THIS IS A REPORT FROM PROJECT SAVE THE WORLD TO THE CANADIAN PUGWASH GROUP ABOUT THE SERIES OF FORUMS ADDRESSING THE USE OF “CARBON NEGATIVE” CONCRETE

Report on Forums on Carbon Negative Concrete

By Metta Spencer

19 June 2023

Panelists: Adeyemi Adesina, Michael Barnard, Paul Beckwith, Adele Buckley, Chris Cheeseman, Robin Collins, Brent Constantz, Michael Cook, Robert Cumming, Peter Fiekowsky, Michel Duguay, Martin Halliwell, Douglas Hooton, Neil Hoult, Ellen Judd, Peter Meincke, John Orr, Derek Paul, Tariq Rauf, Karen Scrivener, Ryan Zizzo.
 
On October 22, 2022, the Canadian Pugwash Group adopted a proposal I’d submitted to explore the possibility of reducing climate change by promoting (a) urban forestry, (b) chilling the Arctic with marine cloud brightening, (c) the use of rock dust, biochar, and seaweed bio-stimulants as soil amendments, and (d) the use of carbon negative concrete in government-funded construction. Since then, Pugwashites have participated in selecting experts and indigenous stakeholders and in discussing with them in at least four (and up to nine) one-hour-long forums, which were recorded and made continuously available on the website of Project Save the World, a not-for-profit organization of which I am president. I am now writing separate reports for all four of these inquiries. This is my summary of information gleaned from six forums about carbon negative concrete. I expect to circulate it to the Pugwash panelists and incorporate their editorial amendments before submitting it for an online discussion by all Canadian Pugwashites. The names shown above are the experts and Pugwash panelists who participated in one or more of the forums. Complete records of all 24 forums in the Pugwash series are accessible as videos, audio podcasts, transcripts, and summaries here: https://tosavetheworld.ca.

It should be emphasized that this is not a research report in same sense as a journal article. It is a report on the conversations among a number of experts whose ideas were occasionally incompatible. In such cases, this reporter did not attempt to decide who was right but simply presented a faithful account of what was said, whether right or wrong. All disagreements expressed by the participants who reviewed this report are represented in footnotes. Fortunately, the panelists mainly reached compatible conclusions, enabling a recommendation to be proposed at the end to which they all evidently concur.

*****

 
What is Concrete?
Concrete,[1] the most[2] extensively[3] utilized building material worldwide, has a long history and significant impact on the environment. It is integral to the construction of a wide array of structures, from the smallest residential buildings to the largest infrastructural projects. The use of concrete is so pervasive that it accounts for an astonishing 8% of the world’s CO2 emissions, primarily stemming from the manufacture of Portland cement, a key ingredient in concrete.
The origins of concrete can be traced back over 5,000 years to the ancient Egyptians, who ingeniously combined mud and straw to create crude bricks. They also utilized gypsum and lime to craft mortars, demonstrating an early form of concrete application. The Roman Empire also depended on the use of concrete. To this day, the Pantheon in Rome stands as a testament to the endurance and versatility of this material. Constructed with Roman cement, the Pantheon has withstood the test of time for over two millennia.
Annually, about 4.2 trillion kilograms of cement is manufactured globally, revealing the immense scale of concrete production. Cement, although constituting a mere 12% by volume on average in the concrete mix, is predominantly responsible for more than 8% of the resulting carbon dioxide emissions. This is because the production process of Portland cement involves the calcination of limestone, which inherently releases a significant amount of CO2.
Despite the environmental cost, concrete is fundamentally an environmentally friendly material due to its long lifespan, low maintenance needs, and high thermal mass, which can reduce energy use in buildings. it is the staggering volume at which we use concrete that exacerbates its environmental impact.
Concrete is typically composed of air (1-8%), water (13-20%), cement (10-15%), and aggregate (60-75%). Concrete aggregates are geological materials such as gravel, sand, and crushed rock. The size of the particles determines whether it is a coarse aggregate (e.g. gravel) or a fine aggregate (e.g. sand). At times, supplementary cementitious materials and admixtures are added to concrete to achieve specific properties. These ingredients make up the three main concrete product categories: ready mixed concrete, precast concrete products, and masonry units (concrete blocks).
Focusing on Canada, we find more than 1,100 ready mixed concrete, precast concrete, concrete pipe, and masonry plants scattered across the country. Over the next five years, Canada is projected to produce approximately 55 million tonnes of cement and a whopping 400 million tonnes of concrete. To put this in perspective, the amount of concrete produced could fill enough mixer trucks to circle the globe 4.5 times.
Concrete and Global Warming
Global warming is significantly affected by the production of concrete, specifically the process of creating Portland cement, a key ingredient. Portland cement is intrinsically linked with CO2 emissions due to the chemical reaction involved in creating clinker, an essential intermediate product. This reaction liberates CO2 and is an unavoidable aspect of current cement manufacturing technology. The scale of cement production makes this an important area for potential emissions reduction.
In the face of rising global CO2 levels, innovative solutions are being explored to decrease the contribution of cement production to climate change. To bring atmospheric CO2 levels back to a safer 280 parts per million, which human ecosystems were designed for.[4] Peter Fiekowsky, an engineer and climate restoration advocate, suggests we need to remove around 60 Gigatons of CO2 per year. One promising approach involves substituting current rock production with synthetic limestone, which could sequester approximately 25 Gigatons of CO2 annually. Furthermore, the use of this synthetic limestone in raising coastal cities above the increasing sea level could potentially sequester an additional 35 Gigatons per year.
We invited Brent Constantz, the CEO of Blue Planet, a company specializing in carbon-negative concrete, to speak with Canadian Pugwash members about this technology in a forum. He gave us a geological perspective on carbon mitigation. He states that the majority of the Earth’s carbon is found in the lithosphere, predominantly as limestone, with almost no purified CO2 in nature. As such, traditional carbon mitigation strategies that use purified CO2 are inherently flawed, as they require significant energy input and do not reflect the nature of carbon deposits on Earth.[5]
Constantz proposes a more natural approach[6] to carbon mitigation: converting dilute CO2 into carbonate, replicating the process that occurs in the world’s oceans. When CO2 from the atmosphere enters the ocean, it may end up in the calcium carbonate skeletons of marine organisms, eventually forming limestone deposits. This conversion process results in a stable, long-term sequestration of CO2. It’s worth noting that a tonne[7] of limestone holds approximately 440 kilograms of CO2 in a permanently sequestered state. Limestone is a main ingredient in concrete.
In light of these facts, we should pay attention to the impact of cement production on global industrial emissions. A significant portion of these emissions arises from the chemical reactions required to convert limestone into clinker and the fossil fuel combustion necessary to maintain the high temperatures (approximately 1,450 degrees Celsius) needed for this process. Similarly, Canada’s Greenhouse Gas Reporting Program stated that the cement manufacturing industry was responsible for about 11.2 megatonnes (Mt) of CO2 emissions in 2019, constituting about 1.5% of this country’s total emissions. Worldwide, 8% of total CO₂ emissions come from concrete.
The Concrete Industry is Trying to Lower its Carbon Emissions
The concrete industry is fully aware of the need to develop more sustainable products. Chris Cheeseman, a leading British academic in the field, focuses on the large amount of CO2 emitted during the creation of Portland cement. In response to this problem, Cheeseman’s team has developed Seratech, a new process that utilizes magnesium silicate minerals, abundant in the Earth’s crust, as a substitute for traditional materials. This method splits the magnesium silicate into magnesium and silica, with the silica acting as a supplementary cementitious material and the magnesium carbonate sequestered. This approach offers a promising avenue toward creating carbon-negative cement.
There are several notable advantages to Seratech’s technology. First, its composition is akin to fly ash, a by-product of coal combustion currently used in cement production.[8] Second, it can be seamlessly integrated into existing cement production infrastructures, reducing the barriers to implementation. Cheeseman aims to have a pilot plant for Seratech within the next year, pending funding.
However, new technologies often face a critical challenge: acceptance within an industry. The construction sector is generally conservative, typically hesitant to trust and adopt new materials. To gain acceptance, these new processes and materials need to match or surpass the performance, dependability, and consistency of traditional materials. Nowadays, industry-standard testing methods can provide the necessary validation, reassuring stakeholders of their quality and performance.
Among the alternatives to traditional Portland cement, Portland-Limestone Cement (PLC) is gaining attention. This cement type reduces carbon emissions by using less clinker and more limestone. Furthermore, waste fuels such as tires, wood waste, petrochemical waste, and carpets can replace powdered coal in cement kilns. Electrification in parts of the cement industry is being investigated, though so far not much progress has been made in that direction.
Despite the clear environmental benefits, barriers to adoption persist, rooted in prescriptive limits in old specifications, legal liability concerns, and lack of expertise in managing these changes. But if these obstacles can be overcome, PLC offers a promising avenue for reducing the carbon footprint of cement production by up to 15%. Also, significant strides have been made with other low-carbon cement types such as CEM 3B, used widely in the Netherlands, which has 65% blast furnace slag replacing cement.
Challenges also persist in developing countries, though there are opportunities for innovation here too. For instance, vast clay deposits can be used as a cementitious material for adobe-type buildings, offering a sustainable solution for construction needs.
Yet, despite the promising alternatives and technological advancements, the economics of carbon capture technology for concrete production remains challenging. Replacing traditional materials with carbon capture alternatives will greatly increase costs.
One potential solution is the more efficient use of concrete and reducing over-design. Engineers should use alternative materials where appropriate and concrete only where necessary. By making more deliberate decisions about material use in construction, it is possible to significantly reduce the environmental impact.
Considerations of concrete’s durability, especially in the face of climate change impacts, are equally important. Issues like freeze-thaw cycles and corrosion caused by salt can lead to deterioration over time, particularly when steel reinforcement is used in concrete.[9] Novel solutions such as the use of algae and biochar are being explored, but these methods still require considerable research and validation.
Blue Planet Concrete
Blue Planet Concrete is a California-based company that goes beyond “low-carbon concrete” produce concrete that is to actually carbon negative. Its technological innovation may revolutionize the concrete industry by significantly reducing climate change. Its website makes this astonishing claim in boldface letters: “If we replace just 16% of all aggregate used today with Blue Planet Aggregate, we could achieve the CO2 storage needed by 2050 to keep temperature rise below 1.5C.”
Blue Planet’s method of synthetic limestone production utilizes carbon dioxide (CO2) emissions from nearby flue gases,[10] mixed with demolished concrete and other materials. These are transformed into pellets that become the aggregate component of concrete, essentially creating a building material that not only utilizes waste but also captures carbon and locks it up in permanent structures.
The cornerstone of Blue Planet’s unique approach is calcium. Calcium, a crucial component in their manufacturing process, can be sourced from various places such as the ocean, fly ash from coal plants, steel slag, and saline water from oil wells. So far, the company has been using “low-hanging fruit” – demolished concrete – as the source of its calcium. This capitalizes on waste products while reducing the dependence on quarried materials.
With its ground-breaking technology, Blue Planet has been able to sell its high-quality concrete at a competitive price in San Francisco, where concrete is generally more expensive due to the lack of nearby quarries. Their concrete may not be competitive everywhere at present, for the cost of production depends greatly on the distance of transporting the heavy ingredients, whether stone or demolished concrete.
The impact of Blue Planet’s work extends beyond just the production of carbon-negative concrete. The company is currently planning with Lafarge, a global leader in building materials, to establish concrete plants using their technology in Canada. The company has contracts with Mitsubishi, Chevron, Sulzer, Holcim, and other global companies – partnerships that attest to the practicality and scalability of Blue Planet’s approach.
Blue Planet is proving its remarkable claims of CO2 sequestration by meticulously monitoring its environmental impact. As affirmed by the company’s founder, Brent Constantz, lifecycle carbon analyses are conducted regularly on their process.
The carbon footprint of Blue Planet’s concrete, as per the CarbonStar rating system funded by the Canadian government and implemented by the Canadian Standards Association, is an astonishing negative 700 pounds per yard. [11]This essentially means that the concrete not only neutralizes its own CO2 emissions but also captures additional CO2 from the environment. A normal yard of concrete has a carbon footprint of 600 pounds, mostly because it has 600 pounds of cement in it. But some construction projects are demanding low carbon concrete now; for example, Blue Planet concrete was used at the San Francisco airport, which required a CarbonStar rating of negative 200 pounds of any company even bidding for a contract. Constantz explained that Blue Planet puts about 1300 pounds of CO2 into each yard of concrete,[12] which erases the 600 pounds emitted from the cement production, so they have negative 700 pounds per yard in the concrete.[13]
Constantz added that Blue Planet’s carbon-negative concrete is the cheapest way to attain a carbon-neutral building, and the cheapest way to sequester carbon. That does not mean that it is really cheap or usually even competitive yet. The price goal for capturing CO2 for sequestration is about $75 a tonne but nobody is even close to that yet. Microsoft is committed to using the lowest-carbon concrete in constructing their campus and they are paying over $1,000 a tonne on the voluntary market for CO2 sequestration.
Some critics continue to dispute the company’s claim of being carbon negative. They argue that the label implies direct capture of CO2 from the air, which is not entirely accurate, since Blue Planet pipes in concentrated emissions from flues. In response, Constantz clarified that while the CO2 utilized is primarily from natural gas-fired power plants,[14] Blue Planet does have patents for running air directly through their absorber, removing about half of the CO2 in approximately half a second. It has been demonstrated on gas streams containing as little as 5% CO2. 
With their first factory already operational in the San Francisco area and plans for more plants underway globally, Blue Planet projects to capture around 200,000 tons of CO2 within a year. However, the company acknowledges the challenges, especially in obtaining permits, raising capital, improving the technology, and training personnel.
Blue Planet’s plans require a care in choosing the location of its factories, mainly because the cost of transporting heavy rocks and waste concrete is so crucial. The company prefers to establish plants near ports to minimize the carbon emissions and expense of transportation. Shipping materials by water is less carbon-intensive and cheaper than by land. Plants need to be located close to the sources of their calcium material and, if possible, close to the source of their CO2. Their first plant, in Los Gatos California, is next door to a power plant, the source of their CO2.
Notably, Constantz argues against the common paradigm that businesses must rely on government subsidies to innovate and address climate change. He asserts that the issue is too large for governments alone to handle and encourages private companies to drive the necessary innovation.
Although the Canadian Pugwash panelists on the forum were convinced by Constantz’s assertion that Blue Planet’s concrete is actually carbon negative, they expressed skepticism about some of his assertions after he and Peter Fiekowsky had left the panel. They generally doubted the claim that replacing just 16% of all aggregate used in the world with Blue Planet aggregate would provide sufficient CO2 storage by 2050 to keep global temperature rise below 1.5C. To answer their questions, I wrote to Fiekowsky, who replied by email with these calculations:
“Metta, regarding the claim that if 16% of aggregate were synthetic limestone (which is equivalent to 4 Gt CO2 per year, or about 105 Gt CO2 by 2050) then we could keep global warming to under 1.5 Celsius, here are the numbers for you: Total aggregate consumption now is about 55 Gt/year;[15] 16% of that comes to 8.8 Gt limestone. 44% of limestone’s weight is CO2; thus just under 4 Gt CO2/year would be reduced/removed. Multiply that by 27 years and you get 105 Gt CO2 removed. 105 Gt CO2 removed is proportional to 13 ppm CO2 in the atmosphere (there are roughly 8 Gt CO2 per ppm in the atmosphere. That would reduce the peak CO2 level in 2050 from 460 ppm to 447 ppm. Is that enough reduction to keep warming below 1.5C?[16] That depends on how quickly we reduce emissions and how quickly we increase carbon dioxide removal,[17] especially by using ocean iron fertilization. In any case, 105 Gt CO2 is a lot – three years of emissions and 10% of the total excess CO2 in the air.”
These calculations indicate that no one should count on Blue Planet to save the world’s climate crisis singlehandedly. Other changes are certainly required. However, the panelists have been convinced that carbon negative concrete really can be created, and that it is already in use in some places and should be used more widely around the world in the future. It seems reasonable to suggest that Canada mandate its use, whenever feasible, in all construction projects that the government funds, for this will stimulate its adoption globally.[18]
The Concrete Business
The concrete industry, as we have seen, is a major contributor to global carbon emissions. This reality necessitates innovative and transformative changes within the sector, aiming to both sustain growth and mitigate environmental impacts. And, as we have seen, some major companies are partnering with pioneers like Blue Planet and pursuing other innovations as well.
Robert Cumming, Head of Sustainability, Environment, and Public Affairs of Lafarge Canada, spoke on a forum with Adele Buckley, a physicist, engineer, and leading member of Pugwash. Cumming was invited specifically because of the relationship between his company and Blue Planet. Their partnership aims to integrate Blue Planet’s technology into Lafarge Canada’s concrete production process, offering a promising technology of permanent carbon sequestration.
However, the path to carbon-negative concrete is laden with challenges.[19] One significant issue is the geographical variation in the availability and suitability of old concrete for reuse. While waste concrete can be readily sourced in Western societies where concrete structures are common, emerging markets in Asia, Africa, and other regions exhibit a significant growth in concrete use but lack ample sources of waste concrete.
Cumming[20] emphasizes the need for a multifaceted approach to decarbonization, which extends beyond just the production process. One such facet involves replacing fossil fuels, currently used in the cement production process, with lower carbon alternatives. Canada is making progress in this regard, with around 20% of fuels already being low carbon and a goal of increasing this figure to over 70% by 2030.
While the aim of the concrete industry in Canada is indeed commendable, progress in the development and implementation of electric power in the production process is still lagging. Transitioning from carbon-intensive fuels to renewable sources of energy presents a formidable challenge, requiring not only technological advancements but also regulatory and market adaptations.
Despite these challenges, Cumming is optimistic about Blue Planet’s potential in creating carbon-negative concrete. Yet, he cautions against over-reliance on any single solution. Rather than viewing Blue Planet’s technology as a panacea, he advocates for a diversified approach incorporating multiple strategies and collaborations.
Governments and the Promotion of Carbon Negative Concrete
Addressing climate change requires concerted efforts across different sectors in which government plays a key role. Government infrastructure projects consume about 40% of global cement production. Hence, governmental policies requiring lower carbon materials and adopting performance-based project requirements can significantly incentivize innovation and lead to lower GHG emissions. The Government of Canada’s Greening Government Strategy exemplifies this approach, requiring a 30% reduction in embodied carbon from 2025.[21]
Almost all governments have made commitments to combat climate change, as signified by the Paris Accord, but the journey towards decarbonization is a delicate balancing act between concern for the economy and the dangers of a heating planet. Therefore, governments must manage both compatibly.
Countries like Canada, France, and Israel are examples of governments that support environmental innovations. Canada, with its vast oil sands, can be a location for even bolder innovative projects. And indeed, despite bureaucratic challenges, the Canadian government has developed mandates for concrete producers to start producing low carbon concrete and have committed to purchase low carbon concrete.
One promising strategy is the exploration of alternative materials for concrete production. Fly ash, a byproduct of coal-fired power plants, can substitute for cement in concrete.[22] Recent changes to Canadian standards have allowed the mining of fly ash backfills from landfills, potentially providing a supply for the next half-century to century. However, this process requires additional processing, so it is not a perfect solution, though a significant opportunity.
A shift from prescriptive-based to performance-based design codes is essential to incentivize efficiency and sustainability. Current codes allow for excessive amounts of cement, which is inexpensive, thus resulting in overuse. By focusing on performance goals such as durability and strength, instead of regulating the content of concrete prescriptively, governments can move the concrete industry more rapidly toward efficient and sustainable materials.[23]
Collaborative efforts between industry and government have been instrumental in creating plans such as the Roadmap to Net-Zero Carbon Concrete by 2050 and Greening Government Strategy. Likewise, the Federal Government of Canada’s embodied carbon policy requires all federal construction projects to quantify the concrete’s carbon footprint and demonstrate a reduction of 10% from typical concrete mixes.[24] This policy, due to be implemented from 2023, encourages the construction industry to consider low carbon materials as a standard part of construction.
On the other hand, regulation – the tool most often used by governments to mandate standards – is not the most effective way of encouraging rapid change. [25]
Recommendations
We can see that there is a strong commitment within the concrete industry to improve the regrettable levels of emissions that result from their work. The government of Canada has also taken a good step in the right direction by planning to regulate the amount of carbon emitted every year, tightening the standards.  
Regulation is essential, if only to maintain basic standards of quality and safety. However, regulations only set the lower limits, the minimum criteria that even the worst products should meet. To incentivize advances beyond the minimum level, something additional is required – competition for government contracts.[26] A performance-based criterion mandating the selection of the concrete with the lowest available embodied carbon could drive the industry towards more sustainable practices faster than the just the prescription of increasingly rigorous basic reductions of carbon. This can be done by adding a simple standard to the criteria for government-funded infrastructure: that it must choose the concrete with the lowest carbon emissions available that meet the other basic standards of quality.
Indeed,[27] although we were told that the Canadian government may itself eventually adopt that performance-based criterion, it is worth pressing for that change sooner rather than “eventually.” Probably the most useful contribution that the Canadian Pugwash Group can make in promoting the use of carbon negative concrete such as Blue Planet is to urge the government to quickly adopt performance-based criteria that require concrete companies to compete[28] in reducing the embodied carbon in their products.
I expect that all Pugwashites who participated in these discussions may concur with this recommendation to Canada’s ministry of environment. This is an area where good ideas may actually be accepted.
Canadian Pugwash Group should urge the government to quickly add competitive, performance-based criteria for the purchase of all projects that it funds: the rule that the concrete be selected with the lowest embodied carbon of all the available products that meet its other basic standards of quality.[29]

[1] John Orr writes: The Report looks fine to me.
[2] Ellen Judd writes: Thanks for this report. I am fine with it, but not expert enough on this topic to add to it. Very best wishes!
[3] Michel Duguay wrote a hearty endorsement of the report.
[4] Robin Collins notes: A better phrase would be “are better adapted for.”
[5] Robin Collins writes: “Inherently flawed”. I think if you are going to make this claim, it needs to be backed up. It isn’t self-evident that conversion to limestone is the only or most effective approach. This seems to be the argument someone would make whose business is turning CO2 into limestone.
[6] Robin Collins writes: This may be a natural approach, but it doesn’t have greater credibility given human intervention will not be a natural approach.
[7] Robin Collins notes: 1000 kg.
[8] Robin Collins writes: Does it require continuation of coal production and use? What happens if coal needs to be phased out?                                                                                                                                                                                 Metta Spencer replies: There just won’t be any available fly-ash.
[9] Robin Collins writes: This needs checking or clarification given rebar is also seen as making concrete more robust against freeze-thaw cycles. So which is it?                                                                                                                             Metta Spencer replies: Rebar is typically beneficial in concrete installations, but I believe the speakers agreed that there can be damage water penetration and potential rebar exposure from water penetration and potential rebar exposures because of the freeze-thaw cycles.
[10] Robin Collins writes: This will certainly raise eyebrows. Is this product reliant on continuation of gas power plants or does it make gas plants carbon neutral? The latter seems unlikely.                                                                               Metta Spencer replies: This concrete depends on adding CO2, but there are many sources of CO2 besides power plants. It doesn’t even have to be concentrated for this purpose; they can use CO2 from plain air, but it is obviously more efficient to use what comes out of a smokestack, as long as some CO2 is still coming out. Later on, they will have to get It from other sources.
[11] Robin Collins writes: To be consistent, these number here and below should be in metric.
[12] Robin Collins writes: What is involved in “putting” CO2 into concrete? Does the cement actually gain weight by absorbing CO2?                                                                                                                                                                             Metta Spencer replies: There’s a pipe carrying the CO2 from a nearby smokestack to be mixed with mashed-up demolished concrete and some other ingredients to make a slurry that is formed into pellets that are to be used as the aggregate in the next batch of concrete.
[13] Robin Colllins writes: This accounting needs to be better explained. What is negative 700 lbs?                             Metta Spencer replies: CO2 is captured and locked up in the limestone pellets, so it never gets into the air. That is a “negative emission.”
[14] Robin Collins writes: Again, it needs to be known if the product requires gas power plants to continue; and what is the net impact of continuance of this power source plus new concrete? This is not to argue that continued gas power is a bad idea but the full cycle of the combined industrial CO2 outcomes needs tallyng.
[15] Robin Collins writes: Predictions are based on current levels.
[16] Robin Collins writes: It certainly does not on its own get us down to target 280 ppm levels, so it is absurd to claim this alone would “keep global warming to under 1.5 Celsius.”
[17] Robin Collins writes: Obviously, but he was claiming concrete alone would do it.
[18] Robin Collins writes: I agree, but with the caveats noted in all of the above.
[19] Robin Collins writes: This issue should not be glossed over; and won’t reusable concrete eventually dry up? Metta Spencer replies: Yes. Especially in places like Africa where concrete has not been used so much in the past. The demolished concrete here is “low hanging fruit” that can be used now. When it is all gone, there are many other sources of calcium that presumably may cost more to use.
[20] Robin Collins writes: All of the next three paragraphs are true enough but are about projects other than concrete, so do they belong here?
[21] Robin Collins writes: Compare to numbers below.
[22] Robin Collins writes: Again, is this a call for continued coal plants?                                                                              Metta Spencer replies: I certainly don’t think so. No speaker suggested that. Sometimes they mentioned that fly ash is in limited supply now.
[23] Robin Collins writes: This seems to be an ideologically based argument: “Free industry from government regulation and we will bring the goods!” I think it best to avoid this prescription for CPG. There will need to be goals and regulations. Industry shouldn’t be allowed off the hook. Metta Spencer replies: This was my own suggestion, not that of any representatives of the concrete industry. They generally mentioned that the government regulations were quite minimal and that engineers designing the structures were wasteful and overly cautious. Several experts suggested that more rigorous demands were needed. There is nothing wrong with government regulations but much would be gained by simply adding a requirement that all government-funded projects must use the concrete with the lowest emissions of CO2 available that meets quality standards. 
[24] Robin Collins writes: Compare to $ above. Is it consistent?
[25] Robin Collins writes: Again, says who? CPG doesn’t have to advocate for deregulation. This seems to be a corporate argument.                                                                                                                                                                                 Metta Spencer replies: My point is only that the regulations are often too weak. Additional incentives would help.
[26] Robin Collins writes: This argument has not been proven. I’d avoid it and leave it out.                                        Metta Spencer replies: Then Pugwash has nothing to suggest beyond what the government is already doing. There would be no point in holding this inquiry or writing a report to the government. In fact, however, the government is the most powerful influencer of carbon emissions from concrete. Our objective is to recommend changes that will augment government demand for carbon negative concrete, which the regulations are not now doing. Adding one simple rule would have that effect.
[27] Robin Collins writes: This is repetitive.
[28] Robin Collins writes: Performance-based would be required whether regulation i.e. with baselines, or deregulation.
[29] In this conclusion I have rephrased statements that were in the original draft of this report. As Collins’s preceding comments rightly noted, the previous phraseology misleadingly implied that we propose “deregulation,” which was not the case. This recommendation simply adds a needed criterion that will incentivize rapidity of progress. Fortunately, our guest experts representing the industry were comfortable with this proposal.

Replace Your Lawn!

Soon I’ll blow out the candle on my 90^th birthday, making this wish: that millions of people will replace their lawns with vegetation that benefits our ecosystem instead of harming it.

Lawns are mainly a status symbol. The great old estates of England have vast expanses of lawn because the owners don’t have to raise crops on their land and can pay servants to keep them mowed. In the prosperous days after World War II, tracts of houses were created as suburbs in other countries. People enacted ordinances requiring their neighbors to maintain tidy lawns as a sign of middle-class decency. The United States leads the world in “lawnsmanship,” with Australia and Canada as close competitors.

Lawns have horrible effects on the environment, so let’s replace them with beneficial vegetation: native trees, vegetables, native perennials – even the kind of grass that used to feed herds of bison. Their long roots reach several meters down into the soil, drawing down carbon to sequester it there. And you don’t mow anything.

Every year American lawns consume nearly three trillion gallons of water, 200 million gallons of gas for mowing, and 70 million pounds of pesticides. If half of the lawns were converted to native plants, this area would exceed all the national parks in the lower 48 states. These status symbols lawns are the largest irrigated crop in the country, covering more than 40 million acres. They are depleting our water aquifers, emitting greenhouse gas, and killing insects and birds.

We require insects to pollinate our food crops, and birds require insects for food, but lawns do not support insects. More than one million plant and animal species are at risk of extinction in the US alone (I cannot find figures for other countries). Insects have a rate of extinction eight times faster than mammals. Our ecosystem could collapse unless our plants feed insects..

But do not just dig up your lawn. Every spade of earth that is turned over or ploughed emits carbon back into the air. Instead, replace the lawn without turning over the soil. Dig holes only large enough to plant perennial native plants – vegetables, shrubs, flowers, and trees.  I will be producing a talk show soon about urban forestry: how to select trees and plant them in ways that avoid damage to sidewalks and the foundations of buildings.

Within the next decade most of us will no longer own cars; we’ll call for an electric taxi whenever we need transportation, and this will save us thousands of dollars per year. It also means that we won’t need parking spaces or even parking lots. Let’s plan ahead and arrange to convert these parking lots to urban forests. The world needs an extra one trillion trees to help slow global warming, and we can plant most of them in the lawns and empty old parking spots of cities. I favor a system called “Miyawaki” forests for small urban plots of land. These are very dense forests of native trees. Fortunately, we live close enough to these spaces to join our neighbors in watering them for the first three years until they become self-sufficient and mature. Watch this video of a talk show I did about Miyawaki forests. https://tosavetheworld.ca/53-afforestation-and-our-climate/
Good luck with your new forest!
Metta Spencer

Climate Change, Trees and Cows

By Metta Spencer, Peace Magazine, January 2020

The two most feasible ways to limit global warming are planting a trillion more trees and sequestering carbon in the soil. Yet both could do more harm than good. Shall we plant trees in the Arctic and boreal forest? Shall we go vegan or double the livestock herds? Answer: It depends.

Though we should eagerly seize upon most new means of limiting global warming, there are two seemingly brilliant ideas that deserve closer scrutiny: Should we plant a trillion trees? And should we all become vegans? Unless qualified, both of these ideas may bring unanticipated and unwanted consequences. The current state of evidence is too ambiguous to justify any firm conclusions, but we have to make crucial decisions anyway.

Two things are clear: First, we should keep buried carbon buried. Second, we should suck ambient carbon out of the atmosphere and bury it. What remains uncertain is how best to fulfill these goals.Sometimes trees also can do Earth’s temperature more harm than good. That’s why we need to look so carefully at the unsettling evidence, which is the purpose of this paper.

People have little control over the planet’s carbon, for nature is mostly in charge. All living cells contain carbon. It’s everywhere: in rocks, in plants, in the soil, in petroleum, in the air, in crystals at the bottom of the ocean, and in 30,000-year-old muskox carcasses and frozen grass roots in Siberia’s permafrost. Nature moves carbon around continually, smashing ocean waves against rocks to form soil, then blowing it away as dust or feeding it to trees or flooding it into your basement. For eons, nature has balanced the carbon cycle by locking carbon in storage “sinks” that offset other ongoing emissions. But over the most recent dozen decades humans have botched nature’s routine. We’ve pulled petroleum, coal, and methane out of the earth for fuel and cut down forests for farmland. We’ve degraded and desertified areas of land larger than Newfoundland each year, turning fertile earth into barren dust. Land use (including agriculture and forestry) produces about 24 percent of global greenhouse gas emissions, largely through misuse, for if the land were managed well, it would be a sink instead of a source of emissions. Unless we repair the damage quickly, we shall suffer catastrophic consequences.

The repairs must begin by halting our continuing blunders, so the first task is to stop emitting carbon. That’s easier said than done, but by now it’s insufficient anyway. We also have to undo previous mistakes by recapturing some of the carbon that’s already in the air. Global warming will almost inevitably exceed the two-degree target adopted in the Paris Agreement of 2016, but by promptly using effective “negative emissions technologies” (NETs), scientists believe it possible to reduce it afterward to under 1.5 degrees.

Though several NETs are being developed, only two of them are realistic options for the urgent eleven-year target that scientists have set: First, let’s plant a trillion trees and, second, let’s adopt farming methods that recapture more carbon from the atmosphere than we are emitting. These changes will reverse the ongoing deforestation and desertification trends and may enable the expected human population of about 11 billion¹ to be fed adequately in 2100. The Intergovernmental Panel on Climate Change (IPCC) has called for an increase of one billion hectares of forest to limit global warming to 1.5 degrees. [2] At least 20 countries have begun major efforts to reverse farmland and forest losses, and the effort is only getting underway. It can be accomplished for only about $300 billion—equivalent to the world’s military spending every sixty days.³ But we must hurry!

Our tool is photosynthesis: the mysterious biochemical trick every plant uses for capturing carbon dioxide and making it into sugar for its own functions. Even when a plant dies or is harvested, its roots may leave some carbon in the soil, enriching the fertility for future crops. Moreover, wooden houses and furniture can store carbon for centuries, so, as we shall see, both forests and farmland can be vast carbon “sinks”—or not. Today, farming is a major net source of carbon, emitting more to the atmosphere than it sequesters.

Forests and Climate

A scientific lab in Zurich led by Thomas Crowther has done the most extensive inventory of the world’s forests, estimating that there are now approximately three trillion trees on the planet. Is there room for another one trillion? After examining photos of some 80,000 plots of land around the world, the lab published a report by Jean-François Bastin et al. that gained worldwide attention.⁴ It noted that, whereas about 8.7 billion hectares (two-thirds of all the soil on the planet) could support forests, only 5.5 billion of that land is actually forested. Of the remaining 3.2 billion hectares, most is either cropland or urban areas. That leaves about 0.9 billion hectares as potentially available for restoration of forests. The researchers conclude that “the global forest restoration target proposed by the IPCC of 1 billion hectares (defined as >10% tree cover) is undoubtedly achievable under the current climate.” Those trees could theoretically store an additional 205 gigatonnes of carbon. Since there is an excess of about 300 gigatons of anthropogenic carbon in the atmosphere now, they infer that such enlarged forests could clean up about two-thirds of the mess we humans have made so far. In theory, then, trees can save us.

But the authors emphasize that we must act quickly, for global warming is reducing the amount of suitable land. At the current rate of warming, about 450 million hectares of tropical rainforests will be lost by 2050. This subtracts 46 gigatonnes from the 205 gigatonnes reductions now possible. Nevertheless, the researchers assure us that there is ample available land for the new forests—especially in six countries. More than 50 percent of the tree restoration potential can be found in diminishing order in Russia, United States, Canada, Australia, Brazil, and China.⁵

Most readers worldwide rejoiced upon learning of these findings, but not everyone. Adam Rogers, among others, soon published a withering criticism in the same journal.⁶ He claims that the Zurich research team had greatly over-estimated the total amount of carbon uptake by trees. Correcting such errors would largely negate their upbeat findings.

The report shocked some of us in a different way—by suggesting that many of the anticipated new billion hectares of forest will be in the Arctic. Hadn’t those researchers heard the bad news about forests and permafrost? We wrote to the lead author, Jean-François Bastin, to express our alarm, but he denied that their paper had recommended planting trees anywhere. They had only predicted that trees can, and unless people interfere, probably will proliferate in the tundra of Russia, Canada, and Alaska.

And that is true. Forests can grow in the Arctic and indeed are encroaching into the sparse grasslands of that region.⁷ However, even if quite large canopies grow there, the forests will sequester far less carbon per hectare than those in the tropics. A tree in a boreal forest (or “taiga,” as it is called in Russia) grows too slowly to sequester much carbon. Worse yet, forests in the Arctic may even be increasing global warming.⁸ This detrimental effect, which was discovered by climate scientists, initially surprised many foresters, who had assumed that photosynthesis everywhere has the same benign cooling effect on the planet. The trees in the Arctic do sequester some carbon but they also have another, less desirable, effect. Whereas the snow-covered grass reflects sunlight (the “albedo effect”), the trees make the landscape darker and therefore warmer. Second, it seems that some tree roots also stimulate the decomposition of organic material in the soil, so that long-frozen microbes revive and begin producing methane, which is twenty times more powerful as a greenhouse gas than carbon dioxide.⁹

Iain Hartley has compared carbon stocks of vegetation and soils between tundra and a birch forest. There was far less carbon in the forest than in the tundra nearby.¹⁰ Thus, despite sequestering some carbon, trees in a carbon-rich permafrost may have an overall warming effect on the climate. This possibility is so crucial for the climate crisis that much more research is urgently needed to clarify where trees are beneficial and where they are harmful—and more specifically, which trees, in which types of soil. For example, black spruce forests in some regions may actually protect the permafrost and help keep the earth cold, in contrast to birch forests.¹¹

There is a huge amount of carbon involved: the northern hemisphere contains an estimated 1,672 billion tons of organic carbon. If just ten percent of it thaws, one estimate projects that it will release enough carbon to raise global temperature by 0.07 degrees Celsius by 2100.¹² Another recent study estimates that already more carbon is lost from the permafrost regions during the winter than is taken up during the average growing season.¹³

There’s a major policy implication here: Although overall the Arctic is presumably still a carbon sink (sequestering more carbon than it emits), it will become a net source of greenhouse gas if forests continue encroaching there. That means it would be wholly inadvisable to plant billions of trees in carbon-rich permafrost soil—the type that is most widespread in the Arctic, especially Siberia.

The Zimovs

An even more impassioned warning against Arctic trees comes from two Siberian ecologists, the father and son Sergey and Nikita Zimov. They have spent most of their lives studying the changing climate in Russia’s eastern Arctic. Contrary to the widespread assumption that the Arctic had always been a desert of ice and thin soils, they say that in the Pleistocene era it was a fertile grassland, rich with huge wild animals, such as bison and woolly mammoths, despite the 5 to 10 degree colder average temperature than today. They find vast numbers of ancient bones in the melting permafrost near the river Kolyma. These animals knocked down any saplings and prevented the warming of soil. By trampling the snow in winter, they also kept the soil cold.

“At the time,” writes Sergey Zimov, “the biomass of big herbivores on the planet reached 1.6 billion tons…. Bison and deer killed trees by eating the bark. Elephants and mammoths simply broke trees. Through fertilizing, harvesting, and trampling, herbivores managed their pastures in any climate.”¹⁴ The region still would be entirely grassland, they say, if stone age hunters had not killed off the huge animals —especially woolly mammoths—that had roamed the tundra in herds.

The Zimovs conduct their research in a large reserve called “Pleistocene Park,” which attracts scientist visitors from all over the world. They keep its land colder than the surrounding region by importing large animals and driving a vehicle around, knocking down every tree possible. According to their records, when air temperature sank to –40°C in winter, the temperature of the ground was found to be only –5°C under an intact cover of snow, but –30°C where the animals had trampled down the snow.¹⁵ The Zimovs are eagerly awaiting the progress of George Church, a Harvard geneticist who is trying to breed a larger elephant that can thrive in cold, to repopulate the Arctic with a close approximation of the woolly mammoth.

We cannot wait for that strange solution but there is now a sufficient basis for prohibiting the planting of forests in permafrost regions. However, if trees must not be planted in the Arctic, that will reduce the 0.9 billion hectares that Crowther’s team had defined as potentially available. Worse yet, permafrost is not limited to the Arctic, so it may be necessary to avoid reforesting in other places too. Professor Google explains that “Permafrost is widespread in the northern part of the Northern Hemisphere, where it occurs in 85 percent of Alaska, 55 percent of Russia and Canada, and probably all of Antarctica.” But the northern parts of Alaska, Russia, and Canada are the main places where Crowther et al suggest new forests could be established. To limit global warming, must we also reduce the size of our boreal forest and taiga? Surely almost no one would take seriously such a shocking proposal.

But the expansion proposal also looks difficult. A trillion is a lot of trees— a thousand billions. The current human population in 2019 is 7.7 billion. A trillion trees equal 130 trees per person. When prime ministers of countries are in a good mood, they offer to plant two billion trees, as Justin Trudeau has recently done, but even if every country in the United Nations planted two billion, we would reach only about one-third of our goal. And one trillion is not enough. The realism of any particular target number will depend on the effectiveness of the planting program. China is carrying out the most ambitious planting program of all (their target is 100 billion trees by 2050) but some Beijing researchers report that “on-the-ground surveys have shown that, over time, as many as 85 percent of the plantings fail.”¹⁶ So shall we aim for two trillion, say, or even three?

And if not in most of Russia, the United States, and Canada, where can even one more trillion trees be planted? The Crowther lab’s paper has explicitly excluded land now being used for crops as well as urban land. Most of the remainder therefore can only be in remote areas, beyond cities and farms, mainly far from roads.

Logically, it seems we must (a) choose very promising species, (b) plant them in the most suitable plots of soil © densely enough to maximize the number of trees per hectare, (d) in places where people can reach them easily and care for them regularly, and (e) protect them from fires and deforestation until they are mature and ready to be replaced. And, even so, we cannot rely entirely on new forests to save us, but must adopt other NETs as well—notably regenerative farming.

Regenerative Agriculture

Big trees generally sequester more carbon than other plants, but even vegetables, flowers, grass, and grain put a lot of it into the soil. Although human beings are releasing 9.4 billion metric tons of carbon, the actual concentration of CO₂ that stays in the atmosphere is only about half that. The rest is already being sequestered by oceans and land. Our challenge is to develop methods that sequester much more—even the 320 billion tons excess that we have put into the air and now must remove. Plants make that possible and there is evidence that increasing soil carbon content also increases the amount and quality of food grown there.

In 2015 France launched an exemplary campaign called “4 per 1000” at the COP 21 meeting. This is a plan to increase global soil organic matter stocks by 4 per 1000 (or 0.4%) per year, which would offset 20–35% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration would buy time over the next ten to twenty years while other effective technologies become viable.¹⁷

These agricultural innovations have come from a variety of different traditions such as organic farming, which are merging now and being called “regenerative agriculture”—farming that goes beyond being “sustainable” by actually reversing carbon loss on degraded land. This regeneration is necessary because poor land management is continuously degrading soil all around the world and, if not reversed, will make it impossible to feed the growing human population.

Techniques that increase carbon storage also tend to increase water retention and support the bacteria, fungi, and other organisms in healthy soil that live on carbohydrates produced by decaying roots and other plant materials.

There are promising genetic discoveries now that may soon improve the quality of several plant foods, such as soybeans. By selective breeding (not modifying genes) it is possible to create “super-plants” with deep roots that greatly increase the amount of carbon they sequester. A biochemical called suberin determines the length of roots, and scientists are developing suberin-rich varieties that may become available to farmers within a decade or so.¹⁹

But there are already other practical regenerative methods that about ten percent of North American farmers now are using. And around the world, such innovations are spreading as the extensive use of composts and mulching to avoid chemical fertilizers and pesticides. Leading farmers now keep their land covered year-round with cover crops. They avoid plowing the soil, so as to protect the roots of the plants for transferring carbon downward. And instead of planting crops in furrows, they insert seeds into soil that still is covered with the residue of last season’s crop. They replace annual crops with perennials.

To aerate the surface layer of soil without turning over the earth, some farmers use “key-line” methods, such as slicing narrow grooves into the soil, into which they may pour “compost tea” brewed from special bacteria and fungi, which they serve to the growing plants with minimal damage to the roots.

Such biological additives can multiply the crop yield and the soil sequestration many times over.²⁰ Or they apply biochar— charcoal that is pure carbon, and which can stay in the soil for thousands of years, enriching it and retaining moisture. “Keyline” farming was invented by Australians during droughts; they created ponds and swales to move the water around the contours of hills and allow it to sink in deeper, instead of eroding the topsoil. Indeed, within a few years, these practices together can create 12 inches of new topsoil.²¹

By now, regenerative practices are well-established and uncontroversial, with one exception: “holistic management,” which involves the use of livestock to regenerate degraded soil. Livestock means meat, and meat is a fighting word nowadays, with almost all environmentalists opposing it.

Livestock and Meat

First let me summarize the overwhelming case against meat. Around the world, lush grasslands and gardens are becoming barren wastelands, and for this, livestock is largely blamed. One-third of the planet’s arable land is used to produce crops for livestock,²² which includes about a billion cows and bulls. Nearly one-fifth of the world’s land is threatened with desertification, which is partly attributed to overgrazing by animals. Farmers are urged to remove their cattle from the land and let it rest until the vegetation recovers. Then the world’s grasslands could sequester carbon equivalent to 0.6 gigatonnes of CO₂ per year.²³

Moreover, meat production is clearly a source of global warming. Global livestock supply chains are the source of 14.5 percent of all anthropogenic greenhouse gas emissions—5 percent of the carbon dioxide, 44 percent of the methane, and 53 percent of the nitrous oxide emissions. Although less prevalent than carbon dioxide, methane is more potent because it traps 28 times more heat.²⁴ Nitrous oxide is 264 times more powerful than carbon dioxide over 20 years, and its lifetime in the atmosphere exceeds a century, according to the IPCC.

Farmers feed grain to cows, pigs, and other animals before slaughtering or milking them for human consumption. If we ate that grain our selves, we would supposedly be healthier and there would be enough food for the entire human population. Vegetarians say they get along fine without meat and vegans manage without animal protein at all.

Ruminants such as cows are the worst culprits, for they directly add greenhouse gas to the air from both their front and rear ends. In the cow’s extra stomach—the one that enables it to digest the cellulose in grass and leaves —bacteria ferment its lunch and generate the methane. The nitrous oxide is released by decomposing manure.

These arguments for veganism are powerful and valid. The only logical advice seems to be this: Eat plants, not meat! Nevertheless, there are other facts (or at least claims) that may justify this contradictory response: Eat meat if you want to, and raise more livestock!

Let’s run through the health issue first, since in principle that could be settled by empirical research. In reality, though, such studies produce weak evidence. There are two reasons: First, people fib when reporting what they eat and, second, other factors confound the results. For example, vegetarians are so health conscious that they disproportionately exercise, avoid smoking, get plenty of sleep, etc, and these may be the real causes of any health differences.

One major review compared 54 different studies and concluded that, if there is any difference whatever between the mortality rates of vegetarians and omnivores, it amounts to less than one percent over a twenty-year period—too trivial to warrant any dietary changes.²⁵ One study found that vegetarians and vegans suffer slightly fewer heart attacks but slightly more strokes than omnivores.

India is a good place to make these comparisons because most families there are consistently and permanently either vegetarians or not. Dr. Prabhat Jha is studying the health habits of a million households in India where someone had recently died. He finds no differences in mortality between male vegetarians and non-vegetarians, but vegetarian women have slightly shorter lives. He thinks this sex differential will be found only in India, for women there customarily serve the men and children first and eat only the (mainly carbohydrate) leftovers themselves.²⁶ Vegetarian women in India probably consume too little protein.

In any case, health concerns are not a strong reason for choosing whether to raise livestock and eat meat. The consumer’s decision should probably be based mainly on the effects of livestock on global warming and on the importance of livestock for the livelihood on the world’s population.

As for the effect of cattle on sequestration of carbon in the soil, some, but not all, studies have shown that their grazing is beneficial. As one review of the research reports,

“Reeder and Schuman reported higher soil carbon levels in grazed—compared with ungrazed—pastures, and noted that when animals were excluded, carbon tended to be immobilized as above-ground litter and annuals that lacked deep roots. After reviewing 34 studies of grazed and ungrazed sites (livestock exclusion) around the world, Milchunas and Lauenroth reported soil carbon was both increased (60 percent of cases) and decreased (40 percent of cases).”²⁷

The loss of carbon can be attributed to two forms of mismanagement: over-grazing and under-grazing, both of which will degrade the soil, harming not only the world’s climate but also the survival prospects of the world’s poorest people. Over one billion people depend on livestock—including 70 percent of those living on less than US$1 per day.²⁸ It is unreasonable to espouse a doctrine that would deprive these people of the main or only source of their livelihood. Pastoralism is not about to end. The point is to make it more productive.

Holistic Management

We have already considered the plight of the Zimovs as they struggle to keep the permafrost from melting around them. One is inclined to smile at their solution: Bring vast herds of giant herbivores—preferably woolly mammoths—back to the Arctic. That does not seem feasible. Cattle would have many of the same effects as super-elephants, but they cannot survive the Arctic winters outdoors. Bison can, and if there were a sufficient demand for their meat, quite large bison herds might be raised there, though not as quickly as they are needed.

Anyway, we should not ignore the ecological basis for the Zimovs’ proposal. During the ice age, the tundra flourished superbly as a grassland, while feeding far more animals than exist on the planet today. Those huge creatures stomped around eating constantly, and the grasses sequestered immense quantities of carbon. Today, buried in the circumpolar region of the Arctic, are 1.4 trillion tons of carbon, two times more than in all the forests on the planet. According to our current assumptions, such “overgrazing” should certainly have desertified the Arctic, but it had precisely the opposite effect! Is there a lesson here for cattle-ranchers elsewhere?

Allan Savory did not learn from the Zimovs but from his own observations of the barren land in Zimbabwe. Nevertheless, his conclusions are completely compatible with theirs. He says that saving the world from desertification will require more cattle, not fewer.

And, like the Zimovs, his evidence comes largely from the past, when vast numbers of huge animals roamed the African savannah.²⁹ There were, as in the Arctic, about as many predators as herbivores, which stayed closely bunched together in herds; those closest to the centre were less likely to be eaten. There was luxuriant grass for these herds, which kept moving around, leaving manure behind. As they moved, their hooves trampled the grass and aerated the top layer of soil. If they stayed too long, their overgrazing would indeed degrade the land, but they would not return to the same spots until their previous deposits of manure and urine had been absorbed. Such herds maintained a thick grassland that retained rainwater that would otherwise have run off in gullies.

Savory learned from ecological history; he teaches regenerative farmers to restore their barren soil by enlarging their herds of livestock. He says the key is not their numbers so much as the way they are maintained. Conventional farmers around the world today let their whole herds stay on the same common paddock indefinitely, loosely spaced and grazing independently rather than in tight herds, for there are no longer predators to encourage crowding. By contrast, Savory’s “holistic management” instead requires the farmer to move his animals around in dense, grazing herds from one paddock to another, on a schedule determined by observing their impact, day by day, on the grass. Such a close herd is often surrounded today by a temporary electric fence that can readily be moved to the next paddock within a day or two, as required.

Another factor that must influence herding practice is the quality of soil being grazed. Savory classifies it as either “brittle” or “non-brittle,” which is a more important distinction than the difference between “arid” or “dry” land. “Brittle” soil receives most of its annual rainfall in a brief period, then remains dry for long intervals. The effect on vegetation is more challenging than that of a “non-brittle” landscape, where the humidity is distributed evenly throughout the year. Brittle land requires the services provided by especially large herds of animals, managed holistically. However, even non-brittle cropland that is producing vegetables, grain, and fruit also benefit from having heavy animal impact on the land, though not necessarily every year.

Livestock perform two other remarkable services: counteracting gravity and maintaining biodiversity. Water runs downhill, taking the nutrients with it. If unchecked, this phenomenon would mean that valleys would be fertile but the soil at the top of hills and mountains would be barren. However, herbivores eat the plants that grow in valleys, then wander uphill and excrete. Their manure contains, not only the nutrients that they have consumed, but a number of seeds from all the plants they have eaten along the way. This re-diversifies plant species and fertilizes the ground where they grow.

Holistic management has its critics—more, it seems, in the popular press than among researchers or ranchers, who are apparently becoming converts. Agronomists cite Savory in their FAO reports, asserting for example that

“Overgrazing is a function of time (grazing and recovery) and not of absolute numbers. It results when livestock have access to plants before they have time to recover. Compromised root systems of overgrazed plants are not able to function effectively.”³⁰

On the Internet one can find hundreds of photos of landscapes split down the center by a fence. The land on one side is degraded but on the other side verdant—allegedly because of the proper grazing methods used there. And on Facebook there are regenerative farming and grazing groups with ten thousand members. They prohibit debates about global warming or vegetarianism but exchange the pragmatic know-how that working farmers need.

Sheldon Frith, a farmer-scholar advocate of holistic management, notes in his book Letter to a Vegetarian Nation that there are about 100 million cattle in Canada and the United States now. He estimates that between 27 million and 135 million are needed to maintain the cropland soil; about 58 million cattle to maintain rangelands; and about 59 million to regenerate and maintain North American tundra. That would mean that the existing livestock should be approximately doubled, and of course maintained holistically.³¹ And indeed, farmers around the world are increasingly adopting holistic management because it does evidently restore degraded ecosystems.

But What About the Methane?

Unfortunately, Frith’s proposal seems totally incompatible with our earlier acknowledgment that these animals emit huge quantities of methane—a far more powerful agent of global warming than even carbon dioxide. There is obviously a great need for additional research to resolve much contradictory evidence.

It seems to be an established fact that good grazing practices enhance the health of the soil, enabling plants and soil organisms to flourish. However, we must also ask whether good grazing also increases the long-term sequestration of carbon—and that is a controversial question.

The climate crisis requires clear answers, yet the best methods of measuring carbon uptake are unsettled, and there are obviously so many other factors involved that the evidence is questionable. One meta-analysis, for example, reached the upbeat conclusion that “grazing lands generate carbon surpluses that could not only offset rural emissions, but could also partially or totally offset the emissions of non-rural sectors.”³² (In other words, cows can save us.)

Yet another meta-analysis reported flatly that “study after study arrived at similar conclusions. Grazing did not increase carbon sequestration in soils.” (In other words, cows do great things for the environment and can feed us, but they can’t save us from climate change.)

What does ecological history tell us about the equilibrium between methane emissions and uptake? Remember the astounding biomass of herbivores that lived in the Pleistocene period‚ a total far exceeding that of all animals, including humans and livestock, living today. Woolly mammoths and other megafauna also emitted methane. Nevertheless, ice cores from the Pleistocene period show that the atmosphere contained lower levels of methane than today. How so? Probably the answer lies in the balance between methane-excreting animals and methane-eating microbes in the soil.

It is not easy to break methane molecules apart to sequester the carbon in soil, but there is one category of bacteria that do so: methanotrophs, which eat methane and thrive best in areas where it is abundant—ocean floors, swamps, and pastures. During the Pleistocene, methanotrophs must have flourished, fed by the herds of megafauna. Presumably their abundance explains the stupendous quantities of ice age carbon in today’s Arctic soil.

Methanotrophs have a protein called methane monooxygenase, or MMO—an enzyme that contains copper. The metal us stored energy to destroy the super-strong methane bond and make MMO the only known protein that can break apart methane. Scientists are now studying it with the hope that MMO can be cultivated on a large scale for the fight against global warming.³³ The methane from ruminant animals would be sequestered by methanotrophs instead of emitted into the atmosphere as greenhouse gas. However, this research is not advanced enough to offer the solution to our current predicament—that, although the health of our soil depends on grazing animals, they are probably also worsening our climate crisis.

In the short term, the most promising way reducing the livestock dilemma may be to find ways of limiting the methane produced in ruminant stomachs. Vaccination may be able to eliminate the causative enteric bacteria. Another solution is to feed cows small amounts of seaweed, which reduces about 80 percent of their methane emissions.³⁴ If successful on a large scale, this would diminish the basis for abolishing livestock and the consumption of meat. Unfortunately, seaweed seems to be more effective with cows kept and fed in pens than with cattle that graze on pastures, restoring the fertility of the land.

Thinking about Solutions

So yes, maybe trees and cows can save us—if they don’t kill us first, which is equally likely. Everything depends on how we manage them. A trillion of the right species of trees in the right location might capture and sequester enough carbon to offset our worst past mistakes, giving us a couple of decades to phase in better technologies. But large forests in carbon-rich permafrost might set off a positive feedback loop that becomes irreversible.

Likewise, with proper management, cattle, sheep, bison, and other livestock might restore to fertility a large part of the earth’s degraded land. But poorly managed flocks, especially ones that graze too long or with too little hard impact as a herd, will hasten the desertification of our planet.

Both of these challenges require more scientific information than exists at present. The search for optimum solutions may be the most urgently consequential policy facing humankind, so everyone is obliged to join in the discourse. Every advanced country must immediately speed up the quest for clear answers.

Until more is known, the following policies seem to be the wisest practices:

A. Plant no trees in the Arctic and probably in no other area of permafrost.
B. Do not reduce (and maybe even increase) the number of grazing animals for meat and milk, but use holistic methods of managing them.

Since permafrost areas and savannahs are among the places that Crowther’s lab had counted as potential forest areas, removing them from the plans for afforestation will diminish the prospect of planting a trillion trees—or the several trillion that will be required if they are not cared for properly.

We must recognize the inevitable competition for the use of land, with food crops deserving high priority, and we are ambivalently including meat as one of the foods to be produced. Cities were also excluded from the 0.9 billion hectares that Crowther’s lab initially designated for prospective new forests. Therefore, the remaining available land would mostly be far away from where people live or grow their food. Will governments fly hordes of workers, students, and soldiers out in helicopters with spades and bundles of saplings? And will they fly them back every month to weed and water their trees?

How about less labor-intensive methods? There are stories on the Internet about “seed balls” made of clay and dung containing seeds. They are thrown into vacant lots or even dropped from airplanes with the expectation that they will become new forests. This apparently never happens.

What about drones? We interviewed some people who are using that technique.³⁵ They do know the results of carefully monitored studies but for various reasons would not share that information with us. Probably drone planting succeeds in some environments but we were more pessimistic at the end of our interviews than at the beginning. Tree-planting machines exist too, but no one claims they are quicker than people.

Thus we need a billion hectares of land that will support trees, and we need a lot of human labor to plant them and maintain a good survival rate, so we will have to squeeze many saplings onto land that Crowther’s people declared off-bounds: farms and cities. And perhaps we can plant more trees per hectare than had been planned.

There actually are beneficial ways of maximizing land-use. Silvopasturing, for example, is being praised in FAO publications as a way of raising cattle on pastures where there are also some trees. And some food crops (notably coffee) thrive best in the shade of other trees.

Miyawaki Forests

Biodiversity can actually improve the carbon sequestration of trees, though this depends on the combination of trees that are put together, e.g. planting adjacent trees of differing heights, so they do not compete for canopy space.³⁶ Moreover, biodiversity and dense planting can work together to speed up the growth of trees. This is best demonstrated in the forests created by the Japanese botanist Akira Miyawaki, which actually grow ten times faster than the monoculture plantations that are planted by the logging industry.

An Indian engineer named Shubhendu Sharma studied with Miyawaki and has created a company called Afforestt, which is creating mini-forests in cities and degraded plots of land all around the world.

First Sharma’s team collects seeds from a wide variety (say, 60 or 70) of local indigenous trees, rejecting any alien species. They classify them by expected height at maturity, start them growing in pots until they are saplings about two years old. Next they remove the first meter of degraded soil, mix it with an appropriate blend of organic matter from the same locality, and replace it. Then they plant the trees and shrubs very densely—about four per square meter, with all four plants chosen for their differing expected heights. They water and weed them for about two years, after which the trees generate their own water and can continue growing with no maintenance for hundreds of years.

Of course, many or most of these closely-planted trees die, but Afforestt does not thin them out. They see trees as social beings who form their own friendships and alliances. Sharma lets the trees themselves “decide” which of their companions shall survive, for they all benefit from their closeness. It is impossible to walk through a Miyawaki-type forest, for they are all so dense.³⁷

Most of these mini-forests are in cities, and some are only the size of a parking spot or tennis court. Some communities hire Afforestt to plant urban forests so their children can learn the care of trees. Such urban forestry, if done on a mass scale, could locate billions of trees where people live, work, and can conveniently volunteer their spare time. It enhances the community-spirit in a neighborhood. Certainly not all trillion of the new trees can be planted in cities, but possibly enough urban to compensate for preventing Arctic forests.

In North America and much of Europe, huge amounts of urban space can be reclaimed beneficially, not from degraded land but from lawns. In the United States, lawns take up more acreage than the top eight crops combined.³⁸ This was not always the case. Historically, only the wealthy could afford the space and servants to keep lawns. The invention of the lawnmower, the shortening of the work week to forty hours, and the spread of tract suburban housing after World War II enabled the middle class to acquire the habit. Indeed, having a proper lawn became a badge of respectability.

The climate crisis must call this symbol into question. Matt Weber reminds us that,

“We apply more synthetic fertilizers and pesticides to our lawns than an equivalent area of cropland. Not only can this hurt local wildlife, these chemicals can end up in our own drinking water. The manufacture and use of these chemicals require large amounts of fossil fuels and contribute to global warming. Running a single lawn mower for an hour emits just as much pollution as 40 automobiles, according to the EPA. [Each] lawn mower produces more pollution than multiple cars. In a year, a hectare of lawn can contribute as many greenhouse gases as a jet flying halfway around the world… [and] 50–70 percent of all residential water in the United States goes to landscaping. Irrigated lawns take up nearly three times as much space as irrigated corn.”³⁹

Weber did not mention one of the worst offenses of lawn-owners: they are maintaining major sources of nitrous oxide. This greenhouse gas has global warming effects 298 times greater than carbon dioxide on a 100-year timescale. It is increasing in the atmosphere each year because of fertilizer use in landscaping and lawns.⁴⁰

But perhaps this destructive symbolism is ending. Florida has just passed a law saying that cities cannot prohibit people from growing food on their front yards. Next maybe they will let us plant Miyawaki forests. Those two measures are among the promising changes that can be made on land to save the world. (And we have not even considered here the prospects for increasing carbon sequestration in the oceans. Paul Beckwith helpfully reminds me: “Don’t forget plankton. If you like trees, you’ll love plankton.”)

Current research on forestry and regenerative agriculture is incomplete. The climate emergency requires information that is lacking. Still, we must make fateful decisions in this context of uncertainty. Therefore, the following policies should be considered seriously:

Eat meat if you want to. Raise livestock, using holistic management. Feed them a little seaweed. Replace your lawn with a vegetable garden or a Miyawaki forest. Plant two trillion trees, but none in carbon-rich permafrost areas. Good luck.

Metta Spencer is editor of Peace and Project Save the World.

Notes

¹ Population Division of the UN Department of Economic and Social Affairs, “The World Population Prospects 2019: Highlights”, 17 June 2019. http://www.un.org/development/desa/en/news/population/world-population-prospects-2019.html

² Intergovernmental Panel on Climate Change. “An IPCC Special Report on the Impacts of Global Warming of 1,5 Degrees Centigrade Above Pre-Industrial Levels and Related Global Greenhouse Gas Emission Pathways”. (IPCC, 2018).

³ Adam Majendie and Pratik Parija, “How to Halt Global Warming for $300 Billion,” Bloomberg News, October 24, 2019. business.financialpost.com/commodities/agriculture/how-to-halt-global-warming-for-300-billion.

⁴ Jean-François Bastin, Yelena Finegold, Claude Garcia, Danilo Mollicone, Marcelo Rezende, Devin Routh, Constantin M. Zohner, and Thomas W. Crowther, “The Global Tree Restoration Potential,” Science, 365, 76-69 (2019) 5 July, 2019.

⁵ Ibid.

⁶ Adam Rogers, “Trying to Plant a Trillion Trees Won’t Solve Anything,” Science, Oct. 26, 2019.

⁷ Jonathan A, Wang, Damien Sulla-Menashe, Curtis E. Woodcock, Oliver Sonnentag, Ralph F. Keeling, and Mark A. Friedl, “Extensive Land Cover Change Across Arctic-Boreal Northwestern North America from Disturbance and Climate Forcing.” Global Change Biology 2019, 00.1 -1-16.

⁸ Christa Marshall, “Vegetation May Speed Warming of Arctic,” Scientific American, Sept 1, 2019. http://www.scientificamerican.com/article/vegetation-may-speed-warming-of-arctic

⁹ Bartosz Adamdzyk et al, “Plant Roots Increase both Decomposition and Stable Organic Matter Formation in Boreal Forest soil,” Nature Communications, Sept. 04, 2019. http://www.nature.com/articles/s41467-019-11993-1

¹⁰ Bits of Science, “Trees Starting to Grow in the Arctic due to Climate Change Could Cause Carbon Dioxide Release,” June 17, 2012. Hartley’s research was initially published in Nature Climate Change (no date).

¹¹ Argyro Zerva et al, “Soil Carbon Dynamics in a Sitka Spruce (Picea sitchensis (Bong.) Carr.) Chronosequence on a Peaty Gley,” Forest Ecology and Management 205 (2005) 227–240 .Available online at http://www.sciencedirect.com.

¹² Holli Riebeek “The Carbon Cycle”, NASA Earth Observatory, June 15, 2011. earthobservatory.nasa.gov/features/CarbonCycle

¹³ Susan M Natali, Jennifer D Watts, and Donatella Zona, “Large Loss of CO₂ in Winter Observed Across the Northern Permafrost Region,” Nature Climate Change (2019) http://www.uarctic.org/news/2019/10/large-loss-of-co2-in-winter-observed-across-the-northern-permafrost-region

¹⁴ Sergey Zimov, “This Wild Field Manifesto is a Work in Progress,” Revive and Restore. Nov. 25, 2014. reviverestore.org/projects/woolly-mammoth/sergey-zimovs-manifesto

¹⁵ S.A. Zimov, N.S. Zimov, A.N. Tikhonov, F.S. Chapin III (2012). “Mammoth steppe: a high-productivity phenomenon” (PDF). In: Quaternary Science Reviews, vol. 57, 4 December 2012, p. 42 fig.17. Archived from the original (PDF) on 4 March 2016.

¹⁶ Jon Luoma, China’s Reforestation Programs: Big Success or Just an Illusion?” Yale Environment 360. Jan. 17, 2012. e360.yale.edu/features/chinas_reforestation_programs_big_success_or_just_an_illusion

¹⁷ Budiman Minasny et al, “Soil Carbon 4 per Mille,” Geoderma, Vol. 292. Aril l14, 2017, pp 59-86. http://www.sciencedirect.com/science/article/pii/S0016706117300095

¹⁸ David Fogarty, “Crops with deeper roots capture more carbon, fight drought: study” Reuters Aug 5. 2011. http://www.reuters.com/article/us-crops-carbon/crops-with-deeper-roots-capture-more-carbon-fight-drought-study-idUSTRE77412Q20110805

¹⁹ Joanne Chory’s TED talk, “How Supercharged Plants Could Slow Climate Change.” http://www.ted.com/talks/joanne_chory_how_supercharged_plants_could_slow_climate_change

²⁰ John J. Berger, “Can Soil Microbes Slow Climate Change?” Scientific American Mar 26, 2019.
http://www.scientificamerican.com/author/john-j-berger. See also videos by David Johnson. http://www.youtube.com/watch?v=MuW42tFC4Ss and http://www.youtube.com/watch?v=79qpP0m7SaY

²¹ Ethan Roland video: “Carbon Farming: Tools for Regenerative Agriculture.” http://www.youtube.com/watch?v=ljuJhQtLYt8 and see ethan@regenerativerealestate.com.

²² Alastair Bland, “Is the Livestock Industry Destroying the Planet?” Smithsonian.com. Aug. 21, 2012. http://www.smithsonianmag.com/travel/is-the-livestock-industry-destroying-the-planet-11308007

²³ U.N Food and Agriculture Organization: “Key Facts and Findings,” http://www.fao.org/news/story/en/item/197623/icode

²⁴ FAO, “Key Facts and Findings.”

²⁵ Bradley C. Johnston et al, “Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium Free” Annals of Internal Medicine, 2019. annals.org/aim/fullarticle/2752328/unprocessed-red-meat-processed-meat-consumption-dietary-guideline-recommendations-from

²⁶ Dr. Prabhat Jha reports these results in a lecture to Science for Peace, video http://www.youtube.com/watch?v=-JcPm_bXISU . See also the defence of meat diets by Chris Kressler, “Do Vegetarians and Vegans Live Longer than Meat-Eaters?” chriskresser.com/do-vegetarians-and-vegans-live-longer-than-meat-eaters. “Eating Meat Reduces Stroke Risk? New Study Says Yes” Topical Thunder, Sept. 5, 2019, reporting on a British study of 48,000 adults. topicalthunder.com/2019/09/05/eating-meat-reduces-stroke-risk-new-study-says-yes/

²⁷ Micharel Abberton, Rochard Conant, and Caterina Batello, “Grassland Carbon Sequestration: Management, Policy, and Economics,” Plant Production and Protection Division, Food and Agriculture Organization of the United Nations (FAO), Rome, April 2009.

²⁸ World Bank, 2009.

²⁹ Allan Savory and Jody Butterfield, Hoiistic Management, Third Edition: A Commonsense Revolution to Restore Our Environment, Kindle Book.

³⁰ Abberton et al. op cit.

³¹ Sheldon Frith, Letter to a Vegetarian Nation, an e-book available on Kindle, 2016 sheldonfrith@hotmail.com, http://www.regenerateland.com

³² E.F.Viglizzo et al, “Reassessing the role of grazing lands in carbon-balance estimations: Meta-analysis and review,” Science of The Total Environment Volume 661, 15 April 2019, Pages 531-542. doi.org/10.1016/j.scitotenv.2019.01.130

³³ Alex Berr, “The Bacteria that Eat Methane: An Interview with Soo Ro, Molecular Biophysicist.” Helix, Sept. 15, 2017. helix.northwestern.edu/blog/2017/09/bacteria-eat-methane

³⁴ Emma Bryce “Feeding Cows Seaweed Could Reduce Their Methane Emissions,” Anthropocene Magazine, June 21, 2019. http://www.anthropocenemagazine.org/2019/06/feeding-cows-seaweed-could-reduce-their-methane-emissions

³⁵ “Can drones plant a trillion trees?” Video discussion with Sandy Smith, Eric Davies, Elena Fernadez-Miranda and Eman Hamdan. youtu.be/LU8hCkAaYfs

³⁶ Jean-Baptiste Pichancourt, Jennifer Firn, Iadine Cgades, and Tara G. Martin, “Growing Biodiverse Carbon-Rich Forests,” Global Change Biology (2013) 20, 382-393.

³⁷ See my two video interviews with Afforestt staff. “Afforestation and Climate,” with Gaurav Gurjar. youtu.be/4LuYhSN78sI and Shubhendu Sharma, “Miyawaki Forests,” youtu.be/MfPw5VTNZr4 .

³⁸ Matt J. Weber, “Why Everybody Wants a Lawn, and Why It’s Killing the Planet,” Medium, June 26, 2018 medium.com/s/story/this-is-why-everybody-wants-a-lawn-98066ce7aee3

³⁹ Ibid.

⁴⁰ Amy Townsend Small, Diane E. Pataki, Claudia I. Czimczik, and Stanley C. Tyler, “Nitrous Oxide Emissions and Isotopic Composition in Urban and Agricultural Systems in Southern California,” Journal of Geophysical Research, Vol. 116, G01013, 2011.