Captain Drawdown’s daily logbook on every CDR story, paper, and expert voice — so you don’t have to read them all.

The forecast

Within the next 180 days, at least one major CDR registry will either publish a methodology amendment addressing humidity-swing and water-managed DAC sorbents, or issue an explicit deferral notice acknowledging the gap. The forcing function is a new arXiv preprint, Vacuum Moisture Swing Direct Air Capture: A Low-Thermal, Water-Managed Pathway, which reframes the binding constraint of air capture from regeneration heat to water activity. Current DAC accounting frameworks, including Isometric DAC Protocol v1.3, were engineered around thermal or electrical regeneration energy. They do not separately quantify or audit water as a parasitic load or as a lifecycle input. That mismatch is now visible, and the first non-thermal sorbent project seeking issuance will surface it.

The 30-day window

Expect quiet activity, not announcements. Watch for the preprint to attract formal citations from sorbent developers, and watch the AGU Fall Meeting abstract list to populate. Zeke Hausfather flagged the relevant venue (@hausfath on Bluesky): “My colleague Frauke Kracke is organizing a session on surficial mineralization for carbon dioxide removal at the AGU this year. If you are working on something related, submit an abstract!” That session is the natural stress-test venue for humidity-driven and water-mediated chemistries. Leading indicator: at least three abstracts engaging water-activity-driven capture chemistries appearing in the AGU program by end of month.

The 90-day window

The AGU session itself runs in December, inside this window. That is where the protocol gap moves from a preprint footnote to a publicly discussed methodology problem, with registry technical staff in the room. Expect at least one registry to publish an open consultation, a research note, or a working-group call on water LCA boundaries for sorbent-based capture. In parallel, watch the second non-thermal pathway converging on the same accounting question: VTT and Mitsubishi Electric’s direct ocean capture work introduces a non-heat-swing chemistry on the marine side. Registries cannot treat the atmospheric and oceanic cases as one-off exceptions when both arrive in the same quarter.

The 180-day window

The forcing event is the next credit-issuance attempt from a non-thermal sorbent system. Deep Sky’s first certified North American DAC credits were issued under Protocol v1.3, which assumes thermal or electrical regeneration. A humidity-swing project applying under the same protocol either gets squeezed into an ill-fitting energy boundary, or triggers a v1.4 amendment, or gets routed to a new protocol entirely. By month six, expect one of those three outcomes to be public. Buyers should note: credits purchased under v1.3 in Q3 may not be directly comparable to credits issued under whatever water-LCA addendum lands by year-end. This is the kind of methodology fork that quietly bifurcates a market. We have flagged adjacent durability and accounting questions before in How Can Direct Air Capture Scale; this is the next layer down.

What would falsify this forecast

Three things would kill the thesis. First, if the arXiv preprint fails peer review or gets withdrawn with a substantive defect in its energy or water accounting, the forcing pressure on registries drops sharply. Second, if no non-thermal sorbent project files for issuance under any major registry in the next 180 days, registries have no immediate operational reason to amend. Third, if registries publicly take the position that water inputs are already covered under existing lifecycle assessment requirements and require no methodology-specific treatment, that is a deferral, not the amendment I am predicting. Note: a generic protocol update unrelated to water activity does not count.

The bet

Here is the concrete six-month claim: by the end of the 180-day window, the changelog of at least one major CDR registry running a DAC methodology will contain a dated entry that uses the words “moisture,” “humidity,” “water activity,” or “water lifecycle” in the context of sorbent regeneration. Either as an amendment, a consultation, or an explicit deferral. If the changelog is silent on all four terms across every major DAC-credentialing registry six months from today, I was wrong, and the MRV stack absorbed the humidity-swing problem more slowly than the preprint pipeline suggested it would.

Citations

  1. arXiv preprint — Vacuum Moisture Swing Direct Air Capture: A Low-Thermal, Water-Managed Pathway — preprint
  2. Isometric — Isometric DAC Protocol v1.3
  3. Bluesky — @hausfath on Bluesky — Bluesky post
  4. Renewable Carbon — VTT and Mitsubishi Electric’s direct ocean capture work