Greenhouse gas emissions accounting is measuring the amount of
greenhouse gases (GHG)
emitted during a given period of time by a
polity, usually a country but sometimes a region or city. Such measures are used to conduct
climate science and
climate policy. There are two main, conflicting ways of measuring GHG emissions:
production-based (also known as territorial-based) and
consumption-based. The
Intergovernmental Panel on Climate Change defines production-based emissions as taking place “within national territory and offshore areas over which the country has jurisdiction”. Consumption-based emissions take into account the effects of trade, encompassing the emissions from domestic
final consumption and those caused by the production of its imports. From the perspective of trade, consumption-based emissions accounting is thus the reverse of production-based emissions accounting, which includes exports but excludes imports (Table 1). The choice of accounting method can have very important effects on
policymaking, as each measure can generate a very different result. The application of production-based emissions accounting is currently favoured in policy terms as it is easier to measure,
Comparison of production based and consumption-based accounting Over the last few decades emissions have grown at an increasing rate from 1.0% yr−1 throughout the 1990s to 3.4% yr−1 between 2000 and 2008. These increases have been driven not only by a growing
global population and
per-capita GDP, but also by global increases in the
energy intensity of GDP (energy per unit GDP) and the
carbon intensity of energy (emissions per unit energy). These drivers are most apparent in
developing markets (Kyoto non-Annex B countries), but what is less apparent is that a substantial fraction of the growth in these countries is to satisfy the demand of consumers in
developed countries (Kyoto Annex B countries). Although emissions during the
2008 financial crisis, the longer-term trend of increased emissions has resumed. Today, much international effort is put into slowing the anthropogenic release of GHG and resulting climate change. In order to set benchmarks and emissions targets for - as well as monitor and evaluate the progress of - international and regional policies, the accurate measurement of each country's NEI becomes imperative.
Production-based accounting As production-based emissions accounting is currently favoured in policy terms, its methodology is well established. Emissions are calculated not directly but indirectly from fossil fuel usage and other relevant processes such as industry and agriculture according to 2006 guidelines issued by the
IPCC for GHG reporting. The guidelines span numerous methodologies dependent on the level of sophistication (Tiers 1–3 in Table 2). The simplest methodology combines the extent of human activity with a coefficient quantifying the emissions from that activity, known as an ‘emission factor’. For example, to estimate emissions from the energy sector (typically contributing over 90% of emissions and 75% of all GHG emissions in developed countries) the quantity of fuels combusted is combined with an emission factor - the level of sophistication increasing with the accuracy and complexity of the emission factor.
Consumption-based accounting Consumption-based emissions accounting has an equally established methodology using Input-Output Tables. These "display the interconnection between different sectors of production and allow for a tracing of the production and consumption in an economy" and were originally created for national economies. However, as production has become increasingly international and the import/export market between nations has flourished, Multi-Regional Input-Output (MRIO) models have been developed. The unique feature of MRIO is allowing a product to be traced across its production cycle, "quantifying the contributions to the value of the product from different economic sectors in various countries represented in the model. It hence offers a description of the global supply chains of products consumed". This point is only further emphasized when these trends are studied at a less aggregated scale. Figure 2 shows the percentage surplus of emissions as calculated by production-based accounting over consumption-based accounting. In general, production-based accounting proposes lower emissions for the
EU and
OECD countries (developed countries) and higher emissions for
BRIC and rest of the world (developing countries). However, consumption-based accounting proposes the reverse with lower emissions in BRIC and RoW, and higher emissions in EU and OECD countries. to term EU and OECD ‘CO2 consumers’ and BRIC and RoW ‘CO2 producers’. The large difference in these results is corroborated by further analysis. The
EU-27 in 1994 counted emissions using the consumption-based approach at 11% higher than those counted using the production-based approach, this difference rising to 24% in 2008. Similarly OECD countries reached a peak variance of 16% in 2006 whilst dropping to 14% in 2008. In contrast, although RoW starts and ends relatively equal, in the intervening years it is a clear CO2 producer, as are BRIC with an average consumption-based emissions deficit of 18.5% compared to production-based emissions. Peters and Hertwich completed a MRIO study to calculate emissions embodied in international trade using data from the 2001 Global Trade Analysis Program (GTAP). After manipulation, although their numbers are slightly more conservative (EU 14%; OECD 3%; BRIC 16%; RoW 6%) than Boitier the same trend is evident - developed countries are CO2 consumers and developing countries are CO2 producers. This trend is seen across the literature and supporting the use of consumption-based emissions accounting in policy-making decisions. 2 surplus compared to production-based CO2 from 1995-2008 --> == Tools and standards ==