A new study from Cornell’s Chuan Liao and colleagues, published in Nature Communications Sustainability, models what enhanced rock weathering (ERW) could actually achieve under realistic adoption scenarios. The headline: 700 million to 1.1 billion tonnes of CO₂ per year by 2100.

That’s less than half the theoretical ceiling of 5 Gt/yr that earlier studies floated. But it’s still enormous — roughly 2–3% of current global emissions, achieved by spreading crushed basalt on existing farmland.

The Realistic Adoption Model

Instead of asking “how much rock could physically fit on fields,” the Cornell team modeled how quickly farmers would actually adopt ERW based on historical technology uptake curves for innovations like irrigation and precision agriculture.

Key findings:

  • 350M–750M tCO₂/yr by 2050 under limited-to-widespread adoption
  • 700M–1.1B tCO₂/yr by 2100 as supply chains mature
  • The Global South overtakes the North as the dominant ERW region by mid-century — higher temperatures accelerate weathering, and developing nations gain access to rock supply chains

That last point is critical. ERW could be a genuine equity lever in the carbon market, with tropical and subtropical regions holding the highest removal potential.

The Measurement Problem Nobody Solved

Here’s where it gets complicated — and where CDI’s research becomes essential reading. The Cornell study models potential removal based on rock application rates and weathering kinetics. But modeling isn’t measuring.

CDI’s two-year greenhouse experiment with over 400 lysimeters shows that:

  1. Cation retention is massive — 10-50× more cations stay in soil than export as alkalinity in Year 1
  2. Many treatments don’t produce a detectable alkalinity signal at all
  3. EC tracks alkalinity well at macro scale but breaks down at treatment level

In other words: the theoretical gigatonne potential might exist, but proving any individual tonne was actually removed remains the hard problem. As CDI’s EC proxy series (Part 7) demonstrates, the beautiful macro correlations hide messy treatment-level reality.

What This Means for the ERW Industry

The Cornell study is useful because it sets reasonable expectations. Not 5 gigatonnes of wishful thinking, but 1 gigatonne grounded in how agricultural innovation actually spreads.

But the industry can’t sell what it can’t measure. Every ERW company needs to grapple with MRV before scaling — and right now, that’s where the science is still catching up.

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