The availability of accurate, complete, and timely data is fundamental to support countries in developing and implementing their climate change policies, and critical for achieving the Paris Agreement long-term temperature goal. This information provides insights regarding the countries’ GHG emission trends and can help policy makers to monitor their performance.
However, despite considerable efforts, data on GHG emissions remains limited and insufficient. Official country level data is usually based on emission inventories reported to the UNFCCC. These inventory data are compiled using territory-based and production-based principles following the IPCC guidelines. The territory-based principle does not include emissions from international transport and production-based principle does not include emission from imports of goods to satisfy consumption demand. The approaches underestimate the true carbon footprint of an economy. In addition, data quality varies considerably across countries. Often inventories use a combination of the three tiers of the IPCC guidelines to compile data for a single sector resulting in considerable data quality differences across countries as well as within a country across sectors.1
Furthermore, countries can use varying types of emissions factors that have different degrees of precision, for example, industrial plant specific, IPCC default, country specific data, and models. Moreover some countries do not report annually. These are mainly non-OECD countries. Therefore, GHG emissions data and associated indicators are characterised by gaps, lack of timeliness and granularity as well as varying quality. While recognising these caveats, for the analysis presented above, IPAC has used official data when possible. However, in some cases, such as for aggregates, it was necessary to make estimations. When no other data was available, Climate Watch data (Climate Watch, 2023[6]) was used, particularly for global comparisons and to compare IPAC or OECD totals with global emissions.
The data sources and approach used in this publication are summarised below:
GHG emissions data from national inventories is currently available for all OECD countries that report annually to UNFCCC for the period 1990-2021.
Data for other OECD countries (formerly referred to as “non-Annex 1”) is obtained through the OECD GHG emissions questionnaire. However, the time coverage is not complete, for example, Colombia covers data up to 2018, Costa Rica up to 2017 and Mexico up to 2019. There are also gaps for Israel before 2002.
For OECD partner countries many gaps remain, for example official emissions data for 2020 is not available on the UNFCCC GHG emission data interface. Major gaps are also present for large emitters, such as China and India. China has provided official data for only five years (1994, 2005, 2010, 2012 and 2014), while India has presented data only for four years (1994, 2000, 2010 and 2016). There are also important gaps for Peru (for the 1990-2010 period), Saudi Arabia (presenting only four years between 1990 and 2012), South Africa (for the 1990-2000 period), and Indonesia (for the 1990-2000 period).2
In this report, when official data was not available, estimated data are used to compile country aggregates.