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1,000 | AR6_WGI | 778 | 26 | Forest- based methods can either raise or lower N 2O emissions, depending on tree species, previous land use, soil type and climatic factors | low | 0 | train |
1,001 | AR6_WGI | 778 | 28 | Afforestation will decrease biodiversity if native species are replaced by monocultures | high | 2 | train |
1,002 | AR6_WGI | 779 | 8 | Some soil carbon sequestration methods, such as cover crops and crop diversity, can increase biodiversity | medium | 1 | train |
1,003 | AR6_WGI | 779 | 11 | Biochar application improves many soil qualities and increases crop yield (medium confidence) (Ye et al., 2020; SRCCL, Chapter 4.9.5), particularly in already degraded or weathered soils (Woolf et al., 2010; Lorenz and Lal, 2014; Jeffery et al., 2016), increases soil water holding capacity | medium | 1 | train |
1,004 | AR6_WGI | 779 | 12 | Fischer et al., 2019; Verheijen et al., 2019) and evapotranspiration | low | 0 | train |
1,005 | AR6_WGI | 779 | 14 | The use of biochar reduces nutrient losses | low | 0 | test |
1,006 | AR6_WGI | 779 | 15 | Biochar addition may decrease methane (CH 4) emissions in inundated and acid soils such as rice fields | low | 0 | train |
1,007 | AR6_WGI | 779 | 16 | In non-inundated, neutral soils, CH 4 uptake from the atmosphere is suppressed after biochar application (low confidence) (Jeffery et al., 2016), and soil N2O emissions decline | medium | 1 | train |
1,008 | AR6_WGI | 779 | 21 | High water level and anoxic conditions are prerequisites for restoring by returning drained and/or degraded peatlands back to their natural state as CO 2 sinks, but restoration also results in enhanced CH 4 emissions which are similar to or higher than the pre-drainage fluxes | high | 2 | train |
1,009 | AR6_WGI | 779 | 23 | Rewetting drained peatlands will decrease N2O emissions | medium | 1 | train |
1,010 | AR6_WGI | 779 | 25 | Peatland restoration can also recover much of the original biodiversity | medium | 1 | train |
1,011 | AR6_WGI | 779 | 33 | BECCS has several trade- offs to deal with, including possible threats to water supply and soil nutrient deficiencies | medium | 1 | train |
1,012 | AR6_WGI | 780 | 1 | Highest co-benefits are obtained with methods that seek to restore natural ecosystems and improve soil carbon sequestration (Figure 5.36) while highest trade- off possibilities (symmetry with the highest co-benefits) occur for reforestation or afforestation with monocultures and BECCS, again with strong dependence on scale and context | medium | 1 | train |
1,013 | AR6_WGI | 780 | 15 | While coastal habitat restoration potentially provides significant mitigation of national emissions for some countries (Taillardat et al., 2018; Serrano et al., 2019), the global sequestration potential of blue carbon approaches is <0.02 PgC yr–1 | medium | 1 | train |
1,014 | AR6_WGI | 780 | 20 | EW can also contribute to freshwater salinization as a result of increased salt inputs and cation exchange in watersheds, and so adversely affecting drinking water quality | low | 0 | train |
1,015 | AR6_WGI | 780 | 26 | Ocean alkalinization ameliorates surface ocean acidification | high | 2 | train |
1,016 | AR6_WGI | 784 | 21 | Despite the large uncertainty in modelled NPP response, existing modelling studies consistently show that SRM would increase the global land carbon sink relative to a high-CO 2 world without SRM | high | 2 | train |
1,017 | AR6_WGI | 784 | 22 | Based on available evidence, SRM with elevated CO 2 would increase global mean NPP and carbon storage on land relative to an unperturbed climate, mainly because of CO 2 fertilization of photosynthesis | high | 2 | train |
1,018 | AR6_WGI | 784 | 34 | As a result of enhanced global carbon uptake, SRM would reduce the burden of atmospheric CO 2 | high | 2 | train |
1,019 | AR6_WGI | 785 | 9 | Compared to a high-CO 2 world without SRM, SRM would enhance the net uptake of CO 2 by the terrestrial biosphere and ocean, thus acting to reduce atmospheric CO 2 | high | 2 | train |
1,020 | AR6_WGI | 835 | 8 | Recent Evolution in Short-lived Climate Forcer (SLCF) Emissions and Abundances Over the last decade (2010–2019), strong shifts in the geographical distribution of emissions have led to changes in atmospheric abundances of highly variable SLCFs | high | 2 | train |
1,021 | AR6_WGI | 835 | 9 | Evidence from satellite and surface observations shows strong regional variations in trends of ozone (O 3), aerosols and their precursors | high | 2 | train |
1,022 | AR6_WGI | 835 | 10 | In particular, tropospheric columns of nitrogen dioxide (NO 2) and sulphur dioxide (SO 2) continued to decline over North America and Europe (high confidence), and to increase over Southern Asia (medium confidence), but have declined over Eastern Asia | high | 2 | train |
1,023 | AR6_WGI | 835 | 11 | Global carbon monoxide (CO) abundance has continued to decline | high | 2 | train |
1,024 | AR6_WGI | 835 | 12 | The concentrations of hydrofluorocarbons (HFCs) are increasing | high | 2 | train |
1,025 | AR6_WGI | 835 | 21 | Radiative forcings induced by aerosol changes lead to both local and remote temperature responses | high | 2 | train |
1,026 | AR6_WGI | 835 | 22 | The temperature response preserves the south to north gradient of the aerosol ERF – hemispherical asymmetry – but is more uniform with latitude and is strongly amplified towards the Arctic | medium | 1 | train |
1,027 | AR6_WGI | 835 | 25 | The spatial and temporal distribution of the net aerosol ERF from 1850 to 2014 is highly heterogeneous, with stronger magnitudes in the Northern Hemisphere | high | 2 | test |
1,028 | AR6_WGI | 835 | 27 | Near its maximum, the response slows down but will then take centuries to reach equilibrium | high | 2 | train |
1,029 | AR6_WGI | 835 | 28 | For SLCFs with longer lifetimes (e.g., a decade), a delay equivalent to their lifetimes is appended to the delay due to thermal inertia | high | 2 | train |
1,030 | AR6_WGI | 835 | 30 | The net global emissions‑based ERF of NO x is negative and that of non‑methane volatile organic compounds (NMVOCs) is positive, in agreement with the AR5 Assessment | high | 2 | train |
1,031 | AR6_WGI | 835 | 31 | For methane, the emissions‑based ERF is twice as high as the abundance‑based ERF | high | 2 | train |
1,032 | AR6_WGI | 836 | 1 | Over the 1750–2019 period, the contributions from the emitted compounds to changes in global surface air temperature (GSAT) broadly match their contributions to the ERF | high | 2 | train |
1,033 | AR6_WGI | 836 | 5 | As such, these effects are assessed to be of second order in comparison to the direct CO 2 forcing (high confidence), but effects of ozone on terrestrial vegetation could add a substantial (positive) forcing compared with the direct ozone forcing | low | 0 | train |
1,034 | AR6_WGI | 836 | 10 | A warmer climate is expected to reduce surface ozone in regions remote from pollution sources | high | 2 | train |
1,035 | AR6_WGI | 836 | 11 | Future climate change is expected to have mixed effects, positive or negative, with an overall low effect, on global surface PM and more generally on the aerosol global burden (medium confidence), but stronger effects are not excluded in regions prone to specific meteorological conditions | low | 0 | train |
1,036 | AR6_WGI | 836 | 17 | 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 | test |
1,037 | AR6_WGI | 836 | 18 | Without climate change mitigation but with stringent air pollution control (SSP5‑8.5), PM levels decline through 2100, but high methane levels hamper the decline in global surface ozone at least until 2080 | high | 2 | train |
1,038 | AR6_WGI | 837 | 6 | Sectors producing the largest SLCF-induced warming are those dominated by methane emissions: fossil fuel production and distribution, agriculture and waste management | high | 2 | train |
1,039 | AR6_WGI | 837 | 7 | On these time scales, SLCFs with cooling effects can significantly mask the CO 2 warming in the case of fossil fuel combustion for energy and land transportation, or completely offset the CO 2 warming and lead to an overall net cooling in the case of industry and maritime shipping (prior to the implementation of the revised fuel‑sulphur limit policy for shipping in 2020) | medium | 1 | train |
1,040 | AR6_WGI | 837 | 8 | Ten years after a one‑year pulse of present‑day aviation emissions, SLCFs induce strong but short‑lived warming contributions to the GSAT response | medium | 1 | train |
1,041 | AR6_WGI | 837 | 10 | Consequently, on time scales longer than about 30 years, the net long-term global temperature effects of sectors and regions are dominated by CO 2 | high | 2 | train |
1,042 | AR6_WGI | 837 | 13 | About 30 years or more after a one‑year emission pulse occurs, the sectors contributing the most to global warming are industry, fossil fuel combustion for energy and land transportation, essentially through CO2 | high | 2 | test |
1,043 | AR6_WGI | 837 | 14 | Current emissions of SLCFs, CO 2 and N 2O from Eastern Asia and North America are the largest regional contributors to additional net future warming on both short (medium confidence) and long time scales | high | 2 | train |
1,044 | AR6_WGI | 837 | 17 | Energy and industry are important PM 2.5 contributors in most regions, except Africa | high | 2 | train |
1,045 | AR6_WGI | 837 | 20 | Further improvements in the efficiency of refrigeration and air ‑conditioning equipment during the transition to low‑global‑ warming‑potential refrigerants would bring additional greenhouse gas reductions | medium | 1 | train |
1,046 | AR6_WGI | 837 | 22 | This warming is stable after 2040 in scenarios leading to 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 (induced by growing fossil fuel use and limited air pollution control) | high | 2 | train |
1,047 | AR6_WGI | 837 | 26 | 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 ‑quality benefits by reducing surface ozone levels globally | high | 2 | train |
1,048 | AR6_WGI | 838 | 1 | Additional methane and BC mitigation would contribute to offsetting the additional warming associated with SO 2 reductions that would accompany decarbonization | high | 2 | train |
1,049 | AR6_WGI | 838 | 2 | Strong air pollution control as well as strong climate change mitigation, implemented separately, lead to large reductions in exposure to air pollution by the end of the century | high | 2 | train |
1,050 | AR6_WGI | 838 | 3 | Implementation of air pollution controls, relying on the deployment of existing technologies, leads more rapidly to air quality benefits than climate change mitigation | high | 2 | train |
1,051 | AR6_WGI | 838 | 4 | However, in both cases, significant parts of the population are projected to remain exposed to air pollution exceeding the WHO guidelines | high | 2 | train |
1,052 | AR6_WGI | 838 | 8 | Global anthropogenic NO x emissions decreased by a maximum of about 35% in April 2020 | medium | 1 | train |
1,053 | AR6_WGI | 838 | 10 | Global fossil CO 2 emissions decreased by 7% (with a range of 5.8–13.0%) in 2020 relative to 2019, largely due to reduced emissions from the transportation sector | medium | 1 | train |
1,054 | AR6_WGI | 838 | 12 | Consistent with this small net radiative forcing, and against a large component of internal variability, Earth system model simulations show no detectable effect on global or regional surface temperature or precipitation | high | 2 | train |
1,055 | AR6_WGI | 841 | 30 | The SRCCL concluded that: (i) there is no agreement about the direction of future changes in mineral dust emissions; (ii) fossil fuel and biomass burning, and secondary organic aerosols (SOA) from natural BVOC emissions are the main global sources of carbonaceous aerosols whose emissions are expected to increase in the near future due to possible increases in open biomass burning and increase in SOA from oxidation of BVOCs | medium | 1 | train |
1,056 | AR6_WGI | 843 | 27 | However, Chinese emissions declined by nearly 70% between about 2006 and 2017 | high | 2 | train |
1,057 | AR6_WGI | 843 | 32 | Since about 2011, global NO x emissions appear to have stabilized or slightly declined | medium | 1 | train |
1,058 | AR6_WGI | 843 | 34 | Liu et al., 2016; Miyazaki et al., 2017; Silver et al., 2018): a strong decline of NO 2 column over eastern China | high | 2 | train |
1,059 | AR6_WGI | 844 | 3 | Efforts to control transport emissions (i.e., increasing stringency of vehicle emissions limits) were largely offset by the fast growth of emissions from chemical industries and solvent use, as well as from fossil fuel production and distribution, resulting in continued growth of global anthropogenic NMVOC emissions since 1900 | high | 2 | train |
1,060 | AR6_WGI | 844 | 5 | Increasing (since 2008) oil‑ and gas‑extraction activities in North America lead to a strong growth of NMVOC emissions | high | 2 | train |
1,061 | AR6_WGI | 844 | 13 | Emissions of carbonaceous aerosols (BC, OC) have been steadily increasing and their emissions have almost doubled since 1950 | medium | 1 | train |
1,062 | AR6_WGI | 844 | 14 | Before 1950, North America and Europe contributed about half of the global total but successful introduction of diesel particulate filters on road vehicles (Fiebig et al., 2014; Robinson et al., 2015; Klimont et al., 2017a) and declining reliance on solid fuels for heating brought in large reductions | high | 2 | train |
1,063 | AR6_WGI | 844 | 15 | Currently, global carbonaceous aerosol emissions originate primarily from Asia and Africa (Bond et al., 2013; Hoesly et al., 2018; Elguindi et al., 2020; McDuffie et al., 2020), representing about 80% of the global total | high | 2 | train |
1,064 | AR6_WGI | 844 | 20 | Overall, a factor two uncertainty in global estimates of BC and OC emissions remains, with post‑ 2005 emissions overestimated in Asia (high confidence) and Africa | medium | 1 | train |
1,065 | AR6_WGI | 844 | 21 | Bottom‑up global emissions estimates of methane (Lamarque et al., 2010; Hoesly et al., 2018; Janssens‑Maenhout et al., 2019; Höglund‑Isaksson et al., 2020) for the last two decades are higher than top‑down assessments (e.g., Saunois et al., 2016, 2020) but trends from the two methods are similar and indicate continued growth | high | 2 | train |
1,066 | AR6_WGI | 844 | 24 | NH 3 emissions are estimated to have grown strongly since 1850, especially since 1950, driven by continuously increasing livestock production, widespread application of mineral nitrogen fertilizers, and lack of action to control ammonia | high | 2 | train |
1,067 | AR6_WGI | 847 | 25 | Overall, we assess that historical global isoprene emissions declined between the pre‑industrial period and the present day by 10–25% | low | 0 | train |
1,068 | AR6_WGI | 854 | 12 | This increase is assessed to be 109 ± 25 Tg | medium | 1 | train |
1,069 | AR6_WGI | 855 | 16 | In summary, global tropospheric NO x abundance has increased from 1850–2015 | high | 2 | train |
1,070 | AR6_WGI | 855 | 19 | NO 2 trends have reversed (declining) over China beginning in 2012 and NO 2 has increased over Southern Asia by 50% since 2005 | medium | 1 | train |
1,071 | AR6_WGI | 858 | 7 | 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 | high | 2 | train |
1,072 | AR6_WGI | 858 | 8 | Trends in satellite HCHO observations, used as a proxy of anthropogenic NMVOC over industrialized areas, show a significant positive trend over eastern China | high | 2 | train |
1,073 | AR6_WGI | 864 | 27 | That would give BrC a burden similar to that of BC | low | 0 | train |
1,074 | AR6_WGI | 867 | 6 | In summary, global mean tropospheric OH does not show a significant trend from 1850 up to around 1980 | low | 0 | train |
1,075 | AR6_WGI | 869 | 4 | In summary, the spatial and temporal distribution of the net aerosol ERF from 1850–2014 is highly heterogeneous | high | 2 | train |
1,076 | AR6_WGI | 869 | 5 | 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 | high | 2 | train |
1,077 | AR6_WGI | 871 | 10 | In summary, emissions of SLCFs, especially methane, NO x and SO 2, have substantial effects on effective radiative forcing (ERF) | high | 2 | train |
1,078 | AR6_WGI | 871 | 11 | The net global emissions‑based ERF of NO x is negative and that of NMVOCs is positive, in agreement with the AR5 assessment | high | 2 | train |
1,079 | AR6_WGI | 871 | 12 | For methane, the emissions‑based ERF is twice as high as the abundance‑based ERF | high | 2 | train |
1,080 | AR6_WGI | 871 | 13 | SO 2 emissions make the dominant contribution to the ERF associated with the aerosol–cloud interaction | high | 2 | train |
1,081 | AR6_WGI | 871 | 14 | The contributions from the emitted compounds to GSAT broadly follow their contributions to the ERF | high | 2 | train |
1,082 | AR6_WGI | 871 | 21 | The overall effect of surface cooling from anthropogenic aerosols is to reduce global precipitation and alter large‑ scale atmospheric circulation patterns | high | 2 | train |
1,083 | AR6_WGI | 872 | 2 | The zonal‑mean temperature response is negative at all latitudes | high | 2 | train |
1,084 | AR6_WGI | 872 | 7 | 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 | high | 2 | train |
1,085 | AR6_WGI | 872 | 8 | 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 | high | 2 | train |
1,086 | AR6_WGI | 873 | 1 | In summary, over the historical period, changes in aerosols and their ERF have primarily contributed to cooling, partly masking the human‑induced warming | high | 2 | train |
1,087 | AR6_WGI | 873 | 2 | Radiative forcings induced by aerosol changes lead to both local and remote changes in temperature | high | 2 | train |
1,088 | AR6_WGI | 873 | 3 | The temperature response preserves hemispheric asymmetry of the ERF but is more latitudinally uniform with strong amplification of the temperature response towards the Arctic | medium | 1 | train |
1,089 | AR6_WGI | 873 | 11 | 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 | low | 0 | train |
1,090 | AR6_WGI | 873 | 23 | At large scales the dominant effect of aerosols on the carbon cycle is likely a global cooling effect of the climate | medium | 1 | train |
1,091 | AR6_WGI | 873 | 25 | In summary, reactive nitrogen, ozone and aerosols affect terrestrial vegetation and the carbon cycle through deposition and effects on large‑scale radiation | high | 2 | train |
1,092 | AR6_WGI | 873 | 26 | 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 | low | 0 | train |
1,093 | AR6_WGI | 877 | 6 | Modelling studies have been published with more sophisticated treatment of SRM since AR5, but the uncertainties, such as cloud–aerosol radiation interactions, remain large | high | 2 | train |
1,094 | AR6_WGI | 879 | 7 | Overall, warmer climate is expected to reduce surface ozone in unpolluted regions as a result of greater water vapour abundance accelerating ozone chemical loss | high | 2 | train |
1,095 | AR6_WGI | 879 | 10 | The response of surface ozone to future climate change through stratosphere–troposphere exchange, soil NO x emissions and wildfires is positive | medium | 1 | train |
1,096 | AR6_WGI | 881 | 21 | 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 | high | 2 | test |
1,097 | AR6_WGI | 881 | 22 | Near its maximum, the response slows down but will then take centuries to reach equilibrium | high | 2 | train |
1,098 | AR6_WGI | 881 | 23 | 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 | high | 2 | train |
1,099 | AR6_WGI | 882 | 21 | Residential sector emissions are an important source of indoor and outdoor air pollution in Asia and globally | high | 2 | train |
Subsets and Splits