Is Deploying Biochar as a Climate Geoengineering Tool Scientifically Premature?

Some of biochar’s proponents say the substance will save us from climate change destruction, as we covered in Part 1.

At the very least, its proponents say it has great potential to simultaneously improve agricultural yields, produce clean energy, and mitigate climate change by sequestering carbon. Its most enthusiastic supporters have hailed it as “black gold.” 

But scientists call biochar a false climate change solution, leaving them with more questions than answers.

These questions include:

1) Why hasn’t there been more field trial–based research (as opposed to lab trials) to test biochar’s climate change mitigation potential? And is there any credibility to the claims that biochar could help stave off climate change?

2) Is biochar technology ready to “go big-time?”

3) If biochar is scaled up, could it lead to “land grabs” in the future?

In attempting to answer these questions, DeSmog quickly learned the situation is not as black-and-white as proponents have proclaimed. If anything, the state of science surrounding biochar is myriad shades of gray.

As written by Gar Lipow in Grist in 2010, pointing to a BiofuelWatch study, “the science on this [is] highly uncertain, and we are moving far ahead of our understanding in our haste to implement.” The same diagnosis exists more than half a decade later, and the level of uncertainty has only increased over time. 

Indeed, in October 2016 the United Nations (UN) Convention on Biodiversity published a report stating that “deployment of this technique on a large scale would have significant direct and indirect impacts on the use of land, water and fertilizers to generate the biomass required.”

Terra Preta: A Sober Assessment

Biochar skeptics have long pointed out that while grandiose claims are made regularly about the substance, long-term field trials have yet to take place and even short-term ones are few and far between. 

There have been “a grand total of five [now seven] peer-reviewed field tests of biochar where soil carbon was measured before and after biochar was applied,” wrote Lipow back in 2012 for Grist. “None of these tests used charcoal from the low-pollution charcoal-making stoves that have been developed for use by small farmers to create biochar.” 

Lipow continued:

Nonetheless, looking at what is out there, in two of the five trials, carbon showed no increase after the application of biochar compared to before, or less increase than competing methods of improving the soil, such as adding manure or sawdust. A third trial showed no improvement in two cases, and an increase in one. The results in the other two trials were mixed — showing more carbon in a majority of cases, but less in a minority. So if we look at peer-reviewed field trials, biochar results so far range from outright failure to unreliable. We need to do extensive study to figure out what works and what doesn’t before we move prematurely to deploy.

On top of these inconclusive field tests, many of the studies cited by biochar proponents base their research on the original Amazonian Terra Preta practices and outcomes. Yet, modern-day industrialized biochar production is a far cry from Terra Preta’s ancient methods, for which precise records do not exist.

Lipow again:  

There are a number of studies based on Terra Preta, the black earth created by a complex system of slash-and-burn agriculture once used in the Amazon. That did indeed work, and it would be wonderful if we knew how to recreate it. Unfortunately, long-ago massacres and destruction of indigenous nations in the Amazon mean that we have no idea of the ancient technologies that produced the Terra Preta biological cycle. Burning wood or straw in high-tech charcoal stoves is NOT the same thing, and so far has not been shown to produce the same results.

Two of the co-founders of the International Biochar Initiative (IBI) (the biochar lobby), Johannes Lehmann and Stephen Joseph, readily admit the inspiration behind the current push to scale up biochar came from non-peer-reviewed science and from articles written by science journalists.

In the introductory chapter of Biochar for Environmental Management: Science, Technology and Implementation, the textbook they co-edited and published in 2015, they cited journalistic articles about Terra Pretta appearing in the journals Science (2002) and Nature (2006) in pointing to the current “interest in biochar research and development.” They later concede, though, that “Terra Preta soils do not provide a direct analogue to biochar management.”

The Nature article quotes Lehmann saying, “This is the only way to make a fuel that is actually carbon negative.” It also has a concluding section titled, “The right protocol,” in which Lehmann discusses the possibility of getting biochar inserted into a greenhouse gas offset system protocol.

IBI has tried for years to get “the right protocol” for biochar, but has faced several major setbacks.

Peer Review Fatal Blow?

An October 2013 peer-reviewed study, partially funded by the Union of Concerned Scientists (UCS) and titled “A Systematic Review of Biochar Research, with a Focus on Its Stability in situ and Its Promise as a Climate Mitigation Strategy,” concludes that the jury is still out on biochar’s climate change mitigation potential. 

“Even though they found 311 peer-reviewed research articles on biochar, the overwhelming majority were studies in the laboratory, not in soils under natural conditions. Of those 311, only seven actually estimated the decomposition rates of biochar in situ,” explained a study overview by the Union of Concerned Scientists. “And in those seven, the estimates of the ‘mean residence time’ of biochar in the soil ranged from 8.3 to 3,624 years.”

“This means that scientifically, a critical question remains unanswered. We have hundreds of published studies, but only a handful focus in the issue of stability in the field.”

Furthermore, a 2012 peer-reviewed article published in the journal Global Change Biology explained why considering biochar as a climate change mitigation godsend is putting the deployment cart ahead of the science horse. 

“[I]t is difficult to evaluate the factors controlling its breakdown because there are significant variations in the physicochemical structure and composition of biochar that arise due to differences in starting material and pyrolysis conditions,” the article explained. “After application to soils, biochar decomposition rates vary under different soil conditions … Overall, the use of biochar…requires additional investigation.”

But most recently, the biochar lobby received perhaps its most fatal blow yet: Its marketing protocol for offsets was shot down in March 2015 by an American Carbon Registry (ACR) blind peer-review panel. In its 115-page review, ACR called out IBI for its over-reliance on lab testing, its lack of evidence of biochar’s climate change mitigation potential, and its lack of scrutiny of the potential ecological blowback that could accompany scaling up biochar development.

“The conclusion of the peer reviewers is that the methodology should not be accepted at this time. They stated that the scientific literature does not provide sufficient evidence of the stability of soil carbon sequestration,” American Carbon Registry explains in the introduction on its peer review. “ACR welcomes the opportunity to revisit approval of the methodology at such time as there is clearer scientific consensus behind the approach proposed for methods to measure, monitor and verify biochar carbon stability.”

The lead author of the UCS study, Noel Gurwick, also provided a comment for the public comment portion of the ACR biochar offsets protocol development, echoing the concerns about the lack of field trials and demonstrated soil stability.

(See DeSmog’s analysis of the American Carbon Registry peer review.)

National Research Council on Biochar

The National Research Council of the U.S. National Academy of Sciences panel also made waves in February 2015 by weighing in on biochar and, more broadly, geoengineering as a climate change mitigation tool in a meta-analysis study titled, “Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration.”

Like others before them, the panel concluded that biochar is a false climate change solution.

“Although there has been research associated with the role biochar could play on carbon and nitrogen dynamics, the literature is still limited, and the impacts of utilization on net greenhouse gas emissions are not well defined,” they wrote in the report, “[But] … biochar does have benefits to agricultural practices such as improving soil structure (water and fertilizer retention), removing contaminants, and enhancing fertility in degraded soils.” 

The lack of an endorsement of biochar as a climate mitigation tool, however, got lost in the broader story that the National Academy of Sciences endorsed the limited test project use of other controversial geoengineering tools.

Geoengineering is a device decried by the likes of Naomi Klein, Clive Hamilton, and others. Hamilton wrote in an opinion piece in The New York Times that just by doing the study, the National Research Council has brought the once-fringe idea of deploying geoengineering into the mainstream.

“The report is balanced in its assessment of the science. Yet by bringing geoengineering from the fringes of the climate debate into the mainstream, it legitimizes a dangerous approach,” wrote Hamilton. “Even scarier is the fact that, while most geoengineering boosters see these technologies as a means of buying time for the world to get its act together, others promote them as a substitute for cutting emissions.”

Friends of the Earth went a step further, arguing that to focus on scaling up geoengineering tools like biochar is to deny tackling the root causes of climate change.

“Instead of facing the reality that we need to drastically reduce our carbon emissions, lower our consumption levels and rapidly transition to renewable energy, some hope to simply re-engineer the climate, the land and the oceans to theoretically slow down and reverse climate disruption,” said Friends of the Earth in a press release. “Geoengineering is an attempt by those most responsible for climate disruption to continue polluting instead of committing to the necessary actions and funding needed to help those countries and communities that will be most harmed by climate change.”

The UN Convention on Biodiversity recently agreed, denouncing geoengineering as a climate change tool in its October 2016 report.

Biochar Fans Push Offsets Sans Field Trials

Nevertheless, biochar’s promoters tout the scientific state of play on biochar as a positive.

“I don’t want to throw my hands up in the air and say this is unexplainable uncertainty. I think it’s very much explainable variability and I know this is hard for policymakers,” Lehmann said about this extreme variability at the 2013 North American Biochar Symposium held in Amherst, Massachusetts. “With the understanding that we can predict that variability, I believe this is an opportunity and will ultimately be an opportunity, not a constraint.”

Despite the lack of field trials, John Gaunt — head of the short-lived firm, Biochar Protocol Development, which helped write the failed biochar development protocol — opined that IBI should not include field trials as a requirement in the protocol it released as a draft in November 2013. 

Gaunt spoke of this at the 2013 Symposium. 

“I think we’re at a very critical stage here at the moment with the protocol in review here with the American Carbon Registry,” he said. “I think it may be tough for the protocol to get through this process and there are a couple things here that are really important in my view.”

Gaunt further explained himself (emphases mine):

There’s a real difference between proving the material is stable in the environment in which you’re going to use it and measuring the presence of biochar in soil over time. If we get moved to a point where you have to measure your biochar in soil all those various locations it’s been used, the costs of doing that are going to remove the opportunity you see in this carbon sequestration, this carbon offset that biochar offers. They did the best that you can do today and I think that, from what I’ve seen and heard so far, there is going to be a debate around — with the elements of conservatism that we’ve built into the protocol — whether this predictive capability is good enough.

And anyone who understands this and can contribute to the process and help the process to realize that what we’ve done is really going to make biochar work — it is a safe, sensible strategy — has to make their voice heard. Because if we get pushed in the direction of ‘Oh, we should measure it in soil,’ which is really — you know, really comfortable if you do that — my mom would feel comfortable if I did that. But the problem is it would really set back this opportunity.

So there’s a kind of defining moment here and we shouldn’t take it for granted that this protocol will be approved, in my view.

That Carbon Registry protocol development draft was denied a year and a half later, with IBI‘s official press statement spinning the lack of scientific evidence as a mere shortcoming of the peer reviewers’ scientific prowess.

“Whereas biochar researchers around the globe largely agree on methods to estimate biochar carbon persistence utilized in the ACR methodology … the larger scientific community remains unfamiliar with recent advances in the field,” states IBI‘s website.

Wiley Barbour, former executive director of IBI, sung a similar tune in critiquing ACR via an email sent to DeSmog, while also confirming the central role offsets and carbon markets play in the future (if there is one) of industrial-sized biochar development.

The carbon market may come back, but until regulations and policies generate demand, and as long as prices are too low to stimulate investment, the market signal is inadequate to finance offset projects. We will know when the market comes back because we will see projects arise in response to a clear policy signal. In today’s market, except for a few exceptions, we are kidding ourselves that any of these voluntary actions are meaningful. I briefly reviewed the peer review comments on the biochar methodology, and IBI’s position is understandable: if verification and soil testing is required to prove the longevity of biochar then it becomes too expensive given the relative low density of biochar projects.

The American Carbon Registry could have made its own decision on this issue, but has instead hidden behind comments from scientific reviewers who are unfamiliar with carbon markets and verification options. Personally, I think there is strong evidence that biochar persists for many years in most soil conditions, but I cannot say that in every case, in every environment, all the biochar will last for 100 years. As with so many other aspects of climate change, by the time we have finished studying this it will be too late to avoid dangerous interference with the climate system.

More recently, Lehmann has spoken in similar terms about the “opportunity” of biochar as an attendee of the 2016 UN climate summit held in Morocco in November 2016.

“Lehmann and his colleagues estimate that biochar alone could account for roughly 1.8 of those gigatons annually, or about 12 percent of man-made carbon emissions,” reported Pacific Standard Magazine of an offsite talk held by Lehmann at the summit. “But even if biochar ends up being less fruitful, Lehmann says, and only cuts emissions by 0.5 percent, as long as farmers see a boost in soil fertility, it’s worth investing time and money in creating biochar technologies — especially since developed nations like the United States and China are largely responsible for creating the climate that threatens agriculture across Africa today.”

Lehmann’s talk at the summit came just weeks after he and his colleagues published a study in the journal Nature which called for, once again, the mass deployment of a biochar energy system as a climate solution. They pitted what they branded bioenergy-biochar systems (BEBCS) as a better alternative to the controversial and scientifically dubious use of bioenergy with carbon capture and storage (BECCS) and IBI promoted the study in a press release.

“The relative simplicity of producing and sequestering biochar results in biochar-bioenergy systems that can be built at modest scale and widely distributed,” reads the IBI release. “Their small size reduces the risk of deploying new technology, eases financing, and speeds adoption. Biochar-bioenergy systems can play an important role in a global strategy to actively remove carbon from the atmosphere.”

GAO: Biochar Not Ready for Prime Time

Despite the big push to market biochar on a mass scale and potentially include it in an offsets scheme, another report — this one by the federal government’s nonpartisan Government Accountability Office — further rained on the deployment parade.

Entitled, “Climate engineering: Technical status, future directions, and potential responses” and published in July 2011, the GAO report’s section on biochar sheds the same dim light on its technological readiness as did the National Research Council.  

On the Technology Readiness Level (TRL) scale — a measure used by the U.S. government to assess the maturity of evolving technologies before scaled up to market — biochar rated a two out of nine, still squarely in the range of “basic technology research.”

Image credit: Wikimedia Commons

The Government Accountability Office explained the rating:

While its proof of concept has been demonstrated in published modeling and experimental results, we found uncertainties in experimental data demonstrating the efficacy of biochar as a net carbon sink. Reports show its benefits to soil, but the current immaturity of biochar sequestration technology precludes it from being practiced on a scale large enough to affect the climate.

Looming Land Grabs?

Beyond the science of biochar, detractors point to the massive swaths of land needed to make large-scale biochar a reality. They say that when examined through this lens, it makes the entire thing look either wholly unrealistic  or — worse — a scary future prospect.

“The quantities that would be required per acre of cropland are staggering,” explained Stan Cox, senior scientist at The Land Institute, in a recent article entitled, “Biochar: Not All it’s Ground Up to Be?“ 

“[D]epending on the method used, production of 20 tons of biochar reportedly means burning between 50 and 200 tons of plant material,” Cox further explains. “Research conducted in the Amazon concluded that treating one acre of land with biochar would require clear-cutting, charring and hauling all the biomass from two acres of secondary forest, which then would take many years to regrow.”

As BiofuelWatch’s Almuth Ernsting has explained, this would entail “conversion of 556 million hectares of grasslands and so-called ‘abandoned croplands’ to produce crops and trees for biochar production … 556 million hectares would be more than twenty times the area of land used to produce biofuels at present.”

556 hectares is just under 1.7 times the size India. This raises the question: Do land grabs loom if biochar production is scaled up? 

Anne Maina, executive director of the African Biodiversity Network thinks so. So too do more than 150 grassroots civil society activist groups from around the world who signed onto a 2010 open letter.

Photo of land-grabbing in Eithiopia, courtesy of the Oakland Institute

“Groups have been warning for years that the biochar techno-fix will mean land-grabbing on a vast scale,” Maina said in an August 2010 press statement introducing the letter. “Now they are showing their true colours: Large-scale biochar means large-scale land grabs.”

Speaking at the 2011 International Biochar Initiative conference, Bill McKibben, founder of, expressed similar concerns about the potential for land grabs pertaining to biochar.

“Many people around the world, myself included, are worried about the scale with which this idea is being pursued, especially compared to the relatively puniness of the scale of the science on which it’s so far based,” he said.

Bill McKibben’s Message for International Biochar Initiative from on Vimeo.

McKibben continued:

The very rapid industrialization of these things without analysis at some scale that would allow to understand what they really mean is, I’m afraid, all too characteristic of the hubris that has marked one enterprise after another in the modern era. The many, many difficult and in some cases, ruinous effects that have come with this kind of very quick and not well thought out explosion to scale are things that we should try hard to avoid.

There is a deep social justice and development implication to work on this scale. If it becomes a land grab that damages peasant farmers instead of making their lives easier, then I’m afraid it will be met with fierce resistance.

The truth around the world is that of course, most of the damage of climate change is felt by those who have done the least to cause it. If those people are also damaged — or their livelihoods damaged — in the all-out effort to industrialize and profit from the spread of these new processes, then not only will it be unfair and depressing, but it will make even more difficult to reach an international consensus for how we deal with this problem. 

The Ohio State University Professor Rattan Lal, a former Nobel Peace Prize winner, concurred with McKibben in his study, “Biochar and Soil Carbon Sequestration,” which was published in April 2016 in the book, Agricultural and Environmental Applications of Biochar: Advances and Barriers.

“Adequate research is needed, and any hasty application of biochar on a large scale must be avoided until credible information is available on unforeseen environmental impacts,” wrote Lal. “Claims on universality of the impacts of biochar on soil quality and environment are not supported by the available data, and there are pros and cons of using biochar as a soil amendment.”

Even major biochar promoters, such as Lehmann concede that scaling up biochar could culminate in a massive land grab.

“A final issue is the question of the costs and impacts of biomass supply chains to support any of these technologies at a sufficient scale to make a substantial contribution to climate change mitigation,” wrote Lehman and his colleagues in an October 2016 paper supportive of biochar.

“The land area required to provide sufficient … to meet the requirements of [meeting a global 430-480 parts per million of carbon in the atmosphere, or within the 2-degrees celcius temperature rise goal agreed upon at the U.S. climate summit in Paris in 2015] has been estimated at … two to four times the global area of abandoned or marginal land. These large demands on land would be expected to create competition for productive land with food, fibre, biofuels, habitat and other ecosystem services.”

While biochar land grabs — at least for now — remain a thing of the future, some stakeholders are still pushing hard to insert biochar into greenhouse gas offset schemes. Continue to Part 3 and Part 4.