Dr. Barbara Haya

Methodology focus

Director of the Berkeley Carbon Trading Project at UC Berkeley. The most influential public voice on voluntary carbon market integrity. Built the Voluntary Registry Offsets Database, the most-cited transparency instrument in the field. Her 'contributions approach' reframes carbon finance away from offsetting toward measurable mitigation support — which is precisely what proof-pack-verified tonnes enable.

Trellison / LedgerWell intersection. If she validates LedgerWell proof-pack methodology as the substrate for a contributions-based market, that is the imprimatur. Trellison is the right conduit.

Affiliation

UC Berkeley — Berkeley Carbon Trading Project

Role

Director

Axis

Integrity Critics

Tier

Tier 1

Public signals

REDD+ over-crediting research
cookstove additionality 2026
CA cap-and-trade SF Chronicle op-ed
UNFCCC critique Nature Climate Change Dec 2025

Selected publications

2026 — Quantifying the additionality of cookstove carbon projects. Carbon Management.
2025-12 — UNFCCC Carbon Trading Could Undermine Global Climate Action (commentary). Nature Climate Change.
2025-07 — Quality of Carbon Credit Projects & an Alternative Contributions Approach. World Bank ABCDE Conference.
2025-05 — Policy Brief: California Cap-and-Trade Offset Waste (with Lezak). Berkeley Carbon Trading Project.
2025-01 — Voluntary Registry Offsets Database v10. Berkeley Carbon Trading Project.

Alignment with proof packs

Their methodology / role	Proof-pack / Trellison fit
Voluntary Registry Offsets Database	Proof pack is a per-tonne extension of the registry database — every claim has a full evidentiary chain
Contributions approach	Proof packs enable 'support' claims distinct from offset equivalence
REDD+ over-crediting detection	Proof-pack counterfactual + leakage ledger surfaces over-crediting signatures
Cookstove additionality	Proof pack requires real-world usage data, not modelled assumptions

Collaboration concepts

Concept 1

Joint validation study: VROD + proof packs

Extend the Voluntary Registry Offsets Database with a proof-pack layer for a sample of 500 projects across 5 methodologies. Target: Environmental Research Letters.

Concept 2

Contributions-approach implementation whitepaper

Operationalise Haya's contributions vs. offsets framework as a proof-pack-backed claim taxonomy. Target: Berkeley Carbon Trading Project brief + Trellison co-publication.

Concept 3

REDD+ retrospective audit with proof-pack schema

Apply proof-pack evidentiary chain retrospectively to 10 REDD+ projects identified in the West et al. 2023 study. Target: Science or Nature Climate Change.

Outreach approach

Proposed opening message

Subject: A reference implementation for your integrity thesis

Dear Barbara Haya,

We have been reading your published critique of carbon market integrity as a design specification rather than commentary. Trellison Institute has been building a per-tonne open-data verification instrument — we call the artefact a proof pack — that tries to implement what your work argues for.

I would welcome a 30-minute conversation to show you the current alpha. We are not asking for endorsement; we are asking for methodology critique and, if useful, an offer of alpha access for your active work. Independent negative evaluations would be published alongside positive ones.

A one-page methodology brief that maps your work to proof-pack schema fields — with gaps flagged honestly — is attached.

With respect,
Rob Stillwell
Director, Trellison Institute

What we do not ask for

Endorsement of Trellison, LedgerWell, DaedArch, or any affiliated entity.
Exclusivity or first-look rights on research findings.
Unpaid labour. Any advisor role is compensated with a modest honorarium and disclosed on the record.

Disclosure: Compiled from public sources through April 2026. Inclusion does not imply endorsement, affiliation, or reciprocal interest. Corrections: About.

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