Editing IPCC:AR6/SYR/SPM (section)

=== Future Climate Change ===

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'''B.1 Continued greenhouse gas emissions will lead to increasing global warming, with the best estimate of reaching 1.5°C in the near term in considered scenarios and modelled pathways. Every increment of global warming will intensify multiple and concurrent hazards '''''(high confidence)''''' . Deep, rapid, and sustained reductions in greenhouse gas emissions would lead to a discernible slowdown in global warming within around two decades, and also to discernible changes in atmospheric composition within a few years '''''(high confidence)''''' . [[#figure-spm-2|Figure SPM.2]] [[#box-spm-1|Box SPM.1]] Links to longer report Cross-Section Boxes 1 and 2, 3.1, 3.3, Table 3.1, Figure 3.1, 4.3'''
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B.1.1 Global warming [[#footnote-029|28]] will continue to increase in the near term (2021-2040) mainly due to increased cumulative CO '''2''' emissions in nearly all considered scenarios and modelled pathways. In the near term, global warming ''is more likely'' ''than not'' to reach 1.5°C even under the very low GHG emission scenario (SSP1-1.9) and ''likely'' or ''very likely'' to exceed 1.5°C under higher emissions scenarios. In the considered scenarios and modelled pathways, the best estimates of the time when the level of global warming of 1.5°C is reached lie in the near term [[#footnote-028|29]] . Global warming declines back to below 1.5°C by the end of the 21st century in some scenarios and modelled pathways (see B.7). The assessed climate response to GHG emissions scenarios results in a best estimate of warming for 2081-2100 that spans a range from 1.4°C for a very low GHG emissions scenario (SSP1-1.9) to 2.7°C for an intermediate GHG emissions scenario (SSP2-4.5) and 4.4°C for a very high GHG emissions scenario (SSP5-8.5) [[#footnote-027|30]] , with narrower uncertainty ranges [[#footnote-026|31]] than for corresponding scenarios in AR5. ''[[#box-spm-1|Box SPM.1]] Links to longer report Cross-Section Boxes 1 and 2, 3.1.1, 3.3.4, Table 3.1, 4.3''

B.1.2 Discernible differences in trends of global surface temperature between contrasting GHG emissions scenarios (SSP1-1.9 and SSP1-2.6 vs. SSP3-7.0 and SSP5-8.5) would begin to emerge from natural variability [[#footnote-025|32]] within around 20 years. Under these contrasting scenarios, discernible effects would emerge within years for GHG concentrations, and sooner for air quality improvements, due to the combined targeted air pollution controls and strong and sustained methane emissions reductions. Targeted reductions of air pollutant emissions lead to more rapid improvements in air quality within years compared to reductions in GHG emissions only, but in the long term, further improvements are projected in scenarios that combine efforts to reduce air pollutants as well as GHG emissions [[#footnote-024|33]] . ''(high confidence) Links to longer report 3.1.1''

B.1.3 Continued emissions will further affect all major climate system components. With every additional increment of global warming, changes in extremes continue to become larger. Continued global warming is projected to further intensify the global water cycle, including its variability, global monsoon precipitation, and very wet and very dry weather and climate events and seasons ''(high confidence)'' . In scenarios with increasing CO 2 emissions, natural land and ocean carbon sinks are projected to take up a decreasing proportion of these emissions ''(high confidence)'' . Other projected changes include further reduced extents and/or volumes of almost all cryospheric elements [[#footnote-023|34]] ''(high confidence)'' , further global mean sea level rise ''(virtually certain)'' , and increased ocean acidification ''(virtually certain)'' and deoxygenation ''(high confidence)'' . ''[[#figure-spm-2|Figure SPM.2]] Links to longer report 3.1.1, 3.3.1, Figure 3.4''

B.1.4 With further warming, every region is projected to increasingly experience concurrent and multiple changes in climatic impact-drivers. Compound heatwaves and droughts are projected to become more frequent, including concurrent events across multiple locations ''(high confidence)'' . Due to relative sea level rise, current 1-in-100 year extreme sea level events are projected to occur at least annually in more than half of all tide gauge locations by 2100 under all considered scenarios ''(high confidence).'' Other projected regional changes include intensification of tropical cyclones and/or extratropical storms ''(medium confidence)'' , and increases in aridity and fire weather ''(medium to high confidence).'' Links to longer report 3.1.1, 3.1.3

B.1.5 Natural variability will continue to modulate human-caused climate changes, either attenuating or amplifying projected changes, with little effect on centennial-scale global warming ''(high confidence)'' . These modulations are important to consider in adaptation planning, especially at the regional scale and in the near term. If a large explosive volcanic eruption were to occur [[#footnote-022|35]] , it would temporarily and partially mask human-caused climate change by reducing global surface temperature and precipitation for one to three years ''(medium confidence)'' . Links to longer report 4.3

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[[File:d6c19f23df611250c8ec8e95d7bf8906 IPCC_AR6_SYR_SPM_Figure2.png]]
'''Figure SPM.2: Projected changes of annual maximum daily maximum temperature, annual mean total column soil moisture and annual maximum 1-day precipitation at global warming levels of 1.5°C, 2°C, 3°C, and 4°C relative to 1850-1900.''' Projected '''(a)''' annual maximum daily temperature change (°C), '''(b)''' annual mean total column soil moisture (standard deviation), '''(c)''' annual maximum 1-day precipitation change (%). The panels show CMIP6 multi-model median changes. In panels (b) and (c), large positive relative changes in dry regions may correspond to small absolute changes. In panel (b), the unit is the standard deviation of interannual variability in soil moisture during 1850-1900. Standard deviation is a widely used metric in characterising drought severity. A projected reduction in mean soil moisture by one standard deviation corresponds to soil moisture conditions typical of droughts that occurred about once every six years during 1850-1900. The WGI Interactive Atlas (https://interactive-atlas.ipcc.ch/) can be used to explore additional changes in the climate system across the range of global warming levels presented in this figure. Links to longer report Figure 3.1, Cross-Section Box.2

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