EDGAR and national UNFCCC inventories agree on CO2 but diverge on methane and N2O

Why it matters

Countries and analysts use both datasets to track progress under the Paris Agreement. Knowing where and why they differ helps users read the numbers with care. The authors also point to reporting changes that could make the datasets easier to compare, especially for non-Annex I countries.

What they did

The authors compared EDGAR, a global emissions database, with national inventories submitted to the UNFCCC. They focused on G20 countries, Annex I countries and EU27 members. They looked at CO2, CH4 and N2O, using IPCC AR5 warming potentials for all countries. They treated differences within ±10 % as a practical benchmark for fossil fuel emissions. They traced larger gaps to sectors, methods, emission factors and the timing of submissions.

Key findings

• For Annex I countries, the median ratio of EDGAR to UNFCCC fossil CO2 stayed between 0.98 and 1.01.
• For CH4, EDGAR runs progressively higher than UNFCCC Annex I from 2005 onward. The median ratio reaches 1.21 in 2022. Fugitive emissions in Russia and landfill treatment in Turkey drive much of this.
• For N2O, UNFCCC is systematically higher than EDGAR. The median ratio ranges from 0.83 in 1995 to 0.88 in 2022. EDGAR uses only Tier 1 factors for managed soils, while countries such as the USA use higher-tier methods.
• Total GHG emissions for the EU27 agree within ±3.5 %. Estonia, Lithuania and a few other members exceed ±10 % in some years.
• Non-Annex I inventories are irregular, outdated and often lack data by gas. Argentina’s data on the UNFCCC site, for example, still reflect a 2015 submission.

Limitations

• Complete, comparable data are not available for all countries, especially non-Annex I countries, so some comparisons rest on short or outdated series.
• EDGAR relies on default emission factors and international statistics. Revisions to those statistics can introduce breaks that national recalculations do not have.
• The study explains sources of difference but does not judge which dataset is more accurate.

Glossary

• EDGAR: The Emissions Database for Global Atmospheric Research, a global emissions dataset that applies the same method to all countries.
• Annex I countries: Mostly industrialised countries that must submit annual emissions inventories to the UNFCCC.
• Tier 1/2/3: IPCC levels of method detail. Tier 1 uses default factors, and higher tiers use more country-specific data.
• Fugitive emissions: Emissions released during fossil fuel production, processing and transport.