• Large corporations led by tech are taking a variety of approaches to carbon emissions amid concerns that energy consumption will continue to grow, but measurement methods and efficacy of various CO2 capture and storage methods are still being hotly debated.
• Google, Meta, Microsoft and Salesforce are among the companies involved in a new joint approach to carbon removal focused on nature-based CO2 storage systems such as reforestation, afforestation and revegetation.
• But some experts say nature-based carbon storage is more vulnerable than breakthrough technology like direct air capture and industrial carbon sequestration plants.

The commitment of corporations to climate change isn't as sure a thing as it seemed a few years back when the biggest companies were piling on carbon reduction goals with little pushback. Emissions have gone up rather than down for some big firms, especially as AI's energy needs grow. Some companies are easing up on, or out of, aspirational carbon goals due to fears about cost and what they now say are overly aggressive timelines, as well as fears of legal action.

But four of the biggest technology companies — Google, Meta, Microsoft, and Salesforce — are pushing ahead with a new approach in one of the most contested niches of the climate markets: CO2 removal and storage. They recently announced the formation of the Symbiosis Coalition to jointly create an "advance market commitment" for nature-based removal credits in the carbon market, according to a statement from the group.

The scale of market efforts to remove carbon is increasingly important, according to climate experts. In 2022, the International Panel on Climate Change said that reducing emissions from industrial usage would not alone be enough to stop a worsening climate crisis, and 20 billion metric tons of carbon would need to be removed annually, raising the profile of what are called "negative emissions" in the climate debate, the actual removal of CO2 from the atmosphere, from methods including direct air capture, carbon capture and storage, and nature-based removal and storage.

Symbiosis takes its nature-based scale approach from a model perhaps best known in relation to vaccines, where a buyer or group of buyers will commit to purchase or subsidize an efficacious vaccine — often one for a neglected disease — should one be developed, a process intended to encourage development to occur by frontloading demand. 

Julia Strong, executive director of Symbiosis, says the aim is to encourage the development of "high-quality nature-based carbon removal" technologies, and a commitment to contract for up to 20 million tons of removal credits by 2030. Among the key terms: nature-based, high-quality and measurable. The first term is the easiest to define, with the latter two remaining, according to experts, challenging to pin down amid increased pressure on companies to prove that carbon accounting mechanisms are credible. 

"Science tells us we cannot meet our climate goals without supporting nature conservation and restoration in the near term," Strong said.

Specific initiatives mentioned include afforestation (the conversion of abandoned and degraded land into forest), reforestation, and revegetation projects, each of which comes with project-specific criteria set forth by Symbiosis. Through these nature-based approaches, Symbiosis aims to encourage the development of technologies that "have real, measurable, positive climate impact," Strong said.

Nature as a climate solution is under attack

But even "nature" as a method for climate mitigation is under attack, and the approach being pursued by the tech giants highlights a fundamental divide among climate experts about the best way for companies to tackle the emissions challenge, with some pointing to limitations of nature-based carbon storage.

"Nature-based carbon removals, such as soil carbon sequestration, store carbon temporarily in living biomass," said Dr. Allanah Paul, a CO2 removal and carbon accounting expert based in Europe. These methods can offer "less reliable carbon storage" than non-nature-based methods, she said, with the natural storage systems vulnerable to natural impacts like forest fires, torrential rains and earthquakes. Human activities, too — changes in land usage, for instance — can also upset the functioning of these carbon storage systems in ways that non-nature-based strategies are not necessarily subject to.  

Counter to nature-based systems, tech-based solutions like direct air carbon capture can effectively store carbon indefinitely in minerals or reservoirs deep in the Earth's crust. Strategies that rely primarily on chemically engineered processes to capture the carbon are potentially better able to lock captured carbon away in geological formations permanently, Paul said. 

Ironically, nature-based methods may in fact be disrupted by climate change itself — weather extremes; shifting population locations — and, additionally, said Paul, the aim shouldn't be on capturing carbon but on reducing carbon emissions. "The idea of offsetting an avoidable emission with a temporary removal does not align with the physics of our climate system," she said, as it amounts to "enabling mitigation deterrence."

Nature-based carbon removal does have advantages. It is immediate, it is cheap and, at least in the short-term, it is a highly effective way to remove carbon from the atmosphere, according to the Coalition for Negative Emissions. Afforestation, for example, can be pursued at a local level without the need for major infrastructure and investment. But its "Achilles Heel," according to the Coalition, is the question of its "permanence."

Critics like Paul say regardless of how verifiable the success of such methods may prove to be, capture simply provides a way for emitters to pay their way, rather than make meaningful changes to reduce their emissions, which remains the more effective climate action. "By allowing emissions to be offset in this way, we are at best running to stand still and at worst maintaining business as usual and papering over the cracks with accounting tricks," she said.

Those emissions have come into greater focus given the energy demands of the current artificial intelligence boom and the huge investment tech firms are making in AI data centers.

The emphasis on verifiability is, in part, a response to a recent spate of PR and legal headaches resulting from companies' overzealous or unclear climate claims. Paul remains skeptical of whether or not Symbiosis can overcome this hurdle given the complexities still involved in carbon accounting. "This project presents a significant risk of greenwashing," she said. If verifiability is wanted, Paul said, then simply reducing emissions would provide a more direct route.

"Within the tech sector, which is financing this initiative, there are a suite of interventions which need to be pursued which are arguably more urgent and relevant for their sector, such as the provision of sufficient climate infrastructure and renewable energy deployment to fully decarbonize their activities," she said. 

Strong pointed to the already-established Integrity Council for the Voluntary Carbon Market Core Carbon Principles, and says the companies joining its coalition not only signal demand for nature-based carbon solutions, but will also help drive investment.

The rise of negative emissions

Other climate experts view the criticisms of nature-based carbon removal as missing the central point. Paul Davies, a member of the Coalition for Negative Emissions and a primary author of its report on the urgent need for businesses to focus on multiple approaches to carbon removal, stated that there is no hope of staying below 1.5 degrees of warming if an industry that can remove CO2 from the atmosphere at scale is not developed. "As an emitter, every company should focus on reducing their emissions, but as a purchaser looking to offset residual emissions, they should prioritize purchases of robust negative emissions," he stated.

With the players involved, the Symbiosis Coalition will speed and deepen the development of nature-based carbon-capture methods. And the program doesn't suggest this is the only tool, just that the highest values for the development of nature-based methods is that they be as effective as possible, and that this effectiveness be verifiable. 

Carbon removal approaches are best thought of as existing on a spectrum, according to Haley Leslie-Bole, manager, US Lands and Climate, at the World Resources Institute, including nature-based and tech solutions that will be needed to realize significant carbon removal, including reforestation and direct air capture. "Purely nature-based approaches are intended to increase the amount of carbon sequestered by natural processes like photosynthesis that remove carbon from the air as plants grow," she said.

The downsides, though, are real, with the shorter duration for the removal relative to tech-based approaches, and higher risk of subsequent re-release of the sequestered carbon. It also remains difficult and costly to measure and monitor nature-based carbon removals accurately. As an example, the potential for longer-term reversals of sequestered carbon introduces accounting complexities. 

"My understanding is that Symbiosis intends to create a demand for high-quality nature-based carbon removal by setting very high standards for removal quality," Leslie-Bole said. "The companies in Symbiosis have pledged to purchase CDR from projects that meet their high-quality criteria with the intention of increasing the quality of nature-based CDR projects across the board." 

Some of the same companies backing Symbiosis are also involved in a sister initiative, Frontier, that shows their approach is to not choose between nature or technology, but to pursue both. Frontier is an advanced market commitment for tech-based CDR with the same goal of scaling carbon-capture. "We are supportive of efforts to scale all types of CDR," Leslie-Bole said, "as long as all pathways are held to robust quality criteria and are delivering real removals."  

No one is arguing that carbon removal is a better strategy than emitters reducing their actual emissions, or should be seen as a "get out of jail free" card, in the words of a recent report from the Coalition for Negative Emissions.

"The need for emission reductions outweighs the need for carbon removals 10:1," it stated. "Only through massive reductions in emissions do we stand any chance of meeting climate targets." But it added that the reality of the climate crisis is that negative emissions, in the form of certified carbon removals, are a preferred method to "merely investing in credits for the emissions reductions of others."

It predicts that negative emissions will be available for companies to buy at scale by 2030.

The most recent report from The State of Carbon Dioxide Removal organization summed up the dilemma well given the underlying problem: the failure to reduce actual emissions fast enough. "CDR is no one's first choice for climate restoration - it is the contingency, the backup plan. We know we will need it, but it is still unclear what its true scale of application will ultimately become."