Is Enhanced Rock Weathering Ready for Scale? - with Dirk Paessler and Mel Murphy

In this episode of The CDR Policy Scoop, Sebastian Manhart and Eve Tamme are joined by Mel Murphy, an independent geochemistry consultant, and Dirk Paessler, founder and CEO of Carbon Drawdown Initiative and Vice President of the Negative Emissions Platform, for a very special episode on how anyone actually knows enhanced rock weathering is working.

Mel explains the two dominant measurement approaches, solid phase and aqueous pore water, and why they often tell different stories about the same field. Dirk brings the view from Carbon Drawdown Initiative's own experiments: a field trial with no measurable signal, buried buckets that still show nothing after 1400 days, and a greenhouse programme now running hundreds of soil and rock combinations. The pattern that keeps surfacing is that results depend on the specific rock, soil, and method used.

That uncertainty has not stopped the market. Over 20,000 credits have been certified across Brazil, the US, and India, even as Vera has declined to build a methodology, citing immature science. Mel unpacks Carbon Plan's critique of credits from the US company Lithos, where an implied dissolution rate came out roughly ten times higher than a new peer reviewed estimate, and how registries like Isometric are adjusting requirements accordingly.

The conversation closes on cost. Measurement now eats up 56 percent of enhanced rock weathering's budget, the highest share of any removal method. Dirk and Mel discuss whether machine learning trained on greenhouse data and satellite based field mapping can bring that down, and why neither will commit to a timeline for readiness under something like the EU ETS.

Show notes:

• Eve Tamme: LinkedIn and Website
• Sebastian Manhart: LinkedIn and Website
• Mel Murphy: LinkedIn
• Dirk Paessler: LinkedIn and Carbon Drawdown Initiative
• Questions about Lithos’ first ERW credit issuance
• An Ecosystem of Carbon Dioxide Removal Reviews – Part 3: Enhanced Weathering
• MRV Proxies for EW? A Guided Tour Through Our Data From Our Two-Year Greenhouse Experiment
• Portfolio Spotlight: AEROC — Giving Enhanced Rock Weathering Its Eyes
• Where does the CO₂-removal potential of enhanced weathering actually go?

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