A Brief History of Greenhouse-Gas Inventories
Last updated: · PlainEmissions Editorial
Before the framework: 1958-1990
Continuous atmospheric measurement of CO2 began at Mauna Loa Observatory in 1958, when Charles David Keeling started the famous record that now bears his name. The Keeling Curve showed unambiguously that atmospheric CO2 was rising — but at the time, national inventories of where the emissions were physically coming from did not exist in any systematic form.
The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the World Meteorological Organization and the United Nations Environment Programme. Its First Assessment Report (1990) made the scientific case for human-caused climate change and concluded that an international agreement on emissions accounting was needed.
The UNFCCC framework: 1992-2005
The United Nations Framework Convention on Climate Change was opened for signature at the 1992 Rio Earth Summit. Article 4 obligated parties to develop national inventories of anthropogenic emissions by sources and removals by sinks of all greenhouse gases. The IPCC's 1996 Revised Guidelines for National Greenhouse Gas Inventories provided the methodological scaffolding.
The Kyoto Protocol (1997, in force 2005) added quantified emission-reduction commitments for Annex I countries. Compliance required rigorous national inventories — and the rigor of those inventories varied dramatically by country, even among Annex I parties with full reporting obligations.
EDGAR and bottom-up modelling: 1990s-2010s
The European Commission's Joint Research Centre began work on the Emissions Database for Global Atmospheric Research (EDGAR) in the early 1990s, with the explicit goal of producing globally-consistent emissions estimates that did not depend on country self-reporting. The first public release covered 1970-1995. By the 2000s EDGAR had become the de facto reference for cross-country comparison, even as UNFCCC inventories remained the legal record.
Other bottom-up inventories developed in parallel: the U.S. EPA's national inventory, the IEA's energy-emissions accounting, FAO's agriculture and land-use emissions estimates. These different bottom-up systems disagreed with each other and with UNFCCC self-reports in ways that became progressively better-understood.
Satellite era: 2014-present
NASA's Orbiting Carbon Observatory (OCO-2) launched in 2014, the first dedicated CO2-mapping satellite. Japan's GOSAT had launched earlier (2009) with similar capability. The European Space Agency's TROPOMI instrument launched on Sentinel-5P in 2017, with sufficient methane sensitivity to detect individual large plumes from oil and gas facilities — a step change in inventory verification.
Climate TRACE, founded in 2019 with backing from former US Vice President Al Gore and Google, launched publicly in 2021 with the first systematic country-level emissions estimates derived from satellite observation rather than self-reported activity data. The 2022 release added facility-level resolution for major point sources. The 2024 release added quarterly updates and substantially improved sectoral coverage.
The Paris Agreement and enhanced transparency: 2015-present
The 2015 Paris Agreement replaced Kyoto's top-down emission targets with a bottom-up framework of nationally-determined contributions (NDCs). The Enhanced Transparency Framework (ETF), agreed at COP24 in 2018, requires all parties — Annex I and non-Annex I alike — to submit Biennial Transparency Reports starting 2024, with common reporting guidelines.
The 2024-2025 first BTRs are a watershed: for the first time, every party to the UNFCCC is on a common reporting cadence. Coverage of historically under-reporting developing economies will improve substantially. PlainEmissions will track BTR submissions as they land.
The state of inventory science today
For most well-resourced developed countries, multiple independent measurement systems now produce convergent estimates within roughly 5-10% on the national CO2 total. Disagreement is concentrated in specific sectors (LULUCF, fugitive methane) and specific countries (where capacity constraints or political incentives shape reporting). Satellite verification is rapidly closing the gap.
The frontier challenges are: (a) extending satellite resolution to diffuse sources (transport, residential heating); (b) measuring soil carbon dynamics directly; (c) developing facility-level inventories of process emissions (cement, steel, chemicals); and (d) reconciling the rapidly-improving Climate TRACE estimates with the legally-binding UNFCCC inventory record.
Why PlainEmissions exists in this moment
The science has matured to the point where multiple independent measurements of the same country's emissions can be directly compared. The journalism has not yet caught up — single-source figures are still routinely quoted as if they were ground truth. PlainEmissions exists to make the multi-source comparison the default reading experience, not a footnote.