Taking stock of global climate action

Satellites help to check national greenhouse gas inventories and improve reporting of climate action

A framework, using satellite observations, has been developed by the ESA CCI RECCAP-2 project and provides a way to check and improve national greenhouse gas inventories used to assess progress towards the long-term Paris agreement temperature goal.

National greenhouse gas inventories to report emissions reductions and are assessed collectively to assess progress made to a lower carbon world via the UNFCCC global stocktake - with the first completed in 2023.

Accurate reporting

For this process to be robust, accurate and consistent reporting is needed at a national scale.

Currently, national greenhouse gas emissions inventories, which are reported to the UN Framework Convention on Climate Change (UNFCCC) are compiled using emissions factors and national statistics. To enhance accuracy, the Intergovernmental Panel on Climate Change (IPCC) encourages countries to verify reported emissions against independent measurements, such as Earth observation data, to promote transparency and align emissions reporting with real-world conditions. Research from ESA’s Regional Carbon Assessment and Processes project (RECCAP-2) developed and implemented a comprehensive framework to compare national inventories against state-of-the-art systems making use of satellite observations.

The project researchers combined satellite-derived observations and in situ measurements with inversion models that help to factor the ‘flux’ or movement of greenhouse gas emissions between land and atmosphere, to backtrack greenhouse gas concentrations to their origin. This top-down approach offers a full picture of the emissions that accumulate in the atmosphere at the country scale. This is then used to check national inventories to enhance greenhouse gas reporting.

Benefit of comparison

The research found significant discrepancies between these inversion values and the corresponding national reports were found.

  • Methane emissions were found to be higher using the inversion method compared to most national reports. In particular, emissions from oil and gas extracting states in Central Asia and the Gulf were several times higher than officially reported.
  • Absorbing 1.4 billion tonnes of carbon per year, the observed size of the global land carbon sink comprising ecosystems in both managed and unmanaged land, was several times larger than the 0.3 billion tonnes of carbon per year obtained by summing up countries’ reports. Underreporting of this carbon sink was most evident for temperate and northern hemisphere countries, such as Canada and across the European Union.

Understanding the carbon cycle.

Dr Ana Bastos (left) from the RECCAP-2 project explains how observations are helping to constraint the carbon budget and inform GHG mitigation policy


1 Deng, Z et al (2022) Comparing national greenhouse gas budgets reported in UNFCCC inventories against atmospheric inversions. Earth Syst. Sci. Data, hhttps://doi.org/10.5194/essd-14-1639-2022

2 Bastos et al. (2022) On the use of Earth Observation to support estimates of national greenhouse gas emissions and sinks for the Global stocktake process: lessons learned from ESA‑CCI RECCAP2. Carbon Balance and Management. https://doi.org/10.1186/s13021-022-00214-w