Editing IPCC:AR6/WGIII/Chapter-1 (section)

=== 1.3.2 Global and Regional Emissions ===

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Global GHG emissions have continued to rise since AR5, though the average rate of emissions growth slowed, from 2.4% (from 2000–2010) to 1.3% for 2010–2019 (Figure 1.1). After a period of exceptionally rapid growth from 2000 as charted in AR5, global fossil fuel- and industry-related (FFI) CO 2 emissions almost plateaued between 2014 and 2016 (while the global economy continued to expand ( [[#World%20Bank--2020|World Bank 2020]] ), but increased again over 2017–19, the average annual growth rate for all GHGs since 2014 being around 0.8% yr –1 (IPCC/EDGAR emissions database; see also Chapter 11, Figure 11.2)). Important driving factors include population and GDP growth, as illustrated in panels (b) and (c) of Figure 1.1 respectively. The pause in emissions growth reflected the interplay of strong energy efficiency improvements and low-carbon technology deployment, butthese did not expand fast enough to offset the continued pressures for overall growth at global level ( [[#UNEP--2018a|UNEP 2018a]] ; [[#IEA--2019a|IEA 2019a]] ). However, since 2013/14, the decline in global emissions intensity (GHG/GDP) has accelerated somewhat, and global emissions growth has averaged slightly slower than population growth (Figure 1.1d), which if sustained would imply a peak of global CO 2 (GHG) emissions per capita, at about 5 tCO 2 per person (7 tCO 2 -eq per person) respectively.

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'''Figure 1.1 | Global emission trends since 2000 by groups of gases: absolute, per capita, and intensity.''' Note: shows CO 2 from fossil fuel combustion and industrial processes (FFI); CO 2 from agriculture, forestry and other land use (AFOLU); methane (CH 4 ); nitrous oxide (N 2 O); fluorinated gases (F-gases). Gases reported in GtCO 2 -eq converted based on AR6 global warming potentials with a 100-year time horizon (GWP100).

Due to its much shorter lifetime, methane has a disproportionate impact on near-term temperature, and is estimated to account for almost a third of the warming observed to date (AR6 WGI SPM; AR6 WGIII Chapter 2, Figure 2.4). Methane reductions could be particularly important in relation to near- and medium-term temperatures, including through counteracting the impact of reducing short-lived aerosol pollutants which have an average cooling effect. [[#footnote-007|2]]

The land-use component of CO 2 emissions has different drivers and particularly large uncertainties (Figures 2.2 and 2.5), hence is shown separately. Also, compared to AR5, new evidence showed that the AFOLU CO 2 estimates by the global models assessed in this report are not necessarily comparable with national GHG inventories, due to different approaches to estimate the ‘anthropogenic’ CO 2 sink. Possible ways to reconcile these discrepancies are discussed in Chapter 7.

Regional trends have varied. Emissions from most countries continued to grow, but in absolute terms, 32 countries reduced energy and industry CO 2 emissions for at least a decade, and 24 reduced overall GHG (CO 2 -eq) emissions over the same period, but only half of them by more than 10% over the period in each case (Chapter 2). [[#footnote-006|3]] In total, developed country emissions barely changed from 2010, whilst those from the rest of the world grew.

Figure 1.2 shows the distribution of regional emissions (a) per capita and (b) per GDP based on purchasing power parity (GDP ppp ) of different country groupings in 2019. Plotted against population and GDP respectively, the area of each block is proportional to the region’s emissions. Compared to the equivalent presentations in 2004 (AR4 WGIII Figure SPM.3) and 2010 (AR5 WGIII Figure 1.8), East Asia now forms substantially the biggest group, whilst at about 8 tCO 2 -FFI (/10 tCO 2 -eq all GHGs) per person, its emissions per capita remain about half that of North America. In contrast, a third of the world’s population, in Southern Asia and Africa, emit on average under 2 (2.5 tCO 2 -eq) per person, little more than in the previous assessments. Particularly for these regions, there continue to be substantial differences in GDP, life expectancy and other measures of well-being (Figure 1.6).

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'''Figure 1.2 | Distribution of regional greenhouse gas (GHG) emissions for 10 broad global regions according to territorial accounting (panels (a) and (b), GHG emissions) and consumption-based accounting (panels (c) and (d), CO''' 2 '''-FFI emissions only).''' GHG emissions are categorised into: fossil fuel and industry (CO 2 -FFI); land use, land-use change and forestry (CO 2 -LULUCF); and other greenhouse gases (methane, nitrous oxide and F-gas – converted to 100-year global warming potentials). Per-capita GHGs for territorial '''(panel a)''' and CO 2 -FFI emissions vs population for consumption-based accounting '''(panel c)''' . Panels '''(b)''' and '''(d)''' : GHG emissions per unit GDP ppp vs GDP ppp , weighted with purchasing power parity for territorial accounting (panel b), CO 2 -FFI emissions per unit GDP ppp for consumption-based accounting (panel d). The area of the rectangles refers to the total emissions for each regional category, with the height capturing per-capita emissions (panels a and c) or emissions per unit GDP ppp (panels (b) and (d)), and the width proportional to the population of the regions and GDP ppp . Emissions from international aviation and shipping (2.4% of the total GHG emissions) are not included.

''Emissions'' ''per unit GDP'' are much less diverse than per capita and have also converged significantly. Poorer countries tend to show higher energy/emissions per unit GDP partly because of higher reliance on basic industries, and this remains the case, though in general their energy/GDP has declined faster.

Many developed country regions are net importers of energy-intensive goods, and emissions are affected by the accounting of such ‘embodied emissions’. Panels (c) and (d) show results (only available for CO 2 -FFI, to 2018) on the basis of consumption footprints which include emissions embodied in traded goods. This makes modest changes to the relative position of different regions (for further discussion see [[IPCC:Wg3:Chapter:Chapter-2#2.3|Section 2.3]] ).

While extreme poverty has fallen in more than half of the world’s economies in recent years, nearly one fifth of countries faced poverty rates above 30% in 2015 (below USD1.90 a day), reflecting large income inequality ( [[#Laborde%20Debucquet--2017|Laborde Debucquet and Martin 2017]] ; [[#Rozenberg--2019|Rozenberg and Fay 2019]] ). [[#Diffenbaugh--2019|Diffenbaugh and Burke (2019)]] find that global warming already has increased global economic inequality, even if between-country inequalities have decreased over recent decades. The distributional implications between regional groups in the Shared Socio-economic Pathways (SSPs) diverge according to the scenario ( [[#Frame--2019|Frame et al. 2019]] ).

An important recent development has been commitments by many countries, now covering a large majority of global emissions, to reach net zero CO 2 or greenhouse gas emissions (Chapter 3). [[#footnote-005|4]] Furthermore, globally, net zero targets (whether CO 2 or GHG) have been adopted by about 823 cities and 101 regions (Chapter 8).

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