rlacombe/ClimateX huggingface dataset:
Although ice core records present low-pass filtered time series due to gas diffusion and gradual bubble close- off in the snow layer over the ice sheet (Fourteau et al., 2020), the rate of increase since 1850 CE (about 125 ppm increase over about 170 years) is far greater than implied for any 170-year period by ice core records that cover the last 800 ka (IPCC AR6_WGI, confidence: very high)
The last time CO 2 concentrations were similar to the present-day was over 2 Ma (IPCC AR6_WGI, confidence: high)
Between 1750–2019 mixing ratios increased by 131.6 ± 2.9 ppm (47%), 1137 ± 10 ppb (156%), and 62 ± 6 ppb (23%), for CO 2, CH 4, and N 2O, respectively (IPCC AR6_WGI, confidence: very high)
In summary, limited available isotopic evidence constrains the global tropospheric ozone increase to less than 40% between 1850 and 2005 (IPCC AR6_WGI, confidence: low)
Based on sparse historical surface/low altitude data tropospheric ozone has increased since the mid-20th century by 30–70% across the NH (IPCC AR6_WGI, confidence: medium)
Surface/low altitude ozone trends since the mid-1990s are variable at northern mid-latitudes, but positive in the tropics [2 to 17% per decade] (IPCC AR6_WGI, confidence: high)
Since the mid-1990s, free tropospheric ozone has increased by 2–7% per decade in most regions of the northern mid-latitudes, and 2–12% per decade in the sampled regions of the northern and southern tropics (IPCC AR6_WGI, confidence: high)
Limited coverage by surface observations precludes identification of zonal trends in the SH, while observations of tropospheric column ozone indicate increases of less than 5% per decade at southern mid-latitudes (IPCC AR6_WGI, confidence: medium)
Satellite data and ground-based records indicate that AOD exhibits predominantly negative trends since 2000 over NH mid-latitudes and SH continents, but increased over South Asia and East Africa (IPCC AR6_WGI, confidence: high)
In summary, biophysical effects from historical changes in land use have an overall negative ERF (IPCC AR6_WGI, confidence: medium)
Biophysical effects of land-use change likely resulted in a net global cooling of about 0.1°C since 1750 (IPCC AR6_WGI, confidence: medium)
The net effect of aerosols (Sections 2.2.6 and 6.4) on the radiation budget, including their effect on clouds, and cloud adjustments, as well as the deposition of black carbon on snow (Section 7.3.4.3), was negative throughout the industrial period (IPCC AR6_WGI, confidence: high)
The relative importance of aerosol forcing compared to other forcing agents has decreased globally in the most recent 30 years (IPCC AR6_WGI, confidence: medium)
This effect increased since 1750, reaching current values of about –0.20 W m–2 (IPCC AR6_WGI, confidence: medium)
The AR5 concluded that the reconstructed GMST during the PETM was 4°C–7°C warmer than pre-PETM mean climate (low confidence), and that the EECO and the MPWP were 9°C–14°C and 1.9°C–3.6°C warmer than pre-industrial, respectively (IPCC AR6_WGI, confidence: medium)
The GMST during the LIG was assessed at 1°C–2°C warmer than pre-industrial (IPCC AR6_WGI, confidence: medium)
Together, these studies indicate that GMST was 4°C–10°C warmer during the MCO (IPCC AR6_WGI, confidence: medium)
In summary, GMST during the warmest millennia of the LIG (within the interval of around 129–125 ka) is estimated to have reached 0.5°C–1.5°C higher values than the 1850–1990 reference period (IPCC AR6_WGI, confidence: medium)
In summary, GMST is estimated to have been 5°C–7°C lower during the LGM (around 23–19 ka) compared with 1850–1900 (IPCC AR6_WGI, confidence: medium)
For average annual NH temperatures, the period 1983–2012 was assessed as very likely the warmest 30-year period of the past 800 years (high confidence) and likely the warmest 30-year period of the past 1.4 kyr (medium confidence); the warm multi-decadal periods prior to the 20th century were unsynchronized across regions, in contrast to the warming since the mid-20th century (IPCC AR6_WGI, confidence: high)
Taking all lines of evidence into account, the GMST averaged over the warmest centuries of the current interglacial period (sometime between around 6 and 7 ka) is estimated to have been 0.2°C–1.0°C higher than 1850–1900 (IPCC AR6_WGI, confidence: medium)
Moreover, the new proxy data compilation shows that the warming of the 20th century was more spatially uniform than any other century-scale temperature change of the CE (IPCC AR6_WGI, confidence: medium)
To conclude, following approximately 6 ka, GMST generally decreased, culminating in the coldest multi-century interval of the post-glacial period (since 8 ka), which occurred between around 1450 and 1850 (IPCC AR6_WGI, confidence: high)
Since around 1950, GMST has increased at an observed rate unprecedented for any 50-year period in at least the last 2000 years (IPCC AR6_WGI, confidence: high)
The effect of this change from trend-based to change-based metrics is currently relatively minor at –0.03°C (<5%) for the most recent decade, but this may not remain the case in future (IPCC AR6_WGI, confidence: high)
Given the projected future sea ice losses, the effect will grow in future (IPCC AR6_WGI, confidence: low)
The other half arises because, for central estimates of climate sensitivity, most scenarios show stronger warming over the near term than was assessed as ‘current’ in SR1.5 (IPCC AR6_WGI, confidence: medium)
The assessment of the implications of limiting global warming to 1.5°C compared to 2°C will also remain broadly unchanged by the updated estimate of historical warming, as this depends on the relative impacts rather than the absolute impacts at any specific definition of global temperature anomaly (IPCC AR6_WGI, confidence: high)
The SRCCL concluded that since the pre-industrial period, surface air temperature over land areas has risen nearly twice as much as the global mean surface temperature (IPCC AR6_WGI, confidence: high)
There are indications from multiple sources of a wetting trend during the Holocene, particularly for the NH and parts of the SH tropics (IPCC AR6_WGI, confidence: medium)
Hydroclimate during the CE is dominated by regional variability, generally precluding definitive statements on changes at continental and larger scales, with a general reduction of mega-drought occurrences over the last about 500 years (IPCC AR6_WGI, confidence: medium)
In summary, globally averaged land precipitation has likely increased since the middle of the 20th century (IPCC AR6_WGI, confidence: medium)
A faster increase in global land precipitation was observed since the 1980s (IPCC AR6_WGI, confidence: medium)
In summary, the sign of global streamflow trends remains uncertain, with slightly more globally gauged rivers experiencing significantly decreasing flows than significantly increasing flows since the 1950s (IPCC AR6_WGI, confidence: low)
This has been accompanied by a strengthening of the Hadley circulation, particularly in the NH (IPCC AR6_WGI, confidence: medium)
In summary, observed trends during the last century indicate that the GM precipitation decline reported in AR5 has reversed since the 1980s, with a likely increase mainly due to a significant positive trend in the NH summer monsoon precipitation (IPCC AR6_WGI, confidence: medium)
In summary, the total number of extratropical cyclones has likely increased since the 1980s in the NH (IPCC AR6_WGI, confidence: low)
The number of strong extratropical cyclones has likely increased in the SH (IPCC AR6_WGI, confidence: medium)
The extratropical jets and cyclone tracks have likely been shifting poleward in both hemispheres since the 1980s with marked seasonality in trends (IPCC AR6_WGI, confidence: medium)
This was confirmed by SROCC reporting the strongest reductions in September (12.8 ± 2.3% per decade; 1979–2018) and stating that these changes were likely unprecedented in at least 1 kyr (IPCC AR6_WGI, confidence: medium)
The spatial extent had decreased in all seasons, with the largest decrease for September (IPCC AR6_WGI, confidence: high)
The AR5 reported also that the average winter sea ice thickness within the Arctic Basin had likely decreased by between 1.3 m and 2.3 m from 1980 to 2008 (IPCC AR6_WGI, confidence: high)
Lower sea ice volume in 2010–2012 compared to 2003–2008 was documented in AR5 (IPCC AR6_WGI, confidence: medium)
In summary, over 1979–2019 Arctic SIA has decreased for all months, with the strongest decrease in summer (IPCC AR6_WGI, confidence: very high)
Arctic sea ice has become younger, thinner and faster moving (IPCC AR6_WGI, confidence: very high)
Snow thickness on sea ice has decreased in the western Arctic Ocean (IPCC AR6_WGI, confidence: medium)
Current pan-Arctic sea ice coverage levels (annual mean and late summer) are unprecedentedly low since 1850 (IPCC AR6_WGI, confidence: high)
The SROCC stated also that historical Antarctic sea ice data from different sources indicated a decrease in overall Antarctic sea ice cover since the early 1960s, but was too small to be separated from natural variability (IPCC AR6_WGI, confidence: high)
The 2020 September level (OSISAF) remains below the levels observed over 2012–2014.In summary, Antarctic sea ice has experienced both increases and decreases in SIA over 1979–2019, and substantively lower levels since 2016, with only minor differences between decadal means of SIA for the first (for February 2.04 million km2, for September 15.39 million km2) and last decades (for February 2.17 million km2, for September 15.75 million km2) of satellite observations (IPCC AR6_WGI, confidence: high)
In summary, substantial reductions in spring snow cover extent have occurred in the NH since 1978 (IPCC AR6_WGI, confidence: very high)
Since 1981 there has been a general decline in NH spring snow water equivalent (IPCC AR6_WGI, confidence: high)
The SROCC reported a globally coherent picture of continued glacier recession in recent decades (IPCC AR6_WGI, confidence: very high)
The current global character of glacier mass loss is highly unusual (almost all glaciers simultaneously receding) in the context of at least the last 2 kyr (IPCC AR6_WGI, confidence: medium)
Glacier mass loss rates have increased since the 1970s (IPCC AR6_WGI, confidence: high)
Although many surveyed glaciers are currently more extensive than during the MH (IPCC AR6_WGI, confidence: high)
It reported that the GrIS had lost ice during the prior two decades (very high confidence), that the ice loss had occurred in several sectors, and that high rates of mass loss had both expanded to higher elevations (IPCC AR6_WGI, confidence: high)
The SROCC also found that summer melting rate had increased since the 1990s to a rate unprecedented over the last 350 years (very high confidence), being two to five times greater than the pre-industrial rates (IPCC AR6_WGI, confidence: medium)
In summary, the GrIS was smaller than present during the MPWP (medium confidence), LIG (high confidence) and the MH (IPCC AR6_WGI, confidence: high)
GrIS mass loss began following a peak volume attained during the 1450–1850 period and the rate of loss has increased substantially since the turn of the 21st century (IPCC AR6_WGI, confidence: high)
The SROCC concluded that over 2006–2015, the AIS lost mass at an average rate of 155 ± 19 Gt yr –1 (IPCC AR6_WGI, confidence: very high)
Overall, during the MH, the AIS was retreating, but remained more extensive than present, while some parts of the ice sheet might have been smaller than now (IPCC AR6_WGI, confidence: low)
In summary, the AIS has lost mass between 1992 and 2020 (IPCC AR6_WGI, confidence: very high)
During the MPWP and LIG, the ice sheet was smaller than present (IPCC AR6_WGI, confidence: medium)
The AR5 also noted positive trends in active layer thickness (ALT; the seasonally thawed layer above the permafrost) since the 1990s for many high latitude sites (IPCC AR6_WGI, confidence: medium)
The SROCC concluded permafrost temperatures have increased to record high levels since the 1980s (IPCC AR6_WGI, confidence: very high)
In summary, increases in permafrost temperatures in the upper 30 m have been observed since the start of observational programs over the past three to four decades throughout the permafrost regions (IPCC AR6_WGI, confidence: high)
Limited evidence suggests that permafrost was less extensive during the MPWP (IPCC AR6_WGI, confidence: low)
Permafrost that formed after 3ka still persists in areas of the NH, but there are indications of thaw after the mid-1800s (IPCC AR6_WGI, confidence: medium)
In summary, current multi-decadal to centennial rates of OHC gain are greater than at any point since the last deglaciation (IPCC AR6_WGI, confidence: medium)
At multi-centennial timescales, changes in OHC based upon proxy indicators demonstrate a tight link with surface temperature changes during the last deglaciation (high confidence), as well as during the Holocene and CE (IPCC AR6_WGI, confidence: low)
The differences between high-salinity and low- salinity regions are linked to an intensification of the hydrological cycle (IPCC AR6_WGI, confidence: medium)
AR5 reported that GMSL during the LIG was, over several thousand years, between 5 and 10 m higher than 1985–2004 (medium confidence) whereas SROCC concluded it was virtually certain that GMSL exceeded current levels (high confidence), and reached a peak that was likely 6–9 m higher than today, but did not exceed 10 m (IPCC AR6_WGI, confidence: medium)
Given that GMSL change must be due to some combination of transient land ice growth and changes in terrestrial water storage, additional global mean thermosteric sea-level increase of 7 ± 2 m (Fischer et al., 2018) implies a peak EECO GMSL of 70–76 m (IPCC AR6_WGI, confidence: low)
Thus, consistent with SROCC, GMSL during the MPWP was higher than present by 5–25 m (IPCC AR6_WGI, confidence: medium)
It shows that GMSL during the Holocene was among the highest over this entire interval, and was surpassed only during the LIG (Marine Isotope Stage (MIS 5e)) and MIS 11 (IPCC AR6_WGI, confidence: medium)
The fastest rise occurred during Meltwater Pulse 1A, at about 14.6–14.3 ka (Deschamps et al., 2012; Sanborn et al., 2017), when GMSL rose by between 8 m and 15 m (IPCC AR6_WGI, confidence: medium)
In summary, GMSL is rising, and the rate of GMSL rise since the 20th century is faster than over any preceding century in at least the last three millennia (IPCC AR6_WGI, confidence: high)
SROCC assessed that there was emerging evidence in sustained observations, both in situ (2004–2017) and revealed from SST-based reconstructions, that the AMOC had weakened during the instrumental era relative to 1850–1900 (IPCC AR6_WGI, confidence: medium)
In summary, proxy-based reconstructions suggest that the AMOC was relatively stable during the past 8 kyr (medium confidence), with a weakening beginning since the late 19th century (IPCC AR6_WGI, confidence: medium)
From the mid-2000s to mid-2010s, the directly observed weakening in AMOC (high confidence) cannot be distinguished between decadal-scale variability or a long-term trend (IPCC AR6_WGI, confidence: high)
In summary, over the past 3–4 decades, the WBC strength is highly variable (high confidence), and WBCs and subtropical gyres have shifted poleward since 1993 (IPCC AR6_WGI, confidence: medium)
Net Arctic Ocean volume exchanges with the other ocean basins remained stable over the mid-1990s to the mid-2010s (IPCC AR6_WGI, confidence: high)
To conclude, it is virtually certain that surface open ocean pH has declined globally over the last 40 years by 0.003–0.026 pH per decade, and a decline in the ocean interior has been observed in all ocean basins over the past 2–3 decades (IPCC AR6_WGI, confidence: high)
A long-term increase in surface open ocean pH occurred over the past 50 Myr, and surface open ocean pH as low as recent times is uncommon in the last 2 Myr (IPCC AR6_WGI, confidence: medium)
Multidecadal rates of deoxygenation showed variability throughout the water column and across ocean basins (IPCC AR6_WGI, confidence: high)
In summary, episodes of widespread and long-lasting (100 ka scales) open-ocean deoxygenation were related to warm climate intervals of the Permian-Cretaceous, with conditions becoming generally better oxygenated as the climate cooled over the course of the Cenozoic (IPCC AR6_WGI, confidence: high)
The largest expansions of oxygen depleted waters over the past 25 ka were strongly linked to rapid warming rates (IPCC AR6_WGI, confidence: medium)
Open-ocean deoxygenation has occurred in most regions of the open ocean during the mid-20th to early 21st centuries (high confidence), and shows decadal variability (IPCC AR6_WGI, confidence: medium)
Evidence further confirms SROCC that OMZs are expanding at many locations (IPCC AR6_WGI, confidence: high)
Similarly, globally-integrated results from the SH also show an increase in seasonal amplitude of atmospheric CO 2 signal, from around 2009 to 2018 (IPCC AR6_WGI, confidence: low)
With respect to distributions of marine organisms, AR5 WGII reported range shifts of benthic, pelagic, and demersal species and communities (IPCC AR6_WGI, confidence: high)
A small decrease in productivity is evident globally for the period 1998–2015, but regional changes are larger and of opposing signs (IPCC AR6_WGI, confidence: low)
New in situ data as well as satellite observations strengthen AR5 and SROCC findings that various phenological metrics for many species of marine organisms have changed in the last half century (IPCC AR6_WGI, confidence: high)
The changes vary with location and with species (IPCC AR6_WGI, confidence: high)
There is a strong dependence of survival in higher trophic-level organisms (fish, exploited invertebrates, birds) on the availability of food at various stages in their life cycle, which in turn depends on phenologies of both (IPCC AR6_WGI, confidence: high)
Similarly, SRCCL assessed that many land species have experienced range size and location changes as well as altered abundances over recent decades (IPCC AR6_WGI, confidence: high)
SROCC noted that species composition and abundance have markedly changed in high mountain ecosystems in recent decades (IPCC AR6_WGI, confidence: very high)
The SRCCL subsequently concluded that greening had increased globally over the past 2–3 decades (IPCC AR6_WGI, confidence: high)
Many more integrative components of the climate system (e.g., glaciers, GMSL) are experiencing conditions unseen in millennia, whereas the most slowly responding components (e.g., ice-sheet extent, permafrost, tree line) are at levels unseen in centuries (IPCC AR6_WGI, confidence: high)
The rate at which several assessed climate indicators (e.g., GMSL, OHC, GSAT) have changed over recent decades is highly unusual in the context of preceding slower changes during the current post-glacial period (IPCC AR6_WGI, confidence: high)
Moreover, periods of persistent negative or positive NAO states observed during the latter part of the 20th century were not unusual, based on NAO reconstructions spanning the last half millennium (IPCC AR6_WGI, confidence: high)
In summary, positive trends for the NAM/NAO winter indices were observed between the 1960s and the early 1990s, but these indices have become less positive or even negative thereafter (IPCC AR6_WGI, confidence: high)
In summary, historical station-based reconstructions of the SAM show that there has been a robust positive trend in the SAM index, particularly since 1950 and for the austral summer (IPCC AR6_WGI, confidence: high)
Neither the IOD nor the IOB have exhibited behaviour outside the range implied by proxy records (IPCC AR6_WGI, confidence: low)
In summary, no sustained change in AMV indices has been observed over the instrumental period (IPCC AR6_WGI, confidence: high)
High-resolution models exhibit reduced biases in some but not all aspects of surface and ocean climate (medium confidence), and most Earth system models, which include biogeochemical feedbacks, perform as well as their lower-complexity counterparts (IPCC AR6_WGI, confidence: medium)
The multi-model mean captures most aspects of observed climate change well (IPCC AR6_WGI, confidence: high)
The multi-model mean captures the proxy-reconstructed global-mean surface air temperature (GSAT) change during past high- and low-CO 2 climates (high confidence) and the correct sign of temperature and precipitation change in most assessed regions in the mid-Holocene (IPCC AR6_WGI, confidence: medium)
The simulation of paleoclimates on continental scales has improved compared to AR5 (medium confidence), but models often underestimate large temperature and precipitation differences relative to the present day (IPCC AR6_WGI, confidence: high)
The likely ranges for human-induced GSAT and global mean surface temperature (GMST) warming are equal (IPCC AR6_WGI, confidence: medium)
CMIP6 models broadly reproduce surface temperature variations over the past millennium, including the cooling that follows periods of intense volcanism (IPCC AR6_WGI, confidence: medium)
The latest updates to satellite-derived estimates of stratospheric temperature have resulted in decreased differences between simulated and observed changes of global mean temperature through the depth of the stratosphere (IPCC AR6_WGI, confidence: medium)
All the observed estimates of the 1998–2012 GMST trend lie within the 10th–90th percentile range of CMIP6 simulated trends (IPCC AR6_WGI, confidence: high)
Internal variability, particularly Pacific Decadal Variability, and variations in solar and volcanic forcings partly offset the anthropogenic surface warming trend over the 1998–2012 period (IPCC AR6_WGI, confidence: high)
Since 2012, GMST has warmed strongly, with the past five years (2016–2020) being the warmest five-year period in the instrumental record since at least 1850 (IPCC AR6_WGI, confidence: high)
New attribution studies strengthen previous findings of a detectable increase in Northern Hemisphere mid- to high-latitude land precipitation (IPCC AR6_WGI, confidence: high)
Human influence has contributed to strengthening the zonal mean precipitation contrast between the wet tropics and dry subtropics (IPCC AR6_WGI, confidence: medium)
Yet, anthropogenic aerosols contributed to decreasing global land summer monsoon precipitation from the 1950s to 1980s (IPCC AR6_WGI, confidence: medium)
Despite improvements, models still have deficiencies in simulating precipitation patterns, particularly over the tropical ocean (IPCC AR6_WGI, confidence: high)
The magnitude and frequency of extreme precipitation simulated by CMIP6 models are similar to those simulated by CMIP5 models (IPCC AR6_WGI, confidence: high)
The causes of the observed strengthening of the Pacific Walker circulation since the 1980s are not well understood, and the observed strengthening trend is outside the range of trends simulated in the coupled models (IPCC AR6_WGI, confidence: medium)
While CMIP6 models capture the general characteristics of the tropospheric large-scale circulation (high confidence), systematic biases exist in the mean frequency of atmospheric blocking events, especially in the Euro-Atlantic sector, some of which reduce with increasing model resolution (IPCC AR6_WGI, confidence: medium)
There is new evidence that increases in anthropogenic aerosols have offset part of the greenhouse gas-induced Arctic sea ice loss since the 1950s (IPCC AR6_WGI, confidence: medium)
In the Arctic, despite large differences in the mean sea ice state, loss of sea ice extent and thickness during recent decades is reproduced in all CMIP5 and CMIP6 models (IPCC AR6_WGI, confidence: high)
The seasonal cycle in Northern Hemisphere snow cover is better reproduced by CMIP6 than by CMIP5 models (IPCC AR6_WGI, confidence: high)
Updated observations and model simulations show that warming extends throughout the entire water column (IPCC AR6_WGI, confidence: high)
The structure and magnitude of multi-model mean ocean temperature biases have not changed substantially between CMIP5 and CMIP6 (IPCC AR6_WGI, confidence: medium)
The associated pattern of change corresponds to fresh regions becoming fresher and salty regions becoming saltier (IPCC AR6_WGI, confidence: high)