REPORT TO PUGWASH ON FORUM SERIES ON RESTORING ARCTIC CLIMATE

By Metta Spencer

22 May 2023

 
Panelists: Adele Buckley, Alan Gadian, Blaz Gasparini, Brian von Herzen, Clive Elsworth, David Mitchell, Franz Oeste, Lawrence Martin, Leonid Yurganov, Megan Sheremata, Metta Spencer, Michael Diamond, Oswald Petersen, Paul Beckwith, Peter Fiekowsky, Peter Wadhams, Stephen Salter.
 

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It is generally recognized now that the climate crisis requires, above all, the curtailment of carbon emissions into the atmosphere and the removal of “legacy” carbon emissions. What is less widely understood is that local climatic conditions — especially near the poles – can also affect the severity of the global warming threat.
 
Especially significant are the changes occurring now in or near the Arctic, which is warming four or more times faster than the rest of the world. The rapidity of the loss of white ice will speed up the entire Earth’s warming by exposing more and more of the darker, heat-retentive soil and water. This warming may release methane deposits from permafrost and from beneath the sea in unpredictable explosions. Since methane is at least 26 times more powerful as a greenhouse gas than carbon dioxide, such an explosion can create a “tipping point” when warming will accelerate irreversibly.[1] Hence, besides reducing greenhouse gas emissions over several decades, we urgently need other means to prevent the Arctic’s warming, especially to stop the sea ice melting.
 
Several procedures have been proposed for doing so — the most famous being Stratospheric Aerosol Injection (SAI), a solar geoengineering proposal to spray large quantities of tiny reflective particles such as sulphur into the stratosphere to cool the planet by reflecting sunlight back into space. The widespread opposition to this proposal may well be justified, since such particles could not be captured and returned to earth if unexpected consequences arose.
 
However, not all of the proposed technological solutions are equally risky, and we must balance the unknown dangers of carrying them out against the more certain calamity of failing to carry them out but letting the heating continue.
 
When producing numerous forums to discuss climate change with experts over the past five years, I became interested in four possible interventions that seemed especially promising, so I suggested to the Canadian Pugwash Group that we explore them together in a series of additional video discussions. The members agreed.
 
As a Nobel Peace Prize laureate organization, Pugwash enjoys credibility that might be put to good use in Ottawa to induce government officials to explore these four proposed solutions and possibly implement some of them.
 
I will not discuss here the three proposed interventions that have passed the close scrutiny of Pugwash panelists who questioned experts in this series of conversations. These video forums have all been edited and posted on our website, https://tosavetheworld.ca, where you can watch or listen to them as audio podcasts – or read transcripts and summaries of them.
 
Here, however, I want to discuss the fourth proposal, which dealt with methods of keeping the Arctic covered with ice and snow. Could anyone – including the Canadian government – refreeze the Arctic Ocean? This would have the greatest impact of the four interventions that Pugwash explored with us in the forums. Indeed, it is no exaggeration to say that the intervention might even prevent the sixth “extinction event” on this planet. Here I’ll summarize what I have learned from hosting the nine forums, each one hour long, on the topic.

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Originally what I proposed to Pugwash was that we investigate the possibilities of “marine cloud brightening” over Hudson Bay to keep it frozen longer each year. Hudson Bay actually is somewhat south of the Arctic, but entirely within Canada, so the Canadian government could support a small-scale trial of cloud brightening there without having to win the consent of other countries.
 
Moreover, there are numerous indigenous settlements around the Bay’s shores who depend on the ice and who increasingly suffer from its lengthening absence every summer. It seems likely that the Cree and Inuit communities would be glad for such an experiment to be carried out in their areas, though of course they must be consulted when considering such a proposal.
 
During my nine forums with climatologists, I learned that marine cloud brightening is not the only proposal on offer to keep the far north cold. I heard of several more suggestions, of which at least four may be as promising, or even more so, than marine cloud brightening, which I will explain after noting some disturbing facts about methane.
 
Methane
 
Methane emissions from the Arctic Ocean are increasing at a faster rate than globally, which is increasing by about three parts per billion per year. Methane in the Arctic increased 15 ppb between 2004 and 2019, so it is becoming more significant as a greenhouse gas.
 
Two-thirds of the current Arctic emissions are released in plumes from the ocean – especially the East Siberian Sea – but in the long run, melting permafrost on land will produce a greater amount of methane. However, the rate of methane production from melting permafrost on land is not fully understood. In Siberia over 20 big craters have been found, the result of methane explosions.
 
Under the Arctic Ocean there are huge deposits of methane, some of it frozen in the form of methane hydrates but held down by a layer of permafrost at the bottom of the seabed.
 
In the past, no methane escaped out of the ocean at any time of the year because ice was there in both winter and summer. But now in places like the Barents Sea, the ice is present only in the winter – if at all. In the summer, the water warms up, thawing some of the permafrost on the sea bottom and allowing methane to be released. Scientists fear that if the climate warms up to the point that there is no sea ice at any time of the year, the sediment itself will thaw and the frozen methane hydrates will turn into methane gas and come out in big plumes.
 
This is already happening in the shallow parts of the Arctic Ocean. In the deeper parts, if any methane escapes now, it dissolves before it reaches the surface and there is no plume of gas getting into the atmosphere. But about a third of the Arctic is shallow — only 30 or 40 meters – as compared to 200 meters in the deep parts. Now almost half of the methane in the total Arctic Ocean is emitted from the shallow Barents-Kara Sea area.
 
In the long run, we need to worry about melting permafrost on land, but in the short run, we must be terrified by sudden outbreaks of methane coming out of the East Siberian Sea and other Arctic seas.
 
Marine Cloud Brightening
 
My main informant about marine cloud brightening is Stephen Salter of the University of Edinburgh, who is designing ships to sail on oceans, spraying fine mists of sea water, and a nozzle that will spray droplets of the right size.
 
Marine cloud brightening is a proposal to change dark clouds into whiter clouds. Because white clouds reflect more light back into outer space, less light gets through to warm the planet than would be the case with dark clouds. Doing this could help preserve the ice on Hudson Bay. It will not reduce carbon from the atmosphere but will instead cool the planet directly by shading it, giving us extra time to handle carbon reduction in other ways. Salter explains that the number of required spraying stations would depend on the rate of melting of ice and the amount of energy involved.
 
The climatologists suggested using four different stations, such as shipping containers, with wind turbines to power the nozzle and other electronic equipment and hiring local indigenous persons to run each station. The Churchill Marine Laboratory in Manitoba would be a suitable headquarters for the research project. The potential benefits include mitigating climate change by cooling the planet, preventing coastal erosion caused by increased wave action, and improving the livelihood of indigenous people who are affected by these issues. The cost of this demonstration project is estimated to be around $30 million, which is affordable for the Canadian government.
 
Clouds
 
The world’s climate is determined in large part by clouds, and the physics of clouds is much affected by aerosols – tiny particles in the atmosphere. An aerosol can be composed of almost anything except water that is small enough to stay in the air for long periods without settling under gravity. Natural aerosols include dust, smoke from wildfires, sea spray, and volcanic emissions. Human-made, or anthropogenic, aerosols include smoke from burning fossil fuels, smog, and other forms of air pollution. Aerosols affect the Earth’s water cycle by serving as nucleation sites for cloud droplets.
Some aerosols, especially those composed of black carbon or soot, absorb sunlight and warm the atmosphere. Others, such as sulfate aerosols, reflect sunlight back into space, cooling the atmosphere. A recent change illustrates the importance of this fact. Every ship leaves in its wake a white trail that can be seen from space, much like the contrails behind airliners. In 2020 new shipping regulations were introduced to cut air pollution by banning the sulphur in ships’ fuels. While this had benign effects in terms of limiting pollution, it also reduced the reflectivity of the trails that contained sulfuric aerosols. The unfortunate side effect will be to raise global temperatures by around 0.05C by 2050. This is equivalent to approximately two additional years of emissions.
Clouds have dual cooling and warming effects as determined by their height, size, and aerosol content. Small aerosols and too-large aerosols can warm, with the latter also causing rain, potentially clearing clouds. Mid-sized aerosols are most favorable for cloud brightening.
 
Cirrus clouds, which are in high altitudes, reflect solar energy, causing heating, while low-level clouds cool during the day by reflecting incoming sunlight and warm at night, acting like greenhouse gases. An increase in water vapor due to lower atmosphere warming could amplify infrared heating. Marine cloud brightening, used strategically, might mitigate these effects. However, concerns exist about its potential warming effect, especially over areas like the Arctic Ocean, where sea ice already reflects so much light that nothing more can be gained by cloud cover; indeed, in such circumstances the net effect of the clouds might be to warm rather than cool, for clouds, like greenhouse gases, also absorb and emit infrared radiation.
 
Some of the climatologists argued that Arctic clouds contribute very little to the global heat balance in comparison to clouds in other regions. However, Salter pointed out that for a short time during their summers, the poles receive more solar input within 24 hours than the equator. Therefore, the right approach is to use marine cloud brightening where it is most effective – only during the daytime over water (neither ice nor land) in the Arctic summer, and then from ships that move elsewhere at other seasons. Spray only where the aerosol count is low; spraying over land is useless, for too many aerosols are there in the air.
 
Ocean Stratification and Extinction Events
 
Having hosted a forum when Peter Ward and Paul Werbos discussed previous extinctions in Earth’s history, I became concerned about some apparent similarities to our own period. Previous extinctions have been caused by “euxinia,” a potentially catastrophic event caused by the emission of hydrogen sulfide gas from the ocean floor. This gas is produced by microorganisms called archaea that thrive in the absence of oxygen. Previous extinction events have been caused by the emission of hydrogen sulfide gas.
 
The current trend toward greater ocean stratification may increase the risk of euxinia occurring in the future. The top layers of the ocean have life in them, but as the ocean gets stiller, at the bottom there’s less oxygen, and various things can happen to the thermohaline currents that oxygenate the bottom of the ocean. So potentially, within our lifetime, we may be at risk of having archaea produce large amounts of hydrogen sulfide.
 
I invited Ward and Werbos to discuss this risk with climatologists, but they were unable to be present, so the discussion did not fully reflect their concerns about any current threat of euxinia. What the climatologist panelists did emphasize was the importance of restoring natural upwelling to provide nutrients to the surface layers of the deep ocean.
 
The oceans are indeed stratifying, almost entirely as a result of global warming, 90 percent of which goes into the ocean. This stratification prevents the natural upwelling that is essential for primary production in the ocean and healthy amounts of oxygen in the deep water. The increase in stratification in the subtropical and tropical oceans over the last sixty years has led to a decrease in the production of algae – especially kelp forests – and the loss of marine species.
 
I asked what can keep the water stirred up so that the bottom and top layers interact frequently. One answer: wind. When wind blows offshore, it tends to move the surface water away, so the deep water comes up to take its place, bring up nutrients that produce a lot of fish. It is important to keep the ocean oxygenated, with appropriate levels of nutrient availability in the top 100 meters of the ocean for the marine plants that produce half of the planet’s oxygen.
 
The panelists suggest a comprehensive approach to mitigate the effects of climate change, including refreezing the Arctic, increasing marine protected areas, and brightening the clouds.
 
They also note the importance of whales for vertical mixing and nutrient cycling. Whale poop contains iron that is essential to the biosphere. But the world’s whale population has declined due to human activity such as commercial whaling. Many species, including the blue whale, the right whale, and the humpback whale, have declined in population by over 90% from their pre-whaling levels. This exacerbates the trend toward ocean stratification and in the long term, possibly even euxinia.
 
Kelp in Northern Canadian Waters
 
Almost every forum that Pugwash and Project Save the World produced jointly yielded unexpected discoveries – new ways of helping solve the climate crisis. Repopulating whales was one such idea. Another, more achievable one, was proposed by Brian von Herzen: Reforest the oceans with seaweed.

Many kelp forests are composed of large brown algae, which can grow to impressive heights. They provide habitat and food for a wide variety of marine species, including fish, invertebrates, and marine mammals. They sequester huge amounts of carbon dioxide (CO2) from the atmosphere by photosynthesis. (Some kelp can grow 18 inches per day!) They protect coastlines from erosion by absorbing wave energy and reducing the force of incoming waves. They act as natural barriers, helping to stabilize sediments and protect shorelines from storms and strong currents.
Yet large swaths of kelp forests are being killed through a complex ecological chain of events. Sea urchins eat lots of kelp, so, where their populations have not been limited by predators, they have decimated whole kelp forests, notably on the Pacific Northwest and in California. But sea otters eat sea urchins, keeping them under control. When legislation was introduced to protect sea otters in British Columbia, their numbers increased dramatically, the purple sea urchins declined, and the entire marine life of the region revived.
Seaweed can live in cold northern waters. The panelists recognized this as a potential economic opportunity for the indigenous communities around Hudson Bay who face hardship because the lack of ice makes it impossible for hunters to go procure their food. But if ice is vanishing, kelp is flourishing in Hudson Bay – especially on the Quebec side, which is shallow and rocky. There people traditionally eat kelp, though the people on the west side do not. 
Lawrence Martin, a Cree leader in the Mushkegowuk Council, is leading a feasibility study for the National Marine Conservation Area to partner with Canada and non-government organizations to preserve Hudson Bay’s ecosystem. Martin notes that the region hosts millions of migratory birds, which depend on eelgrass that is disappearing because, as the climate warms, the water becomes murkier due to eutrophication. But Brian von Herzen explained that kelp forests are good at consuming nutrients and making the water clearer, which would allow the eelgrass and migratory birds to thrive. Thus, we discover another solution: Save, not only whales and sea otters, but kelp forests in Hudson Bay – which will protect eelgrass, birds, and even people.
Fortunately, kelp may also create a new occupation for the indigenous hunters who can no longer obtain sufficient meat from seals, walrus, whales, or polar bears. The panelists suggested cultivating and harvesting seaweed to produce food, animal feed, and fertilizers. Perhaps a little industry can be created to manufacture bio-stimulants from kelp. If such a plant can be located near Churchill, Manitoba, a train can carry its products south. That plan would be harder for a community located farther north where there are no roads, though in the winter they do have ice roads.
Another commodity that could be produced from the seaweed is cattle feed supplements. About 40% of all greenhouse gas emissions in agriculture come from ruminant livestock. A cattle feed supplement at even 1% concentration can eliminate most of the enteric methane emissions of ruminant livestock. Lawrence Martin’s feasibility study aims to identify economic opportunities for indigenous communities, and he expects them to consider this opportunity for seaweed cultivation.
Uncertainties and Differences
All the forums were amicable, but the participants did not necessarily agree on all matters, which is inevitable when predicting the future of climate.
Although Lawrence Martin personally would welcome the possibility of extending the duration of ice by experimenting with cloud brightening, he could not say whether most indigenous communities would share his opinion. He said that many communities seem more concerned about permafrost melting than ice thinning in Hudson Bay.
Moreover, the elders believe that climate change is a natural phenomenon and cannot be reversed. Their objective is the keep the earth as it is, and not interfere with the environment. They are concerned, of course, about the impact of climate change on permafrost melting and the release of methane. Nevertheless, Martin will take on the challenge of suggesting to them that some actions might make a difference.[2]
The other panelists declared their full appreciation for the rights of indigenous people living in the North, many of whom have suffered negative consequences from past development projects. It is crucial to respect their self-determination in any future decision-making process. One Pugwash member expressed the view that it is better to help indigenous communities adapt to these changes rather than attempting to restore the ice.
Another panelist, however, argued that no human being has self-determination when it comes to climate change. The Arctic is warming, like it or not; the ice is thinning and more mobile, and soon there will be no sea ice at all. Polar bears are moving inland, farther from the shoreline, and hunting beavers for food. The number of polar bears in the James Bay area has increased, possibly due to lack of ice for hunting them. This also affects the seals, on which the polar bears depend for food. As the ice thaws, it is harder for the bears to hunt seals, so there is an increase in the seal population.
As the ice moves around, it blocks certain routes for hunters and affects the availability of food. The people in the south have more access to food, while those in the north are struggling with blocked routes of travel and hunting. Fortunately, the Inuit, Cree and other communities are cooperating to protect the environment and wildlife. However, it is not certain whether it is feasible to keep parts of Hudson Bay frozen longer in the summer or even whether doing so would create more problems than it solves for certain groups.
The panelists considered alternative proposals for chilling the region. For example, one suggestion is to thicken the ice during the winter by flooding or spraying its surface, thereby extending its duration later into the warm season. This is how ice rinks and ice roads are maintained. However, Stephen Salter doubts the usefulness of such an intervention on a large scale, arguing that it simply moves heat from one place to another.[3]
Salter also expressed misgivings about SAI – increasing the reflectivity in the high stratosphere– since the particles would remain there for a long period, whereas his approach – cloud brightening – has a short lifespan. Fortunately, if some negative result appears, its effects will disappear with the next rain or snow.
The panelists also considered the option of cloud seeding from above but concluded that marine cloud brightening from seawater at the surface is a more cost-effective and practical approach. Nevertheless, everyone open-mindedly considered alternative solutions – especially two such proposals that we should scrutinize here: spraying iron salt aerosols and cirrus cloud thinning.
Iron Salt Aerosol
Of all the alternative possibilities for reducing the climate threat in the Arctic, the most promising is probably the spraying of Iron Salt Aerosol (ISA), which has several beneficial effects, especially the depletion of methane in the atmosphere. Forty percent of current global warming comes from methane and gases other than carbon dioxide. The ISA intervention works in three main ways by using (a) dust to reduce methane, (b) phytoplankton in the oceans to reduce CO2, and (c) cloud brightening to cool the planet directly.
(a) ISA Against Methane. This innovation by Franz D. Oeste and Renaud K. de Richter would be able, if deployed adequately, to eliminate much of the methane in the atmosphere, which has increased by 2.3 times because of human activities. In this system, a catalyst called ferric chloride, FeCl₃, is sprayed into the atmosphere under conditions of sunshine. Upon contact, it converts the methane to carbon dioxide and water. (Of course, we don’t want the CO2 but it is vastly preferable to methane, which is at least 26 times more powerful as a greenhouse gas than CO2.)
Oeste and de Richter note that this natural process of cooling is exactly how previous ice ages were created. Moreover, even today, by spraying dusty particles containing iron into the atmosphere while the sun is shining, we could rapidly diminish the methane in the air. The iron dust can be dispersed in a variety of ways, such as from airplanes, balloons, drones, ships, or the exhaust flues of power stations.
In creating previous ice ages, this process cooled the Earth with wind-blown dust in levels much higher than today. This created a thick layer of ice in polar and subpolar areas. Even today, dust from the Sahara Desert blows across the Atlantic, counteracting the methane molecules it encounters and then falling to fertilize the Amazon rainforest.
The extraordinary thing about the Iron Salt Aerosol intervention is that it helps to solve the climate crisis in several additional ways besides oxidizing methane over oceans, including:
(b) Ocean restoration. Large areas of the oceans are “deserts” because of the lack of iron, which is required for phytoplankton growth. The absence of phytoplankton means that fish and other animals are absent. But luckily, when the ISA has done its job in the atmosphere, it rains onto the oceans and land in a bioavailable form. In the ocean, this revives the phytoplankton, so the “desert” blooms. The fish eat much of the phytoplankton, and the rest falls to the bottom of the ocean, carrying carbon out of the atmosphere to be sequestered below.
The Permian extinction event is thought to have been caused by volcanic eruptions that released large amounts of ash, which fertilized the ocean and led to phytoplankton blooms. This caused oxygen depletion and the release of toxic hydrogen sulfide gas. The group acknowledges the comparable risks of introducing ISA into the atmosphere but emphasizes that they plan to start small and gradually increase dispersion while monitoring the effects.
(c) Marine cloud brightening. The Iron Salt Aerosol is composed of tiny particles that act as cloud condensation nuclei, just as the salt in seawater that Salter and others would use. And, like seawater, it leads to the formation of brighter clouds in the troposphere, which cool the earth by reflecting sunshine back out to space. The ISA also stimulates phytoplankton, which emit sulfur and halogen molecules that oxidise in the troposphere and yield additional cloud condensation nuclei, which leads to further marine cloud brightening.
(d) Chemical cooling. Phytoplankton grow by converting heat energy into chemical energy, which has a cooling effect. Also, about 30 percent of the plants on land are limited by the lack of available iron. When the ISA is rained out onto land, it will increase chemical cooling by increasing terrestrial plant growth. Moreover, some biomass from land runs off into the oceans, falling as the phytoplankton does to the bottom of the ocean where it becomes sediment or crust, removing additional carbon from the atmosphere.
(e) Feeding methanotropic bacteria in wetlands. There are microbes in wetland soil and sediments that “eat” methane and catalyze its oxidation. These microbes require iron and adding it to their environment enables them to reduce even more of the methane from swamps and peatlands. 
There are even more beneficial effects of dispersing ISA, but these five should suffice to convince everyone that the intervention is extremely attractive. Then questions arise about the “downsides,” if any. There seem to be no probable safety hazards, though Clive Elsworth has addressed all those that he could imagine in a brilliant separate website. There is one negative side effect of ISA, however: its color. The iron salt is a reddish-brown hue, and when it falls onto snow or ice it darkens the surface and ruins the reflective albedo effect. Fortunately, Franz Oeste has found an alternative aerosol, titanium oxide, which turns methane into water and CO2 just as effectively as ferric chloride. But titanium is white, so when it falls onto the ice it does not discolor it. Nor is it toxic in small amounts; it is an ingredient in some toothpastes in a concentration far greater than the tiny amounts dispersed to reduce methane.
As to the cost, Elsworth says the technology would be cheap – less than $1 per tonne of CO2 equivalent removal. This is based on 150,000 tonnes of iron in the form of Iron Salt Aerosol, removing 12Gt CO₂ equivalent per year.
I had already interviewed one of the inventors of this system, Renaud de Richter, before proposing the Hudson Bay ice project to Pugwash, and had indeed regarded it as favorably as the cloud brightening proposal that I actually chose. However, at the time, ISA seemed to be in an early phase, so I expected it to require longer than five years to be ready for field testing, whereas cloud brightening seemed to be almost ready. Since our climate crisis is an emergency, it seemed best to pick only projects that the Canadian government could advance quickly.
In retrospect, I think I made a mistake. Designing the nozzles for seawater spraying will take years yet to perfect, whereas field tests of ISA might be possible within a year or two. Considering this new information and the multiple good effects of ISA, it seemed wrong to proceed as originally planned, without taking account of other possible options. By the same token, it would also be wrong to proceed without paying some attention to yet another promising intervention: cirrus cloud thinning.
Cirrus Cloud Thinning
The last intervention that we’ll consider is also one that does not involve any reduction of greenhouse gases from the atmosphere, but simply cools the planet by poking holes in the blanket that keeps us overly warm. This involves thinning the high, wispy cirrus clouds that contain ice.
Cirrus clouds, unlike lower-lying clouds, contribute to a warming effect on the planet, as they trap heat, especially during the darkness of Arctic winter. Therefore, thinning these clouds could potentially allow more heat to escape from Earth. This method would be particularly effective in the Far North, where cirrus cloud thinning would have the greatest effect in releasing trapped heat.
David Mitchell, who was first to propose this intervention, explained that sunlight coming into Earth transforms into longwave (thermal, or heat) radiation when absorbed by the Earth and re-emitted. Cirrus clouds at higher altitudes are colder, meaning they emit less radiation into space, effectively acting as a blanket that traps heat and re-emits it back to the Earth’s surface. This trapping effect is stronger during the winter, making it an optimal period for cirrus thinning to release the trapped longwave radiation.
‘Arctic amplification’ is the phenomenon wherein the Arctic warms faster than the rest of the world due to decreasing albedo from diminishing ice and snow, which reflect sunlight. Amplification is influenced by dark soot falling on snow.
Cirrus clouds are formed in two different ways: by heterogeneous (dirty) or homogeneous (clean) nucleation. “Dirty” cirrus clouds form with the help of ice-nucleating particles, often dust from deserts, that enable quicker ice formation. In contrast, clean cirrus clouds form on tiny liquid particles, which are always present in the atmosphere.
Clean cirrus clouds have a high concentration of ice crystals, which increases the surface area to trap thermal radiation, making them a thicker atmospheric ‘blanket’. As a result, clean cirrus clouds are more effective at warming the Earth than dirty cirrus clouds. Clean cirrus clouds are also more persistent, as they consist of many small ice crystals that do not quickly sediment.
Dirty Cirrus clouds have fewer ice crystals and allow more heat to escape. The goal of climate intervention would be to convert clean Cirrus to dirty Cirrus, thereby releasing more heat into space.
The conversion process involves introducing more ice nuclei or dust particles into the atmosphere. Larger ice crystals in dirty Cirrus fall faster, reducing cloud lifetime and coverage, which allows more radiation to pass through. Concerns are raised about the impact of dust falling to the ground or on ice surfaces, but the consensus is that the amount would be negligible.
This cloud thinning would be done by “seeding” the cirrus clouds with bismuth tri-iodide. About 2755 kilograms would need to be introduced into the atmosphere above 45 degrees latitude in both hemispheres every seven days.
Several methods of distribution are discussed, such as using aircraft or balloons, although these remain largely hypothetical due to a lack of scientific research on the subject. Another approach is using drones to disperse the particles more gradually, thereby ensuring a more even distribution and mitigating the risk of over-seeding. This process, however, would need to be continuously monitored, ideally by satellites.
Unfortunately, research on cloud thinning is not yet advanced, and there are countless questions at this stage. It is, however, expected that if the particles are too concentrated, seeding them could produce the opposite of the desired cooling effect by creating thicker cirrus clouds that trap more heat. Hence, achieving the correct concentration across the Arctic is crucial and presents a significant technical challenge. A nozzle that might work for marine cloud brightening would not be useful for pumping a fine powder that tends to clump together.[4]
The cost of such an experiment, based on estimates from 10 years ago, was roughly $6 million per year. No definitive studies can be designed yet, but the speakers suggested some smaller scale, controlled experiments. David Mitchell proposed a cheaper study involving satellite observation of naturally occurring atmospheric phenomena, such as dust storms from Asia affecting cirrus clouds over the Canadian Rockies. Regrettably, such general, exploratory research will not hasten the practical deployment of knowledge to cool the planet. All the speakers are aware of this tension between urgency and scientific caution in addressing climate change.
With regret, I saw the proponents of cirrus cloud thinning hesitate to predict that their findings can be put to practical use any time soon. There is value in continuing their investigations, but practical engineering planning would now be premature.
Recommendations
I circulated this report to all the experts and Pugwashites who participated in this inquiry, inviting their comments before finalizing this report. Therefore, this final section, which summarizes our recommendations to Pugwash, was written after reading their replies. Unlike our inquiries into the other three interventions (on concrete, urban forestry, and soil amendments) the panelists who discussed Arctic cooling reached no apparent consensus as to whether Canada should now begin actual experimentation in the field.
Everyone seemed to agree on the value of continuing the series of discussions about chilling the Arctic. Everyone seemed to agree on the importance of the issue and that, if successfully applied at scale, some of the proposals might even prevent the climate catastrophes that otherwise seem inevitable. Everyone seemed to agree that experimentation in the field is probably safer than refraining from such experimentation. However, not everyone agreed that the value of cloud brightening, iron salt aerosol dissemination, or cirrus cloud thinning can now be demonstrated with small scale field tests.
The main point of a field test is to prove that the proposal is sufficiently promising to warrant implementation on a huge scale. It would be possible to try out all of these solutions, probably on Hudson Bay, for a price that the Canadian government can afford. We were unsure, however, what kind of results will be required for such a demonstration to be deemed conclusive.
Stephen Salter believes that scientists and politicians would be impressed by satellite photos showing even a five percent increase in the brightness of Arctic clouds. In his opinion, it is unnecessary to measure the temperature of the water underneath, which would also be about five percent cooler because of the clouds’ extra reflectivity.[5] Proving even such a small cooling effect might persuade the world’s leaders to spend billions on cloud brightening projects in all the world’s oceans. The scientists on all the forums seemed to agree that brightening ocean clouds by merely five percent might save us from global warming – at least temporarily, until other long-term climate restoration measures can take effect.
I have to acknowledge my own skepticism about this. In my opinion, the only well-recognized indicator of Arctic warming is highly visible on maps: the loss of ice and snow. Maps clearly show where the white ocean is turning black. I doubt that many people will be impressed by proof that black, open water can be cooled by five percent. Only evidence of actual refreezing will impress most people. I expect politicians will want to see at least a square mile of Arctic water refrozen before they will support cloud brightening on a vastly larger scale.
But Hudson Bay is already too warm to refreeze by any of the three methods alone. Even centuries ago, the ice there melted every summer, and now it stays melted much longer. If all three approaches to chilling the water were adopted simultaneously in an experiment farther north, where the water is usually colder, it might be possible to refreeze Arctic water, but that would be a poor scientific experiment. Combining all three methods would make it impossible to know which of them had worked and which had not.
For these reasons, therefore, I was the chief contrarian in the conversation about recommendations to Pugwash. I proposed that Pugwash should postpone recommending anything about these proposals to the government but continue the discussions for another year, hoping that new research findings will emerge to illuminate the path ahead.
Because the panelists were never all together at the same time, we never took a vote about the matter, nor did they all express opinions in their comments about the draft report that I circulated. However, I sense that almost all the scientists support Salter’s view, not mine. That is certainly true of Brian von Herzen and Peter Wadhams, who both believe that much can be learned from such a study. Wadhams participated in almost all the forums and intended to write a critique of this report, but illness has prevented his doing so.[6] Like von Herzen, he favors headquartering the project in the excellent marine laboratory at Churchill, Manitoba, on the west shore of Hudson Bay.
I hope they are right and I am wrong. Can the Canadian government be persuaded to carry out a real demonstration of cloud brightening, say, in Hudson Bay? Perhaps so. After all, Australia is funding cloud brightening research to protect the Great Barrier reef from bleaching. Why can’t Canada match that effort?
If Canada does undertake a good study of marine cloud brightening, it would make sense to add on a study of Iron Salt Aerosol spraying. The two projects can be carried out simultaneously but far enough apart to keep from mutually contaminating their results. ISA could begin within a year or two and probably at a lower cost than cloud brightening. Together, the two methods might be tested within five years for an estimated cost of Canadian $40 million.
I had also hoped to support the field testing of cirrus cloud thinning, but the leading researchers on that approach all seemed to regard such experimentation as premature, since the science is not sufficiently advanced to warrant it.
In any case, whether or not Pugwash decides to recommend experimentation at this point, it should clearly recommend a continuation of the discussions about ways of chilling the Arctic. The scientists found their conversations useful and were able to talk in plain enough English for non-scientists to follow. This forum series provides a rare opportunity for an average citizen to learn about cutting edge research on possible ways of rescuing humankind.
Finally, I should mention the possibility of facilitating the harvesting of kelp from northern waters. This idea emerged during the course of the Pugwash conversations and may or may not be feasible. In any case, Lawrence Martin’s research group now has heard the idea and will explore it further, presumably with the support of Canada’s ministry of environment and climate change. Such a production opportunity may be achievable without delay. And, as we now realize, delay is our worst enemy.

[1] Stephen Salter notes: “You write that methane is 26 times more powerful as a greenhouse gas than CO2. This is true if you use 100 years as the lifetime. In the first year is it very much more serious, maybe 200 times. If methane warming melts permafrost, it will release even more.”

[2] Lawrence Martin writes in reply to my request for comments on the first draft: “One of the topics that you had raised during one of the podcasts was on Kelp in the Hudson Bay. I am sharing that information with my socio-economic study crew so that they can examine the various possibilities that may exist as per harvesting and marketing that you had asked about. The study will take place this summer. I will let know of the outcome.
         “I spoke to some of my science colleagues from various working groups that we have, and that have helped us with our conservation plans. They are aware of some of the techniques and methods that you described, ie Cloud Brightening, and so forth. Like you said, none of these have been proven just yet. Back to the drawing board! Thank you for including me in these exciting discussions.”
 
In a later letter, Martin wrote: “Hello Metta; I have read your report and I am grateful to you for putting so much time into this important work.
    “I am still working on our feasibility study to establish the National Marine Conservation Area project in the western James Bay and Hudson Bay and we shall have our report available by summer of 2024. I would love to share it with this group. It will have traditional knowledge and science braided together.
    “Your report reflects many good ideas and recommendations, Im glad I was fortunate enough to have been part of it and some of the discussions I participated in. I hope you will continue working with us all in the monthly podcasts; they are so helpful and informative.
   “Many thanks to you and your guests and colleagues.”
 
 
 

[3] I asked Brian von Herzen about this and in a letter he expressed disagreement with Salter, noting: “Freezing water at the surface is moving the heat to space in winter through several steps…This is well established in atmospheric science. He is not perceiving 1. the adiabatic lapse rate, 2. the cold convective tops of the clouds will release heat to space, particularly if the cirrus clouds are thinned in winter.”
 

[4] Blaz Gasparini wrote in reply to the request for comments on the first draft of this report: “If mixed-phase thinning worked scientifically, it would be much easier to implement. While cirrus clouds are high above the surface, mixed-phase clouds in the Arctic winter are directly above the ground. So one could really think about using the same ships/platforms that would be used for cloud brightening in summer.
“The result of the forwarded publications show, however, quite a limited cooling potential, given that the study is highly idealized. However, I would never trust one single study, particularly not when done with a single general circulation model and would advocate for more work on the topic. 
“Also, the cooling potential of such a method is gradually decreasing with the increasing Arctic temperatures, as the mixed-phase clouds (that contain some ice) are being replaced by purely liquid clouds.”
 

[5] Stephen Salter writes: “The reason I am concerned about measuring the temperature below brightened clouds is because cold water sinks and the sink rate depends on how much it is mixed, which depends on wave action, which depends on wind speed. This is a much less reliable measurement than the energy reflected by a brighter cloud.”
[6] Peter Wadhams writes: Dear Metta: Strongly in favour of Stephen and MCB development.”

REPORT TO PUGWASH ON FORUM SERIES ON SOIL AMENDMENTS

By Metta Spencer

24 June 2023

Panelists: Albert Bates, Adele Buckley, Joanna Campe, David Demarey, Gregory Dipple, Thomas Goreau, Benoit Lambert, Peter van Straaten, Thomas Vanacore, Brian von Herzen.

What is Enhanced Rock Weathering?
This Pugwash investigation is studying “Enhanced Rock Weathering,” a solution based on a geological process. Over long periods of time, rain falls on rocks containing carbon, creating carbonated water, which eventually gets washed off into the ocean, where the carbon can be sequestered for aeons. Pulverizing rocks into powder increases their surface area, enhancing their ability to capture CO2. This natural process, when used to accelerate carbon absorption, is known enhanced rock weathering.
We need to apply 10 gigatons of mineral dust to capture a gigaton of CO2 each year. For this, so-called “waste” can be a great asset. Weathering is a significant source of CO2 absorption in nature, but normally takes millions of years. Because conventional practices may take decades or generations to solve the climate problem, other solutions, such as increasing biomass and weathering, need to be applied together to remove carbon.
Here we want to consider the beneficial uses of enhanced weathering, including its use as a substitute for synthetic fertilizer, which unfortunately is a serious source of pollution and eutrophication. Rock dust as a soil amendment is a better substitute for ordinary fertilizer.
However, this raises another challenge: preventing its runoff into the ocean. A promising solution is to add biochar – charcoal that can be mixed with rock dust to retain nutrients and prevent their washout.
Increasing CO2 in the atmosphere acidifies the ocean and dissolves limestone. But there, seaweed offers a solution: It captures huge amounts of CO2, then can be harvested and used as a bio-stimulant to enhance food production. The combination of rock dust, biochar, and seaweed holds promise for sustainable agriculture and carbon removal.

Rock dust provides essential minerals and micronutrients for plant growth. When combined with biochar and compost, it fosters healthy soil microbial communities, including mycorrhizal fungi that aid in nutrient absorption by plants.
Not all rocks are equally beneficial for farming. Black shale is especially good as a growth enhancer for greenhouse crops. Its trace elements improve plant growth while also capturing about 200 pounds of CO2 per ton of rock.

[READ MORE]

There are long-term benefits from combining biochar, rock dust, and seaweed, especially in permaculture and mixed growing environments. The seaweed stabilizes the soil. These materials can be integrated into crop rotations or agronomic strategies.
Mine tailings, another potential source of rock dust, are available in large quantities. These are finely ground material resulting from mineral processing. These can be used for carbon capture through enhanced weathering reactions. However, not all types of mine tailings are suitable for spreading on agricultural land, as some may contain toxic metals – especially nickel and chromium. However, Peter van Straaten recalls having used mine tailings very successfully in Zimbabwe. Canada produces a couple of gigatons of industrial waste each year, including mine tailings; much of it could be used as amendments to soil and forests. We need to inventory such products, which are usually considered “waste” but can be exactly what we need for other purposes.

Fortunately, farmers can easily learn to use these materials. Many small fruit and vegetable growers already are using them in Canada. Tom Vanacore’s quarry supplies rock dust mixed with synthetic fertilizers to create compounds with nitrogen, potassium, and phosphorus. The nutrient-rich rock dust replaces the “dumb mineral” fillers that are often added to commercial fertilizers. Vanacore[1] and Ryan Brophy were two of the panelists in the forums, each of whom provide suitable rock dust products for application to soil.[2]
Plants get all their essential elements except for hydrogen, carbon, oxygen, and nitrogen from the soil. The soil is, therefore, essential to plant growth, and most plants are limited by a deficiency in one or more of the essential elements. Chemical fertilizers only add nitrogen, phosphorus, and potassium, leaving out other essential elements that plants need. The solution, therefore, is to use rock powder and biochar to “re-mineralize” the soil and add the missing minerals.
Remineralization keep soils healthy and to grow nutrient-dense food. Rock dust, with organic matter and biological techniques, is key. Industrial agriculture has depleted up to 70 minerals and trace elements from the soil, leading to nutrient-deficient food.
Use of the right kind of rocks is essential. Basalt is one of the best rocks for this as it has most of the essential minerals in the most balanced levels. Biochar is also essential as it holds on to nutrients and water and makes them available to the fungi that feed the roots. When mixed with mature biochar, rock powder produces tremendous growth. The combination makes the soil drought-resistant, resistant to insects and disease, and changes the pH, leading to higher nutrient uptake.
Remineralisation has been used in Europe since the 1960s. A Munich study showed that when rock dust was applied to a pine forest, there was a fourfold increase in timber volume over 24 years, with one application lasting 60 years. Also, in Brazil, over 5 million hectares of soil have been re-mineralized to grow soybeans, and the country has sold over a million tonnes of rock dust annually. The Amazon can be regenerated through remineralisation and biochar. It improves soil health, increases crop yields, sequesters carbon, and mitigates climate change.
Remineralisation can integrate agroforestry into monoculture technologies, which will be important in the north, where global warming may desertify large swaths of monoculture. The panelists recommend cutting down fast-growing, unproductive weeds in deforested areas and turning them into biochar, which they would mix with rock dust and use to build up biomass in the soil.
Basalt is an ideal source of rock dust, but many other types of alkaline silicates and placers are also widely available, as well as legacy stockpiles of previously pulverized materials that can be repurposed or recycled. Renewable energy can be used to pulverize local rocks that are abundant, then combine with biochar to apply in agroforestry to increase the soil’s biomass. Such places as the Amazon rainforest and depleted farmland need immediate attention. The most promising rapid intervention may be the use of rock dust, biochar, and seaweed to rebuild healthy soil for forests and agriculture.
Farmers’ Concerns
Farming is a business, and farmer must base their decisions on probable returns on their investments. Fortunately, the profitability of adding soil amendments can be measured and demonstrated to farmers. The potential for permanence in carbon sequestration increases its value. The long-term economic advantages of using these materials soon make it apparent that they are a worthwhile investment without ongoing subsidies.
However, it may be beneficial (even necessary) to provide subsidies to farmers initially to incentivize the early adoption of this technology. Even small incentives can make a big difference. With current supply chain disruptions and labor shortages, climate change is a real emergency requiring significant investment. Either a voluntary or government carbon market could offset the costs and provide money for actual carbon dioxide removal.
Noah Planavsky believes that larger corporations on the coasts, not farmers, should pay for the practice, since they are making tremendous amounts of money but not keeping to their climate goals. Such a program is entirely feasible. However, traditional market trajectories can take decades or even generations to bring about change, whereas subsidies can have a quicker influence.
‘Recalcitrant carbon’ – long-chain carbon molecules that can remain in soils for a long time – are especially important to soil microbial communities. Incentivizing the adoption of these integrative practices by subsidizing the first 10% of farmers could have a significant impact.
Enhanced weathering can provide a second income source for farmers through the sale of carbon credits. The carbon credits would become more valuable if the price of carbon removal were to increase to $100 per ton from its current level of $10-20 per ton.
The cost-effectiveness of using previously quarried or mined products for agriculture is extraordinary because all the energy has already been applied for the extraction of the rocks.
Testing of the soil is crucial, and the cost is not prohibitive. The focus should be on finding the right rocks that are locally available for smallholder farmers. The rock dust must be applied with care and lifecycle assessments are required to ensure that an application is not producing more CO2 than it will be capturing. Transportation is the largest cost and largest source of carbon emissions. If rock dust or mine tailings is moved more than about 100 kilometers, its use may be counterproductive.
Rock dust users must take account of such factors as the metal content of the rocks, the composition of the soil, and the type of crops being grown, but the safety and efficacy of these materials are well known because testing practices are normal and well accepted.
What kind of rock dust is best? The most productive crops in the world grow on the volcanic floodplains or the volcanic lowlands. In Italy, farmers cultivate crops around the base of the volcano Mt. Etna, because of the highly productive soil.
In Canada, wollastonite is a good choice; it can work better in colder and less wet locations than basalt, which could be a relatively large component of soil amendments in India but a small component in the US and UK. However, farmers in the US could benefit from using basalt to cover their costs and increase their bottom line. Nitrogen-fixing crops seem to benefit the most from basalt, but it also increases yields in non-nitrogen-fixing crops. Basalt is financially attractive because it costs less than spreading lime. Crushed basalt can also be used to reverse soil acidification in Canadian forests, capturing carbon while also improving tree growth.

Biochar
Biochar is biomass or organic waste that has been pyrolized – cooked without oxygen. The product is simply charcoal that can be used in agriculture, concrete, asphalt, or even to filter water. Albert Bates and others have discovered about 50 different uses for biochar.      
Of course, carbon dioxide removal must not replace the reduction of carbon emissions, but a new economy may develop around biochar, addressing ecological disasters caused by unsustainable practices, such as using marine sand in concrete. Benoit Lambert suggests other technological improvements, such as big tarps to throw over logs and pyrolize them on the spot.
Biochar is created naturally during forest fires. It can be used to improve soil health, retain water, and sequester carbon. We still have 1000 gigatonnes of co2 to extract from the atmosphere and sequester, but it’s a win-win-win because we will put it into farm soils to improve food production with this new product, biochar.
However, biochar alone cannot restore the carbon cycle. Trees and forests are net carbon sequesterers. Leaving some parts of the forest after logging, such as pine needles or branches, can restore nutrients and carbon to the soil.
A forest is an ecosystem –above and below the ground. The roots put carbon exudates into the soil food web and the microbes digest and transport the water in the soil. Unlike monoculture stands, a forest with such a deep fungal network is sustainable. Nature’s ways are regenerative – they repair and restore – rather than extractive. Fortunately, the US Forest Service in Colorado is using pyrolysis to create biochar to restore the fertility of the forest after pine beetle infestations.
Biochar can be produced from various waste streams, including seaweed and sewage, and mixed with asphalt and concrete for use in road construction. This offers lower maintenance costs and greater flexibility in cold climates.
Biochar alone could withdraw 50 gigatons of carbon dioxide from the atmosphere. The limiting factor is the feedstock. We could make it from municipal solid waste, from sewage, or from the seaweed that washes up on beaches, or from the huge Sargassum blooms that are growing in the Atlantic because of climate change. We could farm the oceans for seaweed and turn it into biochar.
But biochar made from the ocean may be contaminated with plastic. Even biochar from sewage is contaminated with heavy metals. There are pharmaceutical contaminants that can get back into the food system. If your sewage, or municipal wastes are contaminated with microplastics or toxins of some form, put it into a road surface. It will stay there for hundreds of years. Tennessee is pouring a biochar highway, replacing the asphalt with biochar, which is stronger than concrete or asphalt and 40 percent cheaper.
Stockholm took waste from their city dump, made it to biochar, and applied it around the roots of the trees in the sidewalks and the median strips. Soon their three-year-old trees looked 30 years old. They ran out of source material and had to bring in wastes from other Scandinavian cities, which started emulating their practices.

Seaweed

Seaweed is also a prebiotic that stimulates the growth of soil microbial communities and upregulates gene expression in plants. It thrives in Canada’s three oceans and can be made into liquid seaweed bio-stimulants which, in small amounts, improve crop yield and reduce the need for traditional nitrogen fertilizers. This approach also reduces emissions by minimizing nitrate runoff and nitrous oxide production in the soil. Additionally, in seaweed farms, a portion of the seaweed falls to the seafloor, sequestering carbon for extended periods.
Pyrolyzing seaweed leads to the loss of nitrogen and carbon, reducing its benefit for soil fertility. Instead of making it into biochar, a better use of seaweed is as bio-stimulants, which enhance plant growth by overriding inhibitory signals and improving nutrient uptake.
Seaweed, as a stress resilience agent, helps plants manage stressors such as drought and heat, improving agricultural yields. Seaweed and rock dust also have health benefits for consumers and livestock, notably for replacing the use of antibiotics.

Logistic challenges

While the application of mineral dusts clearly improves the productivity of agricultural land, its effects on greenhouse gases like methane are still not fully understood. Government researchers especially urgently need to identify the types of mine tailings that are suitable for agriculture. Unfortunately, no maps exist showing the location of mine tailings, so the sources may be hard to locate. Once found, they must be analyzed for mineralogy, carbon capture potential, transport, and logistics. Google Earth and artificial intelligence can map all the tailings deposits of the world based on pattern recognition of existing remote sensing data. And Natural Resources Canada is funding research specifically around battery metals and critical metals, and that could easily be expanded. The industry would benefit by helping develop a database to bring this information together.
A Nature article has used global maps of soils and climate to produce a geochemical weathering model. However, it could be improved with better simulations of carbon drawdown. More research is needed on the impact of rock dust on greenhouse gas mitigation. Also, there are no established methods of carbon accounting, so a lot of work still needs to be done. Government policymakers need to create a national lab for testing rock dusts, develop protocols for measuring greenhouse gas impact, and provide incentives for industry to contribute to a database mapping mine tailings.
Lifecycle analyses are crucial for the development of this technology, for transportation requires a lot of energy and emits carbon. Proximity matters greatly. Seaweed should generally be transported by ship and rail to minimize carbon emission.
Vanacore’s company, Rock Dust Local, has developed a model for sourcing rock dust regionally, which could be beneficial for third-world countries. Fortunately, both rock dust and seaweed are globally available, reducing transport logistics. The cost depends on the transportation distances involved, but sourcing basalt from nearby states could reduce costs.
Construction demolition waste could also be used in place of basalt, taking into account such factors as metal accumulation in soil. Such waste is essentially calcium silicate, which can help regulate soil pH, capture carbon, and provide alkalinity. There is a huge supply of it in China and India that can give billions of tons of CO2 equivalents.
In their joint forum, David Beerling and Noah Planavsky note that there is justifiable distrust of carbon markets and a need for better measurement and tracking of the carbon removal process. They discuss two approaches to measuring carbon removal: using models or using empirical measurements coupled with a modeling framework. Planavsky tracks the amount of carbon dioxide removal by using code and tries to design an ideal application scenario. The speakers urge transparency about the carbon removal process, even if it is more expensive, for clear metrics can build confidence in the process. Ultimately, the question is not whether enhanced rock weathering removes carbon dioxide, but how much carbon dioxide it removes, and the challenge is to clearly measure this.

Nature-based Solutions     

Thomas Vanacore suggests combining the forestry and agriculture industries, municipal sources of waste, and repurposing of these materials into bio-mineral fertilizers.
It’s hard to estimate how much rock weathering can reduce climate problems, compared to other proposed interventions. Cloud brightening, for instance, is a short-term solution that needs to be constantly pumped into the atmosphere, while enhancing rock weathering can sequester CO2 for many years.
It would be possible to pyrolize waste biomass from public parks and grain-processing into biochar or bio-mineral fertilizers that are rich in minerals. This will yield a gas that can power mills and prevent its release as CO2 into the atmosphere. The biochar can then be mixed with rock minerals and biomass to create bio-mineral fertilizers.
The quality of the biochar depends on the type of biomass used and the temperature at which it is burned. Leaves and algae are not as good as hard wood and if you use really high temperatures, you wind up with nothing but carbon, carbon black. Everything else is driven off. But biochar made from hard wood and cooked at around 500 degrees Celsius in the absence of oxygen produces high-quality carbon that lasts millions of years, making it ideal for soil improvement.

The biochar, mixed with rock minerals, provides a high surface area that holds on to water and nutrients that are released by weathering. The farmers can benefit from the nutrient-dense material and the reduced cost of synthetic fertilizer. Traditional cultures did so. The black soils of the Ukraine, for example, are the remnants of a forest burned down, and half of the carbon in the soil is biochar.
Benoit Lambert’s book, Biogeotherapy, promotes holistic grazing management; no-till agriculture with cover crops; biochar; and massive reforestation, along with 15 other “nature-based” solutions, including composting, agroforestry, and living machines. The panelists gave considerable attention to this emphasis on learning solutions from nature.
For example, the “living machine” concept, as developed by John Todd, involves aquatic systems that process waste, such as sewage, to get the nutrients out. This creates an indoors ecology similar to what a swamp does, but in a clean greenhouse where you can produce plants, food, and fish.
Benoit Lambert adds mangroves to the list of nature-based solutions. He is also concerned about the millions of tons of biomass – the dead wood from forest fires, spruce budworms, insects, and the forestry sector – that are left behind but which could be pyrolized on site. It is not necessary to move that biomass from forestry camps, though it is often left decomposing and releasing carbon into the atmosphere.
Instead, there are already tools for producing biochar on site. One is the Tiger Cat 6050, a mobile machine that cooks biomass, and another is the KonTiki, a portable, cone-style kiln that can be used for yard wastes or forestry. And then there is the clever idea of a special tarp that can simply be thrown over logs that are burned.

Where can Enhanced Weathering be Used?

Some of the biggest emitting countries – like China, India, and the US – also have large amounts of agricultural land, warm and wet climates and abundant basalt, so they are best suited to enhanced weathering.
But Canada is also among the top ten countries that could benefit, despite its colder climate. A range of carbon removal techniques are needed to address climate change.
More generally, the use and the need for enhanced weathering are worldwide, for resources are piling up globally and not being used. They are problems now but instead could be contributing to growing crops and removing CO2 from the atmosphere.
Many governments in the world might consider offering incentives such as free soil-testing to farmers or even financial subsidies to adopt this technology. The use of rock dust for its liming effects is suggested as beneficial where the local soil’s pH requires it. There is enormous potential here and the foreseeable effects are only beneficial.

Recommendations

Among the speakers on the five forums about soil amendments we produced with Pugwash, there was no controversy whatever. Surprisingly, although panelists sometimes noted the paucity of definite scientific knowledge about a particular issue (e.g. how best to measure the amount of CO2 uptake), they disagreed about nothing. All the speakers concurred: the use of enhanced rock weathering is promising for its benefits to agricultural productivity, its potential reduction in the use of harmful synthetic fertilizers, and for the mitigation of global warming. No contraindications were identified and it is financially affordable.
Therefore, it is reasonable to anticipate that Pugwash also may reach an easy consensus: to recommend that the Canadian government, which already maintains agencies and research departments to support agriculture, should develop a concerted campaign to expand the use of enhanced rock weathering throughout all agricultural areas of the country.

[1]  Thomas Vanacore writes: I could make some recommendations for edits on the Enhanced Weathering and Remineralization section, though at this point there is enough good science to recommend a whole-systems approach to climate mitigation which includes Enhanced Rock Weathering, Biochar and Regenerative land management as a viable, if not required strategy for adaptation and mitigation of the effects of climatic instability, no matter what I say.  
However, the report is lacking an economic framework, or even a discussion of economics within the topic of environmental mitigation. Subsidy may work, but over time, if the cost of mitigation isn’t depoliticised, at the same time it is baked into the fabric of international monetary policy and trade, a long-term mitigation strategy won’t be feasible. Carbon taxes can’t work. Nothing based on taxation can be considered sustainable over time. 
 
Delton Chen has the right idea with his Global Carbon Reward, based on his Silver Gun Hypothesis. Under this scenario climate mitigation is funded through a small levy on international currency trading, which is managed by the central banks. Because the central banks have an imperative to mitigate systemic threats to the global economy, and climate chaos is certainly a systemic threat, it would stand to reason that the central banks would eventually get involved. See https://globalcarbonreward.org/
You forgot to send a note to Ryan Brophy, of Ontario. He was part of our first discussion. Ryan has announced construction of a new fertilizer compounding plant under Vanguard Crop Nutrition which is a V6 Agronomy company. Ryan is in the Vanguard of the regenerative ag movement in Canada. 
With regard to your last inquiry, I would be happy to endorse your initiative with the Pugwash group and will look forward to your next communications. With the climate emergency engulfing millions of acres of forest in Canada, sending a pall of smoke down into the United States, nothing short of willful negligence would have the politicians do nothing in response. But doing nothing meaningful seems to be the status quo. 
[2] Brophy writes: This report covers such an incredibly important topic and one that will play a large role in our production processes as we onshore our compound fertilizer manufacturing from Europe to Canada. Sustainably-derived basalts and high quality humic substances will be embedded in all of our granular products beginning fall 2024. https://www.globenewswire.com/news-release/2023/06/14/2688214/0/en/Canada-s-First-Compound-Fertilizer-Manufacturing-Facility-to-Supply-Domestic-Export-Markets.html
Additionally, we’re pleased to share that we’ll be commencing the largest yet broadacre deployment of metabasalt over 15,000 acres of Saskatchewan farmland this fall. Over 2 seasons, the product will be mixed with low pH phosphate rock and elemental sulphur (oilsand byproduct) to not only increase reactivity in alkaline prairie soils, but also to boost the agronomic value of the application process for the participant’s soils and on farm ROI. The project will be closely monitored by academics from U of Alberta, U of Sask and Trent U as well as a seasoned environmental technologist (with a focus on land reclamation) with modelling, long-term LCA and project support via Mangrove, a Toronto-based start-up (https://www.mangrove.systems/#Our-Platform-Section).

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.

Bullish on Battery Metals

Here’s a tip for conscientious investors: help promote electric cars and make a profit from it! There is a fierce competition to produce better and better batteries — for cars and all kinds of other potential uses. (Buses, trains, e-bikes, cell phones….) And certain metals are essential.

You already know about lithium, which is king right now. But there are other important metals too–especially nickel, cobalt, manganese and copper, which are needed for lithium batteries. An electric vehicle contains four times as much copper as a fossil-fueled model. Nickel is popular with EV battery-makers because it provides the energy density that gives the battery its power and range.

https://palladiumoneinc.com/investors/articles/2020/bullish-on-battery-metals. Feb 3, 2020

Carbon Parks

Is it time for Canada and the world to create carbon parks?

By Dan Kraus

Over the last 134 years, more than 8,300 parks and protected areas have been established across Canada that protect wildlife, examples of different habitats, spectacular scenery, recreational areas and places of cultural importance.

In a world where rapid climate change is impacting the stability of our planet’s health and threatening the well-being of future generations, we need a new type of protected area.

Nature plays an important role in carbon storage and reducing carbon pollution. When we lose forests, wetlands and grasslands, we lose species and habitats. But we also lose the carbon that these lands store in soil, roots and stems.
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