Biochar in Climate Change Mitigation
Citation: Lehmann J, Cowie A, Masiello CA, Kammann C, Woolf D, Amonette JE, Cayuela ML, Camps-Arbestain M, Whitman T (2021). Biochar in climate change mitigation. Nature Geoscience 14(12): 883–892. https://doi.org/10.1038/s41561-021-00852-8
What it is: A widely cited review of how biochar systems mitigate climate change: emission reductions versus CO₂ removal, energy trade-offs, persistence, and crop responses. The vault uses it for global potential and persistence framing.
Key figures
| Figure | Value | Where | Check |
|---|---|---|---|
| Global emission reductions from biochar systems | 3.4–6.3 PgCO₂e per year, about half of it CO₂ removal | Abstract | ✓ abstract |
| Persistence vs the source biomass | One to two orders of magnitude longer | Abstract | ✓ abstract |
| Energy trade-off | Relative to producing bioenergy, emissions from biochar systems rise 3% where the displaced energy is coal and fall 95% where it’s renewable | Abstract | ✓ abstract |
| Crop yields | No clear relationship between yield responses to fertilizer and to biochar | Abstract | ✓ abstract |
| Residue-only potential of 2.4–3.9 PgCO₂e/yr; up to 7.4–10.3 with land-sparing or CCS pathways | Used in CDR Potential and IPCC Accounting and Quantitative Benchmarks | — | not re-checked (full text paywalled) |
| Of biochars with H/C_org < 0.5, 95% kept more than half their carbon after 100 years (mean ~82%) | Used in Permanence and Quantitative Benchmarks | — | not re-checked (full text paywalled) |
Use with care
- Two of the vault’s most-quoted numbers from this paper, the H/C_org persistence subset and the land-sparing range, come from the full text, which wasn’t accessible. Check them before relying on them.
- The energy trade-off means biochar’s climate advantage depends on what energy it displaces; it isn’t a fixed number.
Related: CDR Potential and IPCC Accounting · Permanence · models soil GHG from biochar · Key Sources