How long does the carbon actually stay in the soil?
The biggest uncertainty is whether the carbon locked in biochar will stay put for centuries or leak back into the atmosphere sooner than expected. A 2026 global meta-analysis found that biochar reduces runoff by 25% and soil erosion by 16% on average, which is a key mechanism for keeping carbon in the ground [1]. In Mediterranean vineyards, the same study observed up to a 65% reduction in soil erosion and an 85% increase in soil organic carbon with a 4% biochar amendment [1]. However, these erosion-reduction benefits are not yet formally counted in carbon removal frameworks, meaning current carbon credit systems may overestimate or underestimate true permanence. The authors argue that integrating erosion data into monitoring, reporting, and verification (MRV) would reduce this uncertainty [1].
Public perception also feeds into this uncertainty. A 2025 UK study involving 60 people in deliberative workshops and a nationally representative survey of 2,027 people found that while the public strongly supports carbon removal, they specifically worry about scientific uncertainty around novel techniques like biochar [6]. People questioned whether biochar would be 'worth it' given concerns about life-cycle emissions and land competition [6]. So the permanence question isn't just technical—it affects whether society will accept and pay for biochar at scale.
What does it really cost, and does it scale?
Cost estimates vary enormously depending on feedstock, location, and whether you count co-products like heat or bio-oil. A 2024 study on China found that biochar could sequester up to 0.92 billion tons of CO₂ per year at an average net cost of US$90 per ton of CO₂, but this is a national average that hides huge local variation [3]. In Great Britain, a 2026 spatial model estimated that straw-based biochar could achieve only 0.6–1.9% of the UK's 2050 carbon removal target at marginal costs below £75 per ton of CO₂ equivalent, and even including higher-cost options only raises that to 0.8–2.1% [2]. The same study found that costs are heavily influenced by feedstock price, biochar yield, and the value of byproducts like energy-dense gases [2].
A 2024 survey of 72 Nordic biochar stakeholders (representing 64 organizations) found that 60% of current producers describe biochar production as a side business, and key barriers include profitability uncertainties and lack of established norms [4]. In Brazil, a 2026 commentary notes that the country is structuring a biochar value chain but faces scientific uncertainties in MRV, regulatory gaps, and the need for economic mechanisms to turn biochar into a credible climate asset [5]. Together, these studies show that cost and scalability are not just engineering problems—they depend on policy support, market development, and public willingness to pay.
Can we trust the numbers? The MRV challenge
Even if biochar works in theory, we need reliable ways to measure, report, and verify how much carbon is actually removed—and that's a major scientific gap. The 2026 global meta-analysis on erosion explicitly calls for integrating erosion-mediated carbon retention into MRV methodologies, arguing that current frameworks undervalue this mechanism [1]. Without it, carbon credits may be less durable than claimed. The Brazil commentary echoes this, stating that scientific uncertainties in MRV are one of three key challenges that will determine whether biochar can scale as a robust carbon removal solution [5].
The public also picks up on this uncertainty. In the UK study, participants raised concerns about life-cycle emissions and scientific uncertainty around biochar, suggesting that even if the science improves, public trust will depend on transparent and credible MRV [6]. The Nordic survey adds that lack of established norms and inadequate policy support are holding back the market [4]. So the MRV challenge is both technical and social: we need better measurement tools, and we need to convince people—and carbon markets—that those tools are trustworthy.
About These Sources
This answer is built on 6 peer-reviewed studies — published from 2024 to 2026, 6 from 2024 or later, 4 in Q1 journals, collectively cited 144 times — selected as the most relevant from 6 studies that passed quality screening, drawn from 54 papers retrieved from a database of over 500 million.
Sources used in this answer
Biochar for durable carbon removal: soil erosion reduction as a key mechanism
A 2026 global meta-analysis found that biochar reduces runoff by 25% and soil erosion by 16% on average, and in Mediterranean vineyards it reduced erosion by up to 65% and increased soil organic carbon by 85% with 4% biochar amendment, arguing that erosion reduction should be integrated into MRV frameworks.
Marginal Cost of Carbon Sequestration Using Straw-Based Biochar in Great Britain
A 2026 spatial model for Great Britain estimated that straw-based biochar could achieve only 0.6–1.9% of the UK's 2050 carbon removal target at marginal costs below £75 per tCO₂e, with costs heavily influenced by feedstock price and biochar yield.
Exploring negative emission potential of biochar to achieve carbon neutrality goal in China
A 2024 spatially explicit analysis for China found that biochar could sequester up to 0.92 billion tons of CO₂ per year at an average net cost of US$90 per ton of CO₂ in a sustainable manner, supporting China's 2060 carbon neutrality goal.
Nordic perspectives on the emerging biochar business
A 2024 survey of 72 Nordic biochar stakeholders (64 organizations) found that 60% of producers see biochar as a side business, and key barriers include profitability uncertainties, lack of norms, and inadequate policy support.
Biochar in Brazil: from potential to climate asset
A 2026 commentary on Brazil argues that the country's emerging biochar value chain faces three key challenges: scientific uncertainties in MRV, regulatory gaps in standardization, and the need for economic mechanisms to make biochar a credible climate asset.
Carbon removal support is tempered by concerns over whether biological methods are worth it
A 2025 UK study using deliberative workshops (n=60) and a nationally representative survey (n=2,027) found strong public support for carbon removal but tempered by concerns about scientific uncertainty around biochar, life-cycle emissions, and land competition.