[This is the final excerpt from my book Age of Consequences. I return to the theme of carbon, climate and hope – the subject of new posts to follow]

Novelist and historian Wallace Stegner once said that every book 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, an anguished question is this: what can we do right now to help reduce atmospheric carbon dioxide (CO2) from its current (and future) dangerously high levels?

In an editorial published in July of 2009, Dr. James Hansen of NASA proposed an answer: “cut off the largest source of emissions—coal—and allow CO2 to drop back down . . . through agricultural and forestry practices that increase carbon storage in trees and soil.” I consider these words to be a sort of ‘Operating Instructions’ for the twenty-first century. Personally, I’m not sure how we accomplish the coal side of the equation, which requires governmental action, but I have an idea about how to increase carbon storage in soils.

I call it a carbon ranch.

The purpose of a carbon ranch is to mitigate climate change by sequestering CO2 in plants and soils, reducing greenhouse gas emissions, and producing co-benefits that build ecological and economic resilience in local landscapes. “Sequester” means to withdraw for safekeeping, to place in seclusion, into custody, or to hold in solution—all of which are good definitions for the process of sequestering CO2 in plants and soils via photosynthesis and sound stewardship.

The process by which atmospheric CO2 gets converted into soil carbon is neither new nor mysterious. It has been going on for millions and millions of years, and all it requires is sunlight, green plants, water, nutrients, and soil microbes. According to Dr. Christine Jones, a pioneering Australian soil scientist, 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 byproduct.

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 percent 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. The amount of increase in organic carbon is governed by the volume of plant roots per unit of soil and their rate of growth. More active green leaves mean more roots, which mean more carbon exuded.

Humification: This is the creation of humus—a chemically stable type of organic matter composed of large, complex molecules made up of carbon, nitrogen, and minerals. Visually, humus is the dark, rich layer of topsoil that people associate with rich gardens, productive farmland, stable wetlands, and healthy rangelands. Land management practices that promote the ecological health of the soil are key to the creation and maintenance of humus. Once carbon is sequestered as humus, it has a high resistance to decomposition and therefore can remain intact and stable for hundreds or thousands of years.

Additionally, high humus content in soil improves water infiltration and storage, due to its spongelike quality and high water-retaining capacity. Recent research demonstrates that one part humus can retain as much as four parts water. This has positive consequences for the recharge of aquifers and base flows to rivers and streams, especially important in times of drought.

In sum, 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, 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 release stored CO2 back into the atmosphere.