Captain Drawdown’s weekly Sunday selection — 9 candidate stories considered, 6-9 picked. Each link carries our 1-2 sentence take so you don’t have to click everything to know what’s there.
The candidate pool this week skews academic, with five research artefacts against two industry items. That makes for a cleaner-than-usual read on where the methodological frontier sits: ocean CDR efficiency, carbon-cycle asymmetries under net-negative pathways, and the discourse layer sitting on top of it all. On the commercial side, Climeworks is the only operator making noise.
Operator signal
- Carbon Herald: Climeworks Hits New DAC Milestone, Achieving Major CO2 Capture Increase At Lower Costs. Climeworks is claiming both a capacity bump and lower opex in the same announcement, which is the pairing buyers have been waiting on since Mammoth’s throughput shortfalls surfaced last year. Worth reading for the specifics on whether the gains come from the plant or the sorbent generation.
Ocean CDR methodology
- CDRXIV: Ocean alkalinity enhancement: Insights and considerations for application. Swoboda et al. frame ocean alkalinity enhancement (OAE) against a scenario where CDR carries 15–20% of current GHG emissions by mid-century, positioning alkalinity enhancement as a candidate within that wedge rather than at its margins.
- Zenodo: Code for: Global intercomparison of ocean-based geochemical carbon dioxide removal efficiencies. Zhou, Timmermans, Yankovsky and co-authors have released the code behind a global intercomparison of geochemical ocean CDR efficiencies, a rare open-science move in a subfield where efficiency numbers still vary widely between modelling groups.
- Zenodo: Modelling approaches to evaluating marine carbon stocks and fluxes. André Visser’s Wellington workshop material on baselining marine carbon across the New Zealand EEZ, relevant for anyone tracking how national-scale measurement, reporting, and verification (MRV) for ocean CDR gets bootstrapped.
Carbon-cycle asymmetry and land pathways
- Biogeosciences: Asymmetry in carbon cycle feedbacks and transient climate response under positive and negative CO2 emissions. Chimuka and Zickfeld examine whether the climate system responds symmetrically to positive versus negative emissions, a question that directly affects how much CDR is required to deliver a given temperature outcome in overshoot scenarios.
- Mendeley Data: Synergy between biochar and root exudates: A key to unlocking soil carbon sequestration potential. Ding and Li’s dataset looks at biochar-root exudate interactions as a driver of soil carbon sequestration, adding to the mechanistic case (or against it) for durability claims in biochar protocols.
Discourse and narrative
- Nature Reviews Clean Technology: Mapping conflicts in carbon removal narratives. A review mapping where CDR narratives clash, drawing on the recent land-use and biodiversity literature; useful ammunition for anyone briefing policymakers who conflate removals with mitigation deterrence.
The dominant signal this week is methodological consolidation on the ocean side, with two open-science releases landing alongside a synthesis preprint. Conspicuously absent: buyer announcements, procurement results, and any policy movement out of Washington or Brussels. A quiet week on the commercial ledger, a busy one in the model code.