rlacombe/ClimateX huggingface dataset:
In summary, global tropospheric NO x abundance has increased from 1850–2015 (IPCC AR6_WGI, confidence: high)
NO 2 trends have reversed (declining) over China beginning in 2012 and NO 2 has increased over Southern Asia by 50% since 2005 (IPCC AR6_WGI, confidence: medium)
In summary, after a decline between 1980 and 2008, abundances of light NMVOCs have increased again over the Northern Hemisphere due to the extraction of oil and gas in North America (IPCC AR6_WGI, confidence: high)
Trends in satellite HCHO observations, used as a proxy of anthropogenic NMVOC over industrialized areas, show a significant positive trend over eastern China (IPCC AR6_WGI, confidence: high)
That would give BrC a burden similar to that of BC (IPCC AR6_WGI, confidence: low)
In summary, global mean tropospheric OH does not show a significant trend from 1850 up to around 1980 (IPCC AR6_WGI, confidence: low)
In summary, the spatial and temporal distribution of the net aerosol ERF from 1850–2014 is highly heterogeneous (IPCC AR6_WGI, confidence: high)
Globally, there has been a shift from increase to decrease of the negative net aerosol ERF driven by trends in aerosol and their precursor emissions (IPCC AR6_WGI, confidence: high)
In summary, emissions of SLCFs, especially methane, NO x and SO 2, have substantial effects on effective radiative forcing (ERF) (IPCC AR6_WGI, confidence: high)
The net global emissions‑based ERF of NO x is negative and that of NMVOCs is positive, in agreement with the AR5 assessment (IPCC AR6_WGI, confidence: high)
SO 2 emissions make the dominant contribution to the ERF associated with the aerosol–cloud interaction (IPCC AR6_WGI, confidence: high)
The contributions from the emitted compounds to GSAT broadly follow their contributions to the ERF (IPCC AR6_WGI, confidence: high)
The overall effect of surface cooling from anthropogenic aerosols is to reduce global precipitation and alter large‑ scale atmospheric circulation patterns (IPCC AR6_WGI, confidence: high)
The zonal‑mean temperature response is negative at all latitudes (IPCC AR6_WGI, confidence: high)
The asymmetric historical radiative forcing due to aerosols led to a southward shift in the tropical rain belt (high confidence) and contributed to the Sahel drought from the 1970s to the 1980s (IPCC AR6_WGI, confidence: high)
Furthermore, the asymmetry of the forcing led to contrasting effects in monsoon precipitation changes over West Africa, Southern Asia and Eastern Asia over much of the mid‑20th century due to GHG‑induced precipitation increases counteracted by anthropogenic aerosol‑ induced decreases (IPCC AR6_WGI, confidence: high)
In summary, over the historical period, changes in aerosols and their ERF have primarily contributed to cooling, partly masking the human‑induced warming (IPCC AR6_WGI, confidence: high)
Radiative forcings induced by aerosol changes lead to both local and remote changes in temperature (IPCC AR6_WGI, confidence: high)
The temperature response preserves hemispheric asymmetry of the ERF but is more latitudinally uniform with strong amplification of the temperature response towards the Arctic (IPCC AR6_WGI, confidence: medium)
The new modelling studies tend to focus on ozone effects on plant productivity rather than the land carbon storage and agree that ozone‑induced gross‑primary productivity (GPP) losses are largest today in the eastern USA, Europe and eastern China, ranging from 5–20% on the regional scale (IPCC AR6_WGI, confidence: low)
At large scales the dominant effect of aerosols on the carbon cycle is likely a global cooling effect of the climate (IPCC AR6_WGI, confidence: medium)
In summary, reactive nitrogen, ozone and aerosols affect terrestrial vegetation and the carbon cycle through deposition and effects on large‑scale radiation (IPCC AR6_WGI, confidence: high)
As such, we assess the effects to be of second order in comparison to the direct CO 2 forcing (high confidence) but, at least for ozone, it could add a substantial (positive) forcing compared with its direct forcing (IPCC AR6_WGI, confidence: low)
Modelling studies have been published with more sophisticated treatment of SRM since AR5, but the uncertainties, such as cloud–aerosol radiation interactions, remain large (IPCC AR6_WGI, confidence: high)
Overall, warmer climate is expected to reduce surface ozone in unpolluted regions as a result of greater water vapour abundance accelerating ozone chemical loss (IPCC AR6_WGI, confidence: high)
The response of surface ozone to future climate change through stratosphere–troposphere exchange, soil NO x emissions and wildfires is positive (IPCC AR6_WGI, confidence: medium)
For SLCFs with short lifetime (e.g., months), the response in surface temperature occurs strongly as soon as a sustained change in emissions is implemented and continues to grow for a few years, primarily due to thermal inertia in the climate system (IPCC AR6_WGI, confidence: high)
For SLCFs with longer lifetimes (e.g., a decade), a delay equivalent to their lifetimes comes in addition to the delay due the thermal inertia (IPCC AR6_WGI, confidence: high)
Residential sector emissions are an important source of indoor and outdoor air pollution in Asia and globally (IPCC AR6_WGI, confidence: high)
In summary, the net aviation ERF is assessed to be +0.1 W m–2 (±0.045) for the year 2018 (IPCC AR6_WGI, confidence: low)
The climate response to SLCF‑related aviation terms exhibits substantial spatio‑temporal heterogeneity in characteristics (IPCC AR6_WGI, confidence: high)
Overall, cirrus and contrail cirrus warming, as well as NO x‑induced ozone increase, induce strong but short‑lived warming contributions to the GSAT response 10 years after a one‑year pulse of present‑day aviation emissions (medium confidence), while CO 2 both gives a warming effect in the near term and dominates the long‑term warming impact (IPCC AR6_WGI, confidence: high)
In summary, a year’s worth of present‑day global shipping emissions (i.e., without the implementation of the 2020 clean fuel standards) cause a net global cooling (–0.0024 ± 0.0025°C) on 10–20 year time horizons (IPCC AR6_WGI, confidence: high)
In summary, the present‑day global land‑based transport pulse emissions cause a net global warming on all time scales (high confidence) and are detrimental to air quality (IPCC AR6_WGI, confidence: high)
By far the largest 10‑year GSAT effects are from the energy production (fossil fuel mining and distribution), agriculture and waste management sectors (IPCC AR6_WGI, confidence: high)
On the 10‑year time horizon, other net warming sectors are residential fossil fuel and energy combustion (dominated by CO 2) and aviation and residential biofuel (dominated by SLCFs and cloud) (IPCC AR6_WGI, confidence: medium)
In terms of source regions, the largest contributions to net short‑ term warming are caused by emissions in Eastern Asia, Latin America and North America, followed by Africa, Eastern Europe, West‑Central Asia and South East Asia (IPCC AR6_WGI, confidence: medium)
Overall, the global sectors that contribute the largest warming on short time scales are the methane‑dominated sources, that is energy production (fossil fuel mining and distribution), and agriculture and waste management (IPCC AR6_WGI, confidence: high)
On short time scales, other net warming sectors are residential fossil fuel and energy combustion (dominated by CO 2), and aviation and residential biofuel (dominated by SLCFs) (IPCC AR6_WGI, confidence: medium)
On short time scales, global emissions from industry and shipping cause a net cooling effect despite a considerable warming from CO 2 emissions (IPCC AR6_WGI, confidence: high)
On longer time horizons, the sectors that contribute the largest warming are energy combustion and industry due to the large CO 2 emissions (IPCC AR6_WGI, confidence: high)
Residential and commercial cooking and heating are among the most important anthropogenic sources of ambient PM 2.5, except in the Middle East and Asia‑Pacific Developed (high confidence) and agriculture is the dominant source in Europe and North America (IPCC AR6_WGI, confidence: medium)
Additional policies (e.g., access to clean energy, waste management) envisaged to attain SDGs bring complementary SLCF reduction (IPCC AR6_WGI, confidence: high)
Sustained methane mitigation, wherever it occurs, stands out as an option that combines near ‑ and long‑term gains on surface temperature (high confidence) and leads to an air pollution benefit by reducing ozone levels globally (IPCC AR6_WGI, confidence: high)
Emissions Global fossil CO 2 emissions are estimated to have declined by 7% (IPCC AR6_WGI, confidence: medium)
Anthropogenic NO x emissions, which are largely from the transport sector, are estimated to have decreased by a maximum of 35% in April (IPCC AR6_WGI, confidence: medium)
Except for ozone, temporary improvement of air quality during lockdown periods was observed in most regions of the world (high confidence), resulting from a combination of interannual meteorological variability and the impact of COVID‑19 containment measures (IPCC AR6_WGI, confidence: high)
Estimated air pollution reductions associated with lockdown periods are lower than what can be expected from integrated mitigation policy leading to lasting reductions (IPCC AR6_WGI, confidence: medium)
The range in peak global mean ERF in spring 2020 was [0.025 to 0.2] W m–2 (IPCC AR6_WGI, confidence: medium)
By the end of 2020, the ERF was at half the peak value (IPCC AR6_WGI, confidence: medium)
Climate responses Changes in atmospheric composition due to COVID‑19 emissions reductions are not thought to have caused a detectable change in global temperature or rainfall in 2020 (IPCC AR6_WGI, confidence: high)
Simulated GSAT and rainfall changes are unlikely to be detectable in observations (IPCC AR6_WGI, confidence: high)
Consequently, SSPs span a wider range of SLCF emissions than considered in the RCPs, better covering the diversity of future options in air pollution management and SLCF‑induced climate effects (IPCC AR6_WGI, confidence: high)
However, this decrease is twice as large when methane emissions are abated simultaneously (SSP3‑7.0‑lowSLCF‑lowCH 4), underlying the importance of methane emissions reduction as an important lever to reduce ozone pollution (IPCC AR6_WGI, confidence: high)
In the latter case, PM levels are estimated to increase until 2050 over large parts of Asia and surface ozone pollution worsens over all continental areas throughout the whole century (IPCC AR6_WGI, confidence: high)
In scenarios without climate change mitigation but with strong air pollution control (SSP5‑8.5), high methane levels hamper the decline in global surface ozone in the near term and only PM levels decrease (IPCC AR6_WGI, confidence: high)
Furthermore, under SSP5‑8.5, HFCs induce a warming of 0.06°C with a very likely range of [0.04 to 0.08] °C in 2050 and 0.2 [0.1 to 0.3] °C by the end of the 21st century, relative to 2019, while under SSP1‑2.6, warming due to HFCs is negligible (below 0.02°C) (IPCC AR6_WGI, confidence: high)
Methane mitigation that also reduces tropospheric ozone, stands out as an option that combines near‑ and long‑term gains on surface temperature (IPCC AR6_WGI, confidence: high)
The assessment shows that both strong air pollution control and strong climate change mitigation, implemented independently, lead to a large reduction of exposure to PM 2.5 and ozone by the end of the century (IPCC AR6_WGI, confidence: high)
However, implementation of air pollution control, relying on the deployment of existing technologies, leads to benefits more rapidly than climate change mitigation (IPCC AR6_WGI, confidence: high)
Notably, under the underlying SSP3 context, significant parts of the population remain exposed to air quality exceeding the WHO guidelines for PM 2.5 over the whole century (IPCC AR6_WGI, confidence: high)
In summary, the warming induced by SLCF changes is stable after 2040 in the WGI core set of SSP scenarios associated with lower global air pollution as long as methane emissions are also mitigated, but the overall warming induced by SLCF changes is higher in scenarios in which air quality continues to deteriorate (caused by growing fossil fuel use and limited air pollution control) (IPCC AR6_WGI, confidence: high)
Sustained methane mitigation, wherever it occurs, stands out as an option that combines near ‑ and long‑term gains on surface temperature (high confidence) and leads to air pollution benefits by reducing surface ozone level globally (IPCC AR6_WGI, confidence: high)
Strong air pollution control as well as strong climate change mitigation, implemented independently, lead to large reduction of the exposure to air pollution by the end of the century (IPCC AR6_WGI, confidence: high)
Implementation of air pollution control, relying on the deployment of existing technologies, leads more rapidly to air ‑quality benefits than climate change mitigation which requires systemic changes but, in both cases, significant parts of the population remain exposed to air pollution exceeding the WHO guidelines (IPCC AR6_WGI, confidence: high)
Energy will continue to accumulate in the Earth system until at least the end of the 21st century, even under strong mitigation scenarios, and will primarily be observed through ocean warming and associated with continued sea level rise through thermal expansion (IPCC AR6_WGI, confidence: high)
More comprehensive analysis of inventory components and cross-validation of global heating rates from satellite and in situ observations lead to a strengthened assessment relative to AR5 (IPCC AR6_WGI, confidence: high)
Both estimates are consistent with an independent observation-based assessment of the global energy increase of 284 [96 to 471] ZJ, (very likely range) expressed relative to the estimated 1850–1900 Earth energy imbalance (IPCC AR6_WGI, confidence: high)
These trends are neither a local phenomenon nor a measurement artefact (IPCC AR6_WGI, confidence: high)
The downward and upward thermal radiation at the surface has increased in recent decades, in line with increased greenhouse gas concentrations and associated surface and atmospheric warming and moistening (IPCC AR6_WGI, confidence: medium)
For carbon dioxide, the adjustments include the physiological effects on vegetation (IPCC AR6_WGI, confidence: high)
The 0.59 W m–2 increase in ERF from greenhouse gases is partly offset by a better-constrained assessment of total aerosol ERF that is more strongly negative than in AR5, based on multiple lines of evidence (IPCC AR6_WGI, confidence: high)
Changes in surface reflectance from land-use change, deposition of light-absorbing particles on ice and snow, and contrails and aviation-induced cirrus have also contributed to the total anthropogenic ERF over the industrial era, with –0.20 [–0.30 to –0.10] W m–2 (medium confidence), +0.08 [0 to 0.18] W m–2 (low confidence) and +0.06 [0.02 to 0.10] W m–2 (IPCC AR6_WGI, confidence: low)
The estimated ERF for methane has slightly increased due to a combination of increases from improved spectroscopic treatments being somewhat offset by accounting for adjustments (IPCC AR6_WGI, confidence: high)
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 (IPCC AR6_WGI, confidence: medium)
It is also assessed to be smaller in magnitude at –1.1 [–1.7 to –0.4] W m–2, primarily due to recent emissions changes (IPCC AR6_WGI, confidence: medium)
A net negative cloud feedback is very unlikely (IPCC AR6_WGI, confidence: high)
Furthermore, on long time scales the ice-sheet feedback parameter is very likely positive, promoting additional warming on millennial time scales as ice sheets come into equilibrium with the forcing (IPCC AR6_WGI, confidence: high)
This new understanding, along with updated estimates of historical temperature change, ERF, and Earth’s energy imbalance, reconciles previously disparate ECS estimates (IPCC AR6_WGI, confidence: high)
Warming over the instrumental record provides robust constraints on the lower end of the ECS range (IPCC AR6_WGI, confidence: high)
These higher ECS and TCR values can, in some models, be traced to changes in extra-tropical cloud feedbacks that have emerged from efforts to reduce biases in these clouds compared to satellite observations (IPCC AR6_WGI, confidence: medium)
The CMIP models with the highest ECS and TCR values provide insights into low-likelihood, high-impact outcomes, which cannot be excluded based on currently available evidence (IPCC AR6_WGI, confidence: high)
The calculated GSAT change is composed of a well-mixed greenhouse gas warming of 1.58 [1.17 to 2.17] °C (high confidence), a warming from ozone changes of 0.23 [0.11 to 0.39] °C (high confidence), a cooling of –0.50 [–0.22 to –0.96] °C from aerosol effects (medium confidence), and a –0.06 [–0.15 to +0.01] °C contribution from surface reflectance changes from land-use change and light-absorbing particles on ice and snow (IPCC AR6_WGI, confidence: medium)
Changes in solar and volcanic activity are assessed to have together contributed a small change of –0.02 [–0.06 to +0.02] °C since 1750 (IPCC AR6_WGI, confidence: medium)
Global ocean heat uptake is a smaller source of uncertainty in centennial-time scale surface warming (IPCC AR6_WGI, confidence: high)
When used for multi-scenario experiments, calibrated physically based emulators can adequately reflect assessments regarding future GSAT from Earth system models and/or other lines of evidence (IPCC AR6_WGI, confidence: high)
The causes of this polar amplification are well understood, and the evidence is stronger than at the time of AR5, supported by better agreement between modelled and observed polar amplification during warm paleo time periods (IPCC AR6_WGI, confidence: high)
The rate of Arctic surface warming will continue to exceed the global average over this century (IPCC AR6_WGI, confidence: high)
Metrics for methane from fossil fuel sources account for the extra fossil CO 2 that these emissions contribute to the atmosphere and so have slightly higher emissions metric values than those from biogenic sources (IPCC AR6_WGI, confidence: high)
By contrast, if emissions are weighted by their 100-year GWP or GTP values, different multi-gas emissions pathways with the same aggregated CO 2 equivalent emissions rarely lead to the same estimated temperature outcome (IPCC AR6_WGI, confidence: high)
In contrast, reaching net zero GHG emissions when quantified using new emissions metrics such as CGTP or GWP* would lead to approximate temperature stabilization (IPCC AR6_WGI, confidence: high)
In summary, since AR5, the magnitudes of the global mean energy budget components have been quantified more accurately, not only at the TOA, but also at the Earth’s surface, where independent estimates of the radiative components have converged (IPCC AR6_WGI, confidence: high)
In summary, variations in the energy exchange between Earth and space can be accurately tracked since the advent of improved observations since the year 2000 (high confidence), while reconstructions indicate that the Earth’s energy imbalance was larger in the 2000s than in the 1985–1999 period (IPCC AR6_WGI, confidence: high)
The assessed changes in the global energy inventory (Box 7.2, Figure 1, and Table 7.1) yields an average value for Earth’s energy imbalance (N in Box 7.1, Equation 7.1) of 0.57 [0.43 to 0.72] W m–2 for the period 1971–2018, expressed relative to Earth’s surface area (IPCC AR6_WGI, confidence: high)
The estimates for the periods 1993–2018 and 2006–2018 yield substantially larger values of 0.72 [0.55 to 0.89] W m–2 and 0.79 [0.52 to 1.06] W m–2, respectively, consistent with the increased radiative forcing from GHGs (IPCC AR6_WGI, confidence: high)
To put these numbers in context, the 2006–2018 average Earth system heating is equivalent to approximately 20 times the annual rate of global energy consumption in 2018.1 Consistent with AR5 (Rhein et al., 2013), this Report finds that ocean warming dominates the changes in the global energy inventory (IPCC AR6_WGI, confidence: high)
The contributions from the other components across all periods are approximately 5% from land heating, 3% for cryosphere heating and 1% associated with warming of the atmosphere (IPCC AR6_WGI, confidence: high)
The origin of these trends is not fully understood, although there is evidence that anthropogenic aerosols have made a substantial contribution (IPCC AR6_WGI, confidence: medium)
For the period 1970–2011, AR5 reported that the global energy budget was closed within uncertainties (IPCC AR6_WGI, confidence: high)
The physiological adjustments are therefore assessed to make a substantial contribution to the overall tropospheric adjustment for CO 2 (IPCC AR6_WGI, confidence: high)
Due to the agreement between the studies and the understanding of the physical mechanisms there is medium confidence in the mechanisms underpinning the tropospheric adjustment, but low confidence in its magnitude.The ERF from doubling CO 2 (2×CO 2) from the 1750 level (278 ppm; Section 2.2.3.3) is assessed to be 3.93 ± 0.47 W m–2 (IPCC AR6_WGI, confidence: high)
This does not correspond to the division between ozone production and ozone depletion and is sensitive to the choice of tropopause (IPCC AR6_WGI, confidence: high)
This small positive (but with uncertainty encompassing negative values) stratospheric ozone SARF is due to contributions from ozone precursors to lower stratospheric ozone and some of the CMIP6 models showing ozone depletion in the upper stratosphere, where depletion contributes a positive radiative forcing (IPCC AR6_WGI, confidence: medium)
As there is insufficient evidence to quantify adjustments, for total ozone the assessed central estimate for ERF is assumed to be equal to SARF (IPCC AR6_WGI, confidence: low)
It has increased by 0.49 W m–2 compared to AR5 (reference year 2011) (IPCC AR6_WGI, confidence: high)
Changes in the radiative efficiencies (including adjustments) of CO 2, CH 4, N 2O and halogenated compounds have increased the ERF by an additional 0.15 W m–2 compared to the AR5 values (IPCC AR6_WGI, confidence: high)
The combined ERF from ozone and stratospheric water vapour has increased since AR5 by 0.10 ± 0.50 W m–2 (IPCC AR6_WGI, confidence: high)
Based on the above, IRFari is assessed to be –0.25 ± 0.2 W m–2 (IPCC AR6_WGI, confidence: medium)
Adding this small adjustment to our assessed IRFari estimate of –0.25 W m–2, and accounting for additional uncertainty in the adjustments, ERFari is assessed to –0.3 ± 0.3 (IPCC AR6_WGI, confidence: medium)
Taking the average across the studies providing IRFaci estimates discussed above and considering the general agreement among estimates (Table 7.7), IRFaci is assessed to be –0.7 ± 0.5 W m–2 (IPCC AR6_WGI, confidence: medium)
These three studies together suggest a global Cf adjustment that augments ERFaci relative to IRFaci by –0.5 ± 0.4 W m–2 (IPCC AR6_WGI, confidence: medium)
Combining IRFaci and the associated adjustments in Cf and LWP (adding uncertainties in quadrature), considering only liquid-water clouds and evidence from satellite observations alone, the central estimate and very likely range for ERFaci is assessed to be –1.0 ± 0.7 W m–2 (IPCC AR6_WGI, confidence: medium)
There is thus limited evidence and medium agreement for a small negative contribution to ERFaci from anthropogenic INP-induced cirrus modifications (IPCC AR6_WGI, confidence: low)
From model-based evidence, ERFaci is assessed to –1.0 ± 0.8 W m–2 (IPCC AR6_WGI, confidence: medium)
The strong agreement between the two largely independent lines of evidence increases confidence in the overall assessment of the central estimate and very likely range for ERFaci of –1.0 ± 0.7 W m–2 (IPCC AR6_WGI, confidence: medium)
Based solely on energy balance considerations or other observational constraints, it is extremely likely that the total aerosol ERF is negative (high confidence), but extremely unlikely that the total aerosol ERF is more negative than –2.0 W m–2 (IPCC AR6_WGI, confidence: high)