suffocating marine life.
Seeding the ocean with substances that increase alkalinity and plankton can reduce light, create harmful levels of cadmium and nickel, cause destructive algae blooms, and increase ocean acidity. there is.
“This technology is largely unproven,” she says. “I’m concerned that if people are thinking about the ocean, they’re thinking about it in the wrong way as a waste disposal system,” she said.
More research and integrated policies are needed to ensure that the costs of mCDR do not outweigh the benefits, she said.
Ack agreed, noting that Ocean Visions has created a blueprint to accelerate the science and action needed to prove or disprove the feasibility of new ocean carbon removal methods by 2030. .
“We are a consortium of scientific organizations trying to answer the most important questions, including whether this can be scaled up, whether it can be done safely and effectively, and how it compares to all the other alternatives. ,” Mr. Ack said.
Until now, the focus on carbon cleanup has been on land-based natural solutions, which simply cannot meet the significant carbon removal needed, Ack said.
Recent studies show that 2 billion tonnes, or 2 gigatonnes (GtCO2) of CO2, are removed annually, with the majority using traditional land-based methods such as forest protection and restoration and soil management. It has been.
Only 1% of that total comes from emerging technologies such as direct air capture (DAC) and storage.
But natural terrestrial carbon removal alone will not be enough to reach net zero, even if scaled up to 5 GtCO2 by 2050.
It is estimated that new methods, including ocean-based options, should provide half of the 10GtCO2 removal needed by mid-century. These strategies should increase to an estimated 15 GtCO2 by the end of this century.
While there are undoubtedly trade-offs with large-scale interventions, the climate crisis is currently immune to interim interventions, he said.
This is similar to using chemotherapy to treat a deadly cancer, with its unpleasant symptoms, he added.
He stressed that global warming is becoming increasingly life-threatening.
“We know it and we see it in real life,” Ack said.
“The question here is: How many different forms of medical intervention are we going to try to keep ourselves alive?”
Rochelle Baker / Local Journalism Initiative / Canadian National Observer
