In a perspective article published in the journal Biochar, authors Robert W. Brown, David R. Chadwick, and Davey L. Jones address a widespread point of confusion in environmental science and green policy discussions. As the global push for carbon dioxide removal accelerates, market demand for fast, scalable technologies has pushed biochar to the forefront of voluntary carbon networks. In fact, recent industry data indicates that biochar accounts for ninety-four percent of delivered carbon credits worldwide despite receiving only twelve percent of direct climate funding. Because crop and pasture lands encompass roughly forty percent of the earth’s ice-free surface, applying this material to agricultural soils has become the most common disposal route. However, this rapid commercial scaling has led to a major problem where scientists, practitioners, and politicians frequently conflate the long-term persistence of black carbon with its immediate agricultural benefits. The authors clarify that these two goals operate on a distinct chemical spectrum, meaning that a single batch cannot be optimized for both properties simultaneously.

The primary findings of the manuscript show that the internal structure of biochar undergoes a radical shift based on the heat levels applied during the manufacturing process. When plant matter is baked at extreme temperatures exceeding seven hundred degrees Celsius, the intense heat drives off most volatile gases and forces the remaining material into highly dense, repeating ring networks known as polycyclic aromatic carbon. These ring networks are exceptionally inert, making the resulting charcoalCharcoal is a black, brittle, and porous material produced by heating wood or other organic substances in a low-oxygen environment. It is primarily used as a fuel source for cooking and heating.   More highly resistant to biological decay and chemical breakdown. Scientific models estimate that this high-temperature material can safely lock away carbon in the ground for more than a millennium, representing the absolute gold standard for permanent carbon removal. Unfortunately, this extreme baking process also vaporizes the critical oxygen-rich functional groups that sit on the surface of the charcoal. Without these chemical bonding sites, the highly stable charcoal becomes entirely passive, meaning it lacks the ability to pull in moisture, capture passing nutrients, or aid in soil cation exchange. Consequently, inserting highly durable charcoal into fertile, temperate soils yields little to no noticeable boost in plant growth or crop output.

Conversely, when organic waste is processed at lower temperatures between three hundred and fifty and five hundred degrees Celsius, the resulting material retains a wealth of oxygen-containing surface structures. These functional groups give the low-temperature material a high surface porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More and a massive relative area, turning each particle into a chemical sponge. This sponge-like behavior allows the low-temperature material to actively filter out heavy metals, bind organic pollutants, and dramatically boost water and nutrient retention in degraded soils. This active environmental interaction explains why low-heat batches excel as soil conditioners, particularly when applied to weathered tropical soils or ruined landscapes. The key drawback, however, is that these low-heat matrices break down far more rapidly in standard aerobic soils, with an estimated lifespan of only one hundred to three hundred years. Because this material decays several centuries faster than its high-temperature counterpart, its capacity to serve as a reliable carbon removal tool is fundamentally compromised.

To solve these systemic trade-offs, the researchers suggest that the industry must abandon the generic use of terms and transition entirely toward designer biochar tailored for specific regional needs. For instance, operators can utilize high-temperature charcoal for maximum permanence, then artificially coat the particles with nutrient-rich compost, manure, or microbial inoculants to restore surface function without sacrificing storage integrity. Alternatively, burying low-temperature material in waterlogged, anaerobic peatlands can protect the less stable matrices from rotting, allowing for unique combinations of soil restoration and carbon removal. Ultimately, the authors warn that failing to explicitly communicate these trade-offs risks overstating environmental additionality, which could severely undermine public and corporate trust in the integrity of voluntary carbon removal markets.

Source: Brown, R. W., Chadwick, D. R., & Jones, D. L. (2026). Clarifying the conflation of biochar carbon stability and its soil co-benefits. Biochar, 8(67), 1-4.