Accountability is catching up with the rapid growth in CDR initiatives. A new group has been formed to look at what happens if we don’t stay within 1.5C? The Climate Overshoot Commission held its first meeting in early June, launching a 15-month process to develop a governance strategy for removing carbon dioxide from the atmosphere, lowering temperatures by reflecting sunlight with artificial methods and adapting to climate change. The American Geophysical Union, the largest society of scientists working on climate issues, has also announced it is forming an ethics framework for “climate intervention” that would be ready for debate during COP27 in Egypt. 

Both groups will discuss CDR and the more controversial aspects of geoengineering. A recent briefing by Transparency International criticises the lack of public accountability and governance gaps in the market today. It warns that increased interest and funding in scaling up CDR and geoengineering technologies increases the risk of corruption by creating incentives to influence current regulatory grey zones and to patent new technologies.

CDR governance and policy is also making its way into national and regional agendas. An article by the German Institute for International and Security Affairs outlines how CDR can be an integral building block of the European Green Deal. The current focus under the Fit-for-55 package is on enhancing ecosystem-based sinks, increasing funding for innovation and establishing certification rules. But after 2030, more comprehensive CDR reforms in EU climate policy are expected, in line with the development of new 2040 climate targets. CDR was also highlighted by the G7 science ministers as a key area to promote interdisciplinary research on sustainable solutions, highlighting the need for more research on carbon dioxide removal and storage, particularly on monitoring, reporting and verification. In the UK context, a policy brief for the deployment of geological greenhouse gas removals outlines government-sponsored, market-based and hybrid options for policy intervention. Meanwhile in the US, California’s carbon neutrality plan has come under fire for relying too heavily on unproven and energy-intensive carbon removal technology.

The industry itself is responding to increasing calls for accountability. The Direct Air Capture Coalition has been formed to bring together leaders from technology, business, finance, government and civil society to “educate, engage and mobilise” the world on carbon removal. Members include for-profit companies such as Climeworks, which opened the world’s largest carbon removal facility in Iceland last year. The coalition will have a global focus and seeks to include NGO and civil society groups that are concerned about equity and sustainability, according to co-founder and board member Nicholas Eisenberger.

Running Tide, a company focused on ocean-based CDR, has received a lot of media attention lately. It has raised millions in venture funding and counts big names like Stripe and the Chan Zuckerberg Initiative among its customers, with plans to develop farms of floating, fast-growing kelp that will sink to the ocean floor, storing a billion tonnes of CO2 in the process. However, this month MIT Tech Review delved into the scientific credibility of the company and found not only that it has struggled to grow kelp along rope lines in the open ocean during initial attempts last year, but also that it has lost a string of scientists in recent months. The Review reported that the proposed speed of scale-up is extremely unlikely (storing even a tenth of the proposed billion tonnes of CO2 would require 73,000 sq kms of ocean) and rife with ecological oversight. The Atlantic has a more positive take on the company, arguing that while much of the “science remains unvetted, the researchers seem to be thinking about all the right problems in all the right ways”. Another challenge faced by ocean CDR companies is that the deep ocean might store far less carbon than we hoped. New research finds that, on average, only 66% of carbon reaching a depth of 1,000 metres in the North Atlantic Ocean can be stored for a century or more.

Doubt has also been cast over the much-hyped potential of soil carbon sequestration, claimed to be capable of sequestering one trillion tonnes of CO2 (equivalent to all human emissions over the last 25 years) by sustainable farming company Indigo Ag. The Sierra Club highlights that the science behind storing carbon in soil is incredibly speculative, calling into question the actual amount of carbon that is and can be stored long-term in soil.

Governments also need to be careful about overhyping science and sharing false narratives. Incredibly, the UK Department for Transport stated that CDR technologies will enable Britons to take “guilt-free flights” by the end of next year. Those involved in the UK’s Greenhouse Gas Removal Programme (GGR) confirmed the “cheeky” claim was inaccurate. Experts speaking at a GGR event in London also warned that CDR techniques are not a silver bullet and should make up just a fraction of overall decarbonisation efforts. 

The carbon removal industry is still in its infancy and will require significant effort to scale up. But this is difficult in practice - for example, research shows that in the more mature carbon capture and storage market, 78% of large-scale projects have been cancelled or put on hold because of challenges with funding and economic feasibility. Even for CDR plants that are under development, there are reasons for concern. There are worries that the DAC 1 facility (a joint project by Carbon Engineering and Occidental Petroleum)​​, touted to be the world's largest DAC facility when it is fully operational in 2024, will actually use the carbon it captures to pump more oil out of the ground. Climate advocacy groups warn that carbon removal facilities partnering with oil and gas companies are only using DAC technology to increase the efficiency of their extraction business.

Researchers at Tokyo Metropolitan University have developed what they say is the world's fastest carbon capture system that extracts CO2 straight from the air with unparalleled efficiency. The system is reusable, requires little heating, and is at least twice as quick as previous devices, they claim. 

Meanwhile, the nature vs tech CDR debate has been reignited. A new study identifies  terrestrial biomass as the greatest opportunity for carbon removal and storage in the near term, claiming 287 gigatonnes of untapped carbon storage (over eight times total carbon emissions last year). Others think we should not pretend planting trees is a permanent climate solution. But research using life cycle analysis suggests that both natural and technological approaches have benefits and the specific aim of carbon removal should guide the choice of the approach used. For consistent removal of CO2 over longer time horizons, afforestation/reforestation and mangrove restoration have the lowest environmental impacts, but for large and quick CO2 removal, technological approaches (enhanced weathering, DAC and BECCs) have a similar or lower impact.

There have also been new developments in the quest to store carbon in concrete - just as new data finds that CO2 emissions from cement production have doubled in the last 20 years. One study suggests CO2 mineralisation in recycled concrete aggregates in Europe could permanently store up to eight million tonnes of CO2 a year. Another suggests that retrofitting cement plants with oxyfuel (burning fuel using pure oxygen) and using biomass as an alternative fuel can result in plants reaching negative emissions. The US Department of Energy has even provided a USD 3.5 million grant for a study focused on a direct air capture and utilisation system that can remove 5,000 tonnes of CO2 from ambient air each year and permanently mineralise it in concrete products.

Some more controversial CDR and geoengineering approaches have also been reported. A new research programme at the Innovative Genomics Institute, supported by a USD 11 million commitment from the Chan Zuckerberg Initiative, seeks to use CRISPR genome editing to enhance the natural ability of plants and soil microbes to both capture and store carbon from the atmosphere.

And finally, a group of MIT researchers is exploring the feasibility of fighting climate change with a raft of "space bubbles" - collectively covering an area roughly the size of Brazil - that would float above the Earth to reflect the sun's rays. The MIT researchers suggest this approach could have advantages over other earth-bound geoengineering proposals that pose risks to ecosystems, but stress that the proposal was designed to supplement not replace current climate change mitigation efforts.