Direct, continuous measurement is needed to increase confidence in reported emissions

Government-published CMM figures are highly uncertain, undermined by both limited reporting and the poor quality of available data. Around 89% of emissions were left unreported in 2023, and where reporting does occur, 87% of coal production is estimated using generic global or national emission factors. Investing in mine-level, real-time monitoring would raise confidence and give a solid foundation for designing mitigation policies.

A barrier to understanding global CMM emissions is infrequent reporting from many of the world’s largest coal-producing nations.

Of the 73 countries that mined coal in 2023, only 23 countries submitted emissions reports to the UNFCCC. These countries reported a combined 3.8 million tonnes of CMM, roughly 11% of the UNFCCC-derived estimate of total global CMM emissions in the same year, leaving 89% unreported.

In 2023, only three of the world’s nine largest coal producers submitted CMM data to the UNFCCC. China, India, Indonesia, the United States, South Africa and Kazakhstan did not report any greenhouse gas emissions that year.

While most industrialised countries and economies in transition (Annex I under UNFCCC rules) reported emissions in 2023, the most recent reporting year for developing countries (Non-Annex I) ranges from 1994 to 2023. Some coal producers, such as Bangladesh, Mozambique and Pakistan, have never reported CMM emissions.

To close these reporting gaps, new UNFCCC rules now require all countries to report annually. The Enhanced Transparency Framework (ETF) is the EU- and UN-agreed system that sets out how countries report their greenhouse gas emissions and the actions taken to reduce them.

Under the ETF, each nation must produce a Biennial Transparency Report (BTR) every two years, with the next round due in 2026. The BTR is a compulsory, standardised report that shows:

1. What the country emitted (including methane from coal mines).
2. What policies or actions it has taken to reduce those emissions.
3. How the figures were calculated.

While submitting a BTR is mandatory under the Enhanced Transparency Framework, the framework is explicitly designed to be non-punitive and flexible, with no formal penalties for non-submission. Non-submission is, however, publicly noted, and may affect a country’s standing in international climate processes, including the Global Stocktake.

Because most CMM estimates are derived from emission factors, the resulting inventories remain highly uncertain and may not reflect the true magnitude of methane released from mines.

The Intergovernmental Panel on Climate Change (IPCC) categorises reporting methods into three tiers that differ in scientific rigour and data requirements:

• Tier 1 uses global CMM emission factors and aggregated national data such as coal production and the number of closed mines.
• Tier 2 incorporates country- or basin-specific emission factors.
• Tier 3 uses process-based models or direct, facility-level measurements and is therefore mainly applied to underground mines.

The overwhelming majority of coal-producing countries (67 of 68) rely exclusively on Tier 1 or Tier 2 methods for estimating emissions rather than direct mine-level measurements, representing 87% of global coal production.

A further 13% of global coal production uses measurement-based Tier 3 reporting to some extent. This tier of measurement is often only applied to underground mining operations, for example in the United States and Poland.

Ember’s assessment, which quantifies data quality across all reporting countries, found that confidence in reported CMM emissions is low-to-medium for most of the world’s coal output.

While the IPCC tier system reflects the methodology a country uses, Ember’s confidence score takes a broader view, also accounting for the recency of reporting to the UNFCCC, the robustness of the methodology used and the degree of alignment with independent measurements. More details on this can be found in the methodology.

CMM emissions from only 4% of countries are rated high confidence, with a further 19% medium-high. The majority of countries (59%) are medium-low confidence, and a further 19% have low confidence.

The confidence scores assigned to the top coal producers are China (medium), India (medium-low), Indonesia (low), Australia (medium), United States (medium), Russia (medium), and Poland (medium-high).

Only countries for which the majority of coal production has measurement-based emissions reporting receive high confidence scores. For example, Poland achieved a high score due to mine-level measurements for much of its coal production and good agreement with independent estimates. Indonesia and India received low scores as they rely on emission factors, and comparisons with independent estimates vary significantly.

Raising confidence in official CMM numbers requires moving from estimates based on emission factors to continuous, direct monitoring and verification.