Estimating national emissions
Historical emissions data
The main sources for historical emissions are:
- Data submitted by governments through the Common Reporting Format (CRF)
- PRIMAP-hist data for countries without CRF data
- GHG inventory data submitted to the UNFCCC, or from other official documents, for example biennial update reports or national inventory reports or databases
CAT reviews these datasets for comprehensiveness and time coverage. Where necessary, it complements the dataset to reflect additional years, for example using CO2 emissions from the International Energy Agency and/or with additional assumptions.
The common reporting format (CRF) data tables are taken from the UNFCCC website for all available countries. These data are updated annually.
PRIMAP-hist data is comprehensive dataset of greenhouse emissions pathways for every country and Kyoto gas compiled by the Potsdam Institute for Climate Impact Research from several published sources. For CAT estimations we use nationally prioritised data. The PRIMAP-hist dataset is updated annually. This dataset excludes emissions from the Land Use, Land Use Change and Forestry (LULUCF) sector. The process of data collection and building of the dataset is described in Gütschow, J. et. al, 2016, and the latest database is available here.
All CAT emissions data uses Global Warming Potential values from the Fourth Assessment Report of the IPCC. Where countries use different metrics in their reporting, CAT converts the data to the extent possible. CAT shows historical emissions from Land Use, Land-Use Change and Forestry (LULUCF) separately.
Emissions for the LULUCF sector are taken from CRF data tables for countries where available, and from the UNFCCC GHG data interface or other submissions to the UNFCCC for countries with no available CRF data. Additional sources include national communications, national inventory reports (NIR), biennial update reports (BUR), and other national databases, particularly for non-Annex I countries reporting using 2006 IPCC guidelines. For countries where only individual years are reported, CAT refrains from interpolating for missing years.
CAT shows historical emissions from 1990 up to one year ago (e.g. in the year 2021, we update the data to show historical data until 2020). This usually requires additional estimates beyond the above mentioned sources for two to three missing years:
- Where countries update their emissions projections as an annual exercise, we take the data directly from the national governments’ databases.
- For other countries, we use a gas-by-gas method:
- For CO2 emissions, we apply growth rates from the Global Carbon Budget;
- For non-CO2 industry emissions, we calculate the emissions intensity of GPD and replace it by the latest GDP estimates/projections from the International Monetary Fund (IMF);
- For non-CO2 agriculture emissions, we extend the last five years’ trend.
The “Assumptions” tab in the individual country assessments describe also the methods for historical data in detail.
Absolute emissions from targets
The first mandatory emission reduction targets for many of the world’s leading economies were agreed for the first commitment period (2008 to 2012) of the Kyoto Protocol, adopted in 1997. In a second commitment period, running from 2013 to 2020, a much smaller number of countries took on additional commitments. Under the Kyoto Protocol, developing countries were not required to reduce emissions.
Under the Copenhagen Accord of 2009 and the Cancun Agreements of 2010, many developed and developing countries communicated pledges for 2020. In the run up to the COP in Paris, countries submitted their post-2020 targets as Intended Nationally Determined Contributions (INDCs). Since then, many countries resubmitted or revised their NDCs under the Paris Agreement. The CAT focuses on targets under the Paris Agreement. Previous targets are included in the archived assessments from earlier years. Use the dropdown menu at the top of a country profile to select the available assessments.
Where CAT assesses EU member states, it looks at their national targets, as the member states do not submit their own NDCs.
Countries submit their emissions reduction targets in different formats. There are, for example, variations in the scope, the reference year or level, and the unit. CAT converts all targets to absolute emissions excl. emissions from LULUCF.
The following sections explain how CAT converts specific target types. In general, we construct pathways using the present emissions reduction commitments and available clarifications coming forward from governments. Where we lack information, we take additional assumptions. For each country, we explain in the “Assumptions” section how exactly we calculated the absolute emissions from the targets, and which data sources we used.
Reductions below a reference pathway
The reference pathways (often also referred to as business-as-usual or BAU) provide information on how emissions are likely to develop in the absence of climate policy. This information is often provided as a range, reflecting uncertainties related to future economic and technological developments. In many cases, countries communicate the reference pathway together with the reduction target.
Where this is the case, the absolute emissions resulting from the target can easily be determined through applying the reduction to the reference level in the target year. Where the country includes emissions from Land Use, Land-Use Change and Forestry, we first calculate the overall reduction and then deduct the amount of LULUF emissions under the target. This is not always provided by the countries, so that often additional assumptions are necessary.
For countries with reduction targets below a reference pathway but without details on the reference, we determine the best data sources for projections on a case-by-case basis. We prioritise the use of nationally reported data (e.g. National Communications to the UNFCCC or governmental data). However, if data is missing, the resolution from these sources is too low, data quality judged too poor, or the data is out-dated, alternative state-of-the-art sources are preferred. Where no other projection can be found, we use the CAT projections under policies and action.
Reductions below a reference year
Many countries express their targets as reductions below a reference year in the past. We use the latest available inventory data to calculate the absolute emissions in the target year. Where possible, we follow the country’s approach to calculating the target excl. LULUCF. Where that approach is unclear, we take additional assumptions.
A few countries have provided emissions reductions targets that are linked to their economic growth, i.e. targets for reducing the emissions intensity. To calculate absolute emissions resulting from these targets, we calculate the emissions intensity in the reference year, using emissions data from GHG inventories and GDP data from World Bank. We then calculate the targeted emissions intensity reduction and multiply this with GDP projections for the target year.
Previous targets under the Kyoto Protocol and Copenhagen pledges
Pledge levels in 2020 are the result of Copenhagen pledges (unconditional and conditional pledges) and previous, Kyoto type targets. For those Annex I countries who are Party to the Second Commitment of the Kyoto Protocol, these levels (depicted by red dots in the country graphs in pre-2021 analyses) serve as the basis for elaboration of the country’s Quantified Emission Limitation or Reduction Objective (QELRO) which denotes the average level of emissions that an Annex I Party is allowed to emit on an annual basis during a given commitment period. Assessment’s post 2020 no longer include these elements in the summary graphs.
Emissions projections under policies and actions
The Climate Action Tracker provides estimates for the future development under current policies through 2030. The scenarios cover implemented policies at the time of the update, and other developments such as expected economic growth or trends in activity and energy consumption.
To derive the projections, CAT uses the following method:
The starting point of the analysis are existing, country-specific policy scenarios from literature. Those come from governments themselves, from national independent research, or from international sources (e.g. the IEA’s World Energy Outlook or APERC’s Energy Demand and Supply Outlook).
CAT checks available scenarios for completeness with respect to sectors, gases and covered policies, and soundness of underlying assumptions (e.g., economic growth). Where necessary we combine or compare those with other scenarios.
Where policies are not considered in external scenarios, for example because they were implemented after the projection was published, CAT integrates a bottom-up quantification of selected policies (with the policies most relevant in terms of potential GHG emissions or of high political interest selected). Where considered relevant, strong implementation barriers such as for example political resistance or technical difficulties are taken into account in projecting the effect of specific policies or targets, by assuming that only a fraction of the target is achieved. We may also consider a range if there are different possible outcomes of a policy that are uncertain (e.g. electricity mix, energy sources, technological development, etc.).
Given that the emission projections do not always match the historical datasets, CAT often harmonises the projections, using their growth applied to actual historical inventory data, rather than the absolute values of the projections.
In 2020, we estimated the impact of the COVID-19 pandemic using a novel method to estimate the dip in greenhouse gas emissions in 2020 and its impact until 2030. The uncertainty surrounding the severity and length of the pandemic created a new level of uncertainty for current and future greenhouse gas emissions. We distilled the emission intensity (GHG emissions/GDP) from the pre-pandemic current policy projections and applied it to the most recent GDP projections that account for the effect of the pandemic. For each country, we selected a range of GPD from international and national sources.
For post-2020 assessments, we use updated policy emissions projections that already incorporate the effect of the pandemic. However, for countries where these projections are not yet available, we apply a similar method than the one we used in 2020. For CO2 emissions from all sectors, and for non-CO2 emissions from industry sector, CAT estimates the emissions intensity of GDP pre-COVID and apply the latest GDP projections. For non-CO2 agriculture emissions, we extend the historic 5-year trend until 2030.
Detailed assumptions behind the current policy projections per country are available on the country pages on our website.
- Gütschow, J.; Jeffery, L.; Gieseke, R.; Gebel, R.; Stevens, D.; Krapp, M.; Rocha, M. (2016): The PRIMAP-hist national historical emissions time series, Earth Syst. Sci. Data, 8, 571-603, https://doi.org/10.5194/essd-8-571-2016
- Gütschow, J.; Günther, A.; Jeffery, L.; Gieseke, R. (2021): The PRIMAP-hist national historical emissions time series (1850-2018). v2.2. zenodo. https://doi.org/10.5281/zenodo.4479172
- IMF. World Economic Outlook Database. Available here: https://www.imf.org/en/Publications/SPROLLs/world-economic-outlook-databases#sort=%40imfdate%20descending
- IPCC (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007. Chapter 2. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.) Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Available at: https://archive.ipcc.ch/report/ar4/wg1/
- Global Carbon project (2020). Data supplement to the Global Carbon Budget 2020. Available at: https://www.icos-cp.eu/science-and-impact/global-carbon-budget/2020
- UNFCCC (2019). Greenhouse gas data interface. Available at: https://unfccc.int/process-and-meetings/transparency-and-reporting/greenhouse-gas-data/ghg-data-unfccc/ghg-data-from-unfccc
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