Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change; Technical Summary
Abstract
The Working Group I (WGI) contribution to the Intergovernmental Panel on Climate Change Sixth Assessment Report (AR6) assess the physical science basis of climate change. As part of that contribution, this Technical Summary (TS) is designed to bridge between the comprehensive assessment of the WGI Chapters and its Summary for Policymakers (SPM). It is primarily built from the Executive Summaries of the individual chapters and atlas and provides a synthesis of key findings based on multiple lines of evidence (e.g., analyses of observations, models, paleoclimate information and understanding of physical, chemical and biological processes and components of the climate system). All the findings and figures here are supported by and traceable to the underlying chapters, with relevant chapter sections indicated in curly brackets.
... Conversely, the southeastern regions of Gansu, such as the Qinling and Minshan Mountains, harbor biodiversity hotspots due to their favorable climatic conditions and rich vegetation cover (Pollock et al., 2014). These areas are highly sensitive to changes in temperature and precipitation, which are predicted to intensify under future climate scenarios (Masson-Delmotte et al., 2021). Shifts in species distributions driven by warming temperatures and altered precipitation patterns in these mountainous areas could disrupt mutualistic interactions (e.g., pollination and seed dispersal) and lead to a loss of biodiversity (Bascompte and Jordano, 2007). ...
The interplay between plant diversity and environmental response strategies is crucial for ecosystem adaptability and stability. A central focus in modern ecology is elucidating how environmental factors shape plant diversity patterns and regulate species distributions across heterogeneous landscapes. This study employed Joint Species Distribution Model (JSDM) to quantitatively analyze the influence of environmental variables on plant spatial distributions in Gansu Province, China, while examining interspecies interactions under varying conditions. Results demonstrated that environmental factors explained 95.4% of the variance, highlighting their predominant role in determining plant distributions. Habitat type accounted for the largest share of variance (33.5%), followed by elevation (22.1%), mean annual temperature (20.3%), mean annual precipitation (15.1%), and solar radiation (4.4%). Species’ responses to environmental covariates were predominantly independent, with weak phylogenetic correlation (posterior mean: 0.17), reflecting limited ecological niche conservatism at the family level. Geographically, regions such as the northern Qilian foothills, Lanzhou-Baiyin wilderness, Loess Plateau, and Gannan Plateau exhibited negative correlations with most plant families, functioning as critical limiting or driving factors in spatial variability. Additionally, 33.7% of seed plant families showed negative correlations with light intensity, underscoring its role as a major limiting factor. Provincially, competition does not primarily constrain seed plant coexistence in Gansu. Regionally, however, pronounced differences in environmental responses were observed. In the northwest, solar radiation (37%) and precipitation (25%) were dominant drivers of plant distribution, while in the southeast, solar radiation (36.3%) and elevation (34.7%) were predominant. These findings underscore that species co-occurrence patterns are scale-dependent and influenced by regional resource availability. In resource-abundant southeastern areas, plant families displayed positive co-occurrence patterns indicative of mutualistic or symbiotic interactions, whereas resource-scarce northwestern areas experienced intensified negative co-occurrences due to heightened interspecific competition. This study highlights the critical role of environmental gradients in structuring seed plant distributions in Gansu, providing insights into the interaction of ecological adaptation and evolutionary history in shaping plant diversity. By identifying the drivers of plant distribution across heterogeneous environments, this research offers significant implications for biodiversity conservation and plant resource management strategies in Gansu Province, while contributing to a broader understanding of plant-environment dynamics in complex ecosystems.
... versus 0.8°[0.5°-1.2°] for CO 2 26,27 ) and is a critical driver of short-term warming dynamics 28,29 , making it instrumental for meeting the 1.5°C target 30,31 . Moreover, methane's GWP varies substantially with the time horizon considered, due to its short lifetime 11,24 . ...
Monitoring companies’ contributions to climate dynamics and their exposure to transition risks requires accurate measurements of their non-carbon dioxide greenhouse gas emissions (non-CO2 GHG). However, carbon accounting standards are not harmonised and allow for some discretion when converting emissions of different GHGs into CO2 equivalent units, the currency in which carbon footprints are expressed. Focusing on methane, we build counterfactual harmonised standards using the latest IPCC Global Warming Potential (GWP) values over 100 years and estimate a cumulative gap in reported methane emissions of 170MtCO2e ( ~6Tg) over a sample of 2864 companies. Changing the counterfactual from GWP100to GWP20, as recently codified in certain jurisdictions and initiatives, increases the cumulative gap to 3300MtCO2e ( ~40Tg). The gap only covers direct emissions and hence understates the extent of potential under-reporting across value chains. Overall, our study underscores the importance of global harmonisation of CO2-equivalence standards to coherently track corporate GHG emissions and their exposure to transition risks.
... This region is experiencing climate change-induced warming at a rate twice as fast as the global average. 4,5 In the early decades of this century, the ratio of the warming in Finland to global warming relative to 1981-2010 is close to 2 or even higher, but toward the end of the century, the ratio converges toward ∼1.6. 6 Precipitation is projected to increase and solar radiation to decrease in future winters. ...
Background
In Northern latitudes, winter is the darkest time of the year, and depressive episodes during winter are prevalent. Although changing weather patterns due to climate change are projected to result in warmer and wetter and, thus, even darker winters, research on the impact of winter-time natural light and precipitation on mental health is scarce. We examined associations of exposure to solar radiation and precipitation with psychotropic medication and antidepressant purchases in winter months.
Methods
Of the 251,268 eligible participants from the Finnish public sector study, aged ≥18 years, 72% were women. Associations for municipality-level 4-week average solar radiation and precipitation with register-based medication purchases from 1999 to 2016 were analyzed using random effects method with Poisson regression. A 6-month washout period with no purchases was applied to each purchase. Confounding by region and year, and effect modifications by sex, age, and socioeconomic status were examined.
Results
No association was observed for an increase in 4-week average of solar radiation by standard deviation (585 kJ/m ² ) with any psychotropic medications (incidence rate ratio: 0.99; 95% confidence interval: 0.98, 1.00) or antidepressants (1.00; 0.99, 1.01). No difference in any psychotropic medication or antidepressant purchases in participants exposed to high solar radiation (≥2000 kJ/m ² ) compared with those with the lowest exposure (<500 kJ/m ² ) was observed. No associations were observed for precipitation.
Conclusion
No evidence linking higher solar radiation exposure to reduced psychotropic medication purchases, nor higher precipitation exposure to increased medication purchases in winter was observed. Further research is needed to validate and expand upon these findings.
... For instance, application of basalt to ~50% global croplands could potentially remove 2.0 Gt CO 2 annually (Beerling et al., 2020). Considering the necessity of removing approximately 10 Gt CO 2 annually to limit global warming below 1.5 ºC (Masson-Delmotte et al., 2021;IPCC, 2018), enhanced basalt weathering in croplands alone could contribute around 20% of the required CDR. Similarly, a recent theoretical study suggests that implementing enhanced basalt weathering in US croplands could fulfill 36%−60% of the nation ' s technological CDR objectives (Beerling et al., 2023). ...
Enhanced silicate weathering (ESW) is a geoengineering method aimed at accelerating carbon dioxide (CO2) removal (CDR) from atmosphere by increasing the weathering flux of silicate rocks and minerals. It has emerged as a promising strategy for CDR. Theoretical studies underscore ESW’s substantial potential for CDR and its diverse benefits for crops when applied to croplands. However, the well-known significant discrepancies in silicate weathering rates between laboratory and field conditions introduce uncertainty in CDR through ESW. By compiling data from recent literature, we calculated and compared CDR efficiency (t CO2 tsilicate−1 ha−1 y−1) observed in mesocosm experiments and field trials. The findings indicate that CDR efficiencies in field trials are comparable to or exceeding that observed in mesocosm experiments by 1–3 orders of magnitude, particularly evident with wollastonite application. The hierarchy of CDR efficiency among silicates suitable for ESW is ranked as follows: olivine ⩾ wollastonite > basalt > albite ⩾ anorthite. We suggest the potential role of biota, especially fungi, in contributing to higher CDR efficiencies observed in field trials compared to mesocosm experiments. We further emphasize introducing fungi known for their effectiveness in silicate weathering could potentially enhance CDR efficiency through ESW in croplands. But before implementing fungal-facilitated ESW, three key questions need addressing: (i) How does the community of introduced fungi evolve over time? (ii) What is the long-term trajectory of CDR efficiency following fungal introduction? and (iii) Could fungal introduction lead to organic matter oxidation, resulting in elevated CO2 emissions? These investigations are crucial for optimizing the efficiency and sustainability of fungal-facilitated ESW strategy.
... Agricultural drought frequency has increased across all continents across the global and the trend is expected to continue under climate change (Seneviratne et al., 2021). Drought has been a recurrent feature of the Australian environment, often affecting agriculture through crop and stock losses, water supply availability, severe bushfires, dust storms and soil loss, and general environmental degradation (Kirono et al., 2020). ...
... Consequently, 190 countries in 2015 signed the Paris Agreement, committing to the conservation of the planet and encouraging the implementation of technologies that take advantage of renewable energy sources, to mitigate the use of fossil fuels [2]. Indeed, solar energy sources in the last decade have been projected as an alternative for the production of electrical and thermal energy through photovoltaic (PV) [3] and Thermosolar (SST) [3] systems, respectively, contributing to generate an energy mix worldwide [4]. ...
This article aims to evaluate the optical and thermal behavior of a small Fresnel linear concentrator prototype developed under the appropriate technology paradigm. The system was developed by the Energy, Automation and Control Systems Research Group of the Technological Units of Santander, Colombia for water heating. The study of the device was developed from a series of simulations that took into account the optical and thermal factors of the real system, and a series of alternative scenarios that seek to improve the performance of the device were evaluated. The simulation process was carried out by applying the "TRNSYS" Software in order to study the dynamic behavior of the concentrator and the "Soltrace" Software applying the Monte Carlo Ray Tracing method. The results obtained showed that the improvement scenarios proposed to evaluate the optical characteristics of the primary reflection system do not significantly increase the performance of the device, while the optical characteristics applied to the secondary reflection system do reflect a significant in-crease. Finally, the variation of flow and the area of the preheater show a direct relationship in performance, reaching values that predict the ideal value of the operating variable.
... The frequency and intensity of extreme heat events have been exacerbated due to the average temperature rise under global warming (Eyring et al., 2021). For instance, extreme heatwaves hit parts of Europe in 2018, 2019, and 2021 (Kay et al., 2020;Xu et al., 2020;Lhotka and Kyselý, 2022), North America in 2021 (Zhang et al., 2023a), and East Asia in 2022 and 2023 (Hua et al., 2023;Nie et al., 2024;Xiao et al., 2024). ...
The Yangtze River Valley (YRV) of China experienced record-breaking heatwaves in July and August 2022. The characteristics, causes, and impacts of this extreme event have been widely explored, but its seasonal predictability remains elusive. This study assessed the real-time one-month-lead prediction skill of the summer 2022 YRV heatwaves using 12 operational seasonal forecast systems. Results indicate that most individual forecast systems and their multi-model ensemble (MME) mean exhibited limited skill in predicting the 2022 YRV heatwaves. Notably, after the removal of the linear trend, the predicted 2-m air temperature anomalies were generally negative in the YRV, except for the Met Office GloSea6 system, which captured a moderate warm anomaly. While the models successfully simulated the influence of La Niña on the East Asian–western North Pacific atmospheric circulation and associated YRV temperature anomalies, only GloSea6 reasonably captured the observed relationship between the YRV heatwaves and an atmospheric teleconnection extending from the North Atlantic to the Eurasian mid-to-high latitudes. Such an atmospheric teleconnection plays a crucial role in intensifying the YRV heatwaves. In contrast, other seasonal forecast systems and the MME predicted a distinctly different atmospheric circulation pattern, particularly over the Eurasian mid-to-high latitudes, and failed to reproduce the observed relationship between the YRV heatwaves and Eurasian mid-to-high latitude atmospheric circulation anomalies. These findings underscore the importance of accurately representing the Eurasian mid-to-high latitude atmospheric teleconnection for successful YRV heatwave prediction.
El objetivo de este trabajo es desarrollar una metodología preliminar que permita identificar las zonas de actuación prioritarias en la restauración post-incendio en el incendio forestal ocurrido en Sierra Bermeja (provincia de Málaga) en 2021. El fuego afectó a un entorno serpentínico donde se produjo uno de los incendios más relevantes de las últimas décadas en la provincia de Málaga, con 8.401 hectáreas calcinadas. Para la delimitación de las zonas de actuación prioritarias, se han utilizado una metodología multicriterio que combina técnicas de teledetección, muestreo y analíticas de suelos y modelos para el cálculo de tasas de erosión. Todo ello integrado en un entorno SIG. Los resultados de la metodología propuesta arrojan que tres áreas de Sierra Bermeja presentan una importante severidad incendiaria y graves problemas de regeneración natural por su afección en suelos, cubierta vegetal y elevadas tasas erosión
Hot extreme events are among the most devastating disasters affecting human health and the natural environment. While there is broad consensus on an increasing severity of these events under anthropogenic warming, their geographical distribution exhibits substantial spatial heterogeneity, and its driving factors remain uncertain. Here, utilizing an eddy-resolving high-resolution climate model alongside multiple simulations from Coupled Model Intercomparison Project Phase 6, we find baseline temperature variability as a key factor shaping the global distribution of projected hot extremes, with over 80% of the global increase in hot extremes anticorrelated with baseline temperature variability. We further demonstrate that the baseline temperature variability is anchored by persistent land-atmosphere coupling, which endures over century timescales and sustains the spatial heterogeneity of future hot extremes. Our findings suggest that baseline temperature variability could serve as a potential indicator for future hot extreme distribution, offering valuable insights for developing targeted adaptation strategies and improving regional resilience.
The impact of aerosols on clouds, which remains one of the largest aspects of uncertainty in current weather forecasting and climate change research, can be influenced by various factors, such as the underlying surface type, cloud type, cloud phase, and aerosol type. To explore the impact of different underlying surfaces on the effect of aerosols on cloud development, this study focused on the Yangtze River Delta (YRD) and its offshore regions (YRD sea) for a comparative analysis based on multi-source satellite data, while also considering the variations in cloud type and cloud phase. The results show lower cloud-top height and depth of single-layer clouds over the ocean than land, and higher liquid cloud in spring over the ocean. Aerosols are found to enhance the cumulus cloud depth through microphysical effects, which is particularly evident over the ocean. Aerosols are also found to decrease the cloud droplet effective radius in the ocean region and during the mature stage of cloud development in the land region, while opposite results are found during the early stage of cloud development in the land region. The quantitative results indicate that the indirect effect is positive (0.05) in the land region at relatively high cloud water path, which is smaller than that in the ocean region (0.11). The findings deepen our understanding of the influence aerosols on cloud development and the mechanisms involved, which could then be applied to improve the ability to simulate cloud-associated weather processes.
Figure 1: Global mean sea level change on different time scales and under different scenarios
- T S Box
Box TS.4, Figure 1: Global mean sea level change on different time scales and under different scenarios. (a)
Lightly shaded thick/thin bars show 1th7-83rd/5th-95th percentile low-confidence ranges
- Ssps
SSPs. Lightly shaded thick/thin bars show 1th7-83rd/5th-95th percentile low-confidence ranges