rlacombe/ClimateX · Datasets at Hugging Face

statement_idx int64 0 8.09k	report stringclasses 3 values	page_num int64 18 2.84k	sent_num int64 0 78	statement stringlengths 13 4.29k	confidence stringclasses 4 values	score int64 0 3	split stringclasses 2 values
300	AR6_WGI	119	21	In SSP5-8.5, a scenario without climate change mitigation but with stringent air pollution control, PM levels decline through 2100, but high CH 4 levels hamper the decline in global surface ozone at least until 2080	high	2	train
301	AR6_WGI	120	11	These investigations have consistently shown that SRM could offset some of the effects of increasing greenhouse gases on global and regional climate, including the carbon and water cycles	high	2	train
302	AR6_WGI	120	12	However, there would be substantial residual or overcompensating climate change at the regional scales and seasonal time scales	high	2	train
303	AR6_WGI	120	13	The cooling caused by SRM would increase the global land and ocean CO 2 sinks (medium confidence), but this would not stop CO 2 from increasing in the atmosphere or affect the resulting ocean acidification under continued anthropogenic emissions	high	2	train
304	AR6_WGI	120	15	A sudden and sustained termination of SRM in a high CO 2 emissions scenario would cause rapid climate change	high	2	train
305	AR6_WGI	120	16	However, a gradual phase-out of SRM combined with emissions reduction and carbon dioxide removal (CDR) would avoid these termination effects	medium	1	train
306	AR6_WGI	121	10	Since AR5, more modelling work has been conducted with more sophisticated treatment of aerosol-based SRM approaches, but the uncertainties in cloud–aerosol–radiation interactions are still large	high	2	train
307	AR6_WGI	121	11	Modelling studies suggest that it is possible to stabilize multiple large-scale temperature indicators simultaneously by tailoring the deployment strategy of SRM options	medium	1	train
308	AR6_WGI	121	13	In contrast, cirrus cloud thinning, targeting longwave radiation, is expected to cause an increase in global mean precipitation	medium	1	train
309	AR6_WGI	121	14	If shortwave approaches are used to offset global mean warming, the magnitude of reduction in regional precipitation minus evapotranspiration (P–E) (Box TS.5), which is more relevant to freshwater availability, is smaller than precipitation decrease because of simultaneous reductions in both precipitation and evapotranspiration	medium	1	train
310	AR6_WGI	121	16	If SRM is used to cool the planet, it would cause a reduction in plant and soil respiration and slow the reduction of ocean carbon uptake due to warming	medium	1	train
311	AR6_WGI	121	17	The result would be an enhancement of the global land and ocean CO 2 sinks	medium	1	train
312	AR6_WGI	121	18	However, SRM would not stop CO 2 from increasing in the atmosphere or affect the resulting ocean acidification under continued anthropogenic emissions	high	2	train
313	AR6_WGI	121	20	A sudden and sustained termination of SRM in a high GHG emissions scenario would cause rapid climate change and a reversal of the SRM effects on the carbon sinks	high	2	train
314	AR6_WGI	121	23	However, a gradual phase-out of SRM combined with emissions reductions and CDR would avoid larger rates of changes	medium	1	train
315	AR6_WGI	122	4	For global climate indicators, evidence for abrupt change is limited, but deep ocean warming, acidification and sea level rise are committed to ongoing change for millennia after global surface temperatures initially stabilize and are irreversible on human time scales	very high	3	train
316	AR6_WGI	122	5	At the regional scale, abrupt responses, tipping points and even reversals in the direction of change cannot be excluded	high	2	train
317	AR6_WGI	122	10	Some processes suspected of having tipping points, such as the Atlantic Meridional Overturning Circulation (AMOC), have been found to often undergo recovery after temperature stabilization with a time delay	low	0	train
318	AR6_WGI	122	13	It is likely that under stabilization of global warming at 1.5°C, 2.0°C or 3.0°C relative to 1850–1900, the AMOC will continue to weaken for several decades by about 15%, 20% and 30% of its strength and then recover to pre-decline values over several centuries	medium	1	train
319	AR6_WGI	122	14	At sustained warming levels between 2°C and 3°C, there is limited evidence that the Greenland and West Antarctic ice sheets will be lost almost completely and irreversibly over multiple millennia; both the probability of their complete loss and the rate of mass loss increases with higher surface temperatures	high	2	train
320	AR6_WGI	122	15	At sustained warming levels between 3°C and 5°C, near-complete loss of the Greenland Ice Sheet and complete loss of the West Antarctic Ice Sheet is projected to occur irreversibly over multiple millennia (medium confidence); with substantial parts or all of Wilkes Subglacial Basin in East Antarctica lost over multiple millennia	low	0	train
321	AR6_WGI	122	17	For other hazards (e.g., ice-sheet behaviour, glacier mass loss and global mean sea level change, coastal floods, coastal erosion, air pollution, and ocean acidification) the time and/or scenario dimensions remain critical, and a simple and robust relationship with global warming level cannot be established	high	2	train
322	AR6_WGI	122	19	For global warming up to 2°C above 1850–1900 levels, paleoclimate records do not indicate abrupt changes in the carbon cycle	low	0	test
323	AR6_WGI	122	20	Despite the wide range of model responses, uncertainty in atmospheric CO 2 by 2100 is dominated by future anthropogenic emissions rather than uncertainties related to carbon–climate feedbacks	high	2	train
324	AR6_WGI	122	22	The increase in global ocean heat content (Section TS.2.4) will likely continue until at least 2300 even for low emissions scenarios, and global mean sea level will continue to rise for centuries to millennia following cessation of emissions (Box TS.4) due to continuing deep ocean heat uptake and mass loss of the Greenland and Antarctic ice sheets	high	2	train
325	AR6_WGI	123	2	Possible abrupt changes and tipping points in biogeochemical cycles lead to additional uncertainty in 21st century atmospheric GHG concentrations, but future anthropogenic emissions remain the dominant uncertainty	high	2	train
326	AR6_WGI	123	5	Continued Amazon deforestation, combined with a warming climate, raises the probability that this ecosystem will cross a tipping point into a dry state during the 21st century	low	0	train
327	AR6_WGI	123	11	A key methodology is distillation – combining lines of evidence and accounting for stakeholder context and values – which helps ensure the information is relevant, useful and trusted for decision-making (see Core Concepts Box)	high	2	train
328	AR6_WGI	123	14	Since AR5, climate change information produced for climate services has increased significantly due to scientific and technological advancements and growing user awareness, requirements, and demand	very high	3	train
329	AR6_WGI	123	20	Discarding models that fundamentally misrepresent relevant processes improves the credibility of regional climate information generated from these ensembles	high	2	train
330	AR6_WGI	123	21	However, multi-model mean and ensemble spread are not a full measure of the range of projection uncertainty and are not sufficient to characterize low-likelihood, high-impact changes (Box TS.3) or situations where different models simulate substantially different or even opposite changes	high	2	train
331	AR6_WGI	123	22	Large single-model ensembles are now available and provide a more comprehensive spectrum of possible changes associated with internal variability	high	2	train
332	AR6_WGI	124	14	No-till farming, irrigation and crop expansion have similarly attenuated increases in summer hot extremes in some regions, such as central North America	medium	1	train
333	AR6_WGI	124	22	In some cases, even the sign of a projected change in regional climate cannot be trusted if relevant regional processes are not represented, for example, for variables such as precipitation and wind speed	medium	1	train
334	AR6_WGI	124	25	However, the performance of these techniques depends on that of the driving climate model: in particular, bias adjustment cannot overcome all consequences of unresolved or strongly misrepresented physical processes, such as large-scale circulation biases or local feedbacks	medium	1	train
335	AR6_WGI	126	18	Distilling regional climate information from multiple lines of evidence and taking the user context into account increases fitness, usefulness, relevance and trust in that information for use in climate services (Box TS.11) and decision-making	high	2	train
336	AR6_WGI	127	1	Since AR5, there has been a significant increase in the range and diversity of climate service activities	very high	3	train
337	AR6_WGI	127	6	Since AR5, climate change information produced in climate service contexts has increased significantly due to scientific and technological advancements and growing user awareness, requirements and demand	very high	3	train
338	AR6_WGI	127	9	They require different types of user–producer engagement depending on what the service aims to deliver	high	2	train
339	AR6_WGI	127	10	Realization of the full potential of climate services is often hindered by limited resources for the co-design and co-production process, including sustained engagement between scientists, service providers and users	high	2	train
340	AR6_WGI	129	2	An exception is the Southern Annular Mode (SAM), which has become systematically more positive (high confidence) and is projected to be more positive in all seasons, except for December–January–February (DJF), in high CO 2 emissions scenarios	high	2	train
341	AR6_WGI	129	3	The influence of stratospheric ozone forcing on the SAM trend has been reduced since the early 2000s compared to earlier decades, contributing to the weakening of its positive trend as observed over 2000– 2019	medium	1	train
342	AR6_WGI	129	10	Along latitudes, it is more uniform, with strong amplification of the temperature response towards the Arctic	medium	1	train
343	AR6_WGI	129	11	The decrease of SO 2 emissions since the 1980s reduces the damping effect of aerosols, leading to a faster increase in surface air temperature that is most pronounced at mid- and high latitudes of the Northern Hemisphere, where the largest emissions reductions have taken place	medium	1	train
344	AR6_WGI	129	13	Multi-decadal variation in anthropogenic aerosol emissions are thought to be a major contributor	medium	1	train
345	AR6_WGI	129	16	Future urbanization will amplify the projected air temperature under different background climates, with a strong effect on minimum temperatures that could be as large as the global warming signal	very high	3	train
346	AR6_WGI	129	17	Irrigation and crop expansion have attenuated increases in summer hot extremes in some regions, such as central North America	medium	1	train
347	AR6_WGI	130	2	The influence of stratospheric ozone forcing on the SAM trend has been reduced since the early 2000s compared to earlier decades, contributing to the weakening of its positive trend observed over 2000–2019	medium	1	train
348	AR6_WGI	130	6	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
349	AR6_WGI	130	12	There is no consensus from models for a systematic change in amplitude of ENSO sea surface temperature (SST) variability over the 21st century in any of the SSP scenarios assessed	medium	1	train
350	AR6_WGI	130	17	Internal variability is the main driver of Pacific Decadal Variability (PDV) observed since the start of the instrumental records	high	2	train
351	AR6_WGI	133	2	Multiple lines of evidence, combining multi-model ensemble global projections with those coming from single-model initial-condition large ensembles, show that internal variability is largely contributing to the delayed or absent emergence of the anthropogenic signal in long-term regional mean precipitation changes	high	2	train
352	AR6_WGI	133	3	Internal variability in ocean dynamics dominates regional patterns on annual to decadal time scales	high	2	train
353	AR6_WGI	133	4	The anthropogenic signal in regional sea level change will emerge in most regions by 2100	medium	1	train
354	AR6_WGI	133	6	Time evolution of mechanisms operating at different time scales can modify the amplitude of the regional-scale response of temperature, and both the amplitude and sign of the response of precipitation, to anthropogenic forcing	high	2	train
355	AR6_WGI	133	8	Land-use and aerosol forcings and land–atmosphere feedback play important roles in modulating regional changes, for instance in weather and climate extremes	high	2	train
356	AR6_WGI	134	8	Multi-model mean and ensemble spread are not sufficient to characterize situations where different models simulate substantially different or even opposite changes	high	2	train
357	AR6_WGI	134	10	In addition, single-model initial-condition large ensembles of many realizations of internal variability are required to separate internal variability from forced changes	high	2	train
358	AR6_WGI	134	12	Northern Hemispheric anthropogenic aerosols weakened the regional monsoon circulations in South Asia, East Asia and West Africa during the second half of the 20th century, thereby offsetting the expected strengthening of monsoon precipitation in response to GHG-induced warming	high	2	train
359	AR6_WGI	134	13	During the 21st century, global land monsoon precipitation is projected to increase in response to GHG warming in all time horizons and scenarios	high	2	train
360	AR6_WGI	134	14	Over South and South East Asia, East Asia and the central Sahel, monsoon precipitation is projected to increase, whereas over North America and the far western Sahel it is projected to decrease	medium	1	train
361	AR6_WGI	134	16	At global and regional scales, near-term monsoon changes will be dominated by the effects of internal variability	medium	1	test
362	AR6_WGI	134	19	Contrary to the expected increase of precipitation under global warming, the Northern Hemisphere monsoon regions experienced declining precipitation from the 1950s to 1980s, which is partly attributable to the influence of anthropogenic aerosols	medium	1	train
363	AR6_WGI	134	21	A slowdown of the tropical circulation with global warming can partly offset the warming-induced strengthening of precipitation in monsoon regions	high	2	train
364	AR6_WGI	134	22	In the near term, global monsoon changes are likely to be dominated by the effects of internal variability and model uncertainties	medium	1	train
365	AR6_WGI	134	23	In the long term, global monsoon rainfall change will feature a robust north–south asymmetry characterized by a greater increase in the Northern Hemisphere than in the Southern Hemisphere and an east–west asymmetry characterized by enhanced Asian– African monsoons and a weakened North American monsoon	medium	1	train
366	AR6_WGI	136	2	The recent partial recovery and enhanced intensity of monsoon precipitation over West Africa is related to the growing influence of GHGs with an additional contribution due to the reduced cooling effect of anthropogenic aerosols, emitted largely from North America and Europe	medium	1	train
367	AR6_WGI	136	5	The annual contrast between the wettest and driest month of the year is likely to increase by 3–5% per degree Celsius in most monsoon regions in terms of precipitation, precipitation minus evaporation, and runoff	medium	1	train
368	AR6_WGI	136	6	For the North American monsoon, projections indicate a decrease in precipitation, whereas increased monsoon rainfall is projected over South and South East Asia and over East Asia	medium	1	train
369	AR6_WGI	136	7	West African monsoon precipitation is projected to increase over the central Sahel and decrease over the far western Sahel	medium	1	train
370	AR6_WGI	136	12	A collapse of the Atlantic Meridional Overturning Circulation could weaken the African and Asian monsoons but strengthen the Southern Hemisphere monsoons	high	2	train
371	AR6_WGI	136	16	It is very likely that mean temperatures have increased in all land regions and will continue to increase at rates greater than the global average	high	2	test
372	AR6_WGI	136	18	These changes are attributed to human influence in almost all regions (medium to high confidence) and will continue through the 21st century	high	2	train
373	AR6_WGI	136	19	In particular, extreme heat would exceed critical thresholds for health, agriculture and other sectors more frequently by the mid 21st century with 2°C of global warming	high	2	train
374	AR6_WGI	136	20	Relative sea level rise is very likely to virtually certain (depending on the region) to continue during the 21st century, contributing to increased coastal flooding in low- lying areas (high confidence) and coastal erosion along most sandy coasts	high	2	train
375	AR6_WGI	136	21	Sea level will continue to rise beyond 2100	high	2	train
376	AR6_WGI	136	22	Every region of the world will experience concurrent changes in multiple CIDs by mid-century or at 2°C global warming and above	high	2	train
377	AR6_WGI	137	2	Changes in many other regional CIDs have higher confidence later in the 21st century or at higher GWLs	high	2	train
378	AR6_WGI	148	18	In tropical regions, recent past temperature distributions have already shifted to a range different to that of the early 20th century	high	2	train
379	AR6_WGI	148	20	On regional-to-continental scales, trends of increased frequency of hot extremes and decreased frequency of cold extremes are generally consistent with the global-scale trends in mean temperature	high	2	train
380	AR6_WGI	148	26	At increasing warming levels, extreme heat will exceed critical thresholds for health, agriculture and other sectors more frequently	high	2	train
381	AR6_WGI	148	27	For example, by the end of the 21st century, dangerous humid heat thresholds, such as the National Oceanic and Atmospheric Administration (NOAA) heat index (HI) threshold of 41°C, will be exceeded much more frequently under the SSP5-8.5 scenario than under SSP1-2.6 and will affect many regions	high	2	train
382	AR6_WGI	148	28	In many tropical regions, the number of days per year where a heat index of 41°C is exceeded would increase by more than 100 days relative to the recent past under SSP5-8.5, while this increase will be limited to less than 50 days under SSP1-2.6	high	2	train
383	AR6_WGI	148	29	The number of days per year where temperature exceeds 35°C would increase by more than 150 days in many tropical areas, such as the Amazon basin and South East Asia, by the end of century for the SSP5-8.5 scenario, while it is expected to increase by less than 60 days in these areas under SSP1-2.6 (except for the Amazon Basin)	high	2	train
384	AR6_WGI	148	31	However, GHG forcing has driven increased contrasts in precipitation amounts between wet and dry seasons and weather regimes over tropical land areas (medium confidence), with a detectable precipitation increase in the northern high latitudes	high	2	train
385	AR6_WGI	148	32	The frequency and intensity of heavy precipitation events have increased over a majority of land regions with good observational coverage	high	2	train
386	AR6_WGI	148	33	A majority of land areas have experienced decreases in available water in dry seasons due to human-induced climate change associated with changes in evapotranspiration	medium	1	train
387	AR6_WGI	148	34	Global hydrological models project a larger fraction of land areas to be affected by an increase rather than by a decrease in river floods	medium	1	train
388	AR6_WGI	148	35	Extreme precipitation and pluvial flooding will increase in many regions around the world on almost all continents	high	2	train
389	AR6_WGI	148	38	The proportion of intense TCs, average peak TC wind speeds, and peak wind speeds of the most intense TCs will increase on the global scale with increasing global warming	high	2	train
390	AR6_WGI	150	17	Glaciers will continue to shrink and permafrost to thaw in all regions where they are present	high	2	train
391	AR6_WGI	150	22	Regional sea level change has been the main driver of changes in extreme sea levels across the quasi-global tide gauge network over the 20th century	high	2	train
392	AR6_WGI	150	23	With the exception of a few regions with substantial land uplift, relative sea level rise is very likely to virtually certain (depending on the region) to continue during the 21st century, contributing to increased coastal flooding in low-lying areas (high confidence) and coastal erosion along most sandy coasts	high	2	train
393	AR6_WGI	150	24	In the open ocean, acidification, changes in sea ice, and deoxygenation have already emerged in many areas	high	2	train
394	AR6_WGI	150	25	Marine heatwaves are also expected to increase around the globe over the 21st century	high	2	train
395	AR6_WGI	151	3	The probability of compound events has increased in the past due to human-induced climate change and will likely continue to increase with further global warming, including for concurrent heatwaves and droughts, compound flooding, and the possibility of connected sectors experiencing multiple regional extreme events at the same time (for example, in multiple breadbaskets)	high	2	train
396	AR6_WGI	151	6	In a number of regions (Southern Africa, the Mediterranean, North Central America, Western North America, the Amazon regions, South-Western South America, and Australia), increases in one or more of drought, aridity and fire weather	high	2	train
397	AR6_WGI	151	7	In another group of regions (North-Western, Central and Eastern North America, Arctic regions, North- Western South America, Northern, Western and Central and Eastern Europe, Siberia, Central, South and East Asia, Southern Australia and New Zealand), decreases in snow and/or ice or increases in pluvial/river flooding	high	2	train
398	AR6_WGI	151	9	Increases in heavy precipitation that can lead to pluvial floods	high	2	train
399	AR6_WGI	151	13	North Eastern Africa, East Southern Africa and Central Africa have experienced a decline in rainfall since about 1980 and parts of West Africa an increase	high	2	train

300

AR6_WGI

119

21

In SSP5-8.5, a scenario without climate change mitigation but with stringent air pollution control, PM levels decline through 2100, but high CH 4 levels hamper the decline in global surface ozone at least until 2080

high

2

train

301

AR6_WGI

120

11

These investigations have consistently shown that SRM could offset some of the effects of increasing greenhouse gases on global and regional climate, including the carbon and water cycles

high

2

train

302

AR6_WGI

120

12

However, there would be substantial residual or overcompensating climate change at the regional scales and seasonal time scales

high

2

train

303

AR6_WGI

120

13

The cooling caused by SRM would increase the global land and ocean CO 2 sinks (medium confidence), but this would not stop CO 2 from increasing in the atmosphere or affect the resulting ocean acidification under continued anthropogenic emissions

high

2

train

304

AR6_WGI

120

15

A sudden and sustained termination of SRM in a high CO 2 emissions scenario would cause rapid climate change

high

2

train

305

AR6_WGI

120

16

However, a gradual phase-out of SRM combined with emissions reduction and carbon dioxide removal (CDR) would avoid these termination effects

medium

1

train

306

AR6_WGI

121

10

Since AR5, more modelling work has been conducted with more sophisticated treatment of aerosol-based SRM approaches, but the uncertainties in cloud–aerosol–radiation interactions are still large

high

2

train

307

AR6_WGI

121

11

Modelling studies suggest that it is possible to stabilize multiple large-scale temperature indicators simultaneously by tailoring the deployment strategy of SRM options

medium

1

train

308

AR6_WGI

121

13

In contrast, cirrus cloud thinning, targeting longwave radiation, is expected to cause an increase in global mean precipitation

medium

1

train

309

AR6_WGI

121

14

If shortwave approaches are used to offset global mean warming, the magnitude of reduction in regional precipitation minus evapotranspiration (P–E) (Box TS.5), which is more relevant to freshwater availability, is smaller than precipitation decrease because of simultaneous reductions in both precipitation and evapotranspiration

medium

1

train

310

AR6_WGI

121

16

If SRM is used to cool the planet, it would cause a reduction in plant and soil respiration and slow the reduction of ocean carbon uptake due to warming

medium

1

train

311

AR6_WGI

121

17

The result would be an enhancement of the global land and ocean CO 2 sinks

medium

1

train

312

AR6_WGI

121

18

However, SRM would not stop CO 2 from increasing in the atmosphere or affect the resulting ocean acidification under continued anthropogenic emissions

high

2

train

313

AR6_WGI

121

20

A sudden and sustained termination of SRM in a high GHG emissions scenario would cause rapid climate change and a reversal of the SRM effects on the carbon sinks

high

2

train

314

AR6_WGI

121

23

However, a gradual phase-out of SRM combined with emissions reductions and CDR would avoid larger rates of changes

medium

1

train

315

AR6_WGI

122

4

For global climate indicators, evidence for abrupt change is limited, but deep ocean warming, acidification and sea level rise are committed to ongoing change for millennia after global surface temperatures initially stabilize and are irreversible on human time scales

very high

3

train

316

AR6_WGI

122

5

At the regional scale, abrupt responses, tipping points and even reversals in the direction of change cannot be excluded

high

2

train

317

AR6_WGI

122

10

Some processes suspected of having tipping points, such as the Atlantic Meridional Overturning Circulation (AMOC), have been found to often undergo recovery after temperature stabilization with a time delay

low

0

train

318

AR6_WGI

122

13

It is likely that under stabilization of global warming at 1.5°C, 2.0°C or 3.0°C relative to 1850–1900, the AMOC will continue to weaken for several decades by about 15%, 20% and 30% of its strength and then recover to pre-decline values over several centuries

medium

1

train

319

AR6_WGI

122

14

At sustained warming levels between 2°C and 3°C, there is limited evidence that the Greenland and West Antarctic ice sheets will be lost almost completely and irreversibly over multiple millennia; both the probability of their complete loss and the rate of mass loss increases with higher surface temperatures

high

2

train

320

AR6_WGI

122

15

At sustained warming levels between 3°C and 5°C, near-complete loss of the Greenland Ice Sheet and complete loss of the West Antarctic Ice Sheet is projected to occur irreversibly over multiple millennia (medium confidence); with substantial parts or all of Wilkes Subglacial Basin in East Antarctica lost over multiple millennia

low

0

train

321

AR6_WGI

122

17

For other hazards (e.g., ice-sheet behaviour, glacier mass loss and global mean sea level change, coastal floods, coastal erosion, air pollution, and ocean acidification) the time and/or scenario dimensions remain critical, and a simple and robust relationship with global warming level cannot be established

high

2

train

322

AR6_WGI

122

19

For global warming up to 2°C above 1850–1900 levels, paleoclimate records do not indicate abrupt changes in the carbon cycle

low

0

test

323

AR6_WGI

122

20

Despite the wide range of model responses, uncertainty in atmospheric CO 2 by 2100 is dominated by future anthropogenic emissions rather than uncertainties related to carbon–climate feedbacks

high

2

train

324

AR6_WGI

122

22

The increase in global ocean heat content (Section TS.2.4) will likely continue until at least 2300 even for low emissions scenarios, and global mean sea level will continue to rise for centuries to millennia following cessation of emissions (Box TS.4) due to continuing deep ocean heat uptake and mass loss of the Greenland and Antarctic ice sheets

high

2

train

325

AR6_WGI

123

2

Possible abrupt changes and tipping points in biogeochemical cycles lead to additional uncertainty in 21st century atmospheric GHG concentrations, but future anthropogenic emissions remain the dominant uncertainty

high

2

train

326

AR6_WGI

123

5

Continued Amazon deforestation, combined with a warming climate, raises the probability that this ecosystem will cross a tipping point into a dry state during the 21st century

low

0

train

327

AR6_WGI

123

11

A key methodology is distillation – combining lines of evidence and accounting for stakeholder context and values – which helps ensure the information is relevant, useful and trusted for decision-making (see Core Concepts Box)

high

2

train

328

AR6_WGI

123

14

Since AR5, climate change information produced for climate services has increased significantly due to scientific and technological advancements and growing user awareness, requirements, and demand

very high

3

train

329

AR6_WGI

123

20

Discarding models that fundamentally misrepresent relevant processes improves the credibility of regional climate information generated from these ensembles

high

2

train

330

AR6_WGI

123

21

However, multi-model mean and ensemble spread are not a full measure of the range of projection uncertainty and are not sufficient to characterize low-likelihood, high-impact changes (Box TS.3) or situations where different models simulate substantially different or even opposite changes

high

2

train

331

AR6_WGI

123

22

Large single-model ensembles are now available and provide a more comprehensive spectrum of possible changes associated with internal variability

high

2

train

332

AR6_WGI

124

14

No-till farming, irrigation and crop expansion have similarly attenuated increases in summer hot extremes in some regions, such as central North America

medium

1

train

333

AR6_WGI

124

22

In some cases, even the sign of a projected change in regional climate cannot be trusted if relevant regional processes are not represented, for example, for variables such as precipitation and wind speed

medium

1

train

334

AR6_WGI

124

25

However, the performance of these techniques depends on that of the driving climate model: in particular, bias adjustment cannot overcome all consequences of unresolved or strongly misrepresented physical processes, such as large-scale circulation biases or local feedbacks

medium

1

train

335

AR6_WGI

126

18

Distilling regional climate information from multiple lines of evidence and taking the user context into account increases fitness, usefulness, relevance and trust in that information for use in climate services (Box TS.11) and decision-making

high

2

train

336

AR6_WGI

127

1

Since AR5, there has been a significant increase in the range and diversity of climate service activities

very high

3

train

337

AR6_WGI

127

6

Since AR5, climate change information produced in climate service contexts has increased significantly due to scientific and technological advancements and growing user awareness, requirements and demand

very high

3

train

338

AR6_WGI

127

9

They require different types of user–producer engagement depending on what the service aims to deliver

high

2

train

339

AR6_WGI

127

10

Realization of the full potential of climate services is often hindered by limited resources for the co-design and co-production process, including sustained engagement between scientists, service providers and users

high

2

train

340

AR6_WGI

129

2

An exception is the Southern Annular Mode (SAM), which has become systematically more positive (high confidence) and is projected to be more positive in all seasons, except for December–January–February (DJF), in high CO 2 emissions scenarios

high

2

train

341

AR6_WGI

129

3

The influence of stratospheric ozone forcing on the SAM trend has been reduced since the early 2000s compared to earlier decades, contributing to the weakening of its positive trend as observed over 2000– 2019

medium

1

train

342

AR6_WGI

129

10

Along latitudes, it is more uniform, with strong amplification of the temperature response towards the Arctic

medium

1

train

343

AR6_WGI

129

11

The decrease of SO 2 emissions since the 1980s reduces the damping effect of aerosols, leading to a faster increase in surface air temperature that is most pronounced at mid- and high latitudes of the Northern Hemisphere, where the largest emissions reductions have taken place

medium

1

train

344

AR6_WGI

129

13

Multi-decadal variation in anthropogenic aerosol emissions are thought to be a major contributor

medium

1

train

345

AR6_WGI

129

16

Future urbanization will amplify the projected air temperature under different background climates, with a strong effect on minimum temperatures that could be as large as the global warming signal

very high

3

train

346

AR6_WGI

129

17

Irrigation and crop expansion have attenuated increases in summer hot extremes in some regions, such as central North America

medium

1

train

347

AR6_WGI

130

2

The influence of stratospheric ozone forcing on the SAM trend has been reduced since the early 2000s compared to earlier decades, contributing to the weakening of its positive trend observed over 2000–2019

medium

1

train

348

AR6_WGI

130

6

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

349

AR6_WGI

130

12

There is no consensus from models for a systematic change in amplitude of ENSO sea surface temperature (SST) variability over the 21st century in any of the SSP scenarios assessed

medium

1

train

350

AR6_WGI

130

17

Internal variability is the main driver of Pacific Decadal Variability (PDV) observed since the start of the instrumental records

high

2

train

351

AR6_WGI

133

2

Multiple lines of evidence, combining multi-model ensemble global projections with those coming from single-model initial-condition large ensembles, show that internal variability is largely contributing to the delayed or absent emergence of the anthropogenic signal in long-term regional mean precipitation changes

high

2

train

352

AR6_WGI

133

3

Internal variability in ocean dynamics dominates regional patterns on annual to decadal time scales

high

2

train

353

AR6_WGI

133

4

The anthropogenic signal in regional sea level change will emerge in most regions by 2100

medium

1

train

354

AR6_WGI

133

6

Time evolution of mechanisms operating at different time scales can modify the amplitude of the regional-scale response of temperature, and both the amplitude and sign of the response of precipitation, to anthropogenic forcing

high

2

train

355

AR6_WGI

133

8

Land-use and aerosol forcings and land–atmosphere feedback play important roles in modulating regional changes, for instance in weather and climate extremes

high

2

train

356

AR6_WGI

134

8

Multi-model mean and ensemble spread are not sufficient to characterize situations where different models simulate substantially different or even opposite changes

high

2

train

357

AR6_WGI

134

10

In addition, single-model initial-condition large ensembles of many realizations of internal variability are required to separate internal variability from forced changes

high

2

train

358

AR6_WGI

134

12

Northern Hemispheric anthropogenic aerosols weakened the regional monsoon circulations in South Asia, East Asia and West Africa during the second half of the 20th century, thereby offsetting the expected strengthening of monsoon precipitation in response to GHG-induced warming

high

2

train

359

AR6_WGI

134

13

During the 21st century, global land monsoon precipitation is projected to increase in response to GHG warming in all time horizons and scenarios

high

2

train

360

AR6_WGI

134

14

Over South and South East Asia, East Asia and the central Sahel, monsoon precipitation is projected to increase, whereas over North America and the far western Sahel it is projected to decrease

medium

1

train

361

AR6_WGI

134

16

At global and regional scales, near-term monsoon changes will be dominated by the effects of internal variability

medium

1

test

362

AR6_WGI

134

19

Contrary to the expected increase of precipitation under global warming, the Northern Hemisphere monsoon regions experienced declining precipitation from the 1950s to 1980s, which is partly attributable to the influence of anthropogenic aerosols

medium

1

train

363

AR6_WGI

134

21

A slowdown of the tropical circulation with global warming can partly offset the warming-induced strengthening of precipitation in monsoon regions

high

2

train

364

AR6_WGI

134

22

In the near term, global monsoon changes are likely to be dominated by the effects of internal variability and model uncertainties

medium

1

train

365

AR6_WGI

134

23

In the long term, global monsoon rainfall change will feature a robust north–south asymmetry characterized by a greater increase in the Northern Hemisphere than in the Southern Hemisphere and an east–west asymmetry characterized by enhanced Asian– African monsoons and a weakened North American monsoon

medium

1

train

366

AR6_WGI

136

2

The recent partial recovery and enhanced intensity of monsoon precipitation over West Africa is related to the growing influence of GHGs with an additional contribution due to the reduced cooling effect of anthropogenic aerosols, emitted largely from North America and Europe

medium

1

train

367

AR6_WGI

136

5

The annual contrast between the wettest and driest month of the year is likely to increase by 3–5% per degree Celsius in most monsoon regions in terms of precipitation, precipitation minus evaporation, and runoff

medium

1

train

368

AR6_WGI

136

6

For the North American monsoon, projections indicate a decrease in precipitation, whereas increased monsoon rainfall is projected over South and South East Asia and over East Asia

medium

1

train

369

AR6_WGI

136

7

West African monsoon precipitation is projected to increase over the central Sahel and decrease over the far western Sahel

medium

1

train

370

AR6_WGI

136

12

A collapse of the Atlantic Meridional Overturning Circulation could weaken the African and Asian monsoons but strengthen the Southern Hemisphere monsoons

high

2

train

371

AR6_WGI

136

16

It is very likely that mean temperatures have increased in all land regions and will continue to increase at rates greater than the global average

high

2

test

372

AR6_WGI

136

18

These changes are attributed to human influence in almost all regions (medium to high confidence) and will continue through the 21st century

high

2

train

373

AR6_WGI

136

19

In particular, extreme heat would exceed critical thresholds for health, agriculture and other sectors more frequently by the mid 21st century with 2°C of global warming

high

2

train

374

AR6_WGI

136

20

Relative sea level rise is very likely to virtually certain (depending on the region) to continue during the 21st century, contributing to increased coastal flooding in low- lying areas (high confidence) and coastal erosion along most sandy coasts

high

2

train

375

AR6_WGI

136

21

Sea level will continue to rise beyond 2100

high

2

train

376

AR6_WGI

136

22

Every region of the world will experience concurrent changes in multiple CIDs by mid-century or at 2°C global warming and above

high

2

train

377

AR6_WGI

137

2

Changes in many other regional CIDs have higher confidence later in the 21st century or at higher GWLs

high

2

train

378

AR6_WGI

148

18

In tropical regions, recent past temperature distributions have already shifted to a range different to that of the early 20th century

high

2

train

379

AR6_WGI

148

20

On regional-to-continental scales, trends of increased frequency of hot extremes and decreased frequency of cold extremes are generally consistent with the global-scale trends in mean temperature

high

2

train

380

AR6_WGI

148

26

At increasing warming levels, extreme heat will exceed critical thresholds for health, agriculture and other sectors more frequently

high

2

train

381

AR6_WGI

148

27

For example, by the end of the 21st century, dangerous humid heat thresholds, such as the National Oceanic and Atmospheric Administration (NOAA) heat index (HI) threshold of 41°C, will be exceeded much more frequently under the SSP5-8.5 scenario than under SSP1-2.6 and will affect many regions

high

2

train

382

AR6_WGI

148

28

In many tropical regions, the number of days per year where a heat index of 41°C is exceeded would increase by more than 100 days relative to the recent past under SSP5-8.5, while this increase will be limited to less than 50 days under SSP1-2.6

high

2

train

383

AR6_WGI

148

29

The number of days per year where temperature exceeds 35°C would increase by more than 150 days in many tropical areas, such as the Amazon basin and South East Asia, by the end of century for the SSP5-8.5 scenario, while it is expected to increase by less than 60 days in these areas under SSP1-2.6 (except for the Amazon Basin)

high

2

train

384

AR6_WGI

148

31

However, GHG forcing has driven increased contrasts in precipitation amounts between wet and dry seasons and weather regimes over tropical land areas (medium confidence), with a detectable precipitation increase in the northern high latitudes

high

2

train

385

AR6_WGI

148

32

The frequency and intensity of heavy precipitation events have increased over a majority of land regions with good observational coverage

high

2

train

386

AR6_WGI

148

33

A majority of land areas have experienced decreases in available water in dry seasons due to human-induced climate change associated with changes in evapotranspiration

medium

1

train

387

AR6_WGI

148

34

Global hydrological models project a larger fraction of land areas to be affected by an increase rather than by a decrease in river floods

medium

1

train

388

AR6_WGI

148

35

Extreme precipitation and pluvial flooding will increase in many regions around the world on almost all continents

high

2

train

389

AR6_WGI

148

38

The proportion of intense TCs, average peak TC wind speeds, and peak wind speeds of the most intense TCs will increase on the global scale with increasing global warming

high

2

train

390

AR6_WGI

150

17

Glaciers will continue to shrink and permafrost to thaw in all regions where they are present

high

2

train

391

AR6_WGI

150

22

Regional sea level change has been the main driver of changes in extreme sea levels across the quasi-global tide gauge network over the 20th century

high

2

train

392

AR6_WGI

150

23

With the exception of a few regions with substantial land uplift, relative sea level rise is very likely to virtually certain (depending on the region) to continue during the 21st century, contributing to increased coastal flooding in low-lying areas (high confidence) and coastal erosion along most sandy coasts

high

2

train

393

AR6_WGI

150

24

In the open ocean, acidification, changes in sea ice, and deoxygenation have already emerged in many areas

high

2

train

394

AR6_WGI

150

25

Marine heatwaves are also expected to increase around the globe over the 21st century

high

2

train

395

AR6_WGI

151

3

The probability of compound events has increased in the past due to human-induced climate change and will likely continue to increase with further global warming, including for concurrent heatwaves and droughts, compound flooding, and the possibility of connected sectors experiencing multiple regional extreme events at the same time (for example, in multiple breadbaskets)

high

2

train

396

AR6_WGI

151

6

In a number of regions (Southern Africa, the Mediterranean, North Central America, Western North America, the Amazon regions, South-Western South America, and Australia), increases in one or more of drought, aridity and fire weather

high

2

train

397

AR6_WGI

151

7

In another group of regions (North-Western, Central and Eastern North America, Arctic regions, North- Western South America, Northern, Western and Central and Eastern Europe, Siberia, Central, South and East Asia, Southern Australia and New Zealand), decreases in snow and/or ice or increases in pluvial/river flooding

high

2

train

398

AR6_WGI

151

9

Increases in heavy precipitation that can lead to pluvial floods

high

2

train

399

AR6_WGI

151

13

North Eastern Africa, East Southern Africa and Central Africa have experienced a decline in rainfall since about 1980 and parts of West Africa an increase

high

2

train