Guest Post: The State of ‘Carbon Dioxide Removal’ in Seven Charts

February 20, 2023

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by Steven Smith, Jan Minx, Greg Nemet and Oliver Geden (Carbon Brief) Taking CO2 out of the air – a practice known as carbon dioxide removal (CDR) – is increasingly recognised as a crucial part of achieving climate goals, alongside rapidly reducing emissions.

Yet, some basic questions remain unanswered: How much is already happening around the world? How fast is it growing? Are we on track to deliver what may be needed?

In a new report, released today, we endeavour to answer these questions and help make information on CDR more accessible.

For the first time, we are able to estimate the total amount of CDR currently being deployed around the world and compare it to what is in modelled pathways that meet the Paris climate goals.

We find a gap between how much CDR countries are planning in the coming decades and what is required to limit warming to 1.5C or 2C above pre-industrial levels. But alongside this “gap”, we also find rapid growth in innovation, academic research and public attention on CDR.

Below, we explain – via seven charts – what light the report sheds on the current state of CDR:

Virtually all CDR happening now comes from managed forests

CDR, sometimes also referred to as “negative emissions”, refers to a number of different activities by which CO2 is captured from the air and stored durably on land, in the ocean, in geological formations or in products.

We estimate that the amount of CDR currently happening around the world is approximately 2bn tonnes of CO2 (GtCO2) per year. This is small relative to current CO2 emissions of 36.6GtCO2 per year from fossil fuels and cement, but perhaps larger than many might expect.

The vast majority of current CDR (99.9%) comes from what we, in this report, term “conventional CDR on land”. This includes the creation of new forests, restoration of previously deforested areas, increases in soil carbon and use of durable wood products, such as panels and sawnwood used in construction.

Only a small amount of current CDR, an additional 0.0023GtCO2 per year, comes from “novel” CDR methods. These include bioenergy with carbon capture and storage (BECCS), biochar, direct air carbon capture and storage (DACCS), enhanced rock weathering and coastal wetland (sometimes called “blue carbon”) management.

While novel CDR projects often get the news coverage, they collectively account for just 0.1% of all current CDR deployment.

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In general, conventional CDR methods on land are already practised at scale. Done well, they can provide additional benefits, notably to biodiversity. But they are limited by available land, and the carbon removed by trees and soils is prone to reversal from disturbances and from climate change itself. READ MORE

Smith, S. M. et al. (2023). The State of Carbon Dioxide Removal - 1st Edition. Available at: www.stateofcdr.org.

Global carbon dioxide removal totals 2 billion tonnes per year - report (Reuters)

The State of Carbon Dioxide Removal (Science Media Center)

Discover the first comprehensive global assessment of the current state of Carbon Dioxide Removal. (The State of Carbon Dioxide Removal)

Occidental delays landmark CO2 removal project -- The company is planning to build the world's largest plant to suck carbon dioxide out of the air. (Politico Energywire)

THE TRUTH ABOUT SOIL'S ABILITY TO SEQUESTER CARBON (Successful Farming)

Excerpt from Reuters: It estimates that roughly 1,300 times more carbon dioxide removal from new technologies — and twice as much from trees and soils — are needed by 2050 to limit temperatures to well below 2 degrees Celsius above pre-industrial temperatures, as set out in the Paris Agreement. READ MORE

Excerpt from Sucessful Farming: “Just about everywhere we look, there are claims about carbon sequestration being akin to the holy grail for agriculture and, by extension, the environment,” says Ben Palen, a fifth-generation Kansas farmer and manager at Ag Management Partners. “There is nothing wrong with modest improvement, but often the promise and the reality do not match.”

“I worry that we are selling ourselves a pie-in-the-sky dream we might not realize, and that it could come back to bite farmers and ultimately not get us any further down the road toward reducing greenhouse gases in the atmosphere,” says Gregg Sanford, senior scientist, Department of Agronomy at the University of Wisconsin-Madison.

REINING IN THE HYPE

About two decades ago, Sanford began reading scientific literature that suggested certain farming systems could help combat climate change by sequestering carbon in the soil.

“We love to support farmers and incentivize them to do things that benefit society, but we also put a ridiculous amount of pressure on farmers to save us from every-thing,” Sanford says. “I don’t feel the science is there to say that if you do these practices (e.g., cover crops, no-till, etc.), you’re going to sequester carbon across the board. In some cases, we will, but in many cases, we won’t.”

Findings from his doctoral work and a decade of subsequent research by Sanford and colleagues bear that out. The data challenges the climate impact of reducing soil tillage and questions how much car-bon cover crops can sequester in some circumstances.

“Even with best management practices like no-till and cover crops, we’re losing carbon in the upper portion of the soil that we’d expect to be able to improve with management,” Sanford says. “The data also shows that carbon is being lost in soil horizons, as much as a meter deep. Those losses are likely due to a combination of historic vegetation, current management, and a changing climate and are much harder to change via farming practices like cover crops or no-till.”

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Our dairy-forage rotations have also incurred losses, although at a slower rate, likely because of the reduction in tillage, application of manure, and deep-rooted perennials.”

It is only in their grassland systems, whether it’s rotation-ally grazed pasture, CRP, or prairie, where they can document carbon sequestration in the surface soils. However, Sanford says that in many cases they are still observing losses of carbon at depth.

RESULTS MAY VARY

One of the caveats with soil carbon sequestration, Sanford says, is there are places in the United States where certain types of ag management will be able to build soil carbon resources, but results may vary.

“There are going to be areas where, despite our best efforts, we continue to lose carbon simply because the amount being respired as carbon dioxide from the soil due to the microbial turnover of organic matter is going to outpace the residue carbon being returned,” he says. “And that gets tricky because the climate is getting warmer, speeding up the process of soil organic matter turnover.”

What’s relevant for farmers in terms of maximizing carbon, Anna Cates says, is whether they can maximize how carbon helps with other functions.

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The main way to build soil organic matter is by adding plant biomass while simultaneously keeping as much of the carbon currently in the soil from being respired as CO2 by limiting soil disturbance. Sanford believes that to make a big impact on soil carbon and use it as a tactic to mitigate climate change, a transformational change must occur in agriculture.

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An approach that Palen believes holds promise is a closed-loop system involving crops and hogs. A project he is currently working on replaces commercial fertilizer with hog manure. “Hopefully, we will achieve carbon-neutral grain, which will be fed to the hogs, and then they can be sold as car-bon-neutral pork, creating a closed-loop system,” Palen explains. “There’s a lot of opportunity there for carbon credits by replacing commercial fertilizer but also by scrubbing the methane out of the hog manure.”

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“In the Upper Midwest, we have some of the highest organic matter soils in the world, so it’s going to be difficult to make them better,” says Jodi DeJong-Hughes, University of Minnesota Extension soil and water quality educator. “What I tell farmers is that it’s a slow process to build organic matter, and while I don’t know if the carbon markets are for you, reducing tillage and adding cover crops are great for the soil.”

DeJong-Hughes also believes we are missing an opportunity when it comes to fossil fuels. “We know how much carbon is emitted from diesel fuel. It’s harder to quantify carbon sequestered in the soil,” she says. “The programs pay to sequester carbon, but carbon is also not being emit-ted through diesel fuel because a farmer makes less tillage passes across the field.”

Palen also notes the potential for generating carbon credits by reducing commercial fertilizer rates via the use of certain biostimulants.

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Initially, Kevin Bahr was among the carbon program skeptics. As he learned more about the Truterra carbon program, Bahr says it seemed like something worth exploring and joined the program in 2021. The Kansas farmer also sits on the program’s advisory board where he and other farmers can provide feedback.

Like most central Kansas farms, Bahr’s land is diversified, handling alfalfa, corn, milo, soybeans, wheat, and a cow-calf herd. His soils range from good black dirt to sandy loam.

“While we may be talking about carbon, this program is more about soil health, which is a journey that doesn’t hap-pen overnight,” he says. “I’m employing certain practices like no-till and cover crops because they are what is best for my soil; the carbon credit money is like gravy on top of my mashed potatoes. It’s a reward for taking care of the land the way I should.”

Payment is based on how much carbon has been stored, which is quantified through a combination of modeling and soil sampling. Growers are paid $30 an acre for every ton of carbon sequestered, which can vary year to year based on crop rotation.

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“Comments that led to that low rating included (a) no recognition of good practices that I’ve already done for years; (b) no clearly defined rules, and vaguely written contracts; (c) too much paperwork; and (d) practicalities of changing some practices because of site-specific conditions,” Palen says. READ MORE