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Soil Health: It’s All About the Carbon

Author: Mark Watson

Adding carbon to the soil is critical to restoring health to the soil by increasing the organic matter content.

Producers in today’s modern agricultural systems are working with soils that contain far less carbon than our soils originally contained prior to the implementation of modern agriculture. All of our soils are now degraded.

The good news is we now know how we can regenerate our soils and put the carbon back in the soil. This is a very simple process, but at the same time, also very difficult.

Finding Stability

So why is carbon so important? It’s the building block for soil health. As you increase the carbon content, you begin to improve the aggregate stability. These aggregates are formed by excretions from the soil microbes, which begin to stabilize the soil particles into larger aggregates. This provides the home for all the soil microbes living in these aggregates.

A healthy soil provides a healthy environment for these soil microbes. The microbes will provide the nutrient cycling of soil organic matter making nutrients available for the plants growing in the soil.

These aggregates also provide the pore space necessary to infiltrate and store water in the soil. In our semi-arid environment on the Plains, the ability to infiltrate and store water is critical to crop production.

Stable aggregates that can infiltrate and store additional water can also lower our irrigation pumping requirements by improving soil water efficiency. Lowering our groundwater consumption is critical to stabilizing the currently rapid decline of our groundwater resource.

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How Carbon Farming Could Reverse Climate Change

Author: Vera Liang Chang 

As the climate crisis heats up, agriculture is in the hot seat, not only as a contributor to climate change, but also as a potential solution. Eric Toensmeier has spent the last several years tracking both. A lecturer at Yale University, a senior fellow with Project Drawdown, and the author of several books on permaculture, Toensmeier is also the author of the newly-released book, The Carbon Farming Solution: A Global Toolkit of Perennial Crops and Regenerative Agriculture Practices for Climate Change Mitigation and Food Security.

Toensmeier argues that when combined with immense reduction in fossil fuel emissions and adaptation strategies, carbon farming has the potential to return the carbon dioxide in our atmosphere to the “magic number” of 350 parts per million, while feeding people, building more fertile soils, and contributing to ecosystem health.

We spoke with Toensmeier about his thoughts on agroforestry, what happened at the climate summit in Paris, and what strategies farmers, communities, and governments can take to launch carbon farming projects. This conversation has been edited for brevity.

When did you start working on carbon farming and why?

In 2009, I read the book Now or Never. Author Tim Flannery wrote that we need to mitigate climate change and a good way to do that is planting forests. But we can’t plant enough forests because we need land for agriculture. I thought to myself: there are trees that are agriculture; perhaps I have a contribution to make.

You note that agroforestry and perennial staple crops—strategies with immense potential to sequester carbon—have been given little attention to date. Why is that?

There are good reasons to focus on lower-sequestration strategies like no-till, organic annual cropping, and managed grazing. They don’t require farmers to make big changes to what they do, they don’t require people to change their diets, and they don’t require us to add unfamiliar foods to our food system. For example, an animal raised in a managed grazing system is raised differently than in a conventional system, but the cheese is still more or less the same. Moving into a fully perennial system would require fundamental transformation of our food system, from development to technologies. The notion that agriculture can incorporate trees—let alone the notion that agriculture be based on trees—is still new for most of us. Agroforestry produces only a tiny percentage of our food in the U.S.

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A Great Day: Saving the World from Catastrophic Climate Change

[ English | Español ]

Author: Courtney White

“Dec 1, 2015, will be one of the most important days in human history. It will be seen as the tipping point when the world was saved from catastrophic climate change.” – André Leu, President of the IFOAM (Organics International)

One of the most significant events at the recent UN climate summit in Paris went largely unnoticed.

We know the headlines: In an effort to slow dangerous climate change, representatives from 197 nations concluded a two-week marathon of negotiations by signing a breakthrough agreement that commits governments to targeted reductions in greenhouse gas emissions starting in 2020.

This was justifiably big news. After 20 years of failed attempts to craft an international consensus on climate action, most spectacularly in Copenhagen in 2009, the world simply had to get its act together. It did so, to well-earned applause, on December 12, 2015.

So what happened on December 1?

That’s the day the French government launched the 4 per 1000 Initiative: Soils for Food Security and Climate, a plan to fight climate change with soil carbon. The initiative’s goal is this: to increase global soil carbon stocks by 0.4 percent per year by drawing down atmospheric carbon dioxide (CO2) via the increased photosynthesis of regenerative farming and land use.

On the surface, that may not sound like a lot of carbon, (it amounts to 10 billion tons of carbon per year sequestered in global soils), but French scientists say it’s enough to halt human-induced annual increases in CO2 globally.

That sounds like a front page headline to me!

How will the initiative succeed? The key is regenerative agriculture. France, for example, intends to hit its 4/1000 target by employing agro-ecological practices on 50 percent of its farms by 2020.

Agro-ecological practices restore damaged land and build biologically healthy soil through the use of cover crops, perennial plants, no-till farming, and livestock grazing patterns that mimic nature. If managed properly, these nature-based practices not only increase carbon stocks in soil, they also can dramatically reduce the amount of greenhouse gases produced by the use of fossil fuel in industrial agriculture, one of the biggest polluters on the planet.

Agro-ecological practices also increase resilience to climate change. In an op-ed published days after the French announcement in Paris, Michael Pollan and Deborah Barker wrote:

Regenerative farming would also increase the fertility of the land, making it more productive and better able to absorb and hold water, a critical function especially in times of climate-related floods and droughts. Carbon-rich fields require less synthetic nitrogen fertilizer and generate more productive crops, cutting farmer expenses.

Those are bold, but as we’ll see later, realistic claims. But here’s the best news: Regenerative agriculture is a shovel-ready solution to climate change.

Agro-ecological practices are practical, profitable and have been ground-tested by farmers and ranchers around the world for decades. In fact, shovel-readiness is a big reason why more than 100 nations, international NGOs and farmers’ organizations signed onto the 4/1000 Initiative–and why many more have signed on since then.

After years of neglect, soil carbon is now viewed as key to how the world manages climate change. “[It] has become a global initiative,” said French Agriculture Minister Stéphane Le Foll. “We need to mobilize even more stakeholders in a transition to achieve both food security and climate mitigation thanks to agriculture.”

“The time for talking is finished,” said IFOAM’s André Leu. “Now is the time for doing. The technology is available to everyone. It is up to us to mobilize in time. Let’s start working to get this done and give our world a better future.”

Paying for regeneration

A critical step will be creating a viable carbon economy where regenerative farmers and ranchers can be paid to build soil carbon. This has been a difficult challenge so far, but thanks to the Paris Agreement, 197 nations now have a huge incentive to draw down their emissions to meet official targets. And regenerative agriculture can help get them there.

From the carbon emitter’s perspective, offsetting carbon dioxide emissions with verifiable increases in soil carbon, validated now by the French government’s 4/1000 Initiative, will likely stimulate other nations to create market-based mechanisms which, in turn, will encourage farmers and ranchers to adopt regenerative practices, round and round. From society’s perspective, all this is great news!

Creating carbon markets isn’t a new idea. Over the past twenty years, a variety of efforts have been made to energize a voluntary carbon credit trading system, including programs in Europe, Australia, New England, California, and Vancouver, British Columbia, each with varying degrees of success. In New Mexico, where I live, the state legislature considered a bill in 2015 that would have created a policy framework for enacting a carbon credit system–a first for the state.

New Mexico attempted to established a carbon credit as a contract right and to create a five-member board to review and audit the credits as potential offsets for carbon emitters. The board specifically identified the removal of greenhouse gases from the atmosphere and its accumulation within plants, soils and geologic formations as a legitimate means by which a credit can be created–also a first (specifically, one carbon credit equaled one metric ton of CO2 or its equivalent).

Unfortunately, the bill didn’t become law, and it’s not the only model for paying for regeneration. But the bill represents an important step toward stimulating market-based responses to climate change.

Serious concerns about the shortcomings of carbon offset markets (sometimes called cap-and-trade) have been raised. This is especially true for organic, regenerative and family-scale agriculture, which could easily be pushed aside by large industrial producers. Here’s a useful primer on how climate-friendly agriculture can be treated fairly in a carbon economy.

The bottom line is this: We need state and federal policies that make the polluters pay, create publicly-controlled pools of money, and pay regenerative farmers and ranchers for building carbon stocks in their soils.

Science is on our side

Markets and their regulators will require sound science and hard numbers–credible and verifiable–to work effectively. This is a challenge, however, because understanding soil carbon involves chemistry, biology, ecology, hydrology, and agronomy—which means the science can get complex quickly, for researchers and laypeople alike. Fortunately, there has been a veritable explosion of soil carbon science recently, creating a clearer portrait of carbon’s potentials.

One researcher whose work has shed exciting light on regenerative agriculture is Dr. David Johnson, a molecular biologist at New Mexico State University. Johnson believes that “getting the biology right” is critical to creating significant increases in soil carbon stocks.

It’s essentially a two-step process, according to Johnson: (1) get life back into soils that have been stripped of their biological fertility by industrial agriculture; and (2) employ practices that bring about a shift in the soil from bacteria-dominated to fungi-dominated communities. The latter is important because fungi are the “carbon brokers” between plant roots and soil microbes. This process also improves soil structure which improves its ability to resist erosion–equally crucial to long-term carbon storage.

Of course, all of this soil rebuilding can be undone by the plow, which exposes microbes to the killing effect of heat and light. That’s why not turning the soil over is a key component of regenerative agriculture.

Johnson’s research also shows that “getting the biology right” reduces the amount of carbon that is “burped” back into the atmosphere (as CO2) by microbes as a waste product. This is important because the viability of long-term carbon storage in soils–and thus the size of monetary payments to farmers and ranchers from markets–depend on there being more carbon flowing into the soil system than flowing back out.

It’s not just about money. Additional carbon improves plant productivity, improves water infiltration and soil water-holding capacity, reduces the use of synthetic amendments, and promotes a healthy environment for pollinators and other beneficial insects.

A win-win for the land and ourselves!

Johnson notes that nature is three to four times more productive than any agricultural system yet devised by humans. And nature achieves that productivity without pesticides, synthetic amendments, irrigation or monocropping.

“Shouldn’t we be asking what we’re doing wrong?” Johnson said in an interview. “Plus, nature had the capacity to increase soil carbon in the past. Our task is to find out how it was done and mimic it in our current practices.”

Improved soil fertility, better food, more efficient use of water, reduced pollution, fewer energy requirements, better animal health, increased biodiversity, and keeping global warming in check–all possible for as little as 4 per 1000 a year!

For more information see:

Carbon Sequestration Potential on Agricultural Land by Daniel Kane, National Sustainable Agriculture Coalition

Soil Carbon Restoration: Can Biology Do the Job? by Jack Kittredge, Northeast Organic Farming Association

***

Courtney White, co-founder and former executive director of the Quivira Coalition, is the author of multiple essays and books, including “Grass, Soil, Hope: A Journey Through Carbon Country” and “The Age of Consequences.”  

French Ministry of Agriculture Official, Leading U.S. Soil Scientists Outline Plan to Stall Global Warming through Soil Carbon Sequestration

Regeneration International, IFOAM Organics International and other NGOs Host Experts and Media for Critical Climate-Agriculture Discussion

FOR IMMEDIATE RELEASE

March 9, 2016

CONTACT: Katherine Paul, katherine@wordpress-409503-1481076.cloudwaysapps.com, 207-653-3090; Alexis Baden-Mayer, alexis@organicconsumers.org, 202-744-0853; Ercilia Sahores, ercilia@wordpress-409503-1481076.cloudwaysapps.com

WASHINGTON DC—Today Catherine Geslain-Lanéelle, Director General for the Economic and Environmental Performance of Enterprises of the French Ministry of Agriculture spoke to climate and agriculture reporters and climate and food activists about “4 per 1000: Soils for Food Security and Climate,” an initiative to mitigate, and eventually reverse, climate change. The Initiative, launched in December at the COP21 Climate Summit in Paris, calls for countries to increase soil carbon worldwide by 0.4% per year. So far, 26 countries and more than 50 organizations have formally signed on to the initiative.

Also speaking at today’s event, held at the National Press Club, was André Leu, president of IFOAM Organics International, and leading soil scientists: David C. Johnson, Ph.D., New Mexico State University; Kris Nichols, Ph.D., Rodale Institute; Tim LaSalle, Ph.D., Cal Poly San Luis Obispo; and Richard Teague, Ph.D., Texas A & M. (Full bios here)

Leu told the audience: “The French Government 4 per 1000 Initiative is a fantastic win, win, win for the planet. By changing agriculture to one that regenerates soil organic carbon we not only reverse climate change we can improve farm yields, increase water holding capacity and drought resilience, reduce the use of toxic agrochemicals, improve farm profitability and produce higher quality food.”

LaSalle said: “If we stopped all GHG emissions today, the planet would still warm for the next 40 years.  We absolutely must stop the emissions.  But what is now also imperative is that we reduce this legacy of CO2 in our atmosphere and oceans.  We have mechanism to do this through photosynthesis and our soils.  And with the right incentives in place, our farmers and ranchers the world over can perform this heroic feat. But this is key: We must create the proper incentives for our civilization’s survival.”

Teague said: “Data from leading conservation ranchers in North America indicates that with appropriate grazing management the goal of the COP21 Climate Summit in Paris to increase soil carbon on grazed agricultural land by 0.4% per year can be exceeded by a factor of 2 or 3. With appropriate grazing management, ruminant livestock consuming only grazed rangeland and forages can increase C sequestered in the soil to more than offset their GHG emissions. This would result in a GHG-negative footprint, while at the same time supporting and improving other essential ecosystem services for local populations. Affected ecosystem services include water infiltration, nutrient cycling, soil formation, reduction of soil erosion, carbon sequestration, biodiversity, and wildlife habitat.”

Nichols said: “Research shows that soils are carbon-deficient, which is not only causing problems with soil erosion, but also negatively impacting air and water quality, water management, increasing flooding and drought, and negatively impacting nutrient cycling in soil and nutritive quality of food. Organic farming practices will regenerate soils by putting carbon back into the earth.”

Johnson said: “Microbes have fashioned the destiny of our planet for over 4 billion years, and they currently facilitate the day-to-day cycling of all earth’s elemental components flowing between terrestrial, oceanic and atmospheric environments. In efforts to sustain our civilizations over the past 200-plus years, we have employed agricultural practices that exhaust soil carbon resources, a practice that in the past has invariably led to the downfall of many civilizations. Restoring the population, structure and function of microbes in soils of our agroecosystems will begin the process of building soil health, and in turn promote development of mutualisms between plants and microbes towards improving soil fertility and soil carbon reserves while concurrently reducing atmospheric CO2.”

Joining Regeneration International in organizing today’s event were Biodiversity for a Livable Climate, GrassPower, IFOAM Organics International, Rodale Institute and Soil4Climate.

Additional materials:

Speaker bios
Fact Sheet
Program

Regeneration International,  a project of the Organic Consumers Association, is a 501(c)(3) nonprofit dedicated to building a global network of farmers, scientists, businesses, activists, educators, journalists, governments and consumers who will promote and put into practice regenerative agriculture and land-use practices that: provide abundant, nutritious food; revive local economies; rebuild soil fertility and biodiversity; and restore climate stability by returning carbon to the soil, through the natural process of photosynthesis. 

The Rise of Regenerative Agriculture

Imagine a world in which industrial crop production supports healthier air, water and soil; a time when rural communities thrive thanks to their local farms; a world where foods are rife with nutrients and the future of agriculture is a thing of beauty and promise …

This is the vision that grows within regenerative agriculture—a practice of farming, based on ecological principles, that builds soil health and recaptures carbon emissions from the atmosphere.

Regenerative agriculture is building on the principles and practices of organic to help communities and soil thrive. “There is an international movement afoot today that says it’s time to take things a step further,” says industry veteran Tom Newmark, founder and chair of Carbon Underground—a nonprofit dedicated to restoring soil health and helping to address climate issues. Regenerative Agriculture is that step, according to Newmark and a growing number of vocal advocates.

Many modern farming systems, which often include the use of heavy machinery, excessive tilling and harmful chemicals, disrupt the organic matter in the soil. Once the carbon molecules in the soil get exposed to the air, they combine with oxygen to create carbon dioxide, turning a natural carbon exchange system from healthy and fertile soil into a toxic atmospheric gas. These unnatural processes have sickened the living systems within the soil, and in many cases have cut off vitality completely—ruining the health and sustainability in all too many agricultural ecosystems.

The healthy side of dirt

In her recent book, The Soil Will Save Us (Rodale Press, Inc., 2014), author Kristin Ohlson writes about the relationship that plants have with microorganisms in the soil, and the impact that disturbing the soil through unnatural, modern methods is having on our food, our climate, our local communities and our future as a whole.

In a teaspoon of healthy soil, Ohlson says, there are billions and billions of microorganisms, all interacting with plants in a “complex and crucial” ecosystem. “Because it’s not visible to the naked eye, humans have only sort of become aware in the last couple of decades what’s going on down there,” she explains.

Organic carbon in soil is a reservoir for plant nutrients—those that are essential to the health of humans that consume them, as well as the ecosystem they are meant to thrive within. These nutrients include calcium, nitrogen, phosphorous, magnesium and micro-nutrients, which are released in the decomposition though microbial processes.

Carbon in the soil ensures these processes become a vital part of nutrient storage, soil structure, microbial activity, water retention, soil temperature and biodiversity—all elements that contribute to nutrient-rich soil and foods from that soil and the living ecosystem they sustain.

Known by scientists as agro-ecological farming, the principles of regenerative agriculture create healthy farms through practices such as crop rotation, cover cropping, composting and reduced tillage.

Healthy farms can be just as productive, if not more productive, than industrial farms, but are much better for the environment, the economy and the people who plant, harvest and eat the food.

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Soils for food security and the climate

Thanks to plants and living organisms, soils contain two to three times more carbon than the atmosphere.  Carbon-rich soil organic matter is essential: it retains the water, nitrogen and phosphorus that are indispensable to agriculture. But alternating phases of drought and intense rainfall accentuate erosive phenomena.  In the long term, almost 30 million hectares of arable land could be lost every ten years.

The solution: carbon storage

If the carbon stocks in the top 40 centimetres of soil could be increased by 4 per 1000 each year, this could theoretically help to stop the current rise in the quantity of CO2 in the atmosphere, on condition that deforestation is halted.

The methods: 5 ways to develop soil management and agroecology

  1. Avoid leaving the soil bare in order to limit carbon losses
  2. Restore degraded crops, grasslands and forests
  3. Plant trees and legumes which fix atmospheric nitrogen in the soil
  4. Feed the soil with manure and composts
  5. Conserve and collect water at the feet of plants to favour plant growth

Applied to the surface horizon of the world’s soils, or a stock of around 860 billion tonnes of carbon, the 4‰ target would result in the annual storage of 3.4 billion tonnes of soil carbon, thus counterbalancing the rise in atmospheric CO2. This measure would be extended beyond agricultural soils to most soils and their uses, including forests.

570 million farms in the world and more than 3 billion people living in rural areas could implement these practices.

The cost for crops, 20 to 40 USD per tonne of CO2. For grasslands and forests, 50 or 80 USD per tonne of CO2. Carbon would continue to accumulate in soils for twenty to thirty years after the introduction of good practices, if they are sustained.

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On World Soil Day, OCA, IFOAM Laud French Government’s Initiative to Address Climate Change via Carbon Sequestration in Organic Soil

FOR IMMEDIATE RELEASE

December 5, 2015

CONTACT:  Organic Consumers Association, Katherine Paul, 207-653-3090, katherine@organicconsumers.org

On World Soil Day, OCA, IFOAM Laud French Government’s Initiative to Address Climate Change via Carbon Sequestration in Organic Soil

December 5 marks end of International Year of the Soils, beginning of work to replace degenerative industrial ag with organic regenerative strategies that can reverse global warming

PARIS – As the International Year of the Soils officially ended on December 5, World Soil Day, Organic Consumers Association (OCA) and IFOAM Organics International (IFOAM) praised the French Government’s 4 per 1000 Initiative as the most important climate strategy to come out of the COP21 Paris Climate Talks.

“This is the most exciting news to come out of COP21,” said Andre Leu, president of IFOAM Organics International. “By launching this Initiative, the French Government has validated the work of scientists and farmers and ranchers who have demonstrated the power of organic regenerative agriculture to restore the soil’s natural ability to draw down and sequester carbon.

“It is imperative that world the decarbonizes the atmosphere from 400 ppm to far less than 350 ppm to stop catastrophic climate change. The combination of renewable energy to stop further emissions and drawing down excess CO2 into the soil is most achievable way to do this and it is readily available to us now.”

“What better way to celebrate World Soil Day than to recognize that healthy soil is our most available, most promising solution to global warming,” said Ronnie Cummins, OCA’s international director. “As we celebrate this important Initiative and also mark the end of the International Year of the Soils, we look forward to what is arguably the most important work our organizations and our governments face—reversing global warming before it’s too late.”

OCA and IFOAM Organics International are among the 100 partners who were signed on at the launch of the “4 per 1000” Initiative. Partners include developed and developing states, international organizations, private foundations, international funds, NGOs and farmers’ organizations.

The partners have agreed to reinforce their actions on appropriate soil management, recognizing the importance of soil health for the transition towards productive, highly resilient agriculture.

The “4/1000 Initiative: Soils for Food Security and Climate” aims to protect and increase carbon stocks in soils.  According to the French Agriculture Ministry, a 0.4-percent annual growth rate in soil carbon content would make it possible to stop the present increase in atmospheric CO2 and achieve the long-term objective of limiting the average global temperature increase to the 1.5°C to 2°C threshold beyond which the Intergovernmental Panel on Climate Change (IPCC) says would lead to a climate disaster.

The initiative consists of a voluntary action plan under the Lima-Paris Action Agenda (LPAA), backed by an ambitious research program.

The United Nations officially declared 2015 the International Year of the Soils, beginning on December 5, 2014, and ending on World Soil Day, December 5, 2015. The official closure took place at FAO headquarters on December 4.

IFOAM – Organics International is the worldwide umbrella organization for the organic agriculture movement, which represents close to 800 member organizations  in about 125 countries.

The Organic Consumers Association (OCA) is an online and grassroots non-profit 501(c)(3) public interest organization representing 2 million U.S. consumers campaigning for health, justice, and sustainability. The Organic Consumers Fund is a 501(c)4 allied organization of the Organic Consumers Association, focused on grassroots lobbying and legislative action.

How ‘Natural Geoengineering’ Can Help Slow Global Warming

Author: Oswald J. Schmitz

As natural wonders go, perhaps the most awe-inspiring is the annual migration of 1.2 million wildebeest flowing across East Africa’s vast Serengeti grassland. It would be a tragedy to lose these animals. But we almost did in the mid-20th century when, decimated by disease and poaching, their numbers crashed to 300,000.

The consequences of that collapse were profound. Much of the Serengeti ecosystem remained ungrazed. The accumulating dead and dried grass in turn became fuel for massive wildfires, which annually burned up to 80 percent of the area, making the Serengeti an important regional source of carbon dioxide emissions.

Then, conservation programs to eradicate disease and crack down on poaching led to the recovery of the wildebeest, restoring the grazing system and reversing the extent of the large-scale wildfires. Grazing now causes much of the carbon in grass to be released as animal dung, which is in turn incorporated by insects into soil reservoirs that are not prone to burning. The Serengeti ecosystem has now reverted to a carbon dioxide sink so large that it is estimated to offset all of East Africa’s current annual fossil fuel carbon emissions.

The wildebeest decline and recovery taught a valuable lesson, not only in how easy it is to loose an iconic animal species, but, more importantly, how the loss of a single species can have far-reaching ramifications for ecosystems — and the climate. Mounting evidence from ecological science is showing that one or a few animal species can help determine the amount of carbon that is exchanged between ecosystems and the atmosphere. It’s not that any single animal species by itself has a huge direct effect on the carbon budget. Rather, as the wildebeest case shows, by being an integral part of a larger food chain the species may trigger knock-on effects that grow through the chain to drive significant amounts of carbon into long-term storage on land or in the ocean.

Keep Reading in Yale Environment 360

Ruminants and methane: Not the fault of the animals

Author: Alan Broughton

Cattle and sheep are blamed for contributing to greenhouse gases, belching out methane, and farmers in the future are likely to be taxed because of it.

The recent Green Left Weekly climate change liftout [issue #1078] calls for a drastic reduction in sheep and cattle numbers. There is a TV advertisement, urging people to “go vego to save the planet”. This is a gross misunderstanding of the ruminant carbon cycle.

Ruminants have always emitted methane; it is not something new. Huge herds of wild buffalo, cattle, goats, sheep, deer, cameloids and wildebeest have grazed the grasslands of the world for millions of years. The American prairies once supported greater numbers of bison than they now do cattle, despite the intensive corn and soy production that feeds them.

Methane emissions from wild ruminants was never a problem because nature does not permit waste — the methane was used as food for methanotrophic bacteria in the soil and neutralised. It was never a problem until agricultural practices started destroying these methanotrophic bacteria, which are very sensitive to chemical fertilisers and herbicides. These bacteria reactivate in biologically managed soil.

However, methane is not the whole picture. When the contribution of livestock to soil carbon sequestration is taken into account it is easy to see that ruminants do not increase greenhouse gases if they are managed well.

Grassland soils are the greatest sequesters of carbon — greater than forests. In the top one metre of soils in temperate grasslands there is an average of 236 tonnes of carbon, compared to 96 in temperate forest soils and 80 in cropland.

Keep Reading in Green Left Weekly

Growing our way out of climate change by building with hemp and wood fibre

Author: Mike Lawrence

How can buildings help with climate change? It’s all about renewables and “sequestered carbon”.

The Department for Business, Innovation and Skills’ 2010 report on Low Carbon Construction concluded that construction was responsible for around 300m tonnes of carbon dioxide emissions, which is almost 47% of the UK’s total. Of this, around 50m tonnes is embedded in the fabric of buildings.

Making one tonne of steel emits 1.46 tonnes of CO2 and 198kg of CO2 is emitted make one tonne of reinforced concrete. One square meter of timber framed, hemp-lime wall (weighing 120kg), after allowing for the energy cost of transporting and assembling the materials actually stores 35.5kg of CO2.

If we can convert plants into building materials, we are in a win-win situation. Plants use the energy of the sun to convert atmospheric CO2 and water into hydrocarbons – the material from which plants are made.

The plant acts as a carbon store, sequestering (absorbing) atmospheric CO2 for as long as the plant continues to exist. This CO2 is only re-released when the material is composted or burnt, and the great thing is that through replanting it you can re-absorb this CO2 annually, in the case of straw or hemp, or every decade or so in the case of timber, rather than the 300m years that it takes to recycle coal or oil.

Keep Reading in The Guardian