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
200	AR6_WGI	95	19	However, over the 21st century, the majority of coastal locations have a median projected regional sea level rise within ±20% of the projected GMSL change	medium	1	train
201	AR6_WGI	95	23	Projections show that while land and ocean sinks absorb more CO 2 under high emissions scenarios than low emissions scenarios, the fraction of emissions removed from the atmosphere by natural sinks decreases with higher concentrations	high	2	train
202	AR6_WGI	96	6	The combustion of fossil fuels and land-use change for the period 1750–2019 resulted in the release of 700 ± 75 PgC (likely range, 1 PgC = 1015 g of carbon) to the atmosphere, of which about 41% ± 11% remains in the atmosphere today	high	2	train
203	AR6_WGI	96	9	During the last decade (2010–2019), average annual anthropogenic CO 2 emissions reached the highest levels in human history at 10.9 ± 0.9 PgC yr–1	high	2	train
204	AR6_WGI	96	10	Of these emissions, 46% accumulated in the atmosphere (5.1 ± 0.02 PgC yr–1), 23% (2.5 ± 0.6 PgC yr–1) was taken up by the ocean and 31% (3.4 ± 0.9 PgC yr–1) was removed by terrestrial ecosystems	high	2	train
205	AR6_WGI	96	12	This coherence between emissions and the growth in ocean and land sinks has resulted in the airborne fraction of anthropogenic CO 2 remaining at 44 ± 10% over the past 60 years	high	2	train
206	AR6_WGI	96	13	Interannual and decadal variability of the ocean and land sinks indicate that they are sensitive to changes in the growth rate of emissions as well as climate variability and are therefore also sensitive to climate change	high	2	train
207	AR6_WGI	96	15	Since the 1980s, carbon fertilization from rising atmospheric CO 2 has increased the strength of the net land CO 2 sink	medium	1	train
208	AR6_WGI	96	21	Carbon dioxide emissions-driven simulations account for uncertainty in these feedbacks, but do not significantly change the projected global surface temperature changes	high	2	train
209	AR6_WGI	96	22	Although land and ocean sinks absorb more CO 2 under high emissions than low emissions scenarios, the fraction of emissions removed from the atmosphere decreases	high	2	train
210	AR6_WGI	96	23	This means that the more CO 2 that is emitted, the less efficient the ocean and land sinks become	high	2	train
211	AR6_WGI	96	26	Under SSP3-7.0 and SSP5-8.5, the initial growth of both sinks in response to increasing atmospheric concentrations of CO 2 is subsequently limited by emerging carbon–climate feedbacks	high	2	train
212	AR6_WGI	96	30	Under SSP1-1.9, models project that combined land and ocean sinks will turn into a weak source by 2100	medium	1	train
213	AR6_WGI	98	18	The frequency and intensity of heavy precipitation events have increased over a majority of those land regions with good observational coverage	high	2	train
214	AR6_WGI	98	19	Over the past half century, key aspects of the biosphere have changed in ways that are consistent with large- scale warming: climate zones have shifted poleward, and the growing season length in the Northern Hemisphere extratropics has increased	high	2	train
215	AR6_WGI	98	20	The amplitude of the seasonal cycle of atmospheric CO 2 poleward of 45°N has increased since the 1960s (very high confidence), with increasing productivity of the land biosphere due to the increasing atmospheric CO 2 concentration as the main driver	medium	1	train
216	AR6_WGI	98	21	Global-scale vegetation greenness has increased since the 1980s	high	2	train
217	AR6_WGI	98	24	Warming of the land surface during the period 1971–2018 contributed about 5% of the increase in the global energy inventory (Section TS.3.1), nearly twice the estimate in AR5	high	2	train
218	AR6_WGI	98	26	The warming pattern will likely vary seasonally, with northern high latitudes warming more during winter than summer	medium	1	train
219	AR6_WGI	98	33	Human-induced climate change has contributed to increases in agricultural and ecological droughts in some regions due to increases in evapotranspiration	medium	1	train
220	AR6_WGI	100	3	Earlier onset of snowmelt has contributed to seasonally dependent changes in streamflow	high	2	train
221	AR6_WGI	100	9	The projected increase in heavy precipitation extremes translates to an increase in the frequency and magnitude of pluvial floods	high	2	train
222	AR6_WGI	100	11	Concurrent heatwaves and droughts have become more frequent over the last century, and this trend will continue with higher global warming	high	2	train
223	AR6_WGI	100	12	The probability of compound flooding (storm surge, extreme rainfall and/or river flow) has increased in some locations and will continue to increase due to both sea level rise and increases in heavy precipitation, including changes in precipitation intensity associated with tropical cyclones	high	2	train
224	AR6_WGI	100	14	At the same time an increase in the amplitude of the seasonal cycle of atmospheric CO 2 poleward of 45°N since the early 1960s (high confidence) and a global-scale increase in vegetation greenness of the terrestrial surface since the early 1980s	high	2	train
225	AR6_WGI	100	17	Reactive nitrogen, ozone and aerosols affect terrestrial vegetation and carbon cycle through deposition and effects on large-scale radiation	high	2	train
226	AR6_WGI	100	20	The SRCCL concluded that continued warming will exacerbate desertification processes (medium confidence) and that ecosystems will become increasingly exposed to climates beyond those that they are currently adapted to	high	2	train
227	AR6_WGI	100	23	There is low confidence in the magnitude of these changes, but the probability of crossing uncertain regional thresholds (e.g., fires, forest dieback) increases with further warming	high	2	train
228	AR6_WGI	100	24	The response of biogeochemical cycles to the anthropogenic perturbation can be abrupt at regional scales, and irreversible on decadal to century time scales	high	2	train
229	AR6_WGI	101	1	Global land precipitation has likely increased since 1950, with a faster increase since the 1980s	medium	1	train
230	AR6_WGI	101	3	Annual global land precipitation will increase over the 21st century as global surface temperature increases	high	2	train
231	AR6_WGI	101	4	Human influence has been detected in amplified surface salinity and precipitation minus evaporation (P–E) patterns over the ocean	high	2	train
232	AR6_WGI	101	5	The severity of very wet and very dry events increase in a warming climate	high	2	train
233	AR6_WGI	101	6	Water cycle variability and related extremes are projected to increase faster than mean changes in most regions of the world and under all emissions scenarios	high	2	test
234	AR6_WGI	101	7	Over the 21st century, the total land area subject to drought will increase and droughts will become more frequent and severe	high	2	train
235	AR6_WGI	101	8	Near-term projected changes in precipitation are uncertain mainly because of internal variability, model uncertainty and uncertainty in forcings from natural and anthropogenic aerosols	medium	1	train
236	AR6_WGI	101	9	Over the 21st century and beyond, abrupt human-caused changes to the water cycle cannot be excluded	medium	1	train
237	AR6_WGI	101	11	Global land precipitation has likely increased since 1950, with a faster increase since the 1980s	medium	1	test
238	AR6_WGI	101	13	The overall effect of anthropogenic aerosols is to reduce global precipitation through surface radiative cooling effects	high	2	train
239	AR6_WGI	101	14	Over much of the 20th century, opposing effects of GHGs and aerosols on precipitation have been observed for some regional monsoons	high	2	train
240	AR6_WGI	101	16	Inter-model differences and internal variability contribute to a substantial range in projections of large-scale and regional water cycle changes	high	2	train
241	AR6_WGI	101	17	The occurrence of volcanic eruptions can alter the water cycle for several years	high	2	train
242	AR6_WGI	101	20	Near-surface specific humidity has increased over the ocean (likely) and land (very likely) since at least the 1970s, with a detectable human influence	medium	1	train
243	AR6_WGI	101	21	Human influence has been detected in amplified surface salinity and precipitation minus evaporation (P–E) patterns over the ocean	high	2	train
244	AR6_WGI	101	24	In response to cryosphere changes (Section TS.2.5), there have been changes in streamflow seasonality, including an earlier occurrence of peak streamflow in high-latitude and mountain catchments	high	2	train
245	AR6_WGI	101	25	Projected runoff (Box TS.6, Figure 1c) is typically decreased by contributions from small glaciers because of glacier mass loss, while runoff from larger glaciers will generally increase with increasing global warming levels until their mass becomes depleted	high	2	train
246	AR6_WGI	102	1	Greater warming over land than over the ocean alters atmospheric circulation patterns and reduces continental near-surface relative humidity, which contributes to regional drying	high	2	train
247	AR6_WGI	102	3	Projected increases in evapotranspiration due to growing atmospheric water demand will decrease soil moisture over the Mediterranean region, south-western North America, South Africa, South-Western South America and south-western Australia	high	2	train
248	AR6_WGI	102	4	Some tropical regions are also projected to experience enhanced aridity, including the Amazon basin and Central America	high	2	train
249	AR6_WGI	102	5	The total land area subject to increasing drought frequency and severity will expand (high confidence), and in the Mediterranean, South-Western South America, and Western North America, future aridification will far exceed the magnitude of change seen in the last millennium	high	2	train
250	AR6_WGI	102	7	Large-scale deforestation likely decreases evapotranspiration and precipitation and increases runoff over the deforested regions relative to the regional effects of climate change	medium	1	train
251	AR6_WGI	102	8	Urbanization increases local precipitation (medium confidence) and runoff intensity	high	2	train
252	AR6_WGI	102	9	Increased precipitation intensities have enhanced groundwater recharge, most notably in tropical regions	medium	1	train
253	AR6_WGI	102	12	A warmer climate increases moisture transport into weather systems, which intensifies wet seasons and events	high	2	train
254	AR6_WGI	102	13	The magnitudes of projected precipitation increases and related extreme events depend on model resolution and the representation of convective processes	high	2	train
255	AR6_WGI	102	14	Increases in near-surface atmospheric moisture capacity of about 7% per 1ºC of warming lead to a similar response in the intensification of heavy precipitation from sub-daily up to seasonal time scales, increasing the severity of flood hazards	high	2	train
256	AR6_WGI	102	15	The average and maximum rain-rates associated with tropical and extratropical cyclones, atmospheric rivers and severe convective storms will therefore also increase with future warming	high	2	train
257	AR6_WGI	102	17	In the tropics year-round and in the summer season elsewhere, interannual variability of precipitation and runoff over land is projected to increase at a faster rate than changes in seasonal mean precipitation (Figure TS.12e,f)	medium	1	train
258	AR6_WGI	102	18	Sub-seasonal precipitation variability is also projected to increase, with fewer rainy days but increased daily mean precipitation intensity over many land regions	high	2	train
259	AR6_WGI	107	5	Improved quantifications of ERF, the climate system radiative response, and the observed energy increase in the Earth system for the period 1971–2018 demonstrate improved closure of the global energy budget (i.e., the extent to which the sum of the integrated forcing and the integrated radiative response equals the energy gain of the Earth system) compared to AR5	high	2	train
260	AR6_WGI	108	6	Changes in sulphur dioxide (SO 2) emissions make the dominant contribution to the ERF from aerosol– cloud interactions	high	2	train
261	AR6_WGI	108	7	Over the 1750–2019 period, the contributions from the emitted compounds to global surface temperature changes broadly match their contributions to the ERF	high	2	train
262	AR6_WGI	109	1	The ERF due to aerosol– cloud interactions (ERFaci) contributes most to the magnitude of the total aerosol ERF (high confidence) and is assessed to be –1.0 [–1.7 to –0.3] W m–2 (medium confidence), with the remainder due to aerosol–radiation interactions (ERFari), assessed to be –0.3 [–0.6 to 0.0] W m–2	medium	1	train
263	AR6_WGI	109	13	Feedback processes are expected to become more positive overall (more amplifying of global surface temperature changes) on multi-decadal time scales as the spatial pattern of surface warming evolves and global surface temperature increases, leading to an ECS that is higher than was inferred in AR5 based on warming over the instrumental record	high	2	train
264	AR6_WGI	109	15	Based on process understanding, climate modelling, and paleoclimate reconstructions of past warm periods, it is expected that future warming will become enhanced over the eastern Pacific Ocean (medium confidence) and Southern Ocean	high	2	train
265	AR6_WGI	109	21	There is a high level of agreement among the different lines of evidence (Figure TS.16c)	high	2	train
266	AR6_WGI	111	7	Because the total biogeophysical and non-CO 2 biogeochemical feedback is assessed to have a central value that is near zero	low	0	train
267	AR6_WGI	111	15	The CMIP5 and CMIP6 ranges of cloud feedback are similar to this assessed range, with CMIP6 having a slightly more positive median cloud feedback	high	2	train
268	AR6_WGI	113	7	This near-linear relationship further implies that mitigation requirements for limiting warming to specific levels can be quantified in terms of a carbon budget	high	2	train
269	AR6_WGI	113	9	Several factors, including estimates of historical warming, future emissions from thawing permafrost, variations in projected non-CO 2 warming, and the global surface temperature change after cessation of CO 2 emissions, affect the exact value of carbon budgets	high	2	train
270	AR6_WGI	115	14	In the same way that part of current anthropogenic net CO 2 emissions are taken up by land and ocean carbon stores, net CO 2 removal will be partially counteracted by CO 2 release from these stores	very high	3	train
271	AR6_WGI	115	15	Asymmetry in the carbon cycle response to simultaneous CO 2 emissions and removals implies that a larger amount of CO 2 would need to be removed to compensate for an emission of a given magnitude to attain the same change in atmospheric CO 2	medium	1	train
272	AR6_WGI	115	16	CDR methods have wide-ranging side- effects that can either weaken or strengthen the carbon sequestration and cooling potential of these methods and affect the achievement of sustainable development goals	high	2	train
273	AR6_WGI	115	25	In the same way part of current anthropogenic net CO 2 emissions are taken up by land and ocean carbon stores, net CO 2 removal will be partially counteracted by CO 2 release from these stores, such that the amount of CO 2 sequestered by CDR will not result in an equivalent drop in atmospheric CO 2	very high	3	train
274	AR6_WGI	115	26	The fraction of CO 2 removed from the atmosphere that is not replaced by CO 2 released from carbon stores – a measure of CDR effectiveness – decreases slightly with increasing amounts of removal (medium confidence) and decreases strongly if CDR is applied at lower atmospheric CO 2 concentrations	medium	1	train
275	AR6_WGI	115	27	The reduction in global surface temperature is approximately linearly related to cumulative CO 2 removal	high	2	train
276	AR6_WGI	115	28	Because of this near-linear relationship, the amount of cooling per unit CO 2 removed is approximately independent of the rate and amount of removal	medium	1	train
277	AR6_WGI	116	7	For instance, sea level rise due to ocean thermal expansion would not reverse for several centuries to millennia	high	2	train
278	AR6_WGI	116	9	Biophysical and biogeochemical side-effects of CDR methods are associated with changes in surface albedo, the water cycle, emissions of CH 4 and N 2O, ocean acidification and marine ecosystem productivity	high	2	train
279	AR6_WGI	116	10	These side-effects and associated Earth system feedbacks can decrease carbon uptake and/or change local and regional climate and in turn limit the CO 2 sequestration and cooling potential of specific CDR methods	medium	1	train
280	AR6_WGI	116	11	Deployment of CDR, particularly on land, can also affect water quality and quantity, food production and biodiversity	high	2	train
281	AR6_WGI	116	12	These effects are often highly dependent on local context, management regime, prior land use, and scale	high	2	train
282	AR6_WGI	116	13	The largest co-benefits are obtained with methods that seek to restore natural ecosystems or improve soil carbon sequestration	medium	1	test
283	AR6_WGI	116	14	The climate and biogeochemical effects of terminating CDR are expected to be small for most CDR methods	medium	1	train
284	AR6_WGI	117	2	Carbon-cycle responses are more robustly accounted for in emissions metrics compared to AR5	high	2	train
285	AR6_WGI	117	9	The methodology for doing this has been placed on a more robust scientific footing compared to AR5	high	2	train
286	AR6_WGI	117	10	Methane from fossil fuel sources has slightly higher emissions metric values than those from biogenic sources since it leads to additional fossil CO 2 in the atmosphere	high	2	train
287	AR6_WGI	117	11	Updates to the chemical adjustments for CH 4 and N2O emissions (Section TS.3.1) and revisions in their lifetimes result in emissions metrics for GWP and GTP that are slightly lower than in AR5	medium	1	train
288	AR6_WGI	117	15	When GHGs are aggregated using standard metrics such as GWP or GTP, cumulative CO 2-e emissions are not necessarily proportional to future global surface temperature outcomes	high	2	train
289	AR6_WGI	117	19	The warming evolution resulting from net zero GHG emissions defined in this way corresponds approximately to reaching net zero CO 2 emissions, and would thus not lead to declining temperatures after net zero GHG emissions are achieved but to an approximate temperature stabilization	high	2	train
290	AR6_WGI	117	20	The choice of emissions metric hence affects the quantification of net zero GHG emissions, and therefore the resulting temperature outcome of reaching and sustaining net zero GHG emissions levels	high	2	train
291	AR6_WGI	117	29	Fossil fuel combustion for energy, industry and land transportation are the largest contributing sectors on a 100-year time scale	high	2	train
292	AR6_WGI	117	30	Current emissions of CO 2, N2O and SLCFs from East Asia and North America are the largest regional contributors to additional net future warming on both short (medium confidence) and long time scales (10 and 100 years, respectively)	high	2	train
293	AR6_WGI	118	2	However, these reductions were lower than what would be expected from sustained implementation of policies addressing air quality and climate change	medium	1	train
294	AR6_WGI	118	4	Consistent with this small net radiative forcing, and against a large component of internal variability, Earth system models show no detectable effect on global or regional surface temperature or precipitation	high	2	train
295	AR6_WGI	119	2	This additional warming is stable after 2040 in SSPs associated with lower global air pollution as long as CH 4 emissions are also mitigated, but the overall warming induced by SLCF changes is higher in scenarios in which air quality continues to deteriorate (induced by growing fossil fuel use and limited air pollution control)	high	2	train
296	AR6_WGI	119	3	Sustained CH 4 mitigation reduces global surface ozone, contributing to air quality improvements, and also reduces surface temperature in the longer term, but only sustained CO 2 emissions reductions allow long-term climate stabilization	high	2	train
297	AR6_WGI	119	4	Future changes in air quality (near-surface ozone and particulate matter, or PM) at global and local scales are predominantly driven by changes in ozone and aerosol precursor emissions rather than climate	high	2	train
298	AR6_WGI	119	5	Air quality improvements driven by rapid decarbonization strategies, as in SSP1-1.9 and SSP1-2.6, are not sufficient in the near term to achieve air quality guidelines set by the World Health Organization in some highly polluted regions	high	2	train
299	AR6_WGI	119	20	Under the SSP3-7.0 scenario, PM levels are projected to increase until 2050 over large parts of Asia, and surface ozone pollution is projected to worsen over all continental areas through 2100	high	2	train

200

AR6_WGI

95

19

However, over the 21st century, the majority of coastal locations have a median projected regional sea level rise within ±20% of the projected GMSL change

medium

1

train

201

AR6_WGI

95

23

Projections show that while land and ocean sinks absorb more CO 2 under high emissions scenarios than low emissions scenarios, the fraction of emissions removed from the atmosphere by natural sinks decreases with higher concentrations

high

2

train

202

AR6_WGI

96

6

The combustion of fossil fuels and land-use change for the period 1750–2019 resulted in the release of 700 ± 75 PgC (likely range, 1 PgC = 1015 g of carbon) to the atmosphere, of which about 41% ± 11% remains in the atmosphere today

high

2

train

203

AR6_WGI

96

9

During the last decade (2010–2019), average annual anthropogenic CO 2 emissions reached the highest levels in human history at 10.9 ± 0.9 PgC yr–1

high

2

train

204

AR6_WGI

96

10

Of these emissions, 46% accumulated in the atmosphere (5.1 ± 0.02 PgC yr–1), 23% (2.5 ± 0.6 PgC yr–1) was taken up by the ocean and 31% (3.4 ± 0.9 PgC yr–1) was removed by terrestrial ecosystems

high

2

train

205

AR6_WGI

96

12

This coherence between emissions and the growth in ocean and land sinks has resulted in the airborne fraction of anthropogenic CO 2 remaining at 44 ± 10% over the past 60 years

high

2

train

206

AR6_WGI

96

13

Interannual and decadal variability of the ocean and land sinks indicate that they are sensitive to changes in the growth rate of emissions as well as climate variability and are therefore also sensitive to climate change

high

2

train

207

AR6_WGI

96

15

Since the 1980s, carbon fertilization from rising atmospheric CO 2 has increased the strength of the net land CO 2 sink

medium

1

train

208

AR6_WGI

96

21

Carbon dioxide emissions-driven simulations account for uncertainty in these feedbacks, but do not significantly change the projected global surface temperature changes

high

2

train

209

AR6_WGI

96

22

Although land and ocean sinks absorb more CO 2 under high emissions than low emissions scenarios, the fraction of emissions removed from the atmosphere decreases

high

2

train

210

AR6_WGI

96

23

This means that the more CO 2 that is emitted, the less efficient the ocean and land sinks become

high

2

train

211

AR6_WGI

96

26

Under SSP3-7.0 and SSP5-8.5, the initial growth of both sinks in response to increasing atmospheric concentrations of CO 2 is subsequently limited by emerging carbon–climate feedbacks

high

2

train

212

AR6_WGI

96

30

Under SSP1-1.9, models project that combined land and ocean sinks will turn into a weak source by 2100

medium

1

train

213

AR6_WGI

98

18

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

high

2

train

214

AR6_WGI

98

19

Over the past half century, key aspects of the biosphere have changed in ways that are consistent with large- scale warming: climate zones have shifted poleward, and the growing season length in the Northern Hemisphere extratropics has increased

high

2

train

215

AR6_WGI

98

20

The amplitude of the seasonal cycle of atmospheric CO 2 poleward of 45°N has increased since the 1960s (very high confidence), with increasing productivity of the land biosphere due to the increasing atmospheric CO 2 concentration as the main driver

medium

1

train

216

AR6_WGI

98

21

Global-scale vegetation greenness has increased since the 1980s

high

2

train

217

AR6_WGI

98

24

Warming of the land surface during the period 1971–2018 contributed about 5% of the increase in the global energy inventory (Section TS.3.1), nearly twice the estimate in AR5

high

2

train

218

AR6_WGI

98

26

The warming pattern will likely vary seasonally, with northern high latitudes warming more during winter than summer

medium

1

train

219

AR6_WGI

98

33

Human-induced climate change has contributed to increases in agricultural and ecological droughts in some regions due to increases in evapotranspiration

medium

1

train

220

AR6_WGI

100

3

Earlier onset of snowmelt has contributed to seasonally dependent changes in streamflow

high

2

train

221

AR6_WGI

100

9

The projected increase in heavy precipitation extremes translates to an increase in the frequency and magnitude of pluvial floods

high

2

train

222

AR6_WGI

100

11

Concurrent heatwaves and droughts have become more frequent over the last century, and this trend will continue with higher global warming

high

2

train

223

AR6_WGI

100

12

The probability of compound flooding (storm surge, extreme rainfall and/or river flow) has increased in some locations and will continue to increase due to both sea level rise and increases in heavy precipitation, including changes in precipitation intensity associated with tropical cyclones

high

2

train

224

AR6_WGI

100

14

At the same time an increase in the amplitude of the seasonal cycle of atmospheric CO 2 poleward of 45°N since the early 1960s (high confidence) and a global-scale increase in vegetation greenness of the terrestrial surface since the early 1980s

high

2

train

225

AR6_WGI

100

17

Reactive nitrogen, ozone and aerosols affect terrestrial vegetation and carbon cycle through deposition and effects on large-scale radiation

high

2

train

226

AR6_WGI

100

20

The SRCCL concluded that continued warming will exacerbate desertification processes (medium confidence) and that ecosystems will become increasingly exposed to climates beyond those that they are currently adapted to

high

2

train

227

AR6_WGI

100

23

There is low confidence in the magnitude of these changes, but the probability of crossing uncertain regional thresholds (e.g., fires, forest dieback) increases with further warming

high

2

train

228

AR6_WGI

100

24

The response of biogeochemical cycles to the anthropogenic perturbation can be abrupt at regional scales, and irreversible on decadal to century time scales

high

2

train

229

AR6_WGI

101

1

Global land precipitation has likely increased since 1950, with a faster increase since the 1980s

medium

1

train

230

AR6_WGI

101

3

Annual global land precipitation will increase over the 21st century as global surface temperature increases

high

2

train

231

AR6_WGI

101

4

Human influence has been detected in amplified surface salinity and precipitation minus evaporation (P–E) patterns over the ocean

high

2

train

232

AR6_WGI

101

5

The severity of very wet and very dry events increase in a warming climate

high

2

train

233

AR6_WGI

101

6

Water cycle variability and related extremes are projected to increase faster than mean changes in most regions of the world and under all emissions scenarios

high

2

test

234

AR6_WGI

101

7

Over the 21st century, the total land area subject to drought will increase and droughts will become more frequent and severe

high

2

train

235

AR6_WGI

101

8

Near-term projected changes in precipitation are uncertain mainly because of internal variability, model uncertainty and uncertainty in forcings from natural and anthropogenic aerosols

medium

1

train

236

AR6_WGI

101

9

Over the 21st century and beyond, abrupt human-caused changes to the water cycle cannot be excluded

medium

1

train

237

AR6_WGI

101

11

Global land precipitation has likely increased since 1950, with a faster increase since the 1980s

medium

1

test

238

AR6_WGI

101

13

The overall effect of anthropogenic aerosols is to reduce global precipitation through surface radiative cooling effects

high

2

train

239

AR6_WGI

101

14

Over much of the 20th century, opposing effects of GHGs and aerosols on precipitation have been observed for some regional monsoons

high

2

train

240

AR6_WGI

101

16

Inter-model differences and internal variability contribute to a substantial range in projections of large-scale and regional water cycle changes

high

2

train

241

AR6_WGI

101

17

The occurrence of volcanic eruptions can alter the water cycle for several years

high

2

train

242

AR6_WGI

101

20

Near-surface specific humidity has increased over the ocean (likely) and land (very likely) since at least the 1970s, with a detectable human influence

medium

1

train

243

AR6_WGI

101

21

Human influence has been detected in amplified surface salinity and precipitation minus evaporation (P–E) patterns over the ocean

high

2

train

244

AR6_WGI

101

24

In response to cryosphere changes (Section TS.2.5), there have been changes in streamflow seasonality, including an earlier occurrence of peak streamflow in high-latitude and mountain catchments

high

2

train

245

AR6_WGI

101

25

Projected runoff (Box TS.6, Figure 1c) is typically decreased by contributions from small glaciers because of glacier mass loss, while runoff from larger glaciers will generally increase with increasing global warming levels until their mass becomes depleted

high

2

train

246

AR6_WGI

102

1

Greater warming over land than over the ocean alters atmospheric circulation patterns and reduces continental near-surface relative humidity, which contributes to regional drying

high

2

train

247

AR6_WGI

102

3

Projected increases in evapotranspiration due to growing atmospheric water demand will decrease soil moisture over the Mediterranean region, south-western North America, South Africa, South-Western South America and south-western Australia

high

2

train

248

AR6_WGI

102

4

Some tropical regions are also projected to experience enhanced aridity, including the Amazon basin and Central America

high

2

train

249

AR6_WGI

102

5

The total land area subject to increasing drought frequency and severity will expand (high confidence), and in the Mediterranean, South-Western South America, and Western North America, future aridification will far exceed the magnitude of change seen in the last millennium

high

2

train

250

AR6_WGI

102

7

Large-scale deforestation likely decreases evapotranspiration and precipitation and increases runoff over the deforested regions relative to the regional effects of climate change

medium

1

train

251

AR6_WGI

102

8

Urbanization increases local precipitation (medium confidence) and runoff intensity

high

2

train

252

AR6_WGI

102

9

Increased precipitation intensities have enhanced groundwater recharge, most notably in tropical regions

medium

1

train

253

AR6_WGI

102

12

A warmer climate increases moisture transport into weather systems, which intensifies wet seasons and events

high

2

train

254

AR6_WGI

102

13

The magnitudes of projected precipitation increases and related extreme events depend on model resolution and the representation of convective processes

high

2

train

255

AR6_WGI

102

14

Increases in near-surface atmospheric moisture capacity of about 7% per 1ºC of warming lead to a similar response in the intensification of heavy precipitation from sub-daily up to seasonal time scales, increasing the severity of flood hazards

high

2

train

256

AR6_WGI

102

15

The average and maximum rain-rates associated with tropical and extratropical cyclones, atmospheric rivers and severe convective storms will therefore also increase with future warming

high

2

train

257

AR6_WGI

102

17

In the tropics year-round and in the summer season elsewhere, interannual variability of precipitation and runoff over land is projected to increase at a faster rate than changes in seasonal mean precipitation (Figure TS.12e,f)

medium

1

train

258

AR6_WGI

102

18

Sub-seasonal precipitation variability is also projected to increase, with fewer rainy days but increased daily mean precipitation intensity over many land regions

high

2

train

259

AR6_WGI

107

5

Improved quantifications of ERF, the climate system radiative response, and the observed energy increase in the Earth system for the period 1971–2018 demonstrate improved closure of the global energy budget (i.e., the extent to which the sum of the integrated forcing and the integrated radiative response equals the energy gain of the Earth system) compared to AR5

high

2

train

260

AR6_WGI

108

6

Changes in sulphur dioxide (SO 2) emissions make the dominant contribution to the ERF from aerosol– cloud interactions

high

2

train

261

AR6_WGI

108

7

Over the 1750–2019 period, the contributions from the emitted compounds to global surface temperature changes broadly match their contributions to the ERF

high

2

train

262

AR6_WGI

109

1

The ERF due to aerosol– cloud interactions (ERFaci) contributes most to the magnitude of the total aerosol ERF (high confidence) and is assessed to be –1.0 [–1.7 to –0.3] W m–2 (medium confidence), with the remainder due to aerosol–radiation interactions (ERFari), assessed to be –0.3 [–0.6 to 0.0] W m–2

medium

1

train

263

AR6_WGI

109

13

Feedback processes are expected to become more positive overall (more amplifying of global surface temperature changes) on multi-decadal time scales as the spatial pattern of surface warming evolves and global surface temperature increases, leading to an ECS that is higher than was inferred in AR5 based on warming over the instrumental record

high

2

train

264

AR6_WGI

109

15

Based on process understanding, climate modelling, and paleoclimate reconstructions of past warm periods, it is expected that future warming will become enhanced over the eastern Pacific Ocean (medium confidence) and Southern Ocean

high

2

train

265

AR6_WGI

109

21

There is a high level of agreement among the different lines of evidence (Figure TS.16c)

high

2

train

266

AR6_WGI

111

7

Because the total biogeophysical and non-CO 2 biogeochemical feedback is assessed to have a central value that is near zero

low

0

train

267

AR6_WGI

111

15

The CMIP5 and CMIP6 ranges of cloud feedback are similar to this assessed range, with CMIP6 having a slightly more positive median cloud feedback

high

2

train

268

AR6_WGI

113

7

This near-linear relationship further implies that mitigation requirements for limiting warming to specific levels can be quantified in terms of a carbon budget

high

2

train

269

AR6_WGI

113

9

Several factors, including estimates of historical warming, future emissions from thawing permafrost, variations in projected non-CO 2 warming, and the global surface temperature change after cessation of CO 2 emissions, affect the exact value of carbon budgets

high

2

train

270

AR6_WGI

115

14

In the same way that part of current anthropogenic net CO 2 emissions are taken up by land and ocean carbon stores, net CO 2 removal will be partially counteracted by CO 2 release from these stores

very high

3

train

271

AR6_WGI

115

15

Asymmetry in the carbon cycle response to simultaneous CO 2 emissions and removals implies that a larger amount of CO 2 would need to be removed to compensate for an emission of a given magnitude to attain the same change in atmospheric CO 2

medium

1

train

272

AR6_WGI

115

16

CDR methods have wide-ranging side- effects that can either weaken or strengthen the carbon sequestration and cooling potential of these methods and affect the achievement of sustainable development goals

high

2

train

273

AR6_WGI

115

25

In the same way part of current anthropogenic net CO 2 emissions are taken up by land and ocean carbon stores, net CO 2 removal will be partially counteracted by CO 2 release from these stores, such that the amount of CO 2 sequestered by CDR will not result in an equivalent drop in atmospheric CO 2

very high

3

train

274

AR6_WGI

115

26

The fraction of CO 2 removed from the atmosphere that is not replaced by CO 2 released from carbon stores – a measure of CDR effectiveness – decreases slightly with increasing amounts of removal (medium confidence) and decreases strongly if CDR is applied at lower atmospheric CO 2 concentrations

medium

1

train

275

AR6_WGI

115

27

The reduction in global surface temperature is approximately linearly related to cumulative CO 2 removal

high

2

train

276

AR6_WGI

115

28

Because of this near-linear relationship, the amount of cooling per unit CO 2 removed is approximately independent of the rate and amount of removal

medium

1

train

277

AR6_WGI

116

7

For instance, sea level rise due to ocean thermal expansion would not reverse for several centuries to millennia

high

2

train

278

AR6_WGI

116

9

Biophysical and biogeochemical side-effects of CDR methods are associated with changes in surface albedo, the water cycle, emissions of CH 4 and N 2O, ocean acidification and marine ecosystem productivity

high

2

train

279

AR6_WGI

116

10

These side-effects and associated Earth system feedbacks can decrease carbon uptake and/or change local and regional climate and in turn limit the CO 2 sequestration and cooling potential of specific CDR methods

medium

1

train

280

AR6_WGI

116

11

Deployment of CDR, particularly on land, can also affect water quality and quantity, food production and biodiversity

high

2

train

281

AR6_WGI

116

12

These effects are often highly dependent on local context, management regime, prior land use, and scale

high

2

train

282

AR6_WGI

116

13

The largest co-benefits are obtained with methods that seek to restore natural ecosystems or improve soil carbon sequestration

medium

1

test

283

AR6_WGI

116

14

The climate and biogeochemical effects of terminating CDR are expected to be small for most CDR methods

medium

1

train

284

AR6_WGI

117

2

Carbon-cycle responses are more robustly accounted for in emissions metrics compared to AR5

high

2

train

285

AR6_WGI

117

9

The methodology for doing this has been placed on a more robust scientific footing compared to AR5

high

2

train

286

AR6_WGI

117

10

Methane from fossil fuel sources has slightly higher emissions metric values than those from biogenic sources since it leads to additional fossil CO 2 in the atmosphere

high

2

train

287

AR6_WGI

117

11

Updates to the chemical adjustments for CH 4 and N2O emissions (Section TS.3.1) and revisions in their lifetimes result in emissions metrics for GWP and GTP that are slightly lower than in AR5

medium

1

train

288

AR6_WGI

117

15

When GHGs are aggregated using standard metrics such as GWP or GTP, cumulative CO 2-e emissions are not necessarily proportional to future global surface temperature outcomes

high

2

train

289

AR6_WGI

117

19

The warming evolution resulting from net zero GHG emissions defined in this way corresponds approximately to reaching net zero CO 2 emissions, and would thus not lead to declining temperatures after net zero GHG emissions are achieved but to an approximate temperature stabilization

high

2

train

290

AR6_WGI

117

20

The choice of emissions metric hence affects the quantification of net zero GHG emissions, and therefore the resulting temperature outcome of reaching and sustaining net zero GHG emissions levels

high

2

train

291

AR6_WGI

117

29

Fossil fuel combustion for energy, industry and land transportation are the largest contributing sectors on a 100-year time scale

high

2

train

292

AR6_WGI

117

30

Current emissions of CO 2, N2O and SLCFs from East Asia and North America are the largest regional contributors to additional net future warming on both short (medium confidence) and long time scales (10 and 100 years, respectively)

high

2

train

293

AR6_WGI

118

2

However, these reductions were lower than what would be expected from sustained implementation of policies addressing air quality and climate change

medium

1

train

294

AR6_WGI

118

4

Consistent with this small net radiative forcing, and against a large component of internal variability, Earth system models show no detectable effect on global or regional surface temperature or precipitation

high

2

train

295

AR6_WGI

119

2

This additional warming is stable after 2040 in SSPs associated with lower global air pollution as long as CH 4 emissions are also mitigated, but the overall warming induced by SLCF changes is higher in scenarios in which air quality continues to deteriorate (induced by growing fossil fuel use and limited air pollution control)

high

2

train

296

AR6_WGI

119

3

Sustained CH 4 mitigation reduces global surface ozone, contributing to air quality improvements, and also reduces surface temperature in the longer term, but only sustained CO 2 emissions reductions allow long-term climate stabilization

high

2

train

297

AR6_WGI

119

4

Future changes in air quality (near-surface ozone and particulate matter, or PM) at global and local scales are predominantly driven by changes in ozone and aerosol precursor emissions rather than climate

high

2

train

298

AR6_WGI

119

5

Air quality improvements driven by rapid decarbonization strategies, as in SSP1-1.9 and SSP1-2.6, are not sufficient in the near term to achieve air quality guidelines set by the World Health Organization in some highly polluted regions

high

2

train

299

AR6_WGI

119

20

Under the SSP3-7.0 scenario, PM levels are projected to increase until 2050 over large parts of Asia, and surface ozone pollution is projected to worsen over all continental areas through 2100

high

2

train