Separating carbon cartons: Different eggs go in different baskets

Here in Brussels, spring has arrived. The sun has been making more frequent appearances, the trees are in bloom, and Easter is around the corner. Easter, that time to celebrate the rebirth of nature, as wildflowers multiply along with decorative baskets of eggs (left behind by a notoriously multiplying rabbit). But this year, the season has been a bit of a basket case, and the evidence of climate change is indeed multiplying.

With these basket-themed musings in mind, I’m reminded of a conversation Carbon Gap hosted earlier this year about how it’s imperative that we don’t put all our mitigation eggs in the same basket. It all comes down to ensuring parity between the fossil carbon we emit into the atmosphere and the carbon we remove from it, what we call the Like-for-Like principle. Simply put, carbon stored for millions of years in geology should be stored geologically, ergo, for millions of years; carbon stored in living things, i.e. the biosphere, should be reabsorbed through natural processes. Planting trees and boosting biodiversity will only get us so far in tackling climate change. Trees die, forests burn, and the carbon that was stored is re-released. We can’t rely only on natural solutions; we must make sure the baskets stay separate–that biogenic emissions and nature-based carbon removals compensate for each other, that geologic removals balance fossil emissions.

But to scramble the proverbial eggs a bit more, there are more baskets to consider, first and foremost because we actually emit a lovely bouquet of not only CO₂, but also methane, nitrous oxide, and F gases, all of which have warming properties. Yet we currently only have methods for eliminating CO₂; for the rest, it’s a question of steep emissions reductions and waiting for them to breakdown. Basically, there are actually three baskets – fossil CO₂, biological CO₂ and short-lived gasses – and you need to define each in order to create appropriate mitigation strategies.

This basket analogy is not my own, but rather was used by Professor Friedlingstein at our Like-for-Like Fireside Chat in January to explain the issues around making sure we know exactly how much carbon we have emitted and therefore how much we need to store. This confusion is why, in our recent publication, we examined equivalencies between greenhouse gasses to better codify the Like-for-Like principle and set out key principles to ensure we not only reach net zero but sustain net zero by keeping baskets separate and not inter-weaving or hampering our efforts at credible climate accounting.2

But keeping baskets separate is no slam dunk. But if we hammer out current sticking points in our efforts to market and scale carbon dioxide removal (CDR) and equilibrate mitigation efforts, we may just be able to reach and stay at net-zero in the long-run.

1) A permanence problem

We have established that there are different baskets of carbon, but how big is each? That’s not a straightforward question, because it really depends on how many eggs we put in each. Not all carbon storage is created equal. Storage duration among carbon removal methods can vary from centuries to hundreds of millennia. So where do we draw the cutoff between permanent and temporary? And how do we decide what should count in establishing that cutoff?

For example, a carbon removal operator could sell carbon removal credits promising to store carbon for centuries. The contract is signed, underwritten by insurance, and sold, and the operator stores the carbon. But like any human operation, it is open to errors. Mistakes happen, companies go bankrupt, and insurers have limits, so even though a company promises to be able to store carbon for a thousand years, promises are cheap, but the undertaking is not.

Herein lies the difference between physical permanence and contractual permanence, the latter being far thornier to define, as Ken Branson explained during the fireside chat. He was behind an effort to try and pass a 1,000-year durability threshold through the California legislature. Although this limit was scientifically laudable, it proved political impossible and the threshold was instead significantly reduced to 100 years, a figure similar to the EU Carbon Removal Certification Framework’s 200-year threshold.

2) A muddled market

It’s not just the size of the baskets that’s hard to establish; not every egg in each basket is the same either. For example, if the threshold for establishing permanence is set at 100 years, why would a company buy more expensive carbon removal that guarantees permanence for a thousand years or more? That’s the issue facing current efforts to scale up the market for removals. As Beth Weed put it during the January fireside, currently, there is a market of one, where 92% of the current 44 megatonnes purchased come from just three buyers, with Microsoft alone responsible for 85%.

At the moment, this market is purely voluntary and relies on reputational signalling from big companies wanting to be seen to go for the costlier eggs. But without a universal and robust standard for permanence, there will never really be a viable market for all the eggs in the basket. Currently, the value of durable carbon removal varies entirely by buyer — there is no common currency, no label that distinguishes a 100-year credit from a 1,000-year one. Institutional buyers remain on the fence, waiting for clarity, a problem the voluntary market cannot solve on its own.

3) The political predicament

The Like-for-Like principle aims to codify basket and egg size, making sure volume of eggs in each basket stays the same over time, but it will really depend on regulation to enshrine this principle into law and ensure we reach durable net-zero. There have been several efforts already, most notably in California where they tried to push forward a compliance mechanism requiring polluters covered by cap-and-trade to purchase a small, growing share of high-quality CDR, modelled on the renewable portfolio standards that successfully built the solar and wind markets. The pushback was significant, including from environmental groups, many of which haven’t even bought into the idea that we need significant carbon removal to get to net-zero. Instead, California turned to CARB, the aptly named regulator, to develop the framework  and avoid the politics. Whether CARB delivers a credible plan remains to be seen, but the concern is that they might opt for political convenience and let California claim net-zero by 2045 on the back of questionable offsets.

The situation is equally as complicated at the international level. National climate pledges are almost universally a single aggregate number—no breakdown between fossil and biological CO₂, no specification of removal type, no transparency about what the “net” in net-zero actually consists of; not only are there no separate biogenic and fossil emissions/removals baskets, but there is also no carbon removal basket at all. All mitigation and reductions fall in the same bin. It’s a bit of a grab-bag where countries report what they want.

Where there’s a will, there’s a way forward

As with most things, it all comes down to political will. The Like-for-Like principle needs to emerge from being a dubious basket-based metaphor and become mainstream among activists, politicians, academics, and market actors. Yet progress is eking forward – the EU’s CRCF has a 200-year durability threshold, the EU Emissions Trading System (ETS) is considering integrating CDR credits, the UK’s recent geological net-zero review named the concept explicitly, and Switzerland has embedded a strong preference for permanent CDR in its national climate strategy. There’s much work to be done and it’s hard to know where to start, but enshrining the like-for-like principle is a climate imperative. First and foremost, we need a clear account of where our emissions come from. Better source data, alongside science-based durability standards and transparent accounting that distinguishes between types of removal can help move the political narrative that frames like-for-like not as an extra burden on business, but as the minimum necessary to make net-zero mean something.

With our upcoming paper, we do just that: we try to determine the size of each basket. By categorising global emissions, we identify a clear need for nature-based removals based on the current volume of biogenic emissions and find that the current weave of EU policies does nothing to clarify how we will remove these emissions to get to net-zero.

Crafting policies that ensure we don’t put all our removal eggs in a single carbon carton is doable. We can build a market for eggs of all shapes and sizes. The deviled eggs are in the details, but the recipe is ready for the making.

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