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

== Executive Summary ==

<div id="h1-1-siblings" class="h1-siblings"></div>

'''Global net anthropogenic greenhouse gas (GHG) emissions during the last decade (2010–2019) were higher than at any previous time in human history (''' '''''high confidence''''' ''').''' Since 2010, GHG emissions have continued to grow, reaching 59 ± 6.6 GtCO 2 -eq in 2019, [[#footnote-013|1]] but the average annual growth in the last decade (1.3%, 2010–2019) was lower than in the previous decade (2.1%, 2000–2009) ( ''high confidence'' ). Average annual GHG emissions were 56 ± 6.0 GtCO 2 -eq yr –1 for the decade 2010–2019 growing by about 9.1 GtCO 2 -eq yr –1 from the previous decade (2000–2009) – the highest decadal average on record ( ''high confidence'' ). {2.2.2, Table 2.1, Figure 2.2, Figure 2.5}

'''Emissions growth has varied, but persisted across all groups of GHGs (''' '''''high confidence''''' ''').''' The average annual emission levels of the last decade (2010–2019) were higher than in any previous decade for each group of GHGs ( ''high confidence'' ). In 2019, CO 2 emissions were 45 ± 5.5 GtCO 2 , [[#footnote-012|2]] CH 4 11 ± 3.2 GtCO 2 -eq, N 2 O 2.7 ± 1.6 GtCO 2 -eq and fluorinated gases (F-gases: HFCs, PFCs, SF 6 , NF 3 ) 1.4 ± 0.41 GtCO 2 -eq. Compared to 1990, the magnitude and speed of these increases differed across gases: CO 2 from fossil fuel and industry (FFI) grew by 15 GtCO 2 -eq yr –1 (67%), CH 4 by 2.4 GtCO 2 -eq yr –1 (29%), F-gases by 0.97 GtCO 2 -eq yr –1 (254%), and N 2 O by 0.65 GtCO 2 -eq yr –1 (33%). CO 2 emissions from net land use, land-use change and forestry (LULUCF) have shown little long-term change, with large uncertainties preventing the detection of statistically significant trends. F-gases excluded from GHG emissions inventories such as ''chlorofluorocarbons'' and ''hydrochlorofluorocarbons'' are about the same size as those included ( ''high confidence'' ). {2.2.1, 2.2.2, Table 2.1, Figures 2.2, 2.3 and 2.5}

'''Globally, gross domestic product (GDP) per capita and population growth remained the strongest drivers of CO''' 2 '''emissions from fossil fuel combustion in the last decade (''' '''''robust evidence, high agreement''''' ''').''' Trends since 1990 continued in the years 2010 to 2019 with GDP per capita and population growth increasing emissions by 2.3% and 1.2% yr –1 , respectively. This growth outpaced the reduction in the use of energy per unit of GDP (–2% yr –1 , globally) as well as improvements in the carbon intensity of energy (–0.3% yr –1 ) ( ''high confidence'' ). {2.4.1, Figure 2.16}

'''The global COVID-19 pandemic led to a steep drop in CO''' 2 '''emissions from fossil fuel and industry (''' '''''high confidence''''' ''').''' Global CO 2 -FFI emissions dropped in 2020 by about 5.8% (5.1–6.3%) or about 2.2 (1.9–2.4) GtCO 2 compared to 2019. Emissions, however, have rebounded globally by the end of December 2020 ( ''medium confidence'' ). {2.2.2, Figure 2.6}

'''Cumulative net CO''' 2 '''emissions of the last decade (2010–2019) are about the same size as the remaining carbon budget for keeping warming to 1.5°C (''' '''''medium confidence''''' ''').''' Cumulative net CO 2 emissions since 1850 are increasing at an accelerating rate: about 62% of total cumulative CO 2 emissions from 1850 to 2019 occurred since 1970 (1500 ± 140 GtCO 2 ); about 43% since 1990 (1000 ± 90 GtCO 2 ); and about 17% since 2010 (410 ± 30 GtCO 2 ). For comparison, the remaining carbon budget for keeping warming to 1.5°C with a 67% (50%) probability is about 400 (500) ± 220 GtCO 2 ( ''medium confidence'' ). {2.2.2, Figure 2.7; AR6 WGI 5.5; AR6 WGI Table 5.8}

'''A growing number of countries have achieved GHG emission reductions longer than 10 years – a few at rates that are broadly consistent with climate change mitigation scenarios that limit warming to well below 2°C (''' '''''high confidence''''' ''').''' There are at least 18 countries that have reduced CO 2 and GHG emissions for longer than 10 years. Reduction rates in a few countries have reached 4% in some years, in line with rates observed in pathways that limit warming to 2°C (&gt;67%). However, the total reduction in annual GHG emissions of these countries is small (about 3.2 GtCO 2 -eq yr – 1 ) compared to global emissions growth observed over the last decades. Complementary evidence suggests that countries have decoupled territorial CO 2 emissions from GDP, but fewer have decoupled consumption-based emissions from GDP. This decoupling has mostly occurred in countries with high per capita GDP and high per capita CO 2 emissions. {2.2.3, 2.3.3, Figure 2.11, Table 2.3, Table 2.4}

'''Consumption-based CO''' 2 '''emissions in Developed Countries and the Asia and Pacific region are higher than in other regions (''' '''''high confidence''''' ''').''' In Developed Countries, consumption-based CO 2 emissions peaked at 15 GtCO 2 in 2007, declining to about 13 GtCO 2 in 2018. The Asia and Pacific region, with 52% of current global population, has become a major contributor to consumption-based CO 2 emission growth since 2000 (5.5% yr –1 for 2000–2018); it exceeded the Developed Countries region, which accounts for 16% of current global population, as the largest emitter of consumption-based CO 2 . {2.3.2, Figure 2.14}

'''Carbon intensity improvements in the production of traded products have led to a net reduction in CO''' 2 '''emissions embodied in international trade (''' '''''robust evidence,''''' '''''high agreement''''' ''').''' A decrease in the carbon intensity of traded products has offset increased trade volumes between 2006 and 2016. Emissions embodied in internationally traded products depend on the composition of the global supply chain across sectors and countries and the respective carbon intensity of production processes (emissions per unit of economic output). {2.3, 2.4}

'''Developed Countries tend to be net CO''' 2 '''emission importers, whereas developing countries tend to be net emission exporters (''' '''''robust evidence, high agreement''''' ''').''' Net CO 2 emission transfers from developing to Developed Countries via global supply chains have decreased between 2006 and 2016 '''.''' Between 2004 and 2011, CO 2 emission embodied in trade between developing countries have more than doubled (from 0.47 to 1.1 Gt) with the centre of trade activities shifting from Europe to Asia. {2.3.4, Figure 2.15}

'''Emissions from developing countries have continued to grow, starting from a low base of per capita emissions and with a lower contribution to cumulative emissions than Developed Countries (''' '''''robust evidence, high agreement''''' ''').''' Average 2019 per capita CO 2 -FFI emissions in three developing regions – Africa (1.2 tCO 2 per capita), Asia and Pacific (4.4 tCO 2 per capita), and Latin America and Caribbean (2.7 tCO 2 per capita) – remained less than half that of Developed Countries (9.5 tCO 2 per capita) in 2019. 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 and 2019, and by 9.6% between 1990 and 2010. Historically, the three developing regions together contributed 28% to cumulative CO 2 -FFI emissions between 1850 and 2019, whereas Developed Countries contributed 57% and Least-Developed Countries contributed 0.4%. {2.2.3, Figures 2.9 and 2.10}

'''Globally, GHG emissions continued to rise across all sectors and subsectors; most rapidly in transport and industry (''' '''''high confidence''''' ''').''' In 2019, 34% (20 GtCO 2 -eq) of global GHG emissions came from the energy sector, 24% (14 GtCO 2 -eq) from industry, 22% (13 GtCO 2 -eq) from agriculture, forestry and other land use (AFOLU), 15% (8.7 GtCO 2 -eq) from transport and 5.6% (3.3 GtCO 2 -eq) from buildings. Once indirect emissions from energy use are considered, the relative shares of industry and buildings emissions rise to 34% and 16%, respectively. Average annual GHG emissions growth during 2010 to 2019 slowed compared to the previous decade in energy supply (from 2.3% to 1.0%) and industry (from 3.4% to 1.4%, direct emissions only), but remained roughly constant at about 2% per year in the transport sector ( ''high confidence'' ). Emission growth in AFOLU is more uncertain due to the high share of CO 2 -LULUCF emissions ( ''medium confidence'' ). {2.4.2, Figure 2.13, Figures 2.16 to 2.21}

'''Average annual growth in GHG emissions from energy supply decreased from 2.3% for 2000–2009 to 1.0% for 2010–2019 (''' '''''high confidence''''' ''').''' This slowing of growth is attributable to further improvements in energy efficiency (annually, 1.9% less energy per unit of GDP was used globally between 2010 and 2019). Reductions in global carbon intensity by –0.2% yr –1 contributed further – reversing the trend during 2000 to 2009 (+0.2% yr –1 ) ( ''medium confidence'' ). These carbon intensity improvements were driven by fuel switching from coal to gas, reduced expansion of coal capacity, particularly in Eastern Asia, and the increased use of renewables. {2.2.4, 2.4.2.1, Figure 2.17}

'''GHG emissions in the industry, buildings and transport sectors continue to grow, driven by an increase in the global demand for products and services (''' '''''high confidence''''' ''').''' These final demand sectors make up 44% of global GHG emissions, or 66% when the emissions from electricity and heat production are reallocated as indirect emissions to related sectors, mainly to industry and buildings. Emissions are driven by the large rise in demand for basic materials and manufactured products, a global trend of increasing floor space per capita, building energy service use, travel distances, and vehicle size and weight. Between 2010 and 2019, domestic and international aviation were particularly fast growing at average annual rates of +3.3% and +3.4%. Global energy efficiencies have improved in all three demand sectors, but carbon intensities have not. {2.2.4; Figures 2.18 to 2.20}

'''Providing access to modern energy services universally would increase global GHG emissions by, at most, a few percent (''' '''''medium confidence''''' ''').''' The additional energy demand needed to support decent living standards [[#footnote-011|3]] for all is estimated to be well below current average energy consumption ( ''medium evidence'' , ''high agreement'' ). More equitable income distributions can reduce carbon emissions, but the nature of this relationship can vary by level of income and development ( ''limited evidence'' , ''medium agreement'' ). {2.4.3}

'''Evidence of rapid energy transitions exists, but only at s''' '''ub-glob''' '''al scales (''' '''''medium evidence, medium agreement''''' ''').''' Emerging evidence since the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) on past energy transitions identifies a growing number of cases of accelerated technology diffusion at sub-global scales and describes mechanisms by which future energy transitions may occur more quickly than those in the past. Important drivers include technology transfer and cooperation, intentional policy and financial support, and harnessing synergies among technologies within a sustainable energy system perspective ( ''medium evidence'' , ''medium agreement'' ). A fast global low-carbon energy transition enabled by finance to facilitate low-carbon technology adoption in developing, and particularly in least-developed countries, can facilitate achieving climate stabilisation targets ( ''robust evidence'' , ''high agreement'' ). {2.5.2, Table 2.5}

'''Multiple low-carbon technologies have shown rapid progress since AR5 – in cost, performance, and adoption – enhancing the feasibility of rapid energy transitions (''' '''''robust evidence,''''' '''''high agreement''''' ''').''' The rapid deployment and cost decrease of modular technologies like solar, wind, and batteries have occurred much faster than anticipated by experts and modelled in previous mitigation scenarios ( ''robust evidence'' , ''high agreement'' ). The political, economic, social, and technical feasibility of solar energy, wind energy and electricity storage technologies has improved dramatically over the past few years. In contrast, the adoption of nuclear energy and carbon capture and storage (CCS) in the electricity sector has been slower than the growth rates anticipated in stabilisation scenarios. Emerging evidence since AR5 indicates that small-scale technologies (e.g., solar, batteries) tend to improve faster and be adopted more quickly than large-scale technologies (nuclear, CCS) ( ''medium evidence'' , ''medium agreement'' ). {2.5.3, 2.5.4, Figures 2.22 and 2.23}

'''Robust incentives for investment in innovation, especially incentives reinforced by national policy and international agreements, are central to accelerating low-carbon technological change (''' '''''robust evidence, medium agreement''''' ''').''' Policies have driven innovation, including instruments for technology push (e.g., scientific training, research and development) and demand pull (e.g., carbon pricing, adoption subsidies), as well as those promoting knowledge flows and especially technology transfer. The magnitude of the scale-up challenge elevates the importance of rapid technology development and adoption. This includes ensuring participation of developing countries in an enhanced global flow of knowledge, skills, experience, and equipment. Also, technology itself requires strong financial, institutional, and capacity-building support ( ''robust evidence'' , ''high agreement'' ). {2.5.4, 2.5, 2.8}

'''The global wealthiest 10% contribute about 36–45% of global GHG emissions (''' '''''robust evidence, high agreement''''' ''').''' The global 10% wealthiest consumers live in all continents, with two-thirds in high-income regions and one-third in emerging economies ( ''robust evidence'' , ''medium agreement'' ). The lifestyle consumption emissions of the middle-income and poorest citizens in emerging economies are between 5 and 50 times below their counterparts in high-income countries ( ''medium evidence'' , ''medium agreement'' ). Increasing inequality within a country can exacerbate dilemmas of redistribution and social cohesion, and affect the willingness of rich and poor to accept lifestyle changes for mitigation and policies to protect the environment ( ''medium evidence'' , ''medium agreement'' ) {2.6.1, 2.6.2, Figure 2.25}

'''Estimates of future CO''' 2 '''emissions from existing fossil fuel infrastructures already exceed remaining cumulative net CO''' 2 '''emissions in pathways limiting warming to 1.5°C with no or limited overshoot (''' '''''high confidence''''' ''').''' Assuming variations in historical patterns of use and decommissioning, estimated future CO 2 emissions from existing fossil fuel infrastructure alone are 660 (460–890) GtCO 2 and from existing and currently planned infrastructure 850 (600–1100) GtCO 2 . This compares to overall cumulative netCO 2 emissions until reaching net zero CO 2 of 510 (330–710) Gt in pathways that limit warming to 1.5°C with no or limited overshoot, and 890 (640–1160) Gt in pathways that limit warming to 2°C (&lt;67%) '''(''' ''high confidence'' ). While most future CO 2 emissions from existing and currently planned fossil fuel infrastructure are situated in the power sector, most remaining fossil fuel CO 2 emissions in pathways that limit warming to 2°C (&lt;67%) and below are from non-electric energy – most importantly from the industry and transportation sectors ( ''high confidence'' ). Decommissioning and reduced utilisation of existing fossil fuel installations in the power sector as well as cancellation of new installations are required to align future CO 2 emissions from the power sector with projections in these pathways ( ''high confidence'' ). {2.7.2, 2.7.3, Figure 2.26, Table 2.6, Table 2.7}

'''A broad range of climate policies, including instruments like carbon pricing, play an increasing role in GHG emissions reductions. The literature is in broad agreement, but the magnitude of the reduction rate varies by the data and methodology used, country, and sector (''' '''''robust evidence, high agreement''''' ''').''' Countries with a lower carbon pricing gap (higher carbon price) tend to be less carbon intensive ( ''medium confidence'' ). {2.8.2, 2.8.3}

'''Climate-related policies have also contributed to decreasing GHG emissions. Policies such as taxes and subsidies for clean and public transportation, and renewable policies have reduced GHG emissions in some contexts (''' '''''robust evidence, high agreement''''' ''').''' Pollution control policies and legislations that go beyond end-of-pipe controls have also had climate co-benefits, particularly if complementarities with GHG emissions are considered in policy design ( ''medium evidence'' , ''medium agreement'' ). Policies on AFOLU and sector-related policies such as afforestation can have important impacts on GHG emissions ( ''medium evidence'' , ''medium agreement'' ). {2.8.4}

<div id="2.1" class="h1-container"></div>

<span id="introduction"></span>