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📄 "Ton-Year Accounting"

Carbon Removal Newsroom

Photo by StellrWeb / Unsplash

Host: Radhika Moolgavkar
Guests: Bodie Cabiyo & John Dees | CarbonDirect
Category: 📄 Policy

Podcast’s Essential Bites:

[2:32] BC: “A lot of carbon removal solutions […] have short term carbon storage. So if you think about planting trees, or storing carbon in soils, that doesn't last forever, unlike […] something like direct air capture with CCS, where you're putting it underground and functionally storing it for thousands of years. […] Carbon offsets to be effective basically have to be forever. You can think about […] if I buy a 30 year, carbon credit today, in 30 years, when that carbon credits up, I'm basically re-emitting carbon emissions in 30 years. So I'm delaying my emissions for 30 years, but I'm not actually completely offsetting carbon emissions.”

[3:26] BC: “We don't really have good agreed upon frameworks for how to account for that variability in how long carbon is stored. And it's important because, in an ideal world every carbon offset is one tonne of carbon permanently stored. […] You have no readmission event. But in reality, we have a lot of really good solutions, especially nature based solutions that don't have that quality of storing carbon forever. And so we have to figure out ways that we can effectively integrate those short term storage solutions, like nature based solutions into carbon offsetting frameworks.”

[5:23] BC: “There's two approaches using the short term credits: vertical stacking and horizontal stacking. […] If you imagine like a block of your one tonne of carbon emission laid on a timeline, and that carbon emission lasts forever essentially, one way to offset that carbon emission forever is to buy a 20 year credit today. And then in 20 years, when that carbon credits up, you buy another carbon credit. And then when that credit is up, you buy another one. Alternatively, in 20 years, you could buy a permanent carbon credit, say maybe direct air capture has scaled up effectively and it's cheaper, it's more widely available. The other approach, which is a little bit less straightforward […] is vertical stacking, which is basically instead of stacking up those 20 year credits over time, instead you buy a bunch of 20 year credits today, and you count up all of the carbon benefits, all of the climate benefits of that carbon removal. […] You could run some models and you could decide that if I buy five 20 year credits today, that […] more or less counterbalances the long term impacts of my one tonne of carbon emissions. So these are both potentially valid approaches. And they're both ways of integrating these short term credits.”

[11:37] BC: “Vertical stacking is very uncertain. It requires a lot of assumptions, a lot of modeling. […] At CarbonDirect our ethos and our philosophy about carbon removal is that it should be completely robust. Science comes first and climate comes first. And so for that reason, what we did is we chose the horizontal stacking approach, but we took it a step further. And what we did is […] we bought the credits for today, but then we also bought credits to replace those credits in the future. So we call that a bridge approach. So we bought credits that are gonna last for a few years that are nature based credits. And then we also bought what's called ex ante carbon removal credits from […] a set of companies that are providing permanent engineer carbon removal services. So basically, how that works out is for the next few years, our carbon emissions are covered by the short term credits. And then when they expire, those ex ante permanent credits will come online. So from today until forever, basically, we have offset our emissions. And the beauty of that is that we are simultaneously supporting […] great forestry projects and we're also helping to scale these absolutely critical engineered carbon removal solutions.”

[17:41] JD: “This CarbonPlan critique, for me […] was really exciting, because […] they did a really good job of laying out the issues […] [of] temporary storage. […] Ton-year accounting […] is a family of methods, that is attempting to draw some sort of physical equivalency between carbon stored for some period of time and a […] permanent emission to the atmosphere. I think the CarbonPlan has a […] simple initial way of explaining it, which is you can think of a ton-year as you can take a ton of carbon stored, multiply that times the number of years that you've stored it and that gives you ton-years.

[18:45] JD: “I think conceptually a more useful way to think about it is really a ton-year is a measure of impact. So if you think about the radiative forcing, which is essentially the change in the amount of outgoing infrared thermal energy in the atmosphere that is caused by CO2 being put into the atmosphere, […] that is caused by a ton of CO2 released into the atmosphere in the first year that it's in the atmosphere. That is what we would call a ton-year. […] Now each subsequent year […] after the first year, CO2 is taken up by natural processes, land sinks, ocean sinks. So in each subsequent year its “impact” or radiative forcing effect is going to be less than it was in the first year that it was released. […] In year one, it produces a ton-year of impact. In each subsequent year it produces less than a ton-year of impact.”

[27:52] BC: “Nobody's using ton-year accounting and […] I think NCX is getting a lot of heat for pushing this conversation. But the reality is, you can go on the carbon market today and you can put a 10 year soils project and 1,000 year mineralization projects in the same basket. And they're both just labeled a ton of CO2e. And in a lot of cases the buyer doesn't even know the difference between the two unless they do some digging. So […] I'm glad that the conversation is happening now, because it feels like it's [...] been ignored.”

[30:21] BC: “Transparency is key here. And transparency is exactly what we don't have in the current market. […] We talked about horizontal stacking, which is just basically renting credits over time. It's very transparent, it's very straightforward. With all these ton-year methods, there's always going to be assumptions embedded, […] even if we create the perfect ton-year accounting method, there's inevitably going to be climate modeling assumptions.”

Rating: ⚡⚡⚡⚡

🎙️ Full Episode: Apple | Spotify | Google
🕰️ 44 min | 🗓️ 03/04/2022
✅ Time saved: 42 min

Additional Links:
Article: “Accounting for Short-Term Durability in Carbon Offsetting” (CarbonDirect, 2022)
Article: “Unpacking Ton-Year Accounting” (CarbonPlan, 2022)