There's a lot leather can learn from how wool just made its case. Its trade body's new Green Book is worth studying as a model.
Wool's global trade body just showed what happens when an industry stops objecting to a bad score and starts building the case to contest it. IWTO (the International Wool Textile Organisation) published its Green Book in June 2026, a direct challenge to three carbon-accounting tools apparel brands are utilizing: the EU's PEFCR, the Higg MSI, and France's Ecobalyse. The case it makes is specific. Modeling a 150-gram knit T-shirt with generic ingredients processed in China, all three tools score wool as more environmentally damaging than synthetic alternatives, in some cases ranking it worse than nylon or polyester. IWTO's argument is that this isn't a wool problem, it's a methodology problem, and they funded the study to prove it.
The mechanism IWTO points to is a specific accounting inconsistency. These tools include the emissions from monomer production when scoring bio-based fibers like wool, but exclude that same accounting step when scoring petrochemical fibers like polyester and nylon. IWTO calls this what it is: an inconsistency that "significantly affects" wool's reported footprint, charging wool for a production step that synthetics get to skip. It also means that the positive impacts of that natural cycle on an ecosystem are counted as negative.
IWTO didn't stop at pointing out the flaw. Its own researchers, working with Cape Wools SA since 2024, built a biogenic life cycle model designed to actually count the carbon a grazing system returns to the soil instead of writing it off as a straight emission. That research cleared two bars most industry-funded studies never have to: it was peer-reviewed and published in Agricultural Systems, and its methodology was independently assessed against ISO 14067:2018 by TÜV SÜD in October 2025. The result: when two-thirds of a wool system's manure carbon is credited as a return flow rather than an emission, wool's calculated emissions intensity drops by close to 100%.
IWTO's Green Book never mentions leather, but the approach is the one LHCA is building with IDI: commission independent science, get it peer-reviewed and third-party verified, publish it, then take the tools on directly instead of just disputing the number they produce. For anyone watching brands cite these scores in sourcing decisions, it's a working example of what it actually takes to earn the right to contest one.
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