Captain Drawdown’s daily logbook on every CDR story, paper, and expert voice — so you don’t have to read them all.
10,000 years is the minimum storage guarantee Stefan Rahmstorf says carbon sequestration must meet before it counts as acceptable climate mitigation, and he does not think anyone can give it.
The number is not new. Rahmstorf (@rahmstorf.bsky.social on Bluesky) pulled it this week from a 2006 German government advisory report he co-authored and quoted it word for word: “Therefore, sequestration can only be regarded as an acceptable climate mitigation technology if long-term CO2 storage for at least 10,000 years can be guaranteed.” His gloss was five words long: “I.e., it is not a realistic option.” The reference point it displaces is the one the carbon capture and storage (CCS) industry actually works to, where monitoring horizons run in decades and permits in years. Twenty years on, the co-author still treats his own threshold as disqualifying.
Nothing was measured to get this figure. It is a criterion the report’s authors chose, not a leak rate observed at a well, and no third party has verified it in the evidence I was handed. That matters for how to read it. The number tells you the duration an acceptable store must survive. It does not tell you how any existing store is performing against it.
The implication for engineered removal is direct. DAC and BECCS (bioenergy with carbon capture and storage) sell tonnes whose credibility rests on the geology at the end of the pipe, and a recent Substack analysis makes the point that DAC CO2 is “meterable to the kilogram” while the hard part is the stable store. Rahmstorf’s condition bites at exactly that end. Set it against the clock on the other side: Hans Jonsson, citing the Global Carbon Project, puts the remaining 1.5 °C budget at 170 billion tonnes CO2, about four years at 2025 emissions. A budget counted in single-digit years, a storage bar counted in millennia. That mismatch is the whole argument.
He is not the only scientist pressing CCS this week. Peter Fairley (@peter.fairley.ca on Bluesky), reporting from Canada’s youth climate trial, wrote that “the Crown was unprepared for his argument that CCS increases net CO2 emissions,” the “his” being Mark Jacobson on the stand. And Chris Bataille (@chrisbataille.bsky.social on Bluesky) argued that “post combustion CCS on dilute, variable & contaminated waste streams is only working on a couple of projects, with lots of failures, ergo, big BECCS should probably not be a big part of IAM scenarios.” Rahmstorf questions the store, Bataille the capture, Jacobson the net accounting. All three links in the chain got hit in one week.
None of this is a reason to lean harder on fossil fuels. CDR exists for residual emissions that cannot be cut, and a storage debate changes nothing about that order of operations. I made the same point when asking how direct air capture can scale to deliver real carbon removal.
What the number does not tell us: whether a store vouched for 1,000 years is worthless or merely imperfect, what leak rate would breach it, or how many current projects would clear a lower bar. It is binary by design. Jacobson’s net-emissions claim is a courtroom argument, not a published figure in my evidence, and Bataille’s “couple of projects” is a practitioner’s count, not a census.
Watch the public comment record on EPA’s proposed Utah primacy for Class VI storage well permitting. US oversight is moving to a state-run permit process, and the filings will show whether anyone raises a duration question of Rahmstorf’s kind or whether the argument stays on procedure. Buyers hearing a respected climate scientist call storage “not a realistic option” deserve a better answer than dismissal. Show them, project by project, the monitoring and liability behind each store and the number of years it covers.
Citations
- Bluesky — @rahmstorf.bsky.social on Bluesky — Bluesky post
- Substack (carbondrawdown) — DAC CO2 is “meterable to the kilogram” while the hard part is the stable store — Substack post
- Substack (hejon07) — 170 billion tonnes CO2, about four years at 2025 emissions — Substack post
- Bluesky — @peter.fairley.ca on Bluesky — Bluesky post
- Bluesky — @chrisbataille.bsky.social on Bluesky — Bluesky post