As global emission reduction targets lag behind schedule, the pressure is mounting to actively remove planet-warming carbon dioxide from the atmosphere. While new engineered techniques are emerging to supplement traditional nature-based methods, they are plagued by concerns that they provide heavy polluters a “get out of jail free” card – allowing them to emit now and bank on unproven future removals.

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Living things and geological processes have been taking carbon dioxide (CO2) out of the air since the planet’s earliest days. However, continuous overshoot of climate goals has brought new immediacy to the need for an alternative to reduction-only strategies, and solutions for human-made carbon removal are gaining momentum. 

The United Nations estimates that current policies put the world on track to warm by 2.8C this century, well beyond the globally agreed-upon warming limit of 2C.

Unlike carbon avoidance, which prevents the new release of greenhouse gases, these methods take planet-warming carbon dioxide that is already out of the atmosphere for long-term storage through natural or engineered means.

Axel Renault, CEO of carbon removal company Netzero, told Earth.Org, “IPCC [Intergovernmental Panel on Climate Change] says we need to reduce our greenhouse gas emissions by 80 to 90%. But it’s very likely that by 2050 we will not manage to have zero emissions, because there are some very hard-to-abate industrial processes. Carbon removal comes in to remove what we cannot reduce.”

How Does Carbon Dioxide Removal Work?

Taking carbon dioxide out of the atmosphere can be as simple as planting and maintaining trees – a method for which global standards of verification have been developed. On this basis, carbon credits can be traded on the international “compliance markets” that help countries comply with their Nationally Determined Contributions – national climate plans that every signatory to the Paris Agreement must update every five years. 

However, along with the compliance markets, the voluntary carbon market – where companies, rather than countries, buy carbon credits to offset their emissions – has fueled an explosion of new methods for carbon removals, both natural and engineered.

Natural removals still dominate. Today, the vast majority of carbon removal comes especially from afforestation or reforestation – in other words, low-tech or no-tech approaches. Nature-based solutions for carbon removal can also include changes to agricultural practices that help store carbon in soil. Other lower-tech solutions include capturing carbon with plants and storing it as organic matter in soils; using structural timber in buildings to store carbon from sustainably managed forests; or terrestrial biomass burial, in which biomass can be stored if buried in appropriate conditions. The ocean-based counterpart of this method is marine biomass sinking, in which marine biomass is grown and then sunk to the ocean floor.

Along with nature-based solutions, so-called “engineered solutions” find other pathways for more stable carbon removal. “There’s a huge breadth of technologies,” said Renault. 

One category of engineered solutions includes accelerated or enhanced natural processes. In natural rock weathering, water with dissolved CO2 reacts with rocks to produce stable carbonates. The natural process can take a century, but by crushing and spreading out olivine dust – a waste material from mining – it can be shortened to just four to five years. 

This method, enhanced rock weathering, is currently being used in Brazil by the German company InPlanet, which enables farmers in the tropics to remove atmospheric CO2 and move toward more sustainable agricultural practices. In December, the company signed an agreement with Microsoft to remove more than 28,500 tonnes of CO2 between 2026 and 2028 using this technology.

Likewise, the creation of biochar, which refers to extracting the carbon from biomass and stabilizing it, accelerates the process by which nature creates mineral coal. Asitava Sen, CEO of the Carbon Removal Alliance India, told Earth.Org, “Biomass, like coffee shells and rice husks, has calorific value. When they are pyrolized, the carbon is converted to biochar and it’s a permanent capture. When you apply this to soil, it will stay for 800, up to 2,000 years, and in cement for longer.”

Other engineered solutions are even more high-tech, such as direct air capture. “The idea is to filter out the CO2 from the atmosphere, extract it and then store it underground at very high depth, where it will be locked forever. Or we mineralize it, or a combination of the two,” explained Renault.

In surficial mineralization, carbon reacts with minerals to form chemically stable substances like carbonates, for example in concrete. Another solution, ocean and riverine alkalinity enhancement, involves increasing the alkalinity of water to enhance its ability to absorb carbon. 

Some activists categorize these carbon dioxide removal (CDR) methods as a type of geoengineering, which they claim pose risks to ecosystems.

The Search for Recognition

Modern methods of carbon removal have struggled for legitimacy. “Until the Paris Agreement, the idea was just to do emission reduction. Then it started to become clear that emission reduction alone was not enough,” Lucia Brusegan, Chairperson of the International Biochar Initiative, told Earth.Org. 

Since the 2015 Paris Agreement – which explicitly mentions achieving a “balance between anthropogenic emissions by sources and removals by sinks in the second half of this century” – the global strategy has evolved from a primary focus on emissions reduction to a dual-track approach that pursues aggressive reductions alongside the rapid scaling of carbon removals.

“Before, countries could decide to go with carbon dioxide removals, but they were not forced to. Now, they must both reduce emissions and remove the emissions they cannot reduce,” Brusegan added. According to Article 6.4 of the agreement, credits can be traded internationally based on these removals.

“I think one of the big difficulties of the carbon removal industry today is that there’s a lot of unknowns on what will be the rules of the game,” said Renault. “Regions or countries are deciding whether to include carbon removal in their toolbox. Europe voted that carbon removal could be a solution, but only [from] 2036. So we need first the regulatory framework to become clear.”

This past November, COP30 in Belém, Brazil became the first COP to host a pavilion dedicated to carbon removal in its Blue Zone, where accredited and official representatives negotiate. However, not everyone welcomed this move. In a statement shared with Earth.Org, Brice Böhmer, Climate & Environment Lead at Transparency International, said: “We are seeing yet another striking example of how corporate influence can shape climate negotiations … These lobbyists are shaping the climate discourse by promoting ‘solutions’ from which they stand to profit, rather than taking responsibility for reducing their own emissions.”

Who Is Buying And Who Is Selling

In 2025, oil and gas companies were the biggest buyers of carbon removals, with Shell remaining at the top for the third year in a row. However, large-scale demand for voluntary carbon credits is also coming from technology companies. According to industry analyst Allied Offsets, Microsoft is the top CDR buyer of all time (by volume of credits purchased), followed by Meta. The tech sector as a whole has purchased 50 million CDR credits, while the energy sector has purchased 16 million.

“A lot of new customers for carbon removals are IT companies who have huge data centers because of AI,” said Sen. “They’re taking a preemptive step [to remove carbon] before the government says they must.” 

“We have taken steps to build the nascent carbon removal market into a solution that companies, as well as the public sector can buy from,” Microsoft’s Phillip Goodman, Director of Carbon Removal Portfolio, told Earth.Org in an email. “We consider both nature-based and engineered solutions…building our 2030 portfolio by prioritizing solutions that can deliver meaningful scale on that time horizon while also making smaller purchases of more innovative technology while the science and operational items mature.”

In the case of global technology giant Lenovo, because carbon offsets are part of the sustainability services the company offers to its customers, it is the customers who drive decisions about what kind of offsets to buy.

“Our customers have an interest in purchasing IT equipment from Lenovo, and we are looking at how to make it more sustainable,” Kaixin Huang, a climate engineer in Lenovo’s corporate ESG team, told Earth.Org. “With our Lenovo CO2 offset services, we purchase credits on behalf of our customers. We have a standard portfolio and if the customer has a particular objective we’ll help them achieve it. And the customer may prefer carbon removal rather than avoidance, or they may have a preference on location, a project closer to them.” 

At a corporate level, the company is not yet buying CDR credits on its own behalf, although this may change in the future. “We’re tackling emission reduction in all aspects – operational emissions, our upstream and downstream value chain emissions. And our R&D people are all working on how to improve the overall product lifecycle from product design, energy efficiency or repairability,” said Huang. But certain emissions in the deep value chain would not be able to be reduced, if the company wants to meet its 2050 net-zero target and have it validated by the Science Based Targets Initiative – which will require removals to neutralize the last 10% of emissions. “So as we get closer and closer to 2050, we’re going to start to look for global standards to rely on to neutralize the remaining emissions.”

Fleeting Benefits?

Despite the popularity among some companies, not everyone is convinced. A 2025 study found that there is insufficient evidence to show that corporate investments in the voluntary carbon market increase a company’s climate ambition. “Carbon credits have become a comforting myth, not a catalyst for genuine corporate climate ambition. The unhelpful narrative that buying credits accelerates real decarbonisation runs counter to the evidence and distracts us from meaningful action,” Benja Faecks, Expert on Global Carbon Markets at Carbon Market Watch, said in a press release announcing the study.

Carbon offsetting overall is often linked to the concept of “overshoot” – the idea that business (and emissions) can continue as usual, as long as promises are made to reverse the damage later. “Through this sleight of hand, any given target could be both missed and met and any missing rationalised as part of the journey to meeting it, like Schrödinger’s cat simultaneously alive and dead,” explained Andreas Malm and Wim Carton in their book.

When it comes to implementing carbon removal projects, the devil is in the details. Sumit Roy, Asia Lead for Palm Oil at Solidaridad Asia, a solutions provider for smallholders, highlighted the challenges for farmers engaging in carbon removal activities like biochar. “Not everything you burn is biochar,” he told Earth.Org. “Smallholder farmers are disconnected from the market. How will it be produced, where will it be produced, and how will the farmers be paid for their environmental services? How do you plan in terms of technology and finance? We don’t understand the nuances of the smallholder realities. Who is the user? Have you heard of any farmers using biochar? And you need two to three years of data to verify it.”

James Dyke, Associate Professor in Earth Systems Science at the University of Exeter, said on his blog that CDR is becoming “a molten brown lump of speculation that some use to gum up the wheels of effective climate action.” A recent analysis discovered that a direct air capture plant in Iceland failed even to cover its own emissions.

New Hope in Clean-Up Certificates

One option that might boost the removals market is to require “clean-up certificates” for greenhouse gas emitters.

The idea behind this policy instrument is that emitters can only release carbon dioxide or other greenhouse gases into the atmosphere when they make an advance investment in the future removal of their emissions. A new study by the Potsdam Institute for Climate Impact Research (PIK) found that market forces activated by clean-up certificates can greatly strengthen the fight against global heating without placing an extra burden on the economy. 

“Linking emission rights to a removal obligation would not actually be anything fundamentally new,” Kai Lessmann, PIK researcher and lead author of the study, said in a press release. “This has long been practised in parts of the economy – for example, in the return of deposit bottles or old electrical appliances. It is the principle of extended producer responsibility: companies stand not only for the quality of their goods, but also for the disposal of their waste. And here we show the potential of this principle for climate protection.”

One challenge will be setting a realistic price. For example, while direct air capture has enormous promise, Bjarne Steffen, Professor of Climate Finance and Policy at ETH Zurich, recently estimated the cost of removing one ton of CO2 from the air in the year 2050 to be between US$230 and $540, twice as high as previously believed.

Until then, more effort is necessary to realize the potential of carbon dioxide removals alongside other climate protection efforts. “Just because technologies are available, it certainly doesn’t mean we can relax,” said Steffen.

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