The Scientific Basis for Biochar as a Climate Change Mitigation Strategy: Does it Measure Up?

The report concludes that there is insufficient scientific evidence to support the use of biochar as a reliable climate change mitigation tool. A review of 329 references found that only 15 field studies measured biochar decomposition, and of those, only six provided data to estimate stability. These six studies showed wildly varying results, with mean residence times (MRT) ranging from 8.3 years to over 3,000 years. The authors argue that the science is too immature to justify public investment in biochar for carbon sequestration, as the influence of biochar on the whole system carbon balance remains poorly quantified.

• A comprehensive literature review of 329 unique references revealed that only 212 were original research papers, and of those, approximately 25% (56 papers) provided empirical data on biochar's persistence in soil or its influence on surrounding soil decomposition.
• The evidence base for biochar stability is extremely limited, with only 15 field studies measuring decomposition indicators and only six of those providing enough data to estimate decomposition rates or related parameters critical for quantifying carbon sequestration.
• Estimates of biochar stability vary drastically across the few available field studies, with mean residence times (MRT) ranging from as low as 8.3 years in Kenya to over 1,000 years in the Philippines and Thailand.
• Specific field studies indicate significant carbon loss over time: a study in the Russian steppe found a turnover time of 293 years with a 25% decline in biochar content over a century, while research in Eastern North America suggested at least 23% of biochar carbon escapes to the atmosphere over 130 years.
• There is contradictory evidence regarding how biochar affects the surrounding soil organic matter (SOM); some research suggests biochar can accelerate the decomposition of SOM, while other studies found lower CO2 emissions in biochar-amended plots compared to those with green manure.
• The authors conclude that it is premature to rely on biochar as a climate mitigation tool or to allocate public resources to its deployment because the data required to determine how effectively it sequesters carbon and for how long do not yet exist.

APA

Gurwick, N. P., Kelly, C., & Elias, P. (2012). The Scientific Basis for Biochar as a Climate Change Mitigation Strategy: Does it Measure Up? Union of Concerned Scientists. https://www.ucs.org/sites/default/files/2019-09/Biochar-Climate-Change-Mitigation-Strategy-Does-It-Measure-Up.pdf

Chicago

Gurwick, Noel P., Charlene Kelly, and Pipa Elias. The Scientific Basis for Biochar as a Climate Change Mitigation Strategy: Does it Measure Up? Union of Concerned Scientists, 2012. https://www.ucs.org/sites/default/files/2019-09/Biochar-Climate-Change-Mitigation-Strategy-Does-It-Measure-Up.pdf.

Wikipedia

{{cite report |last1=Gurwick |first1=Noel P. |last2=Kelly |first2=Charlene |last3=Elias |first3=Pipa |title=The Scientific Basis for Biochar as a Climate Change Mitigation Strategy: Does it Measure Up? |publisher=Union of Concerned Scientists |date=September 2012 |url=https://www.ucs.org/sites/default/files/2019-09/Biochar-Climate-Change-Mitigation-Strategy-Does-It-Measure-Up.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{gurwick2012scientific, author = {Gurwick, Noel P. and Kelly, Charlene and Elias, Pipa}, title = {{The Scientific Basis for Biochar as a Climate Change Mitigation Strategy: Does it Measure Up?}}, institution = {Union of Concerned Scientists}, year = {2012}, month = sep, url = {https://www.ucs.org/sites/default/files/2019-09/Biochar-Climate-Change-Mitigation-Strategy-Does-It-Measure-Up.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }