CDR 101
What is carbon removal?
Carbon removal means taking carbon dioxide out of the atmosphere and storing it durably. It is how we neutralise the residual emissions from hard-to-abate sectors — agriculture, aviation, heavy industry — and begin to address the historical emissions already in the atmosphere.
The methods fall into two families: conventional approaches (forests, soil) that are mature and cheap but less durable, and novel approaches (biochar to direct air capture) that are earlier-stage and costlier but lock carbon away for centuries to millennia. Hover or tap any method to see how it works.
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Conventional · Nature-based
Forests & land
Trees and soils store CO₂ as they grow. Cheap and ready today — the bulk of current removal — but fire, disease, or clearing can release it again.
- Storage
- Decades–centuries
- Maturity
- Mature
- Cost
- ~$5–50 / tCO₂
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Conventional · Nature-based
Soil carbon
Cover crops, reduced tillage and rotational grazing build carbon in farm soils. Among the cheapest options, but soils saturate and gains reverse if practices lapse.
- Storage
- Decades
- Maturity
- Mature
- Cost
- −$45 to $100 / tCO₂
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Novel · Biomass
Biochar
Heating biomass without oxygen makes a stable, carbon-rich solid for soils, locking carbon away for centuries. Competes for the same biomass as BECCS.
- Storage
- Centuries
- Maturity
- Emerging
- Cost
- ~$10–345 / tCO₂
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Novel · Geochemical
Enhanced rock weathering
Crushed silicate rock on farmland speeds the natural reaction that turns CO₂ into stable bicarbonate. Very durable, but measuring real removal in the field is hard.
- Storage
- Centuries–millennia
- Maturity
- Early
- Cost
- ~$50–200 / tCO₂
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Novel · Engineered
BECCS
Burn sustainable biomass for energy, capture the CO₂, and store it underground — permanently. Limited by biomass supply, and only a removal if upstream emissions stay low.
- Storage
- Permanent (geological)
- Maturity
- Emerging
- Cost
- ~$40–120 / tCO₂
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Novel · Engineered
Direct air capture
Machines scrub CO₂ straight from the air and inject it into deep rock. The most durable and measurable option, but today the most expensive and energy-hungry.
- Storage
- Permanent (geological)
- Maturity
- Early commercial
- Cost
- ~$600–1,000 / tCO₂ (today)
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Novel · Marine · geochemical
Ocean alkalinity enhancement
Adding alkaline minerals to seawater speeds the ocean’s uptake of CO₂, storing it for millennia. Large potential, but open-ocean monitoring and ecological risks are unresolved.
- Storage
- Centuries–millennia
- Maturity
- Early research
- Cost
- ~$40–260 / tCO₂
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Novel · Marine · nature-based
Blue carbon
Restoring mangroves, seagrass and salt marsh stores carbon with biodiversity co-benefits. Reversible, though — degrade the habitat and the carbon returns.
- Storage
- Decades–centuries
- Maturity
- Variable
- Cost
- Limited data
Sources
Storage durability, maturity, and cost are indicative, drawn from the IPCC Sixth Assessment Report (Working Group III, 2022) and The State of Carbon Dioxide Removal (Smith et al.). Costs vary widely by project and location; for the novel methods, market prices today often exceed modelled costs, and direct air capture’s cost is expected to fall as it scales.