Smart carbon removal strategies could stabilize Earth's climate for centuries

Carbon is at the center of nearly every promise to slow climate change. Corporations say they’ll be “net-zero” by 2050. Governments say they’ll balance out carbon emissions with carbon removal.

But the big question still looms: Can we actually store enough carbon for long enough to keep the planet from heating up?

A new study tackles that question head-on, and the answer is yes – but only if we manage the risk wisely and stop viewing nature and technology as separate options.

The risks behind carbon removal

Carbon dioxide stays in the atmosphere for centuries, heating the planet. The more CO₂ we emit, the more Earth warms.

Removing carbon from the air is one way to cool things down – but it’s not enough to just remove it. We also need to make sure it stays out of the atmosphere for the long haul.

Right now, there are two main types of carbon removal projects. One is nature-based – planting trees, restoring forests, creating biochar from plants, and storing it in soil. The other is tech-based – machines that pull CO₂ from the air and inject it deep underground.

Nature-based projects are cheaper and more common, but they’re risky. Forests can burn. Land use can change. That carbon can come right back into the atmosphere. Tech-based solutions are expensive and slow to grow, but they’re better at locking carbon away permanently.

That trade-off has left climate planners with a tough call: Save money and go with trees? Or pay more for machines that are slow to scale?

Smarter carbon planning for centuries

Researchers from the University of Cambridge came up with a new way to think about this. They created a method to assess whether portfolios of carbon removal projects can actually help keep the planet cool -not just for the next few decades, but for hundreds of years.

Instead of assuming all carbon removal is equal, they looked at the risks. How likely is it that carbon stored by trees or soil will escape? How permanent is tech-based carbon storage? And how much extra CO₂ do we need to remove now to make up for future losses?

Their model lets companies and governments figure out how much of a “buffer” to add. For example, if you’re using mostly nature-based methods, the researchers say you should store about two tons of carbon for every one tons you emit. That cushion helps account for future leaks or reversals.

But if your portfolio relies too heavily on risky options – like forests in fire-prone areas – you may need a massive buffer: up to nine tons removed for every one ton emitted. That’s a big ask.

The authors warn that relying too much on these high-risk projects could backfire because of the cost and uncertainty involved.

What net zero really requires

“Tech giants like Microsoft and Meta are collectively spending billions on carbon removal portfolios to offset their growing carbon footprints,” said Dr. Conor Hickey, the study’s lead author.

“While companies and countries agree that increased investment in carbon removal is essential to reach net-zero targets, they also want to understand whether carbon removal schemes can help stabilize global temperatures over the long term.”

That’s what this study helps solve. “Our risk management approach offers one of the first reliable measures for portfolio managers targeting long-term temperature stabilization,” Hickey said.

“It shows that nature-based carbon storage such as tree planting has a bigger role to play than critics assume when used as part of a diversified carbon removal portfolio.”

But not all experts think nature-based solutions can carry the load forever. “Durable net zero means geological net zero,” said Professor Myles Allen, a co-author of the study.

“To stabilize climate in line with the Paris Agreement goals, anyone still relying on offsets must plan to shift entirely to carbon dioxide removal with geological storage by the middle of the century.”

The case for hybrid carbon plans

This new research pushes back against the idea that only permanent tech-based carbon storage can work. It shows that a mix of methods can still help – if the risks are managed correctly and the right buffers are in place.

“Removing more carbon now can effectively cover carbon storage risk for centuries, and this can be done with a mix of nature and tech, as long as the right buffers are built in,” Hickey said.

“Portfolios can combine expensive permanent solutions like DAC with lower-cost nature-based options like planting trees – matching society’s willingness to pay while still contributing to temperature stabilization goals.”

The team also designed their method to fit how real-world markets work today. “Our approach enables strategic carbon storage choices based on current availability, while targeting long-term temperature stabilization. It provides buyer flexibility while valuing lower-risk storage options, something today’s market lacks,” Hickey said.

Thinking centuries ahead

The U.K. and the E.U. now require that carbon removal projects meet a minimum permanence of 200 years. And by 2050, the UK plans to reach net zero with a heavy focus on geological storage of CO₂ – deep underground.

That means nature-based projects won’t disappear. But they’ll need backup from tech-based methods. And any serious carbon plan will need to start thinking hundreds of years ahead.

This study shows that’s possible. But only if we stop pretending that short-term offsets are enough – and start building portfolios that actually work in the long run.

The full study was published in the journal Joule.

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