Public company disclosures
The core of the database is what companies themselves have published: sustainability reports, annual reports and regulatory filings that are publicly accessible. We extract reported emissions figures from these documents and keep the source alongside the data, so company profiles can link to the report and the pages the figures appear on.
Official company registries
Company identity comes from official registries, including Companies House for UK companies and the GLEIF Legal Entity Identifier system internationally. These registries anchor each profile to a specific legal entity, provide registered names and numbers, and help us map relationships between parents and subsidiaries so that group level reporting can be surfaced in the right places.
Direct submissions
Companies that claim their listing can submit their own emissions data, and carbon accountants can report on behalf of their clients. Submitted data goes through the same checks as extracted data, and profiles show when a listing has been claimed. We place the most weight on figures prepared by an independent third party.
Benchmark and classification datasets
To compare companies fairly and to estimate unreported categories, we use industry classification and benchmark data derived from public datasets, including Carbon Disclosure Project and MSCI derived classifications. These drive our sector groupings, the weightings in the transparency score and the normalisation model described in our methodology.
Freshness
Emissions data is always attached to the reporting year the company states, and profiles show the years we hold data for. We add new disclosures as companies publish them, so coverage grows over time. If a company you care about is missing a recent report, let us know.
Using the data
Mycelium is free to search for everyone. Downloads and API access are available under our emissions data terms, with dedicated licences for commercial, carbon accountant and academic use.
