Editing IPCC:AR6/WGIII/Chapter-2 (section)

=== 2.2.3 Regional GHG Emissions Trends ===

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Regional contributions to global GHG emissions have shifted since the beginning of the international climate negotiations in the 1990s ( ''high confidence'' ). As shown in Figure 2.9, developed countries (North America, Europe, and Australia, Japan, New Zealand) as a group have not managed to reduce GHG emissions substantially, with fairly stable levels at about 15 GtCO 2 -eq yr –1 between 1990 and 2010, while countries in Asia and Pacific (Eastern Asia, Southern Asia, and South-East Asia and Pacific) have rapidly increased their share of global GHG emissions – particularly since the 2000s ( [[#Jackson--2019|Jackson et al. 2019]] ; [[#Peters--2020|Peters et al. 2020]] ; UNEP 2020c; [[#Crippa--2021|Crippa et al. 2021]] ; [[#IEA--2021b|IEA 2021b]] ).

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'''Figure 2.9''' ''': Change in regional GHGs from multiple perspectives and their underlying drivers.''' '''Panel (a):''' Regional GHG emissions trends (in GtCO 2 -eq yr –1 ) for the time period 1990–2019. GHG emissions from international aviation and shipping are not assigned to individual countries and shown separately. '''Panels (b) and (c):''' Changes in GHG emissions for the 20 largest emitters (as of 2019) for the post-AR5 reporting period 2010–2019 in relative (% annual change) and absolute terms (GtCO 2 -eq). '''Panels (d) and (e):''' GHG emissions per capita and per GDP in 2019 for the 20 largest emitters (as of 2019). GDP estimated using constant international purchasing power parity (USD2017). Emissions are converted into CO 2 -equivalents based on global warming potentials with a 100-year time horizon (GWP100) from the IPCC Sixth Assessment Report (Forster et al. 2021a). The black dots represent the emissions data from UNFCCC-CRFs (2021) that were accessed through [[#Gütschow--2021a|Gütschow et al. (2021a)]] . Net LULUCF CO 2 emissions are included in panel (a), based on the average of three bookkeeping models ( [[#2.2|Section 2.2]] ), but are excluded in panels (b–e) due to a lack of country resolution.

Most global GHG emission growth occurred in Asia and Pacific, which accounted for 77% of the net 21 GtCO 2 -eq increase in GHG emissions since 1990, and 83% of the net 6.5 GtCO 2 -eq increase since 2010. [[#footnote-006|8]] Africa contributed 11% of GHG emissions growth since 1990 (2.3 GtCO 2 -eq) and 10% (0.7 GtCO 2 -eq) since 2010. The Middle East contributed 10% of GHG emissions growth since 1990 (2.1 GtCO 2 -eq) and also 10% (0.7 GtCO 2 -eq) since 2010. Latin America and the Caribbean contributed 11% of GHG emissions growth since 1990 (2.2 GtCO 2 -eq), and 5% (0.3 GtCO 2 -eq) since 2010. Two regions, Developed Countries, and Eastern Europe and West Central Asia, reduced emissions overall since 1990, by –1.6 GtCO 2 -eq and –0.8 GtCO 2 -eq, respectively. However, emissions in the latter started to grow again since 2010, contributing to 5% of the global GHG emissions change (0.3 GtCO 2 -eq).

Average annual GHG emission growth across all regions slowed between 2010 and 2019 compared to 1990–2010, with the exception of Eastern Europe and West Central Asia. Global emissions changes tend to be driven by a limited number of countries, principally the G20 Group ( [[#Friedlingstein--2020|Friedlingstein et al. 2020]] ; UNEP 2020c; [[#Xia--2021|Xia et al. 2021]] ). For instance, the slowing of global GHG emissions between 2010 and 2019, compared to the previous decade, was primarily triggered by substantial reductions in GHG emissions growth in China. Ten countries jointly contributed about 75% of the net 6.5 GtCO 2 -eq yr –1 increase in GHG emissions during 2010–2019, of which two countries contributed more than 50% (Figure 2.9) (see also [[#Minx--2021|Minx et al., 2021]] ; [[#Crippa--2021|Crippa et al., 2021]] ).

GHG and CO 2 -FFI levels diverge starkly between countries and regions ( ''high confidence'' ) ( [[#Jackson--2019|Jackson et al. 2019]] ; [[#Friedlingstein--2020|Friedlingstein et al. 2020]] ; UNEP 2020c; [[#Crippa--2021|Crippa et al. 2021]] ). Developed Countries sustained high levels of per capita CO 2 -FFI emissions at 9.5 tCO 2 per capita in 2019 (but with a wide range of 1.9–16 tCO 2 per capita). This is more than double that of three developing regions: 4.4 (0.3–12.8) tCO 2 per capita in Asia and Pacific; 1.2 (0.03–8.5) tCO 2 per capita in Africa; and 2.7 (0.3–24) tCO 2 per capita in Latin America. [[#footnote-005|9]] Per capita CO 2 -FFI emissions were 9.9 (0.89–15) tCO 2 per capita in Eastern Europe and West Central Asia, and 8.6 (0.36–38) tCO 2 per capita in the Middle East. CO 2 -FFI emissions in the three developing regions together grew by 26% between 2010 and 2019, compared to 260% between 1990 and 2010, while in Developed Countries emissions contracted by 9.9% between 2010–2019 and by 9.6% between 1990–2010.

Least-Developed Countries and Small Island Developing States contributed only a negligible proportion of historic GHG emissions growth and have the lowest per capita emissions. As of 2019 Least Developed Countries contribute 3.3% of global GHG emissions, excluding LULUCF CO 2 , despite making up 13% of the global population. Small Island Developing States contributed 0.6% of global GHG emissions in 2019, excluding LULUCF CO 2 , with 0.9% of the global population. Since the start of the industrial revolution in 1850 up until 2019, Least Developed Countries contributed 0.4% of total cumulative CO 2 emissions, while Small Island Developing States contributed 0.5% (Figure 2.10). Conversely, Developed Countries have the highest share of historic cumulative emissions ( [[#Rocha--2015|Rocha et al. 2015]] ; [[#Gütschow--2016|Gütschow et al. 2016]] ; [[#Matthews--2016|Matthews 2016]] ), contributing approximately 57% (Figure 2.10), followed by Asia and Pacific (21%), Eastern Europe and West Central Asia (9%), Latin America and the Caribbean (4%), the Middle East (3%), and Africa (3%). Developed Countries still have the highest share of historic cumulative emissions (45%) when CO 2 -LULUCF emissions are included, which typically account for a higher proportion of emissions in developing regions (Figure 2.10).

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'''Figure 2.10''' '''|''' '''Different perspectives on historic emissions andequity. Panel (a)''' shows the regional proportion (%) of total global population or emissions in 2018 or 2019, for five categories: population (persons); consumption-based CO 2 -FFI emissions (GtCO 2 ); production-based CO 2 -FFI emissions (GtCO 2 ); production-based GHG emissions excluding CO 2 -LULUCF (GtCO 2 -eq); and production-based GHG emissions including CO 2 -LULUCF (GtCO 2 -eq). '''Panel (b)''' shows the regional proportion (%) of total cumulative production-based CO 2 emissions from 1850 to 2019, including and excluding CO 2 -LULUCF (GtCO 2 ). In the lower panels, the proportion of each population or emissions category attributable to Least-Developed Countries and Small Island Developing States (SIDS) are shown, where available (CO 2 -LULUCF data is not available for these regions). GHG emissions are converted into CO 2 -equivalents based on global warming potentials with a 100-year time horizon (GWP100) from the IPCC Sixth Assessment Report (Forster et al. 2021a). Source: data from Friedglinstein et al. (2020).

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'''Figure 2.11''' '''|''' '''Recent average annual GHG emissions changes of countries (left panel) versus rates of reduction in 1.5°C and 2°C mitigation scenarios.''' Scenario data is taken from [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] of this report with the scenario categories defined and summarised in Table 3.2 in Chapter 3. Emissions are converted into CO 2 -equivalents based on global warming potentials with a 100-year time horizon (GWP100) from the IPCC Sixth Assessment Report (Forster et al. 2021a). Circles indicate countries (left panel) or individual scenarios (right panel), the former scaled by total emissions in 2019. Horizontal lines indicate the region average emissions change (left panel), or scenario category average emissions change (right panel). Source: data from [[#Minx--2021|Minx et al. (2021)]] .

A growing number of countries have reduced CO 2 and GHG emissions for longer than 10 years ( ''high confidence'' ) ( [[#Le%20Quéré--2019|Le Quéré et al. 2019]] ; [[#Burck--2021|Burck et al. 2021]] ; [[#Lamb--2021a|Lamb et al. 2021a]] ; [[#Wu--2021|Wu et al. 2021]] ). Data up to 2018 indicates that about 24 countries have reduced territorial CO 2 and GHG emissions (excluding LULUCF CO 2 ), as well as consumption-based CO 2 emissions, for at least 10 years ( [[#Lamb--2021a|Lamb et al. 2021a]] ). Uncertainties in emissions levels and changes over time prevents a precise assessment of reductions in some cases. Of these 24 countries, 12 peaked emissions in the 2000s; six have sustained longer reductions since the 1970s; and six are former members of the Eastern Bloc, where emissions dropped rapidly in the 1990s and continued declining at a slower pace thereafter. Country emissions reductions have been driven by both climate and non-climate policies and factors, including structural changes. To date, most territorial emissions reductions were realised in the electricity and heat sector, followed by industry and buildings, while in many cases transport emissions have increased since countries reached their overall emissions peak ( [[#Climate%20Transparency--2021|Climate Transparency 2021]] ; [[#Lamb--2021a|Lamb et al. 2021a]] ). One estimate of the total reduction in annual GHG emissions – from peak years to 2018 – sums to 3.2 GtCO 2 -eq across all decarbonising countries ( [[#Lamb--2021a|Lamb et al. 2021a]] ). These reductions have therefore been far outweighed by recent emissions growth. However, climate policy related reductions may be even larger when compared against a counterfactual case of emissions growth across different sectors ( [[#Eskander--2020|Eskander and Fankhauser 2020]] ) (Cross-Chapter Box 1 in Chapter 1; [[#2.8|Section 2.8]] ).

The recent (2010–2019) emissions changes of some countries are in line with pathways that limit warming to below 2°C (&lt;67%) '''(''' e.g., –4% average annual reductions) (Figure 2.10). Overall, there are first country cases emerging that highlight the feasibility of sustained emission reductions outside of periods of economic disruption ( [[#Lamb--2021a|Lamb et al. 2021a]] ). However, such pathways will need to be taken by many more countries to keep the goals of the Paris Agreement in reach ( [[#Höhne--2020|Höhne et al. 2020]] ; [[#Roelfsema--2020|Roelfsema et al. 2020]] ; [[#Kriegler--2018a|Kriegler et al. 2018a]] ; [[#den%20Elzen--2019|den Elzen et al. 2019]] ) as analysed by [[IPCC:Wg3:Chapter:Chapter-4|Chapter 4]] of this report. Moreover, observed reductions are not yet consistent and long-term, nor achieved across all sectors, nor fully aligned with country NDC targets ( [[#Le%20Quéré--2019|Le Quéré et al. 2019]] ; [[#Lamb--2021a|Lamb et al. 2021a]] ; [[#den%20Elzen--2019|den Elzen et al. 2019]] ; [[#Burck--2021|Burck et al. 2021]] ; [[#Climate%20Transparency--2021|Climate Transparency 2021]] ).

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