Explore and compare different methods to remove CO₂ from the atmosphere!
| Method | Cost/Ton | Scale Potential | Permanence | Maturity |
|---|---|---|---|---|
| 🌳 Reforestation | $10-50 | High (10+ Gt/yr) | 40-100 years | Proven |
| 🏭 Direct Air Capture | $600-1000 | Medium (5 Gt/yr) | 1000+ years | Early Stage |
| 🔥 Biochar | $100-300 | Medium (2 Gt/yr) | 100-1000 years | Developing |
| 🌊 Ocean Fertilization | $50-200 | High (3+ Gt/yr) | 100-1000 years | Research |
| ⛰️ Enhanced Weathering | $50-200 | High (4+ Gt/yr) | 10,000+ years | Research |
| 🌾 BECCS | $100-300 | High (5+ Gt/yr) | 1000+ years | Pilot Stage |
Even with aggressive emissions reductions, we need carbon dioxide removal (CDR) to limit warming to 1.5-2°C. Here's why:
The Scale Challenge: Climate models show we need to remove 5-10 billion tons of CO₂ annually by 2050 to meet climate goals. Currently, we remove less than 0.01% of that through engineered methods.
These terms are often confused, but they're different:
What: Capturing CO₂ from concentrated sources like power plants and factories
Purpose: Prevent NEW emissions from reaching the atmosphere
Example: CCS (Carbon Capture & Storage) at a coal plant
Climate Impact: Reduces emissions, doesn't reduce atmospheric CO₂
What: Removing CO₂ that's already in the atmosphere
Purpose: Reduce EXISTING atmospheric CO₂ levels
Example: Direct Air Capture, reforestation
Climate Impact: Creates negative emissions, reduces atmospheric CO₂
Both are needed! Carbon capture prevents new pollution; carbon removal cleans up past pollution.
When comparing CDR methods, scientists consider these key criteria:
How much it costs to remove one ton of CO₂. Ranges from $10 (trees) to $600+ (DAC). For perspective, we need to remove billions of tons annually.
Maximum CO₂ that could be removed globally. Some methods can remove gigatons (billions of tons) per year; others are limited to megatons (millions of tons).
How long the CO₂ stays out of the atmosphere:
Is it proven at scale or still in research?
Co-benefits: Additional positive impacts (biodiversity, soil health, jobs)
Risks: Potential negative side effects (ecosystem disruption, land competition)
How accurately can we measure the CO₂ removed? Engineered methods are precise; nature-based solutions are harder to quantify.
These methods use natural ecosystems to capture and store carbon:
How it works: Trees absorb CO₂ through photosynthesis and store it in biomass and soil.
Potential: Could remove 3-18 Gt CO₂/year globally
Cost: $10-50 per ton
Permanence: 40-100 years (vulnerable to fire, disease, logging)
Reality check: We'd need an area the size of the US planted with trees to make a major dent. Competes with agriculture and requires careful management.
How it works: Regenerative agriculture, cover crops, and no-till farming increase soil organic matter.
Potential: 2-5 Gt CO₂/year
Cost: $15-100 per ton
Bonus: Improves crop yields, water retention, and resilience
Challenge: Soil carbon can be released if practices change. Difficult to monitor and verify.
What: Mangroves, salt marshes, and seagrass meadows store carbon in plant biomass and sediments.
Superpower: Sequester carbon 40x faster per area than forests!
Potential: 0.5-1.5 Gt CO₂/year
Challenge: Limited area available; restoration is costly and complex
How it works: Large fans pull air through chemical filters that bind with CO₂. The CO₂ is then separated (using heat) and compressed for storage or use.
Storage: Injected underground into basalt rock or saline aquifers where it mineralizes
Current status: ~20 DAC plants globally removing ~10,000 tons CO₂/year (we need to scale to billions of tons)
Companies: Climeworks (Switzerland), Carbon Engineering (Canada), Global Thermostat (US)
Cost challenge: Currently $600-1,000/ton. Needs to drop to $100-200/ton to be viable at scale.
Energy requirements: Significant - must use renewable energy or it's counterproductive
How it works: Grow biomass (crops/trees) → Burn for energy → Capture CO₂ from smokestack → Store underground
Net effect: Negative emissions + renewable energy
Potential: 3-10 Gt CO₂/year
Major concerns:
How it works: Spreading crushed silicate rocks (like basalt) on land or in oceans accelerates the natural process where rocks react with CO₂ to form stable carbonate minerals.
Natural inspiration: This process has regulated Earth's climate for millions of years - we're just speeding it up.
Potential: 2-4 Gt CO₂/year
Permanence: 100,000+ years (essentially permanent)
Challenges: Mining and transportation impacts, slow reaction times, monitoring difficulty
How it works: Heating biomass (agricultural waste, wood) in low-oxygen environment (pyrolysis) creates a charcoal-like substance rich in stable carbon.
Multiple benefits:
Potential: 0.5-2 Gt CO₂/year
Cost: $100-300/ton
Status: Growing industry with hundreds of facilities worldwide
The ocean naturally absorbs 25% of our CO₂ emissions. Can we enhance this?
How it works: Adding alkaline materials (like crushed limestone) to the ocean increases its capacity to absorb CO₂ and reduces acidification.
Potential: Large (multi-gigaton scale)
Status: Early research phase
Concerns: Ecosystem impacts unknown, monitoring challenges, governance questions
How it works: Adding iron to iron-poor ocean areas stimulates phytoplankton blooms. When phytoplankton die, some carbon sinks to the deep ocean.
Controversy: High uncertainty about effectiveness and side effects (toxic blooms, oxygen depletion, disrupted food webs)
Status: Largely halted due to concerns about unintended consequences and the London Protocol (international treaty)
Carbon removal is essential but faces major challenges:
The bottom line: Carbon removal is necessary but insufficient on its own. The priority must remain rapidly cutting emissions to net-zero.
Carbon removal isn't risk-free. Important concerns include:
Scientists are exploring innovative new approaches: