What is Carbon Removal?
Carbon removal is the process of removing carbon dioxide from the atmosphere and locking it away or re-using it. Carbon removal methods can be broken down into two categories: natural and artificial. Natural carbon removal, often referred to as ‘nature-based solutions,’ are tools that allow us to capture CO2 from the air and sequester it in plants, soils and sediments. They also provide other secondary benefits, such as cleaner air and water, economic benefits and increased biodiversity. Artificial carbon removal is when carbon is sequestered or removed using technology, namely in the form of direct air capture (DAC). The Intergovernmental Panel on Climate Change (IPCC) found carbon removal as crucial to meeting the 1.5°C target. In their 2022 report, they said “the deployment of carbon dioxide removals to counterbalance hard-to-abate residual emissions is unavoidable if net zero…emissions are to be achieved.” Specifically, these tools include forestation, agroforestry, soil sequestration, ocean based methods, direct air capture, and others.
Forestation includes forest restoration, reforestation, and afforestation. Trees and forests provide many environmental benefits, among them is carbon sequestration. The annual rate of carbon sequestration from forestation alone could reach up to 3.6 billion tons of carbon dioxide (GtCO2) per year by 2050, and up to as much as 7 GtCO2 by by 2100, amounting in the total cumulative sequestration of 80-260 GtCO2 in that time frame. Forestation also has the benefit of being eminently implementable, as these practices are already in place world-wide.
While similar to forestation, agroforestry calls for including trees with other agricultural land-uses, including for crops and animal agriculture. Examples of this include planting trees for animals to graze under, and planting crops between trees. Other methods include planting rows of trees or shrubs to divide plots of agricultural land, and grazing animals under fruit-bearing trees. The IPCC estimates that agroforestry has the potential to sequester between .1-5.7 GtCO2 annually. As of 2010, roughly 43 percent of global agricultural land was considered agroforestry (as defined by at least 10 percent tree cover).
Also known as ‘regenerative agriculture’, or ‘soil regeneration’, soil sequestration involves managing land in such a way that allows for the land to serve as a carbon sink. Individual methods of doing this include no-till or low-till agriculture, using cover crops, and implementing rotational livestock grazing. Soils carry three times the amount of carbon currently in the atmosphere. Over the last 10,000 years, changes have caused soil carbon to decrease globally by 840 GtCO2, with some soil having lost 50-70 percent of its original organic carbon. Estimates suggest that soil carbon sequestration can sequester 2-5 GtO2 annually by 2050, with a cumulative potential of 104-130 GtCO2 by 2100 at relatively low cost.
What the previous methods are for land, ocean-based methods are for the oceans; these are ways we can use the oceans to sequester carbon. Examples include: ocean alkalization, ocean fertilization, artificial upwelling, and artificial downwelling. Because ocean-based methods are still in their infancy as far as scientific understanding, their potential is not fully known. The expectation is that these methods could remove many billions of tons of CO2 per year, with thecapacity to store being functionally “unlimited.”
Direct Air Capture
Direct air capture (DAC) is artificial, which, unlike before-mentioned tools, is not meant to naturally sequester carbon, but rather use a machine to do it. When paired with carbon storage capabilities, DAC can use captured carbon to make certain products, ranging from cement to baking soda. Direct air capture is still relatively elementary in its history and is expected to continually improve. According to an independent analysis from 2018, DAC average costs ranged from $100-300 per ton of CO2. That same study estimated that by 2050, potential sequestration rates will be between 0.5 and 5 GtCO2 yearly, with the potential being much higher than that.
Listed above are just some of the major methods being invested in currently. Some of the other methods include:
• Enhanced mineralization: Enhanced mineralization accelerates the process by which various minerals absorb CO2 by mining specific kinds of rocks or using mining/industrial waste, grinding them up, and spreading it over soils – resulting in those soils sequestering more carbon. Estimates for cumulative potential by 2100 ranged from 100-367 GtCO2.
• Biochar: Biochar is a kind of charcoal that is created by burning biomass in a low-oxygen environment. When added to soils, biochar can cause the carbon to remain in the soil/charcoal for decades or even centuries. Growing plants, collecting waste biomass, converting that biomass into biochar, then adding the biochar to soils – removes carbon from the atmosphere. The potential is not guaranteed, but estimates range from 78-477 GtCO2 removed by 2100.
• Bioenergy with carbon capture and storage (BECCS): BECCS Converts biomass into heat, electricity, liquid or gas fuels, then captures the emissions and stores said emissions in geological formations or long-lasting products. Estimates on BECCS potential varies, though a recent study from the U.S. National Academy of Sciences estimates a savings possibility of 3.4-5.2 GtCO2 annually without large adverse effects.
The methods for carbon removal are varied and our understanding of those methods are growing. Whether natural or artificial, the opportunities are as vast as the potential is large.
Why We Need Carbon Removal
In 2015, the Paris Accords were agreed to by 196 countries, who together committed to ensuring that global warming remains below 2°C – ideally 1.5°C – above pre-industrial levels. To meet these goals, global carbon-equivalent emissions need to be reduced by 45 percent from 2010 levels by 2030, and reach net-zero emissions by 2050. The Intergovernmental Panel on Climate Change (IPCC) has called for similar emissions reductions figures. While this is the stated goal for environmental health and stability, the lower the emissions the better. The organization Carbon Brief collected over 80 peer-reviewed articles to find that if the 2°C goal is not met, we would be at significant risk of sea level rise of 56 centimeters and dramatically extend the longevity of droughts, with other ecological problems to follow. There is also a risk of mass migration and hunger if emissions levels exceed the planet’s ability to handle them.
The New York Times has reported that as many of 800 million people in Southeast Asia alone could have their living conditions ‘diminished’ by climate change in the relatively near future, and Oxfam predicts that the numbers of people at risk of hunger around the world could jump by 10 or 20 percent by 2050. Carbon removal offers tools to sequester greenhouse gasses and protect people and our environment from the threat of climate change.
Why We Are Not On Track:
Scale: Solving this problem is not simply a question of political will, either for America or for nations around the world. For even if politicians were on board, there is no guarantee we could meet these goals without carbon removal. Take one example of a government project: light-rail connecting San Francisco and Los Angeles. The project was started in 2008, expecting to cost $33 billion and be completed by 2020. The project is now expected to exceed $100 billion (and counting), and is estimated to be completed in a decade, maybe never. One company involved in the project was SNCF, and they left the project in 2011 to work on a rail system in North Africa. The North Africa project was able to be completed in 2018 because, according to one of SNCF’s project managers, the government was “less politically dysfunctional [than California’s].” If this infrastructure project has proven so difficult in California, what does that say about much larger projects that would have to occur everywhere on Earth in order for all nations to meet stated emissions goals?
Social/Economic: When people think of decarbonization, they often think of things like renewable energy, electric cars, etc. But in reality, there are several parts of the global economy and infrastructure that currently require the emitting of greenhouse gasses, like steel and cement. Steel production releases about 7 percent of global emissions, and cement is responsible for about 8 percent. These emissions come largely not from operating the factories but rather from the chemical process involved in the building of the materials. Meat is another example. Animal agriculture is responsible for more than 14 percent of global emissions, and the vast majority of humans worldwide do not intend to have a vegetarian diet. Meat and dairy also serve as an important cultural staple for many around the world; Muslims eat lamb on Eid El Kebit, the French enjoy the Gastronomic meal, and there are of course countless other examples. This Is not going to change any time soon, and carbon removal presents a method by which we can offset the emissions coming from these practices.
Prior Emissions: Even if we eliminate new carbon emissions, we probably still have to deal with the effects of previous emissions. In fact, it’s estimated that somewhere between 15–40 percent of the carbon dioxide that humanity emits will remain in the atmosphere for as many as a thousand years, with nearly 10– 25 percent of it persisting for tens of thousands of years. Though, while that is based on one set of estimates, there is a growing consensus that argues much of climate change will essentially end when excess emissions end (within “a decade or two”).
Mineral Requirements: The green technology revolution requires mineral harvesting at a scale that has never been seen before in human history. Green technology, as a general rule, requires more minerals than ‘dirtier’ technology like internal combustion engines. In fact, electric vehicles (EVs) require an average of six times the mineral input of a conventional combustion car, and onshore wind plants require nine times more mineral resources than the average gas-fired plant. Since 2010, the minerals required for each new unit of power generation capacity has increased by 50 percent, due to increased renewable investment. The green technology revolution has created a demand increase of over 40 percent for copper and rare earth elements, 60-70 percent for nickel and cobalt and nearly 90 percent for lithium. According to the International Energy Agency, meeting 2050 climate targets requires an increase in mineral use by 6 times, relative to today. Lithium alone is expecting a demand growth of over 40 times by 2040. To put all of this into perspective, the average mining project takes 16.5 years to go from discovery to first production.
In any case, whether used to sequester prior or current emissions, to maximize our chance of meeting these goals and avoiding climate tipping points and mass migration due to a changing climate, carbon removal is essential as a tool to complement other efforts.
The State of Carbon Removal
From 1850 to 2019, around 2390 gigatons of anthropogenic CO2 had been emitted. The most recent IPCC report claims, with high confidence, our remaining ‘carbon budget’ is about 400 gigatons of CO2 (GtCO2), for a two-thirds chance of limiting warming to 1.5°C above pre-industrial levels, and a 500 GtCO2 ‘carbon budget’ for a fifty percent chance. The report estimates that for every 1000 GtCO2 emitted by human activity, global surface temperature rises by 0.45°C. The report also explains that a sufficient amount of carbon removal could “reverse” the “increase in global surface temperature…within a few years,” while stipulating that other climate change impacts would take longer to reverse. On that point, the report explains that if warming exceeds 1.5°C, it could be gradually reduced through net negative CO2 emissions. This is especially important considering only the most ambitious IPCC models predict global warming to be limited to 1.5°C by 2100, without at least exceeding this level temporarily. IPCC also claims that the larger the emissions overshoot, the more negative emissions would be necessary to return to 1.5°C by 2100. In their 2022 report, carbon removal is referred to as “unavoidable” if we want to reach net zero emissions.
Excluding all ocean carbon removal, which has virtually “unlimited” potential, and assuming direct air capture (DAC) does not ‘take off,’ carbon removal can remove roughly 1400 GtCO2** of greenhouse gas emissions from the atmosphere by the end of the century. In 2022, the world released 41.3 GtCO2. Assuming no new changes made, our current trajectory expects us to decrease our global emissions count by roughly 20 percent by 2100. Assuming very conservatively that our emissions stay roughly flat at 40 GtCO2 until 2100, that leaves us with an expected emissions count of about 3200 GtCO2 total by 2100. Given our ‘budget’ of 400 GTCO2, that leaves us with 2800 GtCO2 to spare; meaning carbon removal can eliminate roughly 50 percent of emissions, if utilized to their potential. Though, this is of course looking at it from the 2100 perspective. The IPCC report calls for the decline in emissions to occur roughly this decade, considering we have a ‘budget’ of 400GtCO2, and we emit roughly 40GtCO2 yearly. Based on mean emissions reduction possibilities, and again excluding ocean carbon removal and DAC ‘take off,’ carbon removal can offer around 191GtCO2 of removal potential by the end of the decade, amounting to around 47 percent of expected emissions during that time-frame, which would buy us time and better allow us to meet our 2030 50 percent emissions reduction targets, as stipulated by IPCC. This could be followed by a comparable carbon removal rate from 2030 to 2050 in order to meet net zero emissions targets.
Direct Air Capture
Technology: Studies predict “massive implementation” of DAC would “significantly reduce the CO2 capture costs,” with capture costs below $59/tCO2 being achievable by 2040. Presently, those costs hover at around $600/tCO2. As of today, two methods are employed for capturing CO2 from the atmosphere: solid and liquid direct air capture. The solid DAC (S-DAC) approach utilizes solid adsorbents at moderate temperatures (80-120°C) and operates at ambient to low pressure, often under a vacuum. Liquid DAC (L-DAC) relies on an aqueous basic solution, typically potassium hydroxide, which releases the captured CO2 through a sequence of units operating at high temperatures ranging from 300°C to 900°C. Presently, the S-DAC model requires more energy to power than the L-DAC model per tcCO2 sequestered, but both could be successful.
Private Sector: There currently exist 18 operational direct air capture plants across the globe, which are able to capture nearly 0.01 Mt of CO2 per year. Additionally, there is advanced development of a 1 MTCO2 per year capture plant in the United States, which is expected to be up and running sometime within the next decade. These facilities operate on a small scale, with the majority primarily capturing CO2 for specific purposes like carbonation in beverages, or using the carbon to extract extra oil from wells. Only two plants engage in the storage of captured CO2 in geological formations for permanent removal. While a few commercial agreements are established for the sale or storage of captured CO2, the remaining plants are primarily utilized for testing and demonstration objectives.
Rising investment has led to the creation of many new projects on the horizon. New plants are underway to be built in the U.K., Chile, Norway and more. Two companies, 1PointFive and Carbon Engineering, announced plans to deploy 70 large-scale DAC facilities by 2035, each with a capacity to capture up to 1 million tons per year. Another major company in this space, Climeworks, announced the construction of their largest plant yet, ‘Mammoth,’ which intends to have a capture capacity of as much as 26,0000tCO2/year by 2024. Eleven DAC facilities are now in advanced development with the hope that DAC will sequester an estimated 5.5MtC02 by 2030, more than 700 times more than the current rate.
Policies: The United States has implemented a range of policies and initiatives to back research, development, and deployment (RD&D) of direct air capture. These include the 45Q tax credit, which offers financial incentives of $60 per ton of CO2 utilized in enhanced oil recovery and up to $180 per ton of CO2 stored. Additionally, the California Low Carbon Fuel Standard credit supports DAC projects that meet the requirements of the Carbon Capture and Sequestration Protocol. Moreover, the Infrastructure Investment and Jobs Act, allocates $3.5 billion in funding to establish four large-scale DAC hubs, along with associated transport and storage infrastructure.
In the European Commission, DAC has been receiving support through diverse research and innovation programs, such as the Horizon Europe program and the Innovation Fund. The Innovation Fund had an initial budget of approximately $11.8 billion for 2020-2030, to contribute to the advancement of DAC and other carbon dioxide removal techniques. The European Commission’s first Communication on Sustainable Carbon Cycles was published in December 2021, which emphasizes the objective of removing 5 Mt of CO2 annually from the atmosphere by 2030 using land- and technology-based approaches, including DAC.
Natural Carbon Removal/ Nature-Based Solutions (NBS)
NBS, which differs from DAC, entails more than just one tool. This section focuses where the multiple instruments of natural carbon removal are with regards to their deployment and development.
Programs and Status: Forest conservation is an essential part of NBS. The largest 1 percent of trees store approximately half of the carbon held in all live forest trees, worldwide. Globally, forests store nearly 862 Gt of carbon in both dead and live vegetation and soil, which removed the equivalent of about 30 percent of fossil fuel emissions annually from 2009 to 2018. 36 percent of global intact forests are protected legally, which is too low of a number if we want to rely on NBS to sequester carbon to its fullest potential. Regenerative agriculture are the agricultural techniques aimed at restoring soil quality to sequester carbon. Many private companies are investing in regenerative agriculture, including General Mills, inc., which plans on advancing 1 million acres of regenerative agriculture farmland by 2030. It’s not just large companies, some small companies are intertwining regenerative agriculture into their business models, as well. Regenerative agriculture is currently valued at a $7.74B market cap (2021) and is expected to experience 14.4 percent CAGR growth until reaching a $23.84B market cap in 2030. Agroforestry is another option; it covers 43 percent of global agricultural land. The barriers to expanding this practice tend to be social, financial and infrastructure-based.
Policies: at the federal government level, numerous bills have passed in recent years to further incentivize natural carbon removal. The recently passed Inflation Reduction Act (IRA) included funding for NBS. The Infrastructure Investment and Jobs Act (IIJA) included billions of dollars in funding for carbon removal including $8 billion for reforestation and forest restoration. The IIJA included the REPLANT Act, which assists the US Forest Service in planting 1.2 billion trees over the next 10 years, along with other comparable measures. Beyond those, there are many other smaller, oftentimes department level programs. Many states are implementing their own policies on top of IIJA and IRA, as carbon removal becomes a more important part of the US economy.
On the international level, The German government and the international Union for Conservation of Nature (IUCN) developed ENACT (Enhancing Nature-based Solutions for an Accelerated Climate Transformation), a series of policies meant to boost NBS. At the COP27 summit, NBS was on the MainStage as Egypt’s Minister of the Environment proclaimed that NBS is a “largely untapped” resource, with “huge potential” before committing to implement ENACT policies in his country.
While there is still tremendous progress to be made, there are also tremendous opportunities to be seized. Carbon removal offers tools that go beyond mitigation, it actively reverses damages done to the planet and global ecosystems. By removing excess carbon from the atmosphere, carbon removal can allow us to, and is vital in, restoring balance to our global carbon cycle and creating a sustainable ecological future.
** This number is based on the mean emissions reduction possibility from afforestation/reforestation, soil carbon sequestration, biochar, BECCs, enhanced mineralization, and direct air capture from American University’s Institute for Carbon Removal Law and Policy’s figures during the relevant time frame, then adding them up.