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1,400 | AR6_WGI | 1,231 | 5 | The practically ice-free state is projected to occur more often with higher greenhouse gas concentrations, and it will become the new normal for high-emissions scenarios by the end of this century | high | 2 | train |
1,401 | AR6_WGI | 1,231 | 6 | Based on observational evidence, Coupled Model Intercomparison Project Phase 6 (CMIP6) models and conceptual understanding, the substantial satellite-observed decrease of Arctic sea ice area over the period 1979 –2019 is well described as a linear function of global mean surface temperature, and thus of cumulative anthropogenic carbon dioxide (CO 2) emissions, with superimposed internal variability | high | 2 | train |
1,402 | AR6_WGI | 1,231 | 9 | The regionally opposing trends result primarily from changing regional wind forcing | medium | 1 | train |
1,403 | AR6_WGI | 1,231 | 13 | This mass loss is driven by both discharge and surface melt, with the latter increasingly becoming the dominating component of mass loss with high interannual variability in the last decade | high | 2 | train |
1,404 | AR6_WGI | 1,231 | 14 | The largest mass losses occurred in the north-west and the south-east of Greenland | high | 2 | train |
1,405 | AR6_WGI | 1,231 | 18 | Mass losses from West Antarctic outlet glaciers outpaced mass gain from increased snow accumulation on the continent and dominated the ice-sheet mass losses since 1992 | very high | 3 | train |
1,406 | AR6_WGI | 1,231 | 19 | These mass losses from the West Antarctic outlet glaciers were mainly induced by ice-shelf basal melt (high confidence) and locally by ice-shelf disintegration preceded by strong surface melt | high | 2 | train |
1,407 | AR6_WGI | 1,231 | 20 | Parts of the East Antarctic Ice Sheet have lost mass in the last two decades | high | 2 | train |
1,408 | AR6_WGI | 1,231 | 23 | The loss of ice from Greenland will become increasingly dominated by surface melt, as marine margins retreat and the ocean-forced dynamic response of ice-sheet margins diminishes | high | 2 | train |
1,409 | AR6_WGI | 1,231 | 24 | In the Antarctic, dynamic losses driven by ocean warming and ice-shelf disintegration will likely continue to outpace increasing snowfall this century | medium | 1 | train |
1,410 | AR6_WGI | 1,231 | 25 | Beyond 2100, total mass loss from both ice sheets will be greater under high-emissions scenarios than under low-emissions scenarios | high | 2 | train |
1,411 | AR6_WGI | 1,231 | 29 | During the decade 2010–2019, glaciers lost more mass than in any other decade since the beginning of the observational record | very high | 3 | train |
1,412 | AR6_WGI | 1,231 | 30 | For all regions with long-term observations, glacier mass in the decade 2010 –2019 is the smallest since at least the beginning of the 20th century | medium | 1 | train |
1,413 | AR6_WGI | 1,231 | 31 | Because of their lagged response, glaciers will continue to lose mass at least for several decades even if global temperature is stabilized | very high | 3 | train |
1,414 | AR6_WGI | 1,232 | 2 | Complete permafrost thaw in recent decades is a common phenomenon in discontinuous and sporadic permafrost regions | medium | 1 | train |
1,415 | AR6_WGI | 1,232 | 3 | Permafrost warmed globally by 0.29 [0.17 to 0.41, likely range] °C between 2007 and 2016 | medium | 1 | train |
1,416 | AR6_WGI | 1,232 | 4 | An increase in the active layer thickness is a pan-Arctic phenomenon | medium | 1 | train |
1,417 | AR6_WGI | 1,232 | 5 | The volume of perennially frozen soil within the upper 3 m of the ground will decrease by about 25% per 1°C of global surface air temperature change (up to 4°C above pre-industrial temperature) | medium | 1 | train |
1,418 | AR6_WGI | 1,232 | 9 | It is virtually certain that Northern Hemisphere snow cover extent will continue to decrease as global climate continues to warm, and process understanding strongly suggests that this also applies to Southern Hemisphere seasonal snow cover | high | 2 | train |
1,419 | AR6_WGI | 1,232 | 10 | Northern Hemisphere spring snow cover extent will decrease by about 8% per 1°C of global surface air temperature change (up to 4°C above pre-industrial temperature) | medium | 1 | train |
1,420 | AR6_WGI | 1,232 | 12 | GMSL rise has accelerated since the late 1960s, with an average rate of 2.3 [1.6 to 3.1] mm yr –1 over the period 1971–2018 increasing to 3.7 [3.2 to 4.2] mm yr –1 over the period 2006–2018 | high | 2 | train |
1,421 | AR6_WGI | 1,232 | 15 | The contribution of Greenland and Antarctica to GMSL rise was four times larger during 2010–2019 than during 1992 –1999 | high | 2 | train |
1,422 | AR6_WGI | 1,232 | 16 | Because of the increased ice-sheet mass loss, the total loss of land ice (glaciers and ice sheets) was the largest contributor to global mean sea level rise over the period 2006–2018 | high | 2 | train |
1,423 | AR6_WGI | 1,232 | 19 | Temporal variability in ocean dynamics dominates regional patterns on annual to decadal time scales | high | 2 | train |
1,424 | AR6_WGI | 1,232 | 20 | The anthropogenic signal in regional sea level change will emerge in most regions by 2100 | medium | 1 | train |
1,425 | AR6_WGI | 1,232 | 22 | Observations show that high-tide flooding events that occurred five times per year during the period 1960–1980 occurred, on average, more than eight times per year during the period 1995–2014 | high | 2 | train |
1,426 | AR6_WGI | 1,232 | 23 | Under the assumption that other contributors to extreme sea levels remain constant (e.g., stationary tides, storm-surge, and wave climate), extreme sea levels that occurred once per century in the recent past will occur annually or more frequently at about 19–31% of tide gauges by 2050 and at about 60% (SSP1-2.6) to 82% (SSP5-8.5) of tide gauges by 2100 | medium | 1 | train |
1,427 | AR6_WGI | 1,232 | 24 | In total, such extreme sea levels will occur about 20 to 30 times more frequently by 2050 and 160 to 530 times more frequently by 2100 compared to the recent past, as inferred from the median amplification factors for SSP1-2.6, SSP2-4.5, and SSP5-8.5 | medium | 1 | train |
1,428 | AR6_WGI | 1,232 | 25 | Over the 21st century, the majority of coastal locations will experience a median projected regional sea level rise within ±20% of the median projected GMSL change | medium | 1 | train |
1,429 | AR6_WGI | 1,233 | 5 | By 2300, GMSL will rise between 0.3 m and 3.1 m under SSP1-2.6, between 1.7 m and 6.8 m under SSP5-8.5 in the absence of marine ice cliff instability, and by up to 16 m under SSP5-8.5 considering marine ice cliff instability | low | 0 | train |
1,430 | AR6_WGI | 1,239 | 6 | Common regional biases in SST or historical SST trends are not exclusively linked to the representation of the ocean | high | 2 | train |
1,431 | AR6_WGI | 1,239 | 10 | In summary, CMIP6 models show persistent regional biases in representing the climatological SST state | very high | 3 | train |
1,432 | AR6_WGI | 1,239 | 15 | Warming is projected at varying rates in all regions by 2050, except the North Atlantic Subpolar Region, the equatorial Pacific, and the Southern Ocean where models disagree | high | 2 | train |
1,433 | AR6_WGI | 1,239 | 24 | Similarly, the SST change pattern observed in the tropical Pacific Ocean will transition on centennial time scales to a mean pattern resembling the El Niño pattern | medium | 1 | train |
1,434 | AR6_WGI | 1,241 | 7 | In summary, globally integrated and large-scale fluxes are more reliably inferred from heat content and salinity change, while regional trends are rarely robust in observations; where they are robust, they tend to be underestimated or in disagreement in models | very high | 3 | train |
1,435 | AR6_WGI | 1,241 | 9 | The AR5 (Rhein et al., 2013) assessed with medium confidence that zonal wind stress over the Southern Ocean increased from the early 1980s to the 1990s | medium | 1 | train |
1,436 | AR6_WGI | 1,242 | 6 | In summary, there is limited observational evidence that the mixed layer is globally deepening, while models show no emergence of a trend until later in the 21st century under strong emissions.The SROCC assessed that upper-ocean stratification will continue to increase in the 21st century under increased radiative forcing | high | 2 | train |
1,437 | AR6_WGI | 1,243 | 17 | The SROCC highlighted that future change of MHWs will not be globally uniform, with the largest changes in the frequency of marine heatwaves being projected to occur in the western tropical Pacific and the Arctic Ocean | medium | 1 | train |
1,438 | AR6_WGI | 1,243 | 19 | Moderate increases are projected for mid-latitudes, and only small increases are projected for the Southern Ocean | medium | 1 | train |
1,439 | AR6_WGI | 1,243 | 21 | The resolution of current climate models (CMIP5 and CMIP6) capture the broad features of MHWs, but they may have a bias towards weaker and longer MHWs in the historical period | medium | 1 | train |
1,440 | AR6_WGI | 1,244 | 4 | Section 2.3.3.1 reports that current multi-decadal to centennial rates of OHC gain are greater than at any point since the last deglaciation | medium | 1 | train |
1,441 | AR6_WGI | 1,244 | 9 | Section 3.5.1.3 assessed that it is extremely likely that human influence was the main driver of the ocean heat content increase observed since the 1970s, which extends into the deeper ocean | very high | 3 | train |
1,442 | AR6_WGI | 1,246 | 1 | In summary, in the upper 2000 m since the 1970s, the subpolar North Atlantic has been slowly warming, and the Southern Ocean has stored a disproportionally large amount of anthropogenic heat | medium | 1 | train |
1,443 | AR6_WGI | 1,247 | 4 | In summary, and strengthening SROCC assessment, ocean warming is not globally uniform due to patterns of uptake predominantly along known water mass pathways, and due to changing ocean circulation redistributing heat within the ocean | high | 2 | train |
1,444 | AR6_WGI | 1,247 | 11 | Despite a decrease of AMOC northward heat (0.17 PW) and mass (2.5 Sverdrup (Sv); 1 Sv = 109 kg s–1) transport, OHT has increased toward the Arctic through increased upper northern North Atlantic temperatures and stronger wind-driven gyres | medium | 1 | train |
1,445 | AR6_WGI | 1,247 | 12 | In summary, OHT has increased toward the Arctic in recent decades, which at least partially explains the recent OHC change in the Arctic | medium | 1 | train |
1,446 | AR6_WGI | 1,248 | 12 | In summary, climate models have more skill in representing OHC change from added heat than from ocean circulation change | high | 2 | train |
1,447 | AR6_WGI | 1,249 | 2 | In summary, on decadal time scales, redistribution will dominate regional patterns of OHC change without affecting the globally integrated OHC; however, by 2100, particularly under strong warming scenarios, there is high confidence that regional patterns of OHC change will be dominated by added heat entering the sea surface, primarily in water mass formation regions in the subtropics; and reduced aerosols will increase the relative rate of Northern Hemisphere heat uptake | medium | 1 | train |
1,448 | AR6_WGI | 1,250 | 2 | Section 2.3.3.2 strengthens evidence that subsurface salinity trends are connected to surface trends (very likely), which are, in turn, linked to an intensifying hydrological cycle | medium | 1 | train |
1,449 | AR6_WGI | 1,250 | 21 | Section 3.5.2.1 reports, however, that the fidelity of ocean salinity simulation has improved in CMIP6, and near-surface and subsurface biases have been reduced | medium | 1 | train |
1,450 | AR6_WGI | 1,250 | 26 | Projections confirm SROCC assessment that fresh ocean regions will continue to get fresher and salty ocean regions will continue to get saltier in the 21st century | medium | 1 | test |
1,451 | AR6_WGI | 1,251 | 5 | Consistently, we assess that STMW have deepened worldwide, with greatest deepening in the Southern Hemisphere | high | 2 | train |
1,452 | AR6_WGI | 1,251 | 12 | The SROCC connected SAMW and AAIW to Southern Ocean temperature changes as the large Southern Ocean surface heat uptake is circulated and mixed along with these water masses | high | 2 | train |
1,453 | AR6_WGI | 1,253 | 18 | The SROCC (Collins et al., 2019) assessed that in situ observations (2004–2017) and sea surface temperature reconstructions indicate that AMOC has weakened relative to 1850–1900 | medium | 1 | train |
1,454 | AR6_WGI | 1,254 | 10 | This suggests that the observed AMOC-shift between 2007 and 2011 may be part of a longer-term decrease | medium | 1 | train |
1,455 | AR6_WGI | 1,255 | 4 | Projected AMOC decline by 2100 ranges from 24 [4 to 46] % in SSP1-2.6 to 39 [17–55] % in SSP5-8.5 | medium | 1 | train |
1,456 | AR6_WGI | 1,255 | 11 | Tuning towards stability and model biases (Valdes, 2011; Liu et al., 2017; Mecking et al., 2017; Weijer et al., 2019) provides CMIP models a tendency toward unrealistic stability | medium | 1 | train |
1,457 | AR6_WGI | 1,256 | 2 | It also reported that, instead of increasing the mean ACC transport, additional energy input associated with increased wind stress cascades into the eddy field | medium | 1 | train |
1,458 | AR6_WGI | 1,256 | 22 | For the lower cell overturning circulation, SROCC assessed that a slowdown of its transport is consistent with the observed decrease in volume | medium | 1 | train |
1,459 | AR6_WGI | 1,257 | 9 | Section 2.4 concludes that a sustained shift beyond multi-centennial variability has not been observed for El Niño–Southern Oscillation (ENSO) | medium | 1 | train |
1,460 | AR6_WGI | 1,257 | 17 | In summary, while future changes in tropical modes of variability remain unclear, change in atmospheric and ocean circulation will drive continued change in tropical ocean temperature in the 21st century (medium confidence), with part of the region experiencing drastic marine heat wave conditions | high | 2 | train |
1,461 | AR6_WGI | 1,257 | 23 | Section 2.3.3.4 assesses that, while WBC strength is highly variable at multi-decadal scale (high confidence), WBCs and subtropical gyres have shifted poleward since 1993 | medium | 1 | train |
1,462 | AR6_WGI | 1,258 | 3 | In the North Pacific, there has been an increasing trend in the Alaska Gyre from 1993 to 2017 (Cummins and Masson, 2018), which might be attributed to Pacific Decadal Oscillation | low | 0 | train |
1,463 | AR6_WGI | 1,258 | 5 | All climate models reproduce WBCs and gyres, but eddy- present or eddy-rich models (roughly 10–25 km and about 10 km resolution, respectively) represent these currents more realistically than eddy-parameterized models | very high | 3 | train |
1,464 | AR6_WGI | 1,258 | 7 | Increased resolution admits mesoscale eddies, and also improves simulation of the strength and position of WBCs such as the Kuroshio Current, Gulf Stream, and East Australian Current | very high | 3 | train |
1,465 | AR6_WGI | 1,258 | 9 | The wind-current feedback, implemented by considering relative velocity of currents and wind, realistically dampens mesoscale eddies and WBCs, through mesoscale air–sea interaction (Ma et al., 2016; Renault et al., 2016, 2019), even though sub-mesoscale wind- current damping feedback is missing in these models | medium | 1 | train |
1,466 | AR6_WGI | 1,258 | 10 | As eddies potentially play a role in determining the strength of gyre circulations and their low- frequency variability (Fox-Kemper and Pedlosky, 2004; Berloff et al., 2007), it is expected that eddy-present and eddy-rich models will differ in their decadal variability and sensitivity to changes in the wind stress of gyres from eddy-parameterized models | medium | 1 | test |
1,467 | AR6_WGI | 1,259 | 5 | The SROCC (Collins et al., 2019) concluded with high confidence that Indonesian Throughflow (ITF) transport from the Pacific Ocean to the Indian Ocean has increased in the past two decades as a result | medium | 1 | train |
1,468 | AR6_WGI | 1,260 | 6 | Projected future annual cumulative upwelling wind changes at most locations, and seasons remain within ±10–20% of present-day values in the 21st century, even in the context of high-end emissions scenarios (4×CO 2 or RCP8.5) | medium | 1 | train |
1,469 | AR6_WGI | 1,260 | 10 | Change in upper-ocean stratification (Section 9.2.1.3) is projected to increase confinement of upwelling vertical velocities to near the ocean surface | high | 2 | train |
1,470 | AR6_WGI | 1,260 | 11 | The California Current system has experienced some upwelling-favourable wind intensification since the 1980s | high | 2 | test |
1,471 | AR6_WGI | 1,260 | 13 | New evidence reinforces our confidence in SROCC assessment that, under increased radiative forcing, EBUS winds will change with a dipole spatial pattern within each EBUS of reduction (weaker and/or shorter) at low latitude, and enhancement (stronger and/or longer) at high latitude | high | 2 | train |
1,472 | AR6_WGI | 1,261 | 19 | Thus, while conversions between OHC, mean ocean temperature and GMTSL across applications are within uncertainty ranges | medium | 1 | train |
1,473 | AR6_WGI | 1,263 | 3 | Patterns of change are consistent between model simulations and observations | medium | 1 | train |
1,474 | AR6_WGI | 1,263 | 15 | Projections of dynamic sea level variability require fully three-dimensional ocean models, and only high-resolution ocean models are statistically consistent on short time scales with satellite altimeter observations | very high | 3 | train |
1,475 | AR6_WGI | 1,263 | 17 | The SROCC (Meredith et al., 2019) assesses that sea ice extent, which is the total area of all grid cells with at least 15% sea ice concentration, has declined since 1979 in each month of the year | very high | 3 | train |
1,476 | AR6_WGI | 1,263 | 21 | Sea ice area has decreased in every month of the year from 1979 to the present | very high | 3 | train |
1,477 | AR6_WGI | 1,263 | 22 | The absolute and the relative ice losses are highest in late summer-early autumn | high | 2 | train |
1,478 | AR6_WGI | 1,263 | 23 | Averaged over the decade 2010–2019, the monthly Arctic sea ice area from August to October has been around 2 million km² (or about 25%) smaller than during 1979–1988 | high | 2 | train |
1,479 | AR6_WGI | 1,263 | 26 | In the Bering Sea, expanding winter sea ice cover was observed until 2017 (Frey et al., 2015; Onarheim et al., 2018; Peng and Meier, 2018), but a marked reduction in sea ice concentration has occurred since then | high | 2 | train |
1,480 | AR6_WGI | 1,264 | 7 | Since 1953, the years 2015 to 2018 had the four lowest values of maximum Arctic sea ice area, which usually occurs in March | high | 2 | train |
1,481 | AR6_WGI | 1,264 | 11 | These records and other proposed paleo proxies, including bromine in ice cores (Spolaor et al., 2016), dinocyst assemblages (e.g., De Vernal et al., 2013b) and driftwood (e.g., Funder et al., 2011), provide evidence of sea ice fluctuations that exceed internal variability | high | 2 | train |
1,482 | AR6_WGI | 1,265 | 2 | The SROCC assessed that approximately half of the satellite-observed Arctic summer sea ice loss is driven by increased concentrations of atmospheric greenhouse gases | medium | 1 | train |
1,483 | AR6_WGI | 1,265 | 10 | In addition to changes in the external forcing, internal variability substantially affects Arctic sea ice, evidenced from both paleorecords (e.g., Chan et al., 2017; Hörner et al., 2017; Kolling et al., 2018) and satellites after 1979 (e.g., Notz and Stroeve, 2018; Roberts et al., 2020) | high | 2 | train |
1,484 | AR6_WGI | 1,265 | 20 | In examining temperature thresholds for the loss of Arctic summer sea ice, the Special Report on Global Warming of 1.5°C (SR1.5; Hoegh-Guldberg et al., 2018) and SROCC assess that a reduction of September mean sea ice area to below 1 million km2, practically a sea ice-free Arctic Ocean, is more probable for a global mean warming of 2°C compared to global mean warming of 1.5°C | high | 2 | train |
1,485 | AR6_WGI | 1,265 | 22 | Quantitatively, existing studies (Screen and Williamson, 2017; Jahn, 2018; Ridley and Blockley, 2018; Sigmond et al., 2018; Notz and SIMIP Community, 2020) also show that, for a warming between 1.5 and 2°C, the Arctic will only be practically sea ice free in September in some years, while at 3°C warming, the Arctic is practically sea ice free in September in most years, with longer practically sea ice-free periods at higher warming levels | medium | 1 | train |
1,486 | AR6_WGI | 1,267 | 8 | In addition, there is no tipping point or critical threshold in global mean temperature beyond which the loss of summer sea ice becomes self-accelerating and irreversible | high | 2 | train |
1,487 | AR6_WGI | 1,267 | 11 | The loss of winter sea ice is reversible as well, but the loss of winter sea ice area per degree of warming in CMIP5 and CMIP6 projections increases as the ice retreats from the continental shore lines, because these limit the possible areal fluctuations | high | 2 | train |
1,488 | AR6_WGI | 1,267 | 29 | As assessed by SROCC, the evolution of mean Antarctic sea ice area is the result of opposing regional trends | high | 2 | train |
1,489 | AR6_WGI | 1,268 | 5 | The changes in stratification result partly from surface freshening (De Lavergne et al., 2014), associated with increased northward sea ice advection (Haumann et al., 2020) and/or melting of the Antarctic ice sheet | medium | 1 | test |
1,490 | AR6_WGI | 1,268 | 6 | In the Amundsen Sea, strong ice shelf melting can cause local sea ice melt next to the ice shelf front by entraining warm circumpolar deep water to the ice shelf cavity and surface ocean | medium | 1 | train |
1,491 | AR6_WGI | 1,269 | 14 | Paleo-proxy data indicate that, on multi-decadal to multi-centennial time scales, sea ice coverage of the Southern Ocean follows large-scale temperature trends (e.g., Crosta et al., 2018; Chadwick et al., 2020; Lamping et al., 2020), for example linked to fluctuations in the El Niño–Southern Oscillation and Southern Annular Mode (Crosta et al., 2021), and that during the Last Glacial Maximum, Antarctic sea ice extended to about the polar front latitude in most regions during winter, whereas the extent during summer is less well understood (e.g., Benz et al., 2016; Xiao et al., 2016; Nair et al., 2019).Regionally, proxy data from ice cores consistently indicate that the increase of sea ice area in the Ross Sea and the decrease of sea ice area in the Bellingshausen Sea are part of longer centennial trends and exceed internal variability on multi-decadal time scales | medium | 1 | train |
1,492 | AR6_WGI | 1,269 | 25 | Data from ICESat-1 laser altimetry (Kurtz and Markus, 2012), from Operation IceBridge (Kwok and Kacimi, 2018), and long-term shipboard observations collected in the Antarctic Sea Ice Processes and Climate (ASPeCt) dataset (Worby et al., 2008) suggest that sea ice thicker than 1 m prevails in regions of multi-year ice along the eastern coast of the Antarctic Peninsula in the Weddell Sea, in the high-latitude embayment of the Weddell Sea, and along the coast of the Amundsen Sea, with remaining regions dominated by thinner first-year sea ice | high | 2 | train |
1,493 | AR6_WGI | 1,272 | 6 | In summary, the detailed regional records show an increase in mass loss in all regions after the 1980s, caused by both increases in discharge and decreases in SMB | high | 2 | train |
1,494 | AR6_WGI | 1,272 | 7 | The largest mass loss occurred in the north-west and the south-east of Greenland | high | 2 | train |
1,495 | AR6_WGI | 1,276 | 1 | The SROCC stated that surface processes, rather than ice discharged into the ocean, will dominate Greenland ice loss over the 21st century, regardless of the emissions scenario | high | 2 | train |
1,496 | AR6_WGI | 1,276 | 3 | The projected mass loss of Greenland is predominantly due to increased surface meltwater and loss in refreezing capacity resulting in decreasing SMB | high | 2 | train |
1,497 | AR6_WGI | 1,277 | 22 | The SROCC adopted the AR5 assessment that complete loss of Greenland ice, contributing about 7 m to sea level, over a millennium or more would occur for a sustained global mean surface temperature (GMST) between 1°C (low confidence) and 4°C | medium | 1 | train |
1,498 | AR6_WGI | 1,279 | 5 | Mass loss of the West Antarctic and Antarctic Peninsula ice sheets has increased since about 2000 | very high | 3 | train |
1,499 | AR6_WGI | 1,279 | 11 | In summary, WAIS losses, through acceleration, retreat and thinning of the principal outlet glaciers, dominated the AIS mass losses over the last decades | very high | 3 | train |
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