Novelist Wallace Stegner once said that all books should try to answer an “anguished question.” I believe the same is true for ideas, movements and emergency efforts. In the case of climate change, one anguished question is this: what can we do right now to help reduce atmospheric carbon dioxide from its current level back to 350 ppm?
Today, the only possibility of large-scale removal of carbon dioxide (CO2) from the atmosphere is through plant photosynthesis and related land-based carbon sequestration activities. Strategies include: enriching soil carbon, no-till farming with perennials, employing climate-friendly livestock practices, conserving natural habitat, restoring degraded watersheds, forests and rangelands, increasing biodiversity, lowering agricultural emissions, and producing local food.
Over the past decade, these strategies have been demonstrated individually to be both practical and profitable. The key is to bundle them into an economic and ecological whole with the aim of reducing the atmospheric content of CO2 while producing substantial co-benefits for all living things.
The climate challenge now confronting all societies on the planet is as daunting as it is straightforward: under a Business-As-Usual scenario, the rising content of heat-trapping trace gases in the atmosphere, principally carbon dioxide, pose a dramatic and potentially catastrophic threat to life on Earth.
The science of climate change and its correlation with industrial activity is clear. The challenge – and the opportunity – we face can be summed up in two pertinent graphs from the Scripps Institute at UC San Diego (http://scrippsco2.ucsd.edu/program_history) which chart the rise of the atmospheric content of CO2, a heat-trapping gas that has significantly contributed to the rise in the Earth’s temperature since 1750.
The dips correspond with planetary cooling periods (“ice ages”) and the subsequent rises correlate with warming trends. Note that past CO2 maximums barely exceeded 300 ppm. Today, it is nearly 400ppm – the highest level in at least 4 million years.
Under a Business-as-Usual model, CO2 will rise to 1500 ppm, or thereabouts, and not return to pre-industrial levels even tens of thousands of years into the future.
What does this mean? Human civilization is synonymous with the Holocene epoch, whose remarkably stable climate over the past 10,000 years gave rise to the agricultural revolution, among many other developments. However, a rising level of CO2 in the atmosphere jeopardizes this stability, perhaps permanently (on human time-scales).
Dr. James Hansen, the former Director of NASA’s Goddard Institute for Space Studies, and the nation’s top climate scientist, put it this way: “Business-as-usual greenhouse gas emissions, without any doubt, will commit the planet to global warming of a magnitude that will lead eventually to an ice-free planet.”
Since 2008, many climate activists and researchers have embraced a target of 350 ppm. For example, journalist Bill McKibben, who raised the first popular alarm about global warming back in 1989 with his book The End of Nature, co-founded the nonprofit 350.org, with the mission to get atmospheric CO2 back down to that level.
How do we get there?
In a 2009 editorial, Dr. Hansen proposed an answer: “cut off the largest source of these emissions – coal – and allow CO2 to drop back down to 350 ppm through agricultural and forestry practices that increase carbon storage in trees and soil.” In a research paper, Hansen specifically says that a 50 ppm drawdown via forestry and agricultural practices is quite plausible.
I consider these words to be a sort of ‘Operating Instructions’ for the 21st century. Personally, I’m not sure what to do about the coal side of his equation, which requires governmental action, but I have an idea about how to increase carbon storage in soils.
“Carbon is the basic building block for life. Over millennia a highly effective carbon cycle has evolved to capture, store, transfer, release and recapture biochemical energy in the form of carbon compounds. The health of the soil, and therefore the vitality of plants, animals and people, depends on the effective functioning of this cycle.” – Dr. Christine Jones, soil scientist (www.amazingcarbon.com)
The process by which atmospheric CO2 gets converted into soil carbon is neither new nor mysterious. It has been going on for tens of millions of years and all it requires is sunlight, green plants, water, nutrients, and soil microbes. According to Dr. Christine Jones, there are four basic steps to the CO2 / soil carbon process:
Photosynthesis: This is the process by which energy in sunlight is transformed into biochemical energy, in the form of a simple sugar called glucose, via green plants – which use CO2 from the air and water from the soil, releasing oxygen as a by-product.
Resynthesis: Through a complex sequence of chemical reactions, glucose is resynthesized into a wide variety of carbon compounds, including carbohydrates (such as cellulose and starch), proteins, organic acids, waxes, and oils (including hydrocarbons) – all of which serve as “fuel” for life on Earth.
Exudation: Around 30-40% of the carbon created by photosynthesis can be exuded directly into soil to nurture the microbes that grow plants and build healthy soil. This process is essential to the creation of topsoil from the lifeless mineral soil produced by the weathering of rocks over time. More active green leaves mean more roots, which mean more carbon exuded.
Humification: or the creation of humus – a chemically stable type of organic matter composed of large, complex molecules made up of carbon, nitrogen, minerals, and soil particles. Visually, humus is the dark, rich layer of topsoil that people generally associate with stable wetlands, healthy rangelands, and productive farmland. Once carbon is sequestered as humus it has a high resistance to decomposition, and therefore can remain intact and stable for hundreds of years.
Additionally, high humus content in soil improves water infiltration and storage, due to its sponge-like quality and high water-retaining capacity. Recent research demonstrates that one part humus can retain as much as four parts water. This has important positive consequences for the recharge of aquifers and base flows to rivers and streams.
The natural process of converting sunlight into humus is an organic way to pull CO2 out of the atmosphere and sequester it in soil for long periods of time. If the land is bare, degraded, or unstable due to erosion and if it can be restored to a healthy condition, with properly functioning carbon, water, mineral, and nutrient cycles, and covered with green plants with deep roots, then the quantity of CO2 that can be sequestered is potentially high. Conversely, when healthy, stable land becomes degraded or loses green plants, the carbon cycle can become disrupted and will release stored CO2 back into the atmosphere.
In other words, healthy soil = healthy carbon cycle = storage of atmospheric CO2. Any land management activity that encourages this equation, especially if it results in the additional storage of CO2, can help fight climate change.
Or as Dr. Christine Jones puts it: “Any…practice that improves soil structure is building soil carbon.”
This is good news for a simple reason: two-thirds of the Earth’s terrestrial surface is grassland – and home to two billion people who depend on livestock at least partially for their livelihood. This means that managing the land for CO2 sequestration, even on a small scale, could have a big impact on people and the planet. Livestock is key because it is an important source of food and wealth (and culture) to much of the Earth’s human population and thus could be mobilized for carbon action.
“Healthy grasslands, livestock and associated livelihoods constitute a win-win option for addressing climate change in fragile dryland areas where pastoralism remains the most rational strategy for the wellbeing of communities,” wrote the authors of a United Nations report in 2010. “It is a win-win scenario for sequestering carbon, reversing environmental degradation and improving the health, well-being and long term sustainability of livestock based livelihoods.” (for citations see www.carbonranching.org)
The effort to sequester carbon in soil also produces a list of co-benefits that make the whole enterprise even more vital. They include:
- Local grassfed and organic food. By managing land for a healthy grass cover, a carbon ranch is the natural setting for raising grass-fed livestock, whose environmental and human-health benefits are well-documented.
- Improved ecosystem services. These services include the provision of food, fresh water, wood, fiber, fuel, and biodiversity; flood, pest and disease regulation; nutrient cycling, soil stability, biotic integrity, watershed function, and photosynthesis; and spiritual, educational, recreational, and aesthetic experiences.
- Rural economic development. Producing local food, restoring creeks and rangelands, marketing ‘climate-friendly’ enterprises, and developing local energy will require a great deal of work, and therefore could create, potentially, a great deal of paychecks for rural residents.
- Maintenance of culture and diversity. This work can strengthen and support local and regional land-based cultures. It will require a mixing of innovation with tradition, but this can be a healthy way of rejuvenating a sense of community and cultural continuity.
- Bridging the Urban-Rural Divide. Most carbon sequestration work will take place in the countryside, which means it has a huge potential to bridge the long-standing and expanding gulf that separates urban and rural residents.
- Opportunities for the next generation. This work will be attractive to young people who want to get into (or back to) farming, ranching, restoration or otherwise pitch in with the effort to fight climate change.
None of this will be easy. In fact, the obstacles standing in the way of this work and sharing its many co-benefits are large and diverse. Some see salvation in high technology, including the ‘capture’ of CO2 at its source to be stored underground. Unfortunately, these technologies, even if practical, are years away from deployment. And the climate crisis is happening now.
We don’t need high technology – we have the miracle of photosynthesis already, the original low technology. It won’t save the planet by itself, of course, but it is essential to the quality of life on Earth no matter how much CO2 exists in the atmosphere. Too often, however, our eyes seem fixed on the stars and our minds dazzled by distant horizons, blinding us to possibilities closer to home. Perhaps we should be looking down, not up.
An answer to our anguished question lies at our feet, among the grass and the roots.