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800 | AR6_WGI | 528 | 28 | During the orbitally-forced mid-Holocene, the CMIP6 multi-model mean captures the sign of the regional changes in temperature and precipitation in most regions assessed, and there have been some regional improvements compared to AR5 | medium | 1 | train |
801 | AR6_WGI | 528 | 29 | The limited number of CMIP6 simulations of the LGM hinders model evaluation of the multi-model mean, but for both LGM and mid-Holocene, models tend to underestimate the magnitude of large changes | high | 2 | train |
802 | AR6_WGI | 528 | 30 | Some long-standing model-data discrepancies, such as a dry bias in North Africa in the mid-Holocene, have not improved in CMIP6 compared with PMIP3 | high | 2 | train |
803 | AR6_WGI | 530 | 7 | In comparison with standard resolution CMIP6 models, higher resolution probed under the HighResMIP activity (Haarsma et al., 2016) improves aspects of the simulation of climate (particularly concerning sea surface temperature) but discrepancies remain and there are some regions, such as parts of the Southern Ocean, where currently attainable resolution produces inferior performance | high | 2 | train |
804 | AR6_WGI | 571 | 16 | The other half arises because for central estimates of climate sensitivity, most scenarios show stronger warming over the near term than was assessed as ‘current’ in SR1.5 | medium | 1 | train |
805 | AR6_WGI | 571 | 19 | If climate sensitivity lies near the lower end of the assessed very likely range, crossing the 1.5°C warming threshold is avoided in scenarios SSP1-1.9 and SSP1-2.6 | medium | 1 | train |
806 | AR6_WGI | 571 | 21 | Uncertainty in near-term projections of annual GSAT arises in roughly equal measure from natural internal variability and model uncertainty | high | 2 | train |
807 | AR6_WGI | 571 | 23 | Forecasts initialized from recent observations simulate annual GSAT changes for the period 2019–2028 relative to the recent past that are consistent with the assessed very likely range | high | 2 | train |
808 | AR6_WGI | 571 | 26 | The uncertainty ranges for the period 2081–2100 continue to be dominated by the uncertainty in ECS and TCR | very high | 3 | train |
809 | AR6_WGI | 571 | 27 | Emissions-driven simulations for SSP5-8.5 show that carbon-cycle uncertainty is too small to change the assessment of GSAT projections | high | 2 | train |
810 | AR6_WGI | 571 | 30 | In SSP1-2.6 and SSP2-4.5, ERF changes also explain about half of the changes in the range of warming | medium | 1 | train |
811 | AR6_WGI | 571 | 31 | For SSP5-8.5, higher climate sensitivity is the primary reason behind the upper end of the warming being higher than in CMIP5 | medium | 1 | train |
812 | AR6_WGI | 571 | 33 | For SSP1-2.6, such a high-warming storyline implies long-term (2081–2100) warming well above, rather than well below, 2°C | high | 2 | train |
813 | AR6_WGI | 571 | 34 | Irrespective of scenario, high-warming storylines imply changes in many aspects of the climate system that exceed the patterns associated with the central estimate of GSAT changes by up to more than 50% | high | 2 | train |
814 | AR6_WGI | 572 | 2 | The warming pattern likely varies across seasons, with northern high latitudes warming more during boreal winter than summer | medium | 1 | train |
815 | AR6_WGI | 572 | 11 | As warming increases, a larger land area will experience statistically significant increases or decreases in precipitation | medium | 1 | train |
816 | AR6_WGI | 572 | 13 | Interannual variability of precipitation over many land regions will increase with global warming | medium | 1 | train |
817 | AR6_WGI | 572 | 15 | In the near term, no discernible differences in precipitation changes are projected between different SSPs | high | 2 | train |
818 | AR6_WGI | 572 | 16 | The anthropogenic aerosol forcing decreases in most scenarios, contributing to increases in GSAT (medium confidence) and global mean land precipitation | low | 0 | train |
819 | AR6_WGI | 572 | 18 | In the long term (2081–2100), monsoon rainfall change will feature a north–south asymmetry characterized by a greater increase in the Northern Hemisphere than in the Southern Hemisphere and an east–west asymmetry characterized by an increase in Asian-African monsoon regions and a decrease in the North American monsoon region | medium | 1 | train |
820 | AR6_WGI | 572 | 19 | Near-term changes in global monsoon precipitation and circulation are uncertain due to model uncertainty and internal variability such as Atlantic Multi-decadal Variability and Pacific Decadal Variability | medium | 1 | train |
821 | AR6_WGI | 572 | 24 | This is because of the opposing influence in the near- to mid-term from stratospheric ozone recovery and increases in other greenhouse gases on the Southern Hemisphere summertime mid-latitude circulation | high | 2 | train |
822 | AR6_WGI | 573 | 1 | One exception is the expected decrease in frequency of atmospheric blocking events over Greenland and the North Pacific in boreal winter in SSP3-7.0 and SSP5-8.5 scenarios | medium | 1 | train |
823 | AR6_WGI | 573 | 5 | AMV influences on the nearby regions can be predicted over lead times of 5–8 years | medium | 1 | train |
824 | AR6_WGI | 573 | 7 | There is no model consensus for a systematic change in intensity of ENSO sea surface temperature variability over the 21st century in any of the SSP scenarios assessed | medium | 1 | train |
825 | AR6_WGI | 573 | 10 | Arctic sea ice area in March, the month of annual maximum sea ice area, also decreases in the future under each of the considered scenarios, but to a much lesser degree (in percentage terms) than in September | high | 2 | train |
826 | AR6_WGI | 573 | 12 | For the period 2081–2100 relative to 1995–2014, GMSL is likely to rise by 0.46–0.74 m under SSP3-7.0 and by 0.30–0.54 m under SSP1-2.6 | medium | 1 | train |
827 | AR6_WGI | 573 | 17 | The fraction of emissions absorbed by land and ocean sinks will be smaller under high emissions scenarios than under low emissions scenarios | high | 2 | train |
828 | AR6_WGI | 573 | 18 | Ocean surface pH will decrease steadily through the 21st century, except for SSP1-1.9 and SSP1-2.6 where values decrease until around 2070 and then increase slightly to 2100 | high | 2 | train |
829 | AR6_WGI | 573 | 20 | However, the response of many other climate quantities to mitigation would be largely masked by internal variability during the near term, especially on the regional scale | high | 2 | train |
830 | AR6_WGI | 573 | 21 | The mitigation benefits for these quantities would emerge only later during the 21st century | high | 2 | train |
831 | AR6_WGI | 573 | 22 | During the near term, a small fraction of the surface can show cooling under all scenarios assessed here, so near-term cooling at any given location is fully consistent with GSAT increase | high | 2 | train |
832 | AR6_WGI | 573 | 23 | Events of reduced and increased GSAT trends at decadal time scales will continue to occur in the 21st century but will not affect the centennial warming | very high | 3 | train |
833 | AR6_WGI | 573 | 27 | The climate effect of a sudden and sustained CDR termination would depend on the amount of CDR-induced cooling prior to termination and the rate of background CO 2 emissions at the time of termination | high | 2 | train |
834 | AR6_WGI | 573 | 31 | A sudden and sustained termination of SRM in a high-emissions scenario such as SSP5-8.5 would cause a rapid climate change | high | 2 | train |
835 | AR6_WGI | 574 | 2 | Overshooting specific global warming levels such as 2°C has effects on the climate system that persist beyond 2100 | medium | 1 | train |
836 | AR6_WGI | 574 | 3 | Under one scenario including a peak and decline in atmospheric CO 2 concentration (SSP5-3.4-OS), some climate metrics such as GSAT begin to decline but do not fully reverse by 2100 to levels prior to the CO 2 peak | medium | 1 | train |
837 | AR6_WGI | 574 | 9 | GSAT projected for the end of the 23rd century under SSP5-8.5 (likely 6.6°C–14.1°C higher than over the period 1850–1900) overlaps with the range estimated for the Miocene Climatic Optimum (5°C–10°C higher) and Early Eocene Climatic Optimum (10°C–18°C higher), about 15 and 50 million years ago, respectively | medium | 1 | train |
838 | AR6_WGI | 584 | 25 | The warming has increased in part because of models with higher ECS in CMIP6, compared to CMIP5 | high | 2 | train |
839 | AR6_WGI | 587 | 3 | The AR5 further assessed that GSAT averaged over the period 2081–2100 are projected to likely exceed 1.5°C above 1850–1900 for RCP4.5, RCP6.0 and RCP8.5 (high confidence) and are likely to exceed 2°C above 1850–1900 for RCP6.0 and RCP8.5 | high | 2 | train |
840 | AR6_WGI | 587 | 4 | Global surface temperature changes above 2°C under RCP2.6 were deemed unlikely | medium | 1 | train |
841 | AR6_WGI | 588 | 4 | In summary, the CMIP6 models show a general tendency toward larger long-term globally averaged surface warming than did the CMIP5 models, for nominally comparable scenarios | very high | 3 | train |
842 | AR6_WGI | 588 | 5 | In SSP1-2.6 and SSP2-4.5, the 5–95% ranges have remained similar to the ranges in RCP2.6 and RCP4.5, respectively, but the distributions have shifted upward by about 0.3°C | high | 2 | train |
843 | AR6_WGI | 588 | 6 | For SSP5-8.5 compared to RCP8.5, the 5% bound of the distribution has hardly changed, but the 95% bound and the range have increased by about 20% and 40%, respectively | high | 2 | train |
844 | AR6_WGI | 588 | 22 | This means that the CMIP6 spread in GSAT response to CO 2 emissions is dominated by climate sensitivity differences between ESMs more than by carbon cycle differences | high | 2 | train |
845 | AR6_WGI | 589 | 4 | These differences due to experimental configuration would be smaller still under scenarios with lower CO 2 levels, and so we assess that results from concentration-driven and emissions- driven configurations do not affect the assessment of GSAT projections | high | 2 | train |
846 | AR6_WGI | 589 | 8 | Based on these results, we conclude that global land precipitation is larger during the period 2081–2100 than during the period 1995–2014, under all scenarios considered here | high | 2 | train |
847 | AR6_WGI | 590 | 4 | There is no change in subtropical precipitation in the North Atlantic following SSP1-1.9, SSP1-2.6, or SSP2-4.5 | high | 2 | train |
848 | AR6_WGI | 590 | 6 | These range from 43% under RCP2.6 and 94% under RCP8.5 in September, and from 8% under RCP2.6 and 34% under RCP8.5 in March | medium | 1 | train |
849 | AR6_WGI | 591 | 3 | Based on results from the CMIP6 models, we conclude that on average the Arctic will become practically ice-free in September by the end of the 21st century under SSP2-4.5, SSP3-7.0, and SSP5-8.5 | high | 2 | train |
850 | AR6_WGI | 591 | 4 | Also, in the CMIP6 models, Arctic SIA in March decreases in the future, but to a much lesser degree, in percentage terms, than in September | high | 2 | train |
851 | AR6_WGI | 591 | 11 | The individual model simulations, for which there are twenty for each stabilized temperature level, show that the probability of the Arctic becoming practically ice free at the end of the 21st century is significantly higher for 2°C warming than for 1.5°C warming above 1850–1900 levels | high | 2 | train |
852 | AR6_WGI | 591 | 13 | Further, AR5 concluded that for the period 2081–2100, compared to 1986–2005, GMSL rise is likely | medium | 1 | train |
853 | AR6_WGI | 592 | 11 | In summary, we assess from the CMIP6 models that AMOC weakening over the 21st century is very likely ; the rate of weakening is approximately independent of the emissions scenario | high | 2 | train |
854 | AR6_WGI | 592 | 15 | In summary, in these model simulations the AMOC recovers over several centuries after the cessation of CO 2 emissions | medium | 1 | train |
855 | AR6_WGI | 593 | 3 | We assess that the cumulative uptake of carbon by the ocean and by land will increase through the 21st century irrespective of the considered emissions scenarios except SSP1-1.9 | very high | 3 | test |
856 | AR6_WGI | 593 | 6 | Based on results from the CMIP6 models we conclude that, except for the lower-emissions scenarios SSP1-1.9 and SSP1-2.6, ocean surface pH decreases monotonically through the 21st century | high | 2 | train |
857 | AR6_WGI | 594 | 7 | Strong positive trends for the NAM/NAO indices were observed since 1960, which have weakened since the 1990s | high | 2 | train |
858 | AR6_WGI | 594 | 13 | Based on CMIP6 model results displayed in Figure 4.9a, we conclude that the boreal wintertime surface NAM is more positive by the end of the 21st century under SSP3-7.0 and SSP5-8.5 | high | 2 | train |
859 | AR6_WGI | 594 | 15 | On the other hand, under neither of the lowest emissions scenarios, SSP1-1.9 and SSP1-2.6, does the NAM show a robust change, by the end of the 21st century | high | 2 | train |
860 | AR6_WGI | 595 | 12 | Over the instrumental period, there has been a robust positive trend in the SAM index, particularly since 1970 | high | 2 | train |
861 | AR6_WGI | 595 | 22 | In summary, under the highest emissions scenarios in the CMIP6 models, the SAM in the austral summer becomes more positive through the 21st century | high | 2 | train |
862 | AR6_WGI | 596 | 14 | Over the mid-term period 2041–2060, the very likely GSAT ranges of SSP1-1.9 and SSP5-8.5 are almost completely distinct | high | 2 | train |
863 | AR6_WGI | 596 | 15 | CMIP6 models project a wider range of GSAT change than the assessed range | high | 2 | train |
864 | AR6_WGI | 598 | 10 | Roughly half of this difference arises from a larger historical warming diagnosed in AR6, while the other half arises because for central estimates of climate sensitivity, most scenarios show stronger warming over the near term than was estimated as ‘current’ in SR1.5 | medium | 1 | train |
865 | AR6_WGI | 598 | 14 | If ECS and TCR lie near the lower end of the assessed very likely range, crossing the 1.5°C warming threshold is avoided in scenarios SSP1-1.9 and SSP1-2.6 | medium | 1 | train |
866 | AR6_WGI | 599 | 5 | The AR5 further assessed that it is more likely than not that the mean GSAT for the period 2016–2035 will be more than 1°C above the mean for 1850–1900, and it is very unlikely that it will be more than 1.5°C above the 1850–1900 mean | medium | 1 | train |
867 | AR6_WGI | 599 | 8 | Averaged over the twenty years of the near term and across all scenarios, GSAT is very likely to be higher than over 1995–2014 by 0.4°C–1.0°C (Table 4.5), with most of the uncertainty arising from that in ECS and TCR | high | 2 | train |
868 | AR6_WGI | 599 | 13 | For annual mean GSAT, uncertainty in near-term projections arises in roughly equal measure from internal variability and model uncertainty | high | 2 | train |
869 | AR6_WGI | 599 | 14 | Forecasts initialized from recent observations simulate GSAT changes for the period 2019–2028 relative to the recent past that are consistent with the assessed very likely range in annual mean GSAT | high | 2 | train |
870 | AR6_WGI | 599 | 19 | By 2030, GSAT in any individual year could exceed 1.5°C relative to 1850–1900 with a likelihood between 40 and 60 percent, across the scenarios considered here | medium | 1 | train |
871 | AR6_WGI | 601 | 9 | Near-term projected changes in precipitation are uncertain mainly because of natural internal variability, model uncertainty, and uncertainty in natural and anthropogenic aerosol forcing | medium | 1 | train |
872 | AR6_WGI | 602 | 7 | In summary, we assess that near-term changes in global monsoon precipitation and circulation will be affected by the combined effects of model uncertainty and internal variability, such as AMV and PDV, which together are larger than the forced signal | medium | 1 | train |
873 | AR6_WGI | 603 | 1 | Based on results from CMIP6 models, we conclude that SSP2-4.5, SSP3-7.0, and SSP5-8.5 all clearly lead to increasing 10-, 20-, and 30-year trends in ocean carbon flux over the near term | high | 2 | train |
874 | AR6_WGI | 604 | 5 | Considering these new results since AR5, in the near-term it is likely that any anthropogenic forced signal in the NAM will be of comparable magnitude or smaller than natural internal variability in the NAM | medium | 1 | train |
875 | AR6_WGI | 605 | 12 | Hence, no robust change in amplitude of ENSO SST and rainfall variability is expected in the near term although the rainfall variability slightly increases | medium | 1 | train |
876 | AR6_WGI | 606 | 1 | However, some studies show that despite severe model biases there are skilful predictions in the mean state of tropical Atlantic surface temperature several years ahead | medium | 1 | train |
877 | AR6_WGI | 607 | 11 | The AR5 assessed that emission reductions aimed at decreasing local air pollution could have a near-term warming impact on climate | high | 2 | train |
878 | AR6_WGI | 608 | 15 | Volcanic eruptions generally result in decreased global precipitation for up to a few years following the eruption (Iles and Hegerl, 2014, 2015; Man et al., 2014), with climatologically wet regions drying and climatologically dry regions wetting | medium | 1 | train |
879 | AR6_WGI | 608 | 22 | In these simulations with multiple volcanic forcing futures there is: (i) an increase in the frequency of extremely cold individual years; (ii) an increased likelihood of decades with negative GSAT trend (decades with negative GSAT trends become 50% more commonplace); (iii) later anthropogenic signal emergence (the mean time at which the signal of global warming emerges from the noise of natural climate variability is delayed almost everywhere) | high | 2 | train |
880 | AR6_WGI | 609 | 20 | Yet, remaining disagreements reflect differences in the volcanic forcing datasets used in the simulations | medium | 1 | train |
881 | AR6_WGI | 612 | 8 | The ratio of land-to-ocean warming is greater than one for almost all regions | high | 2 | train |
882 | AR6_WGI | 612 | 22 | Projected reduction in the strength of the AMOC over the 21st century is expected to reduce Arctic warming, but even a strong AMOC reduction would not eliminate Arctic amplification entirely | medium | 1 | train |
883 | AR6_WGI | 614 | 2 | There is growing evidence that year-to-year and day-to-day temperature variability decreases in winter over northern mid- to high-latitudes (Fischer et al., 2011; De Vries et al., 2012; Screen, 2014; Schneider et al., 2015; Holmes et al., 2016; Borodina et al., 2017; Tamarin-Brodsky et al., 2020) which implies that the lowest temperatures rise more than the respective climatological mean temperatures | medium | 1 | train |
884 | AR6_WGI | 617 | 32 | Consistent with the AR5, patterns of precipitation change are very likely to increase in the high latitudes especially during local winter and over tropical oceans under SSP3-7.0 | high | 2 | train |
885 | AR6_WGI | 617 | 33 | CMIP6 projections show an increase in precipitation over larger parts of the monsoon regions and decreases in many subtropical regions including the Mediterranean, southern Africa and south-west Australia | medium | 1 | train |
886 | AR6_WGI | 618 | 5 | CMIP6 models show greater increases in precipitation over land than either globally or over the ocean | high | 2 | train |
887 | AR6_WGI | 618 | 8 | The patterns of precipitation change will exhibit substantial regional differences and seasonal contrast as GSAT increases over the 21st century | high | 2 | train |
888 | AR6_WGI | 619 | 20 | The patterns of monsoon rainfall change in the mid- to long-term include a north–south asymmetry characterized by greater increase in the NH than the SH, and an East–West asymmetry characterized by enhanced Asian-African monsoons and weakened North American monsoon | medium | 1 | train |
889 | AR6_WGI | 619 | 23 | Monsoon precipitation responses depend on region and emissions scenario | high | 2 | train |
890 | AR6_WGI | 620 | 4 | The AR5 assessed that a poleward shift of the SH westerlies and storm track is likely by the end of the 21st century under RCP8.5 | medium | 1 | train |
891 | AR6_WGI | 624 | 13 | The projected large-scale surface ocean acidification will be primarily determined by the pathway of atmospheric CO 2, with weak dependence on change in climate | high | 2 | train |
892 | AR6_WGI | 624 | 14 | However, for a given atmospheric CO 2 scenario, uncertainty in projected ocean acidification increases with ocean depth because of model-simulated differences in ocean circulation that transports anthropogenic CO 2 from the surface to bottom ocean | high | 2 | train |
893 | AR6_WGI | 627 | 3 | To conclude, the forced change in ENSO SST variability is highly uncertain in CMIP5 and CMIP6 models | medium | 1 | train |
894 | AR6_WGI | 629 | 22 | In the Southern Hemisphere the strongest warming over land is to occur, at any given level of global warming, over the subtropical areas of South America, southern Africa and Australia | high | 2 | train |
895 | AR6_WGI | 629 | 24 | Across the globe, in the tropics, subtropics, and mid- to high latitudes, temperatures tend to scale linearly with the level of increase in GSAT and patterns of change are largely scenario independent | high | 2 | train |
896 | AR6_WGI | 631 | 3 | The increases and decreases in precipitation will amplify at higher levels of global warming | high | 2 | train |
897 | AR6_WGI | 631 | 6 | Over the austral-winter rainfall regions of south-western South America, South Africa and Australia, projected decreases in mean annual rainfall show high agreement across models and a strong climate change signal even under 1.5°C of global warming, with further amplification of the signal at higher levels of global warming | high | 2 | train |
898 | AR6_WGI | 632 | 4 | As warming increases, a larger global and land area will experience statistically significant increases or decreases in precipitation | medium | 1 | train |
899 | AR6_WGI | 634 | 11 | Although these climate quantities are not fully reversible, the overshoot scenario results in reduced climate change compared with stabilisation or continued increase in greenhouse gases (Tsutsui et al., 2006; Palter et al., 2018; Tachiiri et al., 2019) | high | 2 | train |
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