What is carbon removal?

Carbon removal is any process that physically takes carbon dioxide out of the air. Planting new forests can do this, but it has limitations. Trees are vulnerable; land is scarce. So to complement such natural approaches, engineers are developing an array of technologies, including direct air capture, bioenergy with carbon capture and storage, and enhanced rock weathering.

Why do we need it?

We need it to make up for residual emissions: stubborn sources of greenhouse gas that will be hard to shut down by 2050. Removals can enable us to reach net zero despite residual emissions, as well as reducing net emissions in the near term.

We also need it to draw down concentrations of CO2 in the future. Removals can take us beyond net zero, to net negative, reversing climate change.

Why will there be residual emissions?

We should aim to reduce as much as 90% of all emissions,  but it is unrealistic to get it down to zero. Long-haul aviation will be almost impossible to fully decarbonise by 2050. Heavy industry is likely to keep emitting too, especially in developing countries. Cement making in particular may be a stubborn source of CO2. Also, we need to eat, and future agriculture will almost certainly generate greenhouse gases, such as nitrous oxide from fertiliser.

How much do we need?

Predicted quantities range from very large to colossal. The standard unit here is a gigatonne  (billion tonnes) of CO2, and most projections call for several gigatonnes of removals per year. To put that into perspective check out Antti Vihavainen’s (CEO, Puro Earth) breakdown of what it will take to produce 1 gigatonne of biochar carbon removals, during CUR8’s “Why Carbon Removals and Why now?” webinar last month.

The Intergovernmental Panel on Climate Change’s Sixth Assessment Report (2022) makes clear that to limit global warming to 1.5°C with no or limited overshoot would need total carbon removals of around 220 gigatonnes. That implies roughly 5 to 10 gigatonnes of removals per year in mid century, around the time the world reaches net zero CO2 emissions.

While these estimates remain difficult to compare, other approaches size hard-to-avoid emissions at between 1.5 to 3.1 Gt per year, still showing a major role for carbon removals in the future

Avoiding a temperature overshoot is important if we want to reduce the chances of hitting disastrous climate tipping points. Though, the further we stray from our target, the more critical carbon removal becomes to getting back on track.

Recent research predicts climate mitigation efforts will only limit us to an average warming of 1.7°C by mid-century.  Even with a small overshoot, this scenario will require removals to double – to roughly 440 gigatonnes over the period – to re-align us to a 1.5°C pathway.

At least, that’s the optimistic view.  Global mitigation efforts may yet turn out to be more sluggish.  In any scenario, what is clear is that we’ll need to curate a mature range of scalable removal technologies to deploy depending on what we face.

So will we continue planting trees?

Yes, removals of a few gigatonnes per year could be achieved just by nature-based solutions such as planting forests and managing soils more sustainably; but we also have to develop other forms of carbon removal, including those that are more durable (carbon stays down for longer) and are less susceptible to the risk of reversal. Forests can burn down or be felled, and soil management can be reversed, releasing all that stored carbon back into the air, especially as theworld warms.

What other methods of carbon removal are there?

At CUR8 we believe that the optimal carbon removals strategy invests in a range of removals types, for maximum durability and social-and-biodiversity benefits: from tree planting, soil carbon, biochar (burning biomass in low oxygen environments, producing carbon rich charcoal that can be used, among others, as fertiliser), alternative building materials, enhanced rock weathering (speeding up a naturally occurring process which captures carbon while weathering silicate rock), direct air capture (large machines sucking in air, separating carbon dioxide and mineralising it) and blue carbon (methods involving our seas and oceans to remove and store carbon).

How much carbon are we removing today?

We have a very long way to scale up and not very much time.  Already, nature-based removals account for about 2 gigatonnes per year, while everything else amounts only to around 2 million tonnes per year. This 2 million tonnes includes all the durable, engineered solutions that offer to lock up carbon for centuries or millennia.

Looking ahead to existing planned projects doesn’t improve the picture much. According to Boston Consulting Group, all currently announced projects for durable forms of carbon removals  add up to 15-32 million tonnes per year by 2030. That’s a fraction of the gigatonne scale required in 7 years time.

What will make removals grow?

Governments and businesses both need to give a coordinated push to make this happen. Our sister organisation, Rethinking Removals, is helping to coordinate public and private actors, for example with events at COP27 and 28.

Most importantly, removals need investment to supercharge scale-up. Today, finance for removals is running at around $10 billion per year. A report from the Energy Transitions Commission estimates that, to remove enough CO2 soon enough to avoid overshooting 1.5°C, this would need to reach $200 billion a year by 2030.

So CUR8 is helping to create a commercial market for removals. This will let companies invest in durable and verified credits, to show customers and regulators that they are aligned with net-zero. For businesses it is vital to start this process now, to learn how to match a portfolio of removals with residual emissions, so your removals can ramp up as regulations tighten over the next few years.

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