Understanding how carbon capture works and why it matters for climate action
As global climate goals become more ambitious, simply reducing emissions is no longer enough. To reach net-zero – and potentially reverse some of the damage already done – we also need ways to remove or prevent carbon dioxide (CO₂) from entering the atmosphere in the first place. That’s where carbon capture comes in.
But what exactly is carbon capture? And how does it fit into the broader toolkit of climate solutions?
What does “carbon capture” mean?
Carbon capture refers to the process of trapping carbon dioxide emissions, either before they enter the atmosphere or by removing them from the air after the fact. It’s a technology-enabled approach to managing CO₂, the primary greenhouse gas driving global warming.
There are two main types of carbon capture:
- Point-source capture: CO₂ is captured directly at the source, such as power plants, cement factories, or steel mills, before it can be released into the atmosphere. This helps mitigate emissions from industries that are hard to decarbonise.
- Direct air capture (DAC): Specialised machines remove CO₂ already in the atmosphere, tackling emissions that are already dispersed and contributing to climate change.
In both cases, capturing CO₂ is only half the solution. The other half is permanent storage – ensuring that once carbon is captured, it stays out of the atmosphere for the long haul.
Why carbon capture is important
Carbon capture plays a critical role in meeting climate goals, particularly for three key reasons:
- Legacy emissions persist: Even if we stopped emitting tomorrow, the CO₂ already in the atmosphere would continue to warm the planet for generations. Removing it is essential.
- Some sectors are hard to clean up: Industries like aviation, shipping, and cement production will continue emitting for the foreseeable future. Carbon capture can help neutralise these residual emissions.
- It enables net-negative outcomes: Carbon capture is one of the few tools that can actually remove more CO₂ than we emit – a requirement for restoring a livable climate, not just stabilising it.
The IPCC (Intergovernmental Panel on Climate Change) has made it clear: carbon capture is not optional. To stay below 1.5°C or 2°C of warming, carbon capture, alongside deep emissions cuts, is essential.
Where does captured carbon go?
Capturing CO₂ is only valuable if it’s stored securely and durably. There are several approaches to storage:
- Geological storage: CO₂ is injected deep underground into porous rock formations or depleted oil and gas reservoirs. Over time, it mineralises and becomes trapped for thousands of years.
- Biological storage: Natural ecosystems like forests, wetlands, and soils can be enhanced to absorb and hold carbon. This method can provide ecological co-benefits, such as biodiversity restoration.
- Material storage: Captured carbon can also be used in materials like concrete or converted into stable forms like biochar, locking it away for decades or longer.
Each storage option has its own tradeoffs – geological solutions offer high permanence, while biological approaches are more vulnerable to natural disturbances like fire or deforestation.
Key terms to know
As you explore the world of carbon capture, here are a few important terms to understand:
- Carbon Capture and Storage (CCS): A system that captures CO₂ from industrial sources and stores it underground.
- Carbon Dioxide Removal (CDR): A broader term that includes DAC and nature-based methods that pull CO₂ from the air.
- Permanence: The expected duration the carbon will stay out of the atmosphere.
- Leakage: The risk of stored carbon escaping back into the atmosphere.
- Additionality: Ensures that the carbon removal is above and beyond what would have happened anyway.
Understanding these terms is crucial for evaluating the integrity and impact of carbon capture projects, especially in carbon offset markets.
The bigger picture
Carbon capture is not a silver bullet, but it’s one of the few tools we have to actively reverse CO₂ buildup. To meet our climate goals, we need a portfolio of solutions: aggressive emissions cuts, renewable energy transitions, adaptation efforts and large-scale carbon capture and storage.
What was once a futuristic idea is now a rapidly growing field. From innovative startups to national climate strategies, carbon capture is becoming a key part of how we build a climate-resilient future.
