DeCarb / ReCarb: Climate Change and the Balance of Carbon

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“Only a system can be sustainable.”
— Mark Miodownik, materials scientist and author of Stuff Matters

If all carbon emissions ceased tomorrow — if every country that originally signed onto the Paris Accord more than met is commitment — atmospheric carbon levels (CO2) would still continue to rise. Decarbonization is essential, but on its own will not be enough to slow climate change. More sobering is that even if it were and the global temperatures returned to pre-industrial levels, we would still be faced with an existential crisis: The mass loss of carbon from the land, a trend that rapidly accelerated over the 20th century, diminished the fertility of the soil, with profound impacts on hydrology (how water, in all its forms, circulates around the Earth).

As the climate warms during the 21st century, farming is expected to expand north in Russia and Canada. These “frontier soils” hold as much as 177 gigatons of carbon. Worst case, farming could unleash the “equivalent of over a century of current United States CO2 emissions,” according to a new study from Conservation International.

Too much CO2 in the air and global temperatures rise and weather gets weird. Too much CO2 in water turns it acidic, much to the dismay of anything with a shell. But when there is not enough carbon in soil, it turns to dust, blows away and leaves the intricate web of microbial life — the literal foundation of all life on Earth — in tatters. It turns out the meek don’t inherit the Earth. They transform it into an Eden.

“DeCarb / ReCarb” is shorthand for a framework that will restore the carbon balance: Decarbonize air and water. Recarbonize land. This is the yin and the yang that makes the whole complete.


Decarbonization, the first part, is well-understood. Indeed, we have become a world of carbon counters with nations, cities, companies, universities and individuals constantly declaring emissions reduction goals and setting timetables. There are two basic, dovetailing strategies: energy efficiency and switching to renewable power supplies (solar, wind, hydrogen). Use less. Use clean.

Improved battery storage, policy incentives and “green finance” are all important to the transition. So is integrative design, a methodology that prioritizes systemic efficiency gains over incremental improvements through analysis of combined capital and operating expenses (capex and opex). For example, spending more on insulation could mean spending less on HVAC — potentially eliminating the need for a conventional furnace altogether. “Most people don’t yet think of design as a scaling vector — a way to make things big, fast,” notes Amory Lovins, co-founder of Rocky Mountain Institute. Yet the potential is enormous.

Energy efficiency already has an impressive track record. Over the last forty years efficiency gains helped slash primary energy use in the US to half of what had been predicted — and at the same time the economy tripled in size by GDP. This wasn’t a coincidence. Energy efficiency is essential to thriving economy because capital that would have gone to pay utility and fuel bills is freed up to be invested in other things. Consumers have more spending power.

Also, the energy that didn’t need to be generated — the coal, oil and gas that didn’t need to be burned over all those decades — kept as much as a 100 ppm of CO2 from spewing into the atmosphere. Put another way, without efficiency we would already be well past the point of no climate return.

Efficiency means less energy is needed to deliver a service: a 60W equivalent LED bulb uses less than 15% of the energy required by 60W incandescent bulb — and lasts an estimated 21 times as long. This is a classic capex / opex win. Not only is the LED cheaper to run, you also don’t need to buy as many: just one for every 21 incandescents. As architect Ludwig Mies Van Der Rohe famously said, “Less is more.” It really is.

Efficiency is essential for the transition to renewables because it means that fewer solar panels, wind turbines or fuel cells are needed to keep everything humming along. This capital savings, combined with dramatic reductions in the cost of generating clean power (capex and opex), make it increasingly more difficult to justify the mining, drilling, transport and burning of fossil fuels, even before carbon pollution is taken into account.

Historically, efficiency has had 30x the impact of renewables in terms of reducing fossil fuel use. The fastest way to “keep it in the ground” is to crash demand. Together, efficiency and renewables, two sides to the same coin, will do just that.


ReCarb strategies are often lumped together under catch-all heading of sequestration. The dictionary definition of sequester is “to isolate or hide away” and some ReCarb strategies do exactly that. Biochar, for example, an exceptionally stable form of carbon created through a low-oxygen burning process called pyrolosis, is excellent for sequestering carbon.

Depending of the source used to create the biochar (which can range from plant biomass to plastics), it can be used as a soil amendment or as an additive that improves the functionality of materials such as asphalt and cement. The point is that no matter how it is used, the carbon stays locked up and out of the atmosphere for decades, or even centuries.

Corralling Carbon

Molecular recycling is another strategy. There are two main ways to do this: The first involves intercepting CO2 in an industrial smokestack, long before it can become a heat-trapping greenhouse gas in the atmosphere. The second captures CO2 directly from the air, which requires large, expensive machines. Either way, it can be used as a chemical feedstock to create fuel, synthetics, plastics, lubricants and, yes, vodka.

Although the lion’s share of a barrel of oil is used to make fuels — gasoline, jet fuel and diesel — an estimated 7% is used to create chemical feedstocks. Similarly, although natural gas and coal are primarily used for electric power generation or as a source of heat and cooking gas, both can also be used to make plastic.

Diverting CO2 from smokestacks, or sucking it directly out the air, can reduce demand for all three fossil fuels. This is especially important in terms of natural gas which has a “ghost methane” problem. Methane (C4) packs 30 times the greenhouse gas punch of CO2. Leaks from natural gas wells have emerged as a significant emissions issue.

However, when air-captured CO2 is injected into nearly spent oil and natural gas wells as a way to increase pressure in the wells so that more oil and gas can be pumped, it is both a climate and a public health fail. Proponents argue that this oil and gas is carbon neutral — or even carbon negative: CO2 is sequestered underground, while CO2 emitted from burning the additional oil and gas will eventually be removed through direct air capture. But carbon neutral (or even negative) isn’t quite the same as climate-friendly. Burning fossil fuels also emits NOx, SOx and methane, all greenhouse gases. Closer to the ground tailpipes and smokestacks spew particulates linked to smog, respiratory illness and cancer.

DeCarb Plus

When CO2 returns to the soil through the process of plant photosynthesis, it kickstarts a virtuous circles of goodness. Carbon isn’t simply sequestered, but serves as a catalyst the improves the soil’s fertility and also its ability to absorb water. “For each gram of carbon, the soil can absorb 8 grams of water,” explains soil biologist Walter Jehne. This is key.

Jehne calls this the “soil carbon sponge.” Both carbon and water are essential for the soil’s microbiome to flourish. This benefits the biome above the surface. Thriving plants absorb more CO2, sending more carbon through their roots into the soil and around it goes. Since water can more easily soak into the ground rather than run off, the land becomes more resilient to floods as well as drought. The soil stays cooler, too, which is really important for agriculture. Climate change means more days of extreme heat. When the temperature of the soil approaches 100°F, plants slow, or even stop, growing. The difference of only a few degrees can have a tremendous impact on the harvest.

Adding biochar to the soil mix can help. The inert, lattice-like structure of biochar provides a place for soil microbes to gain a toe hold, so it serves as a kind of subterranean coral reef. This is especially effective for stabilizing and building up carbon in thin tropical soils.

The soil microbiome is at the nexus of a dynamic process of chemistry and biology. The industrialization of agriculture, with its heavy dependence on petrochemicals (fertilizers, insecticides, pesticides, herbicides), upends the natural balance. Just as we now know that antibiotics can kill beneficial microbes along with pathogens, the rampant use of chemical poisons over the last 75 years has destroyed the earth’s living skin: the soil microbiome. Plowing (tillage) has also disrupted this gossamer web of mostly invisible life and exposed the soil’s carbon and nitrates to the air, where they transformed into CO2 and NOx, another greenhouse gas.

In a matter of decades, the fertile prairies of the American Midwest became fields of chemically-addicted corn, soy and wheat. Carbon-rich soil whose depth was once measured in feet is now measured in inches. And all the carbon that had been stored for millennia underground was released into the air.

This transformation has happened all over the world. According to the UN, fertile topsoil is now lost at a rate of 24 billion tons a year. All told, about a third of the Earth’s land is now is severely degraded. Not all the damage is linked to the industrialization of agriculture, but a good deal of it is. Which means we can do something about it.

Follow the Fertilizer

When soil loses carbon and is less able to absorb water, fertilizer-laced run-off begins to pour into streams, rivers and, eventually, oceans. This causes massive algal blooms that take up so much oxygen, fish can’t breath, so they either swim away or die. The blooms also create shade that blocks the sun from reaching underwater plants. The result: a dead zone. The algae eventually die off, a process that releases process greenhouse gases, including NOx and methane.

Imagine a chemically-dependent farm as a factory. The stream into which fertilizer-laced run-off first flows is the beginning of a long, meandering smokestack. The massive dead zone where river finally meets ocean is the noxious plume at the top of the smokestack, spewing pollution skyward.

Most of us now live in cities and suburbs. Two hundred and fifty years ago, the US had only 37 states and half the population — about 18 million of 38.5 million — were directly involved in agriculture. According to the 2017 US Census on Agriculture, there are now fewer than 4 million people working on farms out of population of 330 million spread across 50 states.

We see smokestacks and traffic jams every day and understand the connection between emissions and ever-rising atmospheric CO2 levels. If we see farms at all, it is a view from interstate on the way between cities, so it is harder to get a handle on the problem. It isn’t only a matter of disconnects between “farm and fork,” but also a lack of direct experience with how Nature works.

Regenerative Agriculture

The world’s farms present a huge ReCarb opportunity. Regenerative agriculture, also called “carbon farming,” is a win-win on many levels. It requires fewer petrochemical inputs, reducing operational costs and demand for fossil fuels. As soil carbon levels improve, the soil’s microbiome rebounds and the land is able to absorb more water. That means less fertilizer-laced run-off flowing into stream / smokestacks, smaller algal blooms, fewer dead zones and an overall farm-to-ocean reduction in greenhouse gas emissions.

The combination of no-till planting (fields aren’t plowed, so soil carbon stays put) and planting cover crops between cash crops encourages biodiversity both below and above ground. In addition, a minimum three-crop rotation of cash crops makes it difficult for plant-specific pests and pathogens to survive in any number. When dinner only comes around once every three, four or five years, bugs and diseases die off.


Is a plant-based diet better for the environment? That depends. Recently almond milk came under fire because the commercial pollination of the California almond crop takes a toll on honeybees, a beleaguered, critical pollinator. If the soy in soy milk is grown using petrochemicals that destroy the soil’s microbiome and contribute to the large marine dead zone in the Gulf of Mexico that isn’t so good either. Through the lens of “What best for the planet?,” milk from a grass-fed cow raised on an organic farm could be the winner.

Similarly, are you better off eating a highly-processed, faux meat, plant-based burger, or a burger made from the meat of grass-fed and finished cattle? Or maybe a falafel burger made from chickpeas grown using regenerative practices that doesn’t pretend to meat at all? (see sidebar, p 55, The Primer: “The Truth about Cows and Methane”)

In the years since Michael Pollan wrote The Omnivore’s Dilemma, the challenges to ethical eating seem only to have deepened. Perhaps as regenerative practices become more widely adopted that will change.

These kinds of issues are not limited to food crops. If petrochemicals are use to raise corn that is processed into ethanol, a biofuel, what is its true carbon footprint? And if the corn seed is coated in neonicotinoids, then the crop itself may contribute to the demise of bees and other insects.

Everything begins — and ends — with the health of the land.

Follow the water

The climate and water stories are braided together. Water vapor, not CO2, is the most pervasive greenhouse gas, although it cycles through the atmosphere in a matter of days rather than years. Still, with each 1°C rise in temperature, the atmosphere can hold 7% more water as vapor, so the impacts are significant, with ramifications not only for climate, but also for the Earth’s complex hydrology.

This includes pockets of water deep underground called aquifers. All over the world, we have become dependent on these hidden sources for agriculture and drinking water, but have been pumping it out at such volume over the last several decades that many are at now at risk of running dry.

Just like fossil fuel, this “fossil water” is a finite resource whose emissions — in this case, water vapor — impact the planet’s climate. It isn’t only that a warmer planet can hold more water vapor, but that there is more water at the surface ready to evaporate. The addition of fossil water into hydrological mix is not nearly as big a driver of climate change as fossil fuel emissions, but further illustrates how it is all of a piece. From deep beneath the surface to the outer the edges of the atmosphere, everything connects.

For the last 75 years — and at the same as the dramatic increase rise in the use of petrochemical fertilizers, pesticides, herbicides and fungicides — farmers in eight states have tapped into the giant Ogallala Aquifer, transforming the heartland of the US from a vast grassland into one the world’s most productive agricultural breadbaskets. There may yet be another 75 years-worth of water to be pumped, but aquifer levels have dropped so dramatically in some regions that farmers have already been forced to go without. Once the Ogallala is drained, it will take thousands of years to refill (or to use the hydrological term, “recharge”).

Using regenerative practices (no-till and keeping the ground covered with the stubble from last year’s crop), a dryland farmer (no irrigation) in the High Plains of Kansas can capture the equivalent of an inch of rain a year. Given an annual tally of only 18” inches of rain, keeping as much as possible from evaporating is critical. That extra 5.5% of water can spell the difference between profit or loss, feast or famine.

An estimated that 1.8 billion people all over the world — including the US, India and Europe — are dependent on aquifers for food and drinking water. According to a study in 2015, more than half of the biggest aquifers are being drained faster than they can recharge. And although scientists have begun to identify new aquifers beneath oceans, the risks and costs of bringing that water to farms and cities is beyond calculation.

Ecosystem Restoration

Drawing carbon back into the soil is a trick every plant can do, no higher-order brain required. Trees, the biggest plants, store more carbon that little ones, which makes the scheme to plant a trillion trees seem so sensible, appealing and progressive. Tech titans, politicians and the World Economic Forum are all in.

Critics have pointed out logistics issues: It can take decades for trees to mature, too long to make a difference when there’s only a few years left to stabilize the climate. Some of the best land for forests is privately owned and owners may object. And since deforestation continues, there is a proverbial hole in the tree-counting bucket: It is impossible to plant enough trees to make up for such catastrophic losses. According to NRDC, the logging of Canada’s boreal forests releases the carbon equivalent of 55 million cars each and every year. The story gets even worse when you realize that some of these trees are used to manufacture products such a toilet paper, which could just as easily be manufactured using recycled material. Meanwhile rainforests from the Amazon to Indonesia have been shredded.

Planting a trillion trees is more about planting a trillion headlines. All those trees literally make it harder to see the forests. And it is forests, which include everything from microbes in the soil to insects, birds, lizards, snakes, amphibians, fish, mammals, all sorts of plants and, of course, trees, that collectively deliver a broad range of planet-enhancing services, including carbon sequestration. Schemes that call for the mass planting of a single species of tree creates monoculture plantations that often do more harm than good.

A thriving forest impacts hydrology. The combination of evaporation and wind, particularly in the tropics, supports enormous, invisible atmospheric rivers that hold far more water than their terrestrial counterparts. Down below, water flows into streams and percolates through the soil into aquifers.

It seems obvious, but forests work best on land and in climates best suited for forests. That gets lost in the reductionist ardor that is the Trillion Tree movement. In fact, planting trees in grasslands can significantly reduce the amount of water that flows into aquifers. Trees need more water than grass. And when trees can’t get the water they need — through drought or by being planted in areas that don’t get enough — they die, becoming fodder for fire. Instead of serving as a carbon sink, the forest become a carbon emitter.

According to a new study from UC Davis, grasslands may be a better carbon sink than trees in a climate-changed world more prone to drought. While trees store carbon as wood and in leaves, grasses store carbon in the soil. Even when there’s a fire, most of the carbon stays put.

The point is that if the goal is recarbonization, the best results, both in terms of carbon and hydrology, come from ecosystem restoration: plant forests on land suited for forests, grasslands where they can best thrive, and marshes and wetlands where they belong and serve multiple functions from flood mitigation and protection against storm and tidal surges, to nurseries for young fish and other aquatic species.

DeCarb / ReCarb

Decarbonization is about energy, efficiency, economics and equity. Recarbonization is about restoration and resilience. Neither one alone can keep us from catastrophic climate change, especially given the tight time frame of a decade to keep atmospheric CO2 numbers in check. Together they could be enough to make all the difference.

We have what we need to do this, no new technological breakthroughs needed. In fact the work has already begun, but there is no time or money to waste. The DeCarb / ReCarb framework can help identify the solutions that are most readily scaled.

The good news is that this is all within our collective capabilities, with the bonus that each one of these strategies delivers multiple benefits. Even something as simple as reimagining our backyards could make an enormous difference, says ecologist and author Douglas Tallamy. He proposes converting half of America’s lawns — about 20 million acres — into “Homegrown National Park,” the nations’s largest national park. A perfect lawn takes time and money to maintain — fertilizer, water, mowing — but sequesters only 120 lbs.of carbon per acre. By contrast prairies capture 3,000 lbs. of carbon per acre, notes Tallamy, and forests 3,500 lbs. The opportunities to make a significant difference begin at home.

We can leave our children, grandchildren and all the generations to come a trashed planet filled with the detritus of riches squandered. Or we show our children, grandchildren and all the generations to come how to make a regenerative, prosperous, thriving world. Either way, it will be our legacy.

We can do better. We can do good. So let’s get to it.