Editing IPCC:AR6/SYR/SPM (section)

=== Observed Warming and its Causes ===

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'''A.1 Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850-1900 in 2011-2020. Global greenhouse gas emissions have continued to increase, with unequal historical and ongoing contributions arising from unsustainable energy use, land use and land-use change, lifestyles and patterns of consumption and production across regions, between and within countries, and among individuals '''''(high confidence).''''' Links to longer report 2.1, Figure 2.1, Figure 2.2'''
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A.1.1 Global surface temperature was 1.09°C [0.95 to 1.20] °C [[#footnote-052|5]] higher in 2011-2020 than 1850-1900 [[#footnote-051|6]] , with larger increases over land (1.59 [1.34 to 1.83] °C) than over the ocean (0.88 [0.68 to 1.01] °C). Global surface temperature in the first two decades of the 21 st century (2001-2020) was 0.99 [0.84 to 1.10] °C higher than 1850-1900. Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years ''(high confidence)'' . Links to longer report 2.1.1, Figure 2.1

A.1.2 The ''likely'' range of total human-caused global surface temperature increase from 1850-1900 to 2010-2019 [[#footnote-050|7]] is 0.8°C to 1.3°C, with a best estimate of 1.07°C. Over this period, it is ''likely'' that well-mixed greenhouse gases (GHGs) contributed a warming of 1.0°C to 2.0°C [[#footnote-049|8]] , and other human drivers (principally aerosols) contributed a cooling of 0.0°C to 0.8°C, natural drivers changed global surface temperature by –0.1°C to +0.1°C, and internal variability changed it by –0.2°C to +0.2°C. Links to longer report 2.1.1, Figure 2.1

A.1.3 Observed increases in well-mixed GHG concentrations since around 1750 are unequivocally caused by GHG emissions from human activities over this period. Historical cumulative net CO '''2''' emissions from 1850 to 2019 were 2400 ± 240 GtCO '''2''' of which more than half (58%) occurred between 1850 and 1989, and about 42% occurred between 1990 and 2019 ''(high confidence)'' . In 2019, atmospheric CO '''''2''''' concentrations (410 parts per million) were higher than at any time in at least 2 million years ''(high confidence)'' , and concentrations of methane (1866 parts per billion) and nitrous oxide (332 parts per billion) were higher than at any time in at least 800,000 years ''(very high confidence)'' . Links to longer report 2.1.1, Figure 2.1

A.1.4 Global net anthropogenic GHG emissions have been estimated to be 59 ± 6.6 GtCO '''2''' -eq [[#footnote-048|9]] in 2019, about 12% (6.5 GtCO '''2''' -eq) higher than in 2010 and 54% (21 GtCO '''2''' -eq) higher than in 1990, with the largest share and growth in gross GHG emissions occurring in CO '''2''' from fossil fuels combustion and industrial processes (CO '''2''' -FFI) followed by methane, whereas the highest relative growth occurred in fluorinated gases (F-gases), starting from low levels in 1990. Average annual GHG emissions during 2010-2019 were higher than in any previous decade on record, while the rate of growth between 2010 and 2019 (1.3% year -1 ) was lower than that between 2000 and 2009 (2.1% year -1 ). In 2019, approximately 79% of global GHG emissions came from the sectors of energy, industry, transport, and buildings together and 22% [[#footnote-047|10]] from agriculture, forestry and other land use (AFOLU). Emissions reductions in CO 2 -FFI due to improvements in energy intensity of GDP and carbon intensity of energy, have been less than emissions increases from rising global activity levels in industry, energy supply, transport, agriculture and buildings. ''(high confidence)'' Links to longer report 2.1.1

A.1.5 Historical contributions of CO 2 emissions vary substantially across regions in terms of total magnitude, but also in terms of contributions to CO 2 -FFI and net CO 2 emissions from land use, land-use change and forestry (CO 2 -LULUCF). In 2019, around 35% of the global population live in countries emitting more than 9 tCO 2 -eq per capita [[#footnote-046|11]] (excluding CO 2 -LULUCF) while 41% live in countries emitting less than 3 tCO 2 -eq per capita; of the latter a substantial share lacks access to modern energy services. Least Developed Countries (LDCs) and Small Island Developing States (SIDS) have much lower per capita emissions (1.7 tCO 2 -eq and 4.6 tCO 2 -eq, respectively) than the global average (6.9 tCO 2 -eq), excluding CO 2 -LULUCF. The 10% of households with the highest per capita emissions contribute 34–45% of global consumption-based household GHG emissions, while the bottom 50% contribute 13–15%. ''(high confidence)'' Links to longer report 2.1.1, Figure 2.2

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