Comparison Between the IPCC Reporting Framework and Country Practice

The Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories provide a recommended (but not mandatory) methodology for preparing National Inventory Reports (NIR) of greenhouse gas (GHG) emissions. All Annex I Parties to the United Nations Framework Convention on Climate Change (UNFCCC) (including developed countries and economies in transition) must submit a NIR every year. Non-Annex I Parties (most of which developing countries) in turn, are not required to submit NIRs, but must submit national inventories as part of their Biennial Update Reports (BURs).

This study examines the NIRs of Australia, Germany, Japan, and the United States. Though all countries follow the IPCC Guidelines, their NIRs reflect different choices of GHG accounting methodologies and approaches (such as the bottom-up sectoral approach and the top-down reference approach), emission factors, and categories and gases reported. These choices, allowed under the IPCC Guidelines, result in significant differences in the GHG emissions reported.

There often are significant differences between country-specific emission factors and the IPCC’s default emission factors, which were calculated based on data collected in the early 1990s from the countries that were then members of the Organisation on Economic Co-operation and Development (OECD).

The case study on the German iron and steel industry, applying the tier methods and the country-specific method under the IPCC Guidelines, reveals that the choice of different methods results in significantly different emissions calculated for the same categories.

The case study on the national inventories included in China’s BURs reveals that they partly applied the IPCC Guidelines for NIRs and lacked data continuity and periodic key category analysis. This result reinforces that various methodological choices tend to result in differences in GHG emissions reported across inventories of Annex I and Non-Annex I Parties.

The widely diverging emissions reported across countries as a result of the good-faith application of the IPCC Guidelines illustrate the need for a harmonized GHG accounting framework, to improve the consistency and comparability of emissions inventories prepared by various countries.