Carbon removal now unavoidable’ part of fighting climate change, UN says

Emissions cuts alone won’t limit global warming to 1.5°C, IPCC report warns. But can carbon removal from land use and technology scale up in time?

A carbon removal site showing industrial equipment and facilities against a backdrop of a forested mountain range
Carbon Engineering's direct air capture pilot plant in Squamish, British Columbia (Carbon Engineering)
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The latest report from the United Nations’ Intergovernmental Panel on Climate Change quantifies the drastic changes needed to keep global warming below catastrophic levels.

They include an end to fossil fuel investment and a rapid phaseout of existing coal, gas and oil use; an almost-complete shift to carbon-free electricity and fuels for heating, transport and industry; restructuring cities to encourage walking and biking; and reforming agriculture and forestry to capture rather than emit carbon.

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But Monday’s report from the IPCC also finds that these essential changes will not be enough on their own to keep global warming below 1.5 degrees Celsius. It asserts that investments to actively remove carbon dioxide from the atmosphere are now unavoidable” if the world is to achieve net-zero greenhouse gas emissions by 2050.

This is the most explicit statement yet from the world’s leading climate scientists that decades of inaction on curbing fossil-fuel use has left the Earth’s atmosphere with a carbon load that must be actively drawn down to keep the worst effects of climate change at bay. 

It’s also a controversial stance, given the role that fossil-fuel-producing countries have played in the final drafting of the IPCC report’s summary for policymakers, which requires unanimous approval from U.N. member nations. Some climate advocacy groups expressed concern that a delay in the release of Monday’s report due to last-minute negotiations allowed fossil-fuel-exporting countries to add language on carbon capture that could be used to justify a slower phaseout of those fuels. 

But a growing body of research indicates that the confluence of a number of factors has left the world in a position where the most aggressive cuts to greenhouse gas emissions may be out of practical reach. These factors include the lack of commitment to reducing fossil fuel use from major emitters such as China and India, continued fossil fuel investments from U.S. and European financial institutions, and the difficulty of replacing fossil fuels in key industries such as steelmaking and cement production. 

But that doesn’t absolve the world’s governments, industries and societies from taking unprecedentedly dramatic moves to reduce greenhouse gas emissions, Diána Ürge-Vorsatz, vice-chair of the IPCC working group that produced the report, said in a Monday press conference. 

In every sector, there are options available that can at least halve emissions by 2030 and keep open the possibility of limiting warming to 1.5 degrees” Celsius over the coming century, she said. These options range from halting any additional investment in fossil fuel infrastructure, tapping ever-cheaper solar and wind power and battery storage to electrify buildings and transport, turning to carbon-neutral fuels such as hydrogen or sustainable biofuels and dramatically improving energy efficiency, she said. 

But to counterbalance hard-to-eliminate emissions” in sectors such as industry and agriculture, carbon dioxide removal is essential to reach net zero,” she said. 

This view is echoed by a recent paper from the Energy Transitions Commission, a coalition of major energy, metals, mining, transportation and technology companies committed to achieving net-zero carbon emissions by 2050. That paper cites the need for at least 70 to 220 [gigatons] of carbon removals between now and 2050 to limit cumulative net emissions” to levels consistent with a 1.5°C climate objective,” given the current expectations for continued emissions even under the most ambitious possible reductions.” (Think tank RMI is a member of the Energy Transitions Commission. Canary Media is an independent affiliate of RMI.)

A chart of global atmospheric carbon intensities with and without carbon removal technologies
(Energy Transitions Commission)

The ETC report calls for project financing for carbon removal to grow from less than $10 billion per year today to as much as $200 billion per year by 2030 to allow the sector to meet its full potential for keeping global warming in check. 

Some of that investment can come from companies seeking carbon-reduction credits in compliance and voluntary markets, the report states. But corporate purchases alone will be far from sufficient to deliver the scale of removals required. Governments must also play a major role.”

A chart of the Energy Transitions Commission's suggested funding levels for carbon removal technologies
(Energy Transitions Commission)

The unknowns of carbon removal, from nature-based to direct air capture

These carbon-removal options come with dramatically different potential for keeping the world within the budget” of a little under 500 gigatons. That’s the amount that can be emitted in the future and still give the world a 50 percent chance of limiting global warming to 1.5 degrees Celsius. Based on current emissions trends and the existing carbon-reduction commitments from world governments, that budget is set to be used up by 2030, putting the target of 1.5 degrees Celsius out of reach. 

The best-understood and most widely practiced methods for increasing the amount of carbon dioxide pulled from the atmosphere are based on expanding the natural systems that already do this. These biological methods include reforestation and soil-carbon management techniques that improve the carbon-storage capacity of lands used for growing crops or grazing livestock. Biological carbon removal can also come from using biomass to store carbon, as with biochar” methods that convert agricultural residues to charcoal to enrich soil.

The report finds that these techniques come with relatively low costs — about $45 to $100 per metric ton of carbon dioxide captured for soil carbon sequestration — and offer relatively large-scale potential, such as the more than 3 gigatons of carbon dioxide per year that can be sequestered via agroforestry” projects. 

The report models the potential of such agriculture, forestry and land-use methods of carbon removal to meet a temperature rise of 1.5 degrees Celsius through 2100. It finds that they could yield between 20 and 400 gigatons of net negative emissions over that period. However, the report also points out that this carbon removal and storage can be reversed by human or natural disturbances,” such as forest fires or loss of agricultural land from climate change impacts. 

These competing demands have to be carefully managed,” Ürge-Vorsatz said, and land can only do so much in terms of removing and storing carbon, and cannot compensate for delayed emissions reductions in other sectors.” 

There’s also the risk that nature-based carbon-removal investments may be miscalculated or fraudulent, as abuses in the long-running market for forest-preservation-based carbon emissions offsets have revealed. Ürge-Vorsatz highlighted the importance of carefully designed and well-policed methods for accounting for the impacts of land-based projects to make them reliable sources of carbon removal. 

Carbon dioxide can also be removed directly from the air using direct air capture technologies or from carbon capture and storage systems at the source of fossil fuel or industrial emissions. It can then be stored in underground geological formations or via mineralization” technologies that store it in solid form. These technologies could yield from zero to 310 gigatons of net-negative emissions through 2100 under a scenario in which warming is limited to 1.5 degrees, the report finds. 

Bioenergy with carbon capture and storage — a term that describes growing plants and converting that biomass to energy while capturing the resulting carbon emissions — could also contribute between 30 and 780 gigatons of cumulative net-negative emissions through 2100 in a 1.5-degree scenario, the report states. 

The latter two technologies are as yet unproven at commercial scale, however, and require more research, upfront investment and proof of concept at larger scales” before they can be relied upon, Ürge-Vorsatz said. 

A 2018 report from the U.S. National Academies of Sciences, Engineering and Medicine set the cost of bioenergy with carbon capture and storage technologies at between $20 and $100 per metric ton of carbon dioxide captured. But growing enough biomass to meet the higher range of carbon-removal potential risks significant adverse socioeconomic and environmental impacts,” the IPCC report states, such as reducing the acreage of land dedicated to growing food and infringing on the land rights of Indigenous communities. 

Direct air capture technologies are far more costly, with current projects ranging between $100 and $300 per metric ton of carbon dioxide captured and up, according to the IPCC report. Other estimates of current direct air capture pilot projects set their costs at between $200 and $600 per metric ton of CO2 captured. To successfully commercialize these technologies would require major reductions in costs, significantly higher prices on carbon emissions or alternative ways to earn money. 

What’s more, today’s lower-cost direct air capture projects are also tied to using the captured carbon to inject into oil and gas wells to increase their production capacity, which is not compatible with the goal of reducing fossil fuel use in the industry. Meanwhile, carbon capture pilot projects at fossil fuel power plants and extraction sites have so far failed to prove that they can cost-effectively keep emissions within limits. 

The IPCC report finds that a range of mitigation options costing $100 per metric ton of carbon dioxide equivalent or less could reduce global greenhouse gas emissions by at least half their 2019 level by 2030. It’s unclear whether carbon-removal technologies can meet this cost target at scale.

Carbon removal, not fossil fuel extension 

But the IPCC report makes it clear that none of these pathways for keeping global temperatures below 1.5 degrees Celsius can coexist with continuing to invest in fossil fuels. In fact, the report indicates that between $1 trillion and $4 trillion of existing fossil fuel infrastructure will be unable to fully return on its investment” under the IPCC’s models for hitting this target, Ürge-Vorsatz said. 

Building even more infrastructure puts reaching our climate goals at risk, or will expose even more infrastructure to being stranded, which will have negative impacts on all of society,” she said. 

This stark fact underscores a key concern among environmental groups that have criticized the inclusion of carbon-removal technologies in assessments of climate change strategies — that it could be a way for fossil fuel industries to extend the lifespan of their investments. 

A February report from the Center for International Environmental Law and Heinrich Boell Foundation highlights the litany of dire and, in some cases, irreversible harms that will come with global warming beyond the 1.5°C target laid out in an IPCC report last month. These risks are a strong reason to avoid relying on technological solutions such as carbon dioxide removal as an alternative to moving as quickly as possible to reduce emissions, the report cautions. 

Policy choices that lock the world into overshooting 1.5°C and gambling on return, rather than immediately and drastically slashing emissions — including through rapid phaseout of fossil fuel production and use and a halt to deforestation — invite permanent loss and irreversible damage to humans and ecosystems around the world,” the report states. 

Unfortunately, given the increasingly difficult pathway to cutting emissions rapidly enough to affect the course of global warming, the choices available to us are no longer ideal,” Kristina Dahl, a principal climate scientist at the Union of Concerned Scientists, said in a Monday statement. In addition to deep, absolute cuts in heat-trapping emissions, some amount of these emissions will also need to be removed from the atmosphere if nations are to limit planetary warming to 1.5 degrees or even 2 degrees Celsius.” 

The Environmental Defense Fund came to a similar conclusion in a recent report on modeling it carried out in collaboration with Evolved Energy Research to determine the potential role of carbon capture and removal in getting the United States to net-zero emissions by 2050

Excluding carbon management from the model altogether led to extraordinary levels of renewables development and biomass use that would likely be technically challenging and politically infeasible,” the report finds. That means that carbon management” — a term that EDF uses to describe non-nature-based carbon capture, removal and storage technologies — could be needed to capture between 400 million and 1,100 million metric tons of CO2 by 2050, or between 7 and 20 percent of the current U.S. gross emissions.

Environmental Defense Fund chart of potential role of carbon removal in meeting U.S. goal of net-zero carbon by 2050
(Environmental Defense Fund)

EDF recommended that U.S. policymakers invest in innovation and start infrastructure planning to ensure we can leverage these emerging strategies.” 

That call was echoed by Madelyn Morrison, external affairs manager for the Carbon Capture Coalition trade group. In a Monday statement, she called for federal incentives to boost deployment of technologies for managing emissions from existing industrial facilities and power plants, offsetting emissions from hard-to-abate heavy industry, aviation and other sectors, and eventually removing legacy CO2 emissions from the atmosphere.” 

But Derek Walker, the Environmental Defense Fund’s vice president for the U.S. region, highlighted that the environmental group’s support of carbon-removal technologies is balanced by its opposition to policies that support the continued operation of fossil fuels where cleaner alternatives can replace them. 

We don’t know what will be able to scale and reach economic viability while dealing with very real concerns around land use, water use, access to renewable energy,” he said. But you lose a lot of your ability to apply sound scientific and health reasoning if you’re just saying that” capturing carbon from fossil fuel operations and capturing carbon that must be removed from the atmosphere to reduce climate change risks are equally viable solutions. 

If you can’t cut it, capture it, and if you’ve already released it, capture it,” he said. Either way, keeping it out of the atmosphere is job number one.”

Jeff St. John is director of news and special projects at Canary Media.