Global Dimming Research Articles

Sulfur affects multi-scale starch structures and its contribution to the cookie-baking quality of wheat subjected to shade stress.

The components and structure of starch macromolecules critically determine its food-use properties. However, elemental sulfur supplementation affects the relationship between starch structure and the cookie-making quality of wheat under shaded environments remains unclear. Here, we investigated the effect of sulfur on the starch multi-scale structures and its contribution to the cookie-baking quality of wheat after pre- or post-anthesis shading. Compared with the unshaded control, shade stress decreased the amylose and total starch contents, formed smaller B-type starch granules, narrowed the molecular weight distribution, and decreased the amylopectin long-chain proportion, crystallinity, viscosity, and spread ratio of cookies. Weak-gluten cultivars are more sensitive to shade stress than strong-gluten cultivars. Under shaded environments, sulfur increased the amylopectin content, proportion of amylopectin short chains, and total starch content, increasing the mean diameter of starch granules and viscosity, ultimately decreasing the cookie hardness. The random forest model revealed that the surface area of the starch granules (18.7%) and amylopectin B3 chain (6.7%) contributed the most to the variation in the cookie spread ratio. Cookie hardness was determined mainly by the total starch (7.8%), amylopectin (6.3%), and trough viscosity (5.0%). Our results help to design strategies for achieving superior-quality wheat in the context of global dimming.

Can the Artificial Release of Fluorinated Gases Offset Global Cooling Due to Supervolcanic Eruptions?

Large volcanic eruptions, such as the prehistoric Yellowstone eruption, induce abrupt global cooling—by some estimates at a rate of ~1 °C/year, lasting for more than a decade. An abrupt global cooling of several °C—even if only lasting a few years—would present immediate, drastic stress on biodiversity and food production. This cooling poses a global catastrophic risk to human society beyond the immediate and direct impact of eruptions. Using a simple climate model, this paper discusses the possibility of counteracting large volcanic cooling with the intentional release of greenhouse gases. Longer-lived compounds (e.g., CO2 and CH4) are unsuitable for this purpose, but selected fluorinated gases (F-gases), either individually or in combinations, could be released at gigaton scale to offset large volcanic cooling substantially. We identify candidate F-gases (e.g., C4F6 and CH3F) and derive radiative and chemical properties of ‘ideal’ compounds matching specific cooling events. Geophysical constraints on manufacturing and stockpiling due to mineral availability are considered, alongside technical and economic implications based on present-day market assumptions. The effects and uncertainty due to atmospheric chemistry related to aerosol injection, F-gases release, and solar dimming are discussed in the context of large volcanic perturbation. The caveats and future steps using more complex chemistry–climate models are discussed. Despite the speculative nature of the magnitude and composition of F-gases, our conceptual analysis has implications for testing the possibility of mitigating certain global catastrophic cooling risks (e.g., nuclear winter, asteroid impact, and glacier transition) via intentional intervention.

Regional impacts of solar radiation modification on surface temperature and precipitation in Mainland Southeast Asia and the adjacent oceans.

Solar radiation modification (SRM) has been proposed to temporarily reduce anthropogenic warming. This study presents an assessment of the regional impacts of SRM via solar dimming and stratospheric aerosol injection (SAI) on temperature and precipitation over 0°-30° N and 90° E-110° E, covering Mainland Southeast Asia and adjacent oceans. Using data from the Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6), we examine regional impacts of SRM using three SRM experiments: (1) G6Sulfur, which reduces radiative forcing from the high-emission SSP5-8.5 scenario to the moderate-emission SSP2-4.5 scenario by injecting sulfate aerosols; (2) G6Solar, which similarly reduces radiative forcing from the high-emission to moderate-emission scenarios but by uniformly reducing the solar constant; and (3) G1ext, which reduces radiative forcing from a quadrupled carbon dioxide concentration to pre-industrial levels by uniform solar constant reduction. Our findings show that higher greenhouse gas emissions increase overall precipitation, along with tendencies to have extreme rainfall events and more dry episodes in between. While SRM can partially cool down the surface temperature warming caused by increased greenhouse gas emissions, its effects on precipitation are complex: Solar dimming in G6Solar and G1ext tends to reduce overall precipitation, and tropical sulfate injection in G6Sulfur could lead to further drying in the tropics because of the stratospheric warming associated with the injected aerosols. Different SRM strategies might result in different responses on precipitation.

Simulation of source sink partitioning in wheat under varying nitrogen regimes using DSSAT-CERES-wheat model

Grain yields in wheat can be limited by the assimilate supply (source) or by the carbohydrate demand of the grains (sink). Recently, there have been questions regarding the capability of crop models to simulate the physiology of source-sink interactions in crops; however, crop models scarcely tested with source-sink partitioning. DSSAT_CERES_Wheat model was used with details of field experimental data having treatments of manipulated source (i.e., assimilate supply), sink (i.e., kernel number). The aim of the present study was to assess the impact of different levels of nitrogen and source-sink manipulation on wheat crop and to model source-sink partitioning in wheat under varying N-Regimes and climatic conditions. The experiment was conducted during wheat growing seasons of 2015–16 and 2016–17, at two locations (Islamabad and URF Koont Chakwal), under five different levels of nitrogen and three source sink treatments (Control (100 % RUE), 50 % shading pre-anthesis (50 % RUE), 50 % spike removal i.e. spike halving) using randomized complete block design. Recommended rates of fertilizer were applied with the exception of nitrogen which was 0, 50, 100, 150 and 200 kg ha−1, while each treatment was replicated thrice. CERES-Wheat model was calibrated using 2015–16 observed data while model was evaluated using two-year field collected data of two sites i.e. Islamabad and Chakwal. The model was able to simulate treatments impacts on phenology (R2, RMSE and d-index values of 0.89, 2.80 days and 0.97 respectively at Islamabad while at Chakwal R2 = 0.89, RMSE = 2.65 days and d-index = 0.94), leaf area index (R2 = 0.94, 0.94, RMSE = 0.51, 0.38 and d-index = 0.98 and 0.92 at Islamabad and Chakwal respectively), biomass (R2 = 0.98, 0.96, RMSE = 370, 450 kg ha−1 and d-index = 0.96 and 0.95 at Islamabad and Chakwal respectively), grain yield (R2 = 0.97,0.96, RMSE = 0.17, 0.2 t ha−1, and d-index = 0.95 and 0.93 at Islamabad and Chakwal respectively), harvest index, soil nitrogen, crop nitrogen and grain nitrogen with good accuracy. The observed range for biomass water use efficiency (BM_WUE) was 34.1–14.5 kg ha−1 mm−1 while grain WUE remained in the range of 10.3–3.7 kg ha−1 mm−1. The results depicted that model could reproduce observed effects of shading and halving the spikes. Crop response to modified radiation use efficiency (RUE) was variable among sites which could be critical for studying crop environment interactions, improving WUE, estimating genetically and atmospheric CO2-related increased RUE, analyzing impact of solar dimming and source manipulations under biotic stress.

Projected impact of solar radiation modification geoengineering on water deficit risk over major Central African river basins

Abstract The economy of Central African countries strongly depends on rain-fed agriculture and hydropower generation. However, most countries in this subregion do not yet have the irrigation technologies that are already applied in many more advanced nations, which further exposes them to the serious risk of severe drought caused by global warming. This study investigates the potential impact of solar radiation modification (SRM) geoengineering on the water availability over the four major river basins that cross most of Central African countries (i.e. Niger Basin, Lake Chad Basin, Cameroon Atlantic Basin (CAB) and Congo Basin). For this purpose a potential water availability index was computed based on an ensemble-mean simulations carried out in the framework of Phase 6 of the Geoengineering Model Intercomparison Project considering two SRM simulation experiments: the stratospheric sulphate aerosol injection (G6sulfur) and the global solar dimming (G6solar). The climate change simulation results in a robust decreases by up to 60% in water availability, most pronounced over the CAB under the high radiative forcing scenario. Therefore, in a business-as-usual world, the reduction in water availability combined with the rapid population growth expected by 2050 in the studied subregion, could result in a significant water deficit over Central African countries towards the end of the 21st century. This water deficit could affect all activities that depend on water resources, such as water supply, agriculture and hydropower generation. Furthermore, the results also show that SRM methods have the potential to significantly reduce this deficit by increasing water availability (as compared to climate change) by up to 50% over the affected river basins, with a more accentuated increase found in the CAB when the global solar dimming is applied. These results suggest good possibilities of adaptation for populations living in the geographical areas of these river basins.

Ideal phenotypic characteristics and parental lines for hybrid rice breeding to cope with global dimming

The global food crisis has intensified with climate change, and hybrid rice (Oryza sativa L.) is expected to play a crucial role in ensuring world food security. This study analyzed the parental origins and variety characteristics of 930 hybrid rice varieties bred in Sichuan Province, a typical low-light region and one of the main production areas for hybrid rice, from 2002 to 2022. The results indicate that these varieties were hybridized using 329 direct female and 539 direct male parents. Notably, the female parent Peiai 64 and the male parents Yuehesimiao and Fenghuazhan demonstrated a higher probability of breeding rice varieties with high yield and good quality. An ideal panicle type should possess more grains, a lower 1000-grain weight, a higher seed setting percentage, and greater grain density. It is recommended to increase the utilization of excellent parents in Sichuan Province, such as parents with ideal panicle type to improve resistance to climate change, particularly global dimming.

Multi‐Model Simulation of Solar Geoengineering Indicates Avoidable Destabilization of the West Antarctic Ice Sheet

AbstractHeat transported in Circumpolar Deep Water is driving the break‐up of ice shelves in the Amundsen Sea sector of Antarctica, that has been simulated to be unavoidable under all plausible greenhouse gas scenarios. However, Solar geoengineering scenarios remain largely unexplored. Solar geoengineering changes global thermal radiative balance, and atmospheric and oceanic transportation pathways. We simulate stratospheric aerosol injection (SAI) designed to reduce global mean temperatures from those under the unmitigated SSP5‐8.5 scenario to those under the SSP2‐4.5 scenario with six CMIP6‐class Earth System Models. These consistently show intensified Antarctic polar vortex and sub‐polar westerlies, which mitigates changes to easterly winds along the Amundsen Sea continental shelf compared with greenhouse gas scenarios. The models show significantly cooler Amundsen Sea waters and lower heat content at 300–600 m under SAI than with either solar dimming or the SSP5‐8.5 unmitigated greenhouse gas scenarios. However, the heat content increases under all scenarios compared with present day suggesting that although vulnerable ice shelves would continue to thin, the rate would be lower for SAI even with SSP5‐8.5 specified greenhouse gases, than for the moderate (SSP2‐4.5) scenario. The simulations here use solar geoengineering designed to meet global temperature targets; interventions targeted at preserving the frozen high latitudes have also been proposed that might be expected to produce bigger local effects, but potentially deleterious impacts elsewhere. Considering the huge disruptions to society of ice sheet collapse, more research on avoiding them by intervention technology is a moral imperative.

Causes for Decadal Trends in Surface Solar Radiation in the Alpine Region in the 1981–2020 Period

AbstractExtending across seven countries, the Alps represent an important element for climate and atmospheric circulation in Central Europe. Its complex topography affects processes on different scales within the atmospheric system. This is of major relevance for the decadal trends in surface solar radiation (SSR), also known as periods of global dimming and brightening (GDB). In this study we analyzed data from 38 stations in and around the Swiss and Austrian Alps, over a period ranging from the 1980s up to the 2020s, with the aim of characterizing the spatio‐temporal variations of the GDB and understanding the causes for such trends in this region. Our results show a different behavior in the SSR decadal trends in the western part of the Alps in comparison to the eastern part. Our results also suggest a remarkable difference between the causes of such trends at the stations at low altitudes in comparison to the stations at higher altitudes. Significant contributions from changes in cloud optical depth and surface albedo to the SSR decadal trends at high elevation sites were also found, in contrast to a substantial clear‐sky forcing that strongly dominates at low elevations. Results from previous literature and available data suggest that cloud optical depth changes at high altitudes and clear‐sky forcing at low altitudes could be associated with the indirect and direct aerosol effects, respectively, due to differing pollution levels at low and high elevation sites.

Impacts of meteorological conditions on the plummeting surface-reaching solar radiation over a sub-tropical station – Pune, India

The unprecedented rise of solar energy as a dominant power source is a remarkable feat, considering our historical struggle to establish its widespread adoption. However, the dynamics of solar radiation reaching the Earth's surface are greatly influenced by meteorological conditions such as clouds, aerosols, and wind speed. This study investigates the detailed changes in surface-reaching solar radiation within the subtropical region Pune from 1993 to 2022. By employing analytical methodologies including linear regression, wavelet coherence, and quantitative analysis, our study reveals a compelling and alarming pattern of plummeting solar radiation over Pune (also known as solar dimming). The total drop is ∼1.04 Wm−2 year−1 (0.21 % year−1), with a more steep decline registered from 2018 to 2022, providing an astonishing rate of ∼6.01 Wm−2 year−1 (1.21 % year−1). Moreover, wavelet coherence transform revealed an antiphase coherence between solar radiation and both clouds and aerosols, suggesting their substantial influence over a longer timeframe. Extensive analysis utilizing observational data is conducted to find the contributing elements to the significant decline during 2018 to June 2022. Analysis of solar radiation statistics showed that clouds led to a substantial reduction of ∼30.18 % compared to conditions with clear-skies. Similarly, the aerosols have a comparable effect, reducing radiation by ∼17.75 % compared to days characterized by low or negligible aerosol loading for the same period. Furthermore, a through statistical analysis investigates a notable anticorrelation (ρ = −0.64) between wind speed and solar radiation. These findings underscore the imperative of incorporating climatic variables while studying solar dimming trends and devising sustainable renewable energy strategies to ensure the long-term viability of solar energy source.

Spatiotemporal Assessment of Surface Solar Dimming in India: Impacts of Multi-Level Clouds and Atmospheric Aerosols

Surface solar radiation (SSR) is a fundamental energy source for an equitable and sustainable future. Meteorology-induced variability increases uncertainty in SSR, thereby limiting its reliability due to its intermittent nature. This variability depends on several meteorological factors, including clouds, atmospheric gases, and aerosol concentrations. This research investigates the detailed impact of different levels of clouds and aerosols on SSR across India. Utilizing satellite data with reanalysis retrievals, the research covers a span of three decades (30 years), from 1993 to 2022. Aerosols contributed to an average attenuation of ~13.33% on SSR, while high, mid, and low cloud conditions showed much stronger impacts, with an attenuation of ~30.80%, ~40.10%, and ~44.30%, respectively. This study reveals an alarming pattern of increasing cloud impact (Cimpact) on SSR in the recent decade, with a significant increasing rate of ~0.22% year−1 for high cloud (HCimpact) and ~0.13% year−1 for mid cloud (MCimpact) impact, while low cloud impact (LCimpact) showed minimal change. The trend of aerosol impact (Aimpact) also showed an average increase of ~0.14% year−1 across all regions. The findings underscore the imperative of considering climatic variables while studying the growing solar dimming. Our findings also will assist policymakers and planners in better evaluating the solar energy resources across India.

Declining Geoengineering Efficacy Caused by Cloud Feedbacks in Transient Solar Dimming Experiments

Abstract Solar radiation management (SRM) with injections of aerosols into the stratosphere has emerged as a research area of focus with the potential to cool the planet. However, the amount of SRM required to achieve a given level of cooling, and how this relationship evolves in response to increasing greenhouse gas emissions, remains uncertain. Here, we explore the evolution of solar dimming efficacy over time by defining and quantifying a new SRM feedback term, which is analogous to conventional radiative feedbacks. Using Earth system model simulations that dynamically adjust the amount of insolation to offset global mean warming from increasing CO2, we find that positive SRM feedbacks decrease global planetary albedo and diminish the efficacy of solar dimming. Physically, the decrease in albedo is primarily due to reductions in optically thick tropical cloud fraction in the boundary layer and midtroposphere, which is driven by a drying and destabilization of the tropical mid- to lower troposphere. These results offer an energetic explanation for reduced cloud fraction commonly observed in idealized SRM experiments, as well as reaffirm the need to understand the troposphere response, particularly from clouds, in realizable geoengineering experiments and their potential to feed back onto SRM efficacy. Significance Statement The goal of this study is to understand how the effectiveness of solar geoengineering may evolve over time. Using a climate model with the ability to directly tune the amount of incoming sunlight, we explore the potential for feedback loops in the climate system to diminish or amplify the desired effect of solar tuning, which is to offset greenhouse gas–induced warming. For this climate model and this solar geoengineering proxy, in particular, we find that feedback loops reduce Earth’s albedo and therefore diminish the desired effect of turning down the sun over time. This study lays the groundwork for understanding potential feedback loops in climate model simulations that represent solar geoengineering in a more realistic way.

The Indonesian Throughflow circulation under solar geoengineering

Abstract. The Indonesia Throughflow (ITF) is the only low-latitude channel between the Pacific and Indian oceans, and its variability has important effects on global climate and biogeochemical cycles. Climate models consistently predict a decline in ITF transport under global warming, but it has not yet been examined under solar geoengineering scenarios. We use standard parameterized methods for estimating the ITF – the Amended Island Rule and buoyancy forcing – to investigate the ITF under the SSP2-4.5 and SSP5-8.5 greenhouse gas scenarios and the geoengineering experiments G6solar and G6sulfur, which reduce net global mean radiative forcing from SSP5-8.5 levels to SSP2-4.5 levels using solar dimming and sulfate aerosol injection strategies, respectively. Six-model ensemble-mean projections for 2080–2100 show reductions of 19 % under the G6solar scenario and 28 % under the G6sulfur scenario relative to the historical (1980–2014) ITF, which should be compared with reductions of 23 % and 27 % under SSP2-4.5 and SSP5-8.5. Despite standard deviations amounting to 5 %–8 % for each scenario, all scenarios are significantly different from each other (p<0.05) when the whole 2020–2100 simulation period is considered. Thus, significant weakening of the ITF occurs under all scenarios, but G6solar more closely approximates SSP2-4.5 than G6sulfur does. In contrast with the other three scenarios, which show only reductions in forcing due to ocean upwelling, the G6sulfur experiment shows a large reduction in ocean surface wind stress forcing accounting for 47 % (38 %–65 % across the model range) of the decline in wind + upwelling-driven ITF transport. There are also reductions in deep-sea upwelling in extratropical western boundary currents.

Functional and pharmacological analyses of visual habituation learning in larval zebrafish

Habituation allows animals to learn to ignore persistent but inconsequential stimuli. Despite being the most basic form of learning, a consensus model on the underlying mechanisms has yet to emerge. To probe relevant mechanisms, we took advantage of a visual habituation paradigm in larval zebrafish, where larvae reduce their reactions to abrupt global dimming (a dark flash). We used Ca2+ imaging during repeated dark flashes and identified 12 functional classes of neurons that differ based on their rate of adaptation, stimulus response shape, and anatomical location. While most classes of neurons depressed their responses to repeated stimuli, we identified populations that did not adapt or that potentiated their response. These neurons were distributed across brain areas, consistent with a distributed learning process. Using a small-molecule screening approach, we confirmed that habituation manifests from multiple distinct molecular mechanisms, and we have implicated molecular pathways in habituation, including melatonin, oestrogen, and GABA signalling. However, by combining anatomical analyses and pharmacological manipulations with Ca2+ imaging, we failed to identify a simple relationship between pharmacology, altered activity patterns, and habituation behaviour. Collectively, our work indicates that habituation occurs via a complex and distributed plasticity processes that cannot be captured by a simple model. Therefore, untangling the mechanisms of habituation will likely require dedicated approaches aimed at sub-component mechanisms underlying this multidimensional learning process.

Functional and pharmacological analyses of visual habituation learning in larval zebrafish.

Habituation allows animals to learn to ignore persistent but inconsequential stimuli. Despite being the most basic form of learning, a consensus model on the underlying mechanisms has yet to emerge. To probe relevant mechanisms, we took advantage of a visual habituation paradigm in larval zebrafish, where larvae reduce their reactions to abrupt global dimming (a dark flash). We used Ca2+ imaging during repeated dark flashes and identified 12 functional classes of neurons that differ based on their rate of adaptation, stimulus response shape, and anatomical location. While most classes of neurons depressed their responses to repeated stimuli, we identified populations that did not adapt or that potentiated their response. These neurons were distributed across brain areas, consistent with a distributed learning process. Using a small-molecule screening approach, we confirmed that habituation manifests from multiple distinct molecular mechanisms, and we have implicated molecular pathways in habituation, including melatonin, oestrogen, and GABA signalling. However, by combining anatomical analyses and pharmacological manipulations with Ca2+ imaging, we failed to identify a simple relationship between pharmacology, altered activity patterns, and habituation behaviour. Collectively, our work indicates that habituation occurs via a complex and distributed plasticity processes that cannot be captured by a simple model. Therefore, untangling the mechanisms of habituation will likely require dedicated approaches aimed at sub-component mechanisms underlying this multidimensional learning process.

The Situation of Global Dimming in the Regional Major Cities of Thailand: Shedding Light on a Growing Concern

The Situation of Global Dimming in the Regional Major Cities of Thailand: Shedding Light on a Growing Concern

An integrated and homogenized global surface solar radiation dataset and its reconstruction based on a convolutional neural network approach

Abstract. Surface solar radiation (SSR) is an essential factor in the flow of surface energy, enabling accurate capturing of long-term climate change and understanding of the energy balance of Earth's atmosphere system. However, the long-term trend estimation of SSR is subject to significant uncertainties due to the temporal inhomogeneity and the uneven spatial distribution of in situ observations. This paper develops an observational integrated and homogenized global terrestrial (except for Antarctica) station SSR dataset (SSRIHstation) by integrating all available SSR observations, including the existing homogenized SSR results. The series is then interpolated in order to obtain a 5∘ × 5∘ resolution gridded dataset (SSRIHgrid). On this basis, we further reconstruct a long-term (1955–2018) global land (except for Antarctica) SSR anomaly dataset with a 5∘ × 2.5∘ resolution (SSRIH20CR) by training improved partial convolutional neural network deep-learning methods based on 20th Century Reanalysis version 3 (20CRv3). Based on this, we analysed the global land- (except for Antarctica) and regional-scale SSR trends and spatiotemporal variations. The reconstruction results reflect the distribution of SSR anomalies and have high reliability in filling and reconstructing the missing values. At the global land (except for Antarctica) scale, the decreasing trend of the SSRIH20CR (−1.276 ± 0.205 W m−2 per decade) is smaller than the trend of the SSRIHgrid (−1.776 ± 0.230 W m−2 per decade) from 1955 to 1991. The trend of the SSRIH20CR (0.697 ± 0.359 W m−2 per decade) from 1991 to 2018 is also marginally lower than that of the SSRIHgrid (0.851 ± 0.410 W m−2 per decade). At the regional scale, the difference between the SSRIH20CR and SSRIHgrid is more significant in years and areas with insufficient coverage. Asia, Africa, Europe and North America cause the global dimming of the SSRIH20CR, while Europe and North America drive the global brightening of the SSRIH20CR. Spatial sampling inadequacies have largely contributed to a bias in the long-term variation of global and regional SSR. This paper's homogenized gridded dataset and the Artificial Intelligence reconstruction gridded dataset (Jiao and Li, 2023) are both available at https://doi.org/10.6084/m9.figshare.21625079.v1.

Thermosteric and dynamic sea level under solar geoengineering

The IPCC sixth assessment report forecasts sea level rise (SLR) of up to 2 m along coasts by 2100 relative to 1995–2014 following business as usual (SSP585) scenarios. Geoengineering may reduce this threat. We use five Earth System Models simulations of two different solar geoengineering methods (solar dimming and stratospheric sulfate aerosol injection), that offset radiative forcing differences between SSP585 “no-mitigation” and the modest mitigation SSP245 greenhouse gas scenarios, to analyze the impact on global mean thermosteric and dynamic regional sea levels. By 2080–2099, both forms of geoengineering reduce global mean thermosteric sea level by 36–41% (11.2–12.6 cm) relative to SSP585, bringing the global mean SLR under SSP585 in line with that under SSP245, but do not perfectly restore regional SLR patterns. Some of the largest reductions (∼18 cm) are on densely populated coasts of eastern Northern America and Japan and along vulnerable Arctic coastal permafrost.

Regulating the composition and secondary structure of wheat protein through canopy shading to improve dough performance and nutritional index

Viscoelastic properties of gluten proteins critically determine the biscuit-making quality. However, cultivar genetics and light conditions closely regulate the composition of the gluten proteins. The impact of pre- and post-anthesis shading (60 %) on amino acid profile, gluten protein composition, secondary structure, dough performance, and biscuit-making quality were evaluated using four wheat cultivars that differ in gluten protein composition. Pre- and post-anthesis shading increased the contents of gliadin, by 35.8 and 3.1 %; glutenin, by 27.6 and 7.3 %; and total protein, by 21.7 and 10.6 %, respectively, compared with those of unshaded plants. Conversely, the ratios of glutenin/gliadin, ω-/(α,β + γ)-gliadin, and high-molecular-weight/low-molecular-weight glutenin subunits decreased with shading. Strong-gluten cultivars exhibited smaller declines in these parameters than weak-gluten cultivars. Secondary structure analysis of the wheat protein revealed that shading increased β-sheet content but decreased β-turn content. Changes in protein components and their secondary structures caused an increase in wet gluten content, dough development time, and gluten performance index, thereby decreasing the biscuit spread ratio. Shading stress increased the protein content and nutrition index but decreased the biological value of protein by 2.5 %. Transcriptomic results revealed that shading induced 139 differentially expressed genes that decreased carbohydrate metabolism and increased amino acid metabolism, involved in increased protein content. Thus, canopy shading improves dough performance and nutrition index by regulating the amino acid profiles, protein compositions, and secondary structures. The study provides key insights for achieving superior grain quality under global dimming.

An Assessment of Global Dimming and Brightening during 1984–2018 Using the FORTH Radiative Transfer Model and ISCCP Satellite and MERRA-2 Reanalysis Data

In this study, an assessment of the FORTH radiative transfer model (RTM) surface solar radiation (SSR) as well as its interdecadal changes (Δ(SSR)), namely global dimming and brightening (GDB), is performed during the 35-year period of 1984–2018. Furthermore, a thorough evaluation of SSR and (Δ(SSR)) is conducted against high-quality reference surface measurements from 1193 Global Energy Balance Archive (GEBA) and 66 Baseline Surface Radiation Network (BSRN) stations. For the first time, the FORTH-RTM Δ(SSR) was evaluated over an extended period of 35 years and with a spatial resolution of 0.5° × 0.625°. The RTM uses state-of-the-art input products such as MERRA-2 and ISCCP-H and computes 35-year-long monthly SSR and GDB, which are compared to a comprehensive dataset of reference measurements from GEBA and BSRN. Overall, the FORTH-RTM deseasonalized SSR anomalies correlate satisfactorily with either GEBA (R equal to 0.72) or BSRN (R equal to 0.80). The percentage of agreement between the sign of computed GEBA and FORTH-RTM Δ(SSR) is equal to 63.5% and the corresponding percentage for FORTH-RTM and BSRN is 54.5%. The obtained results indicate that a considerable and statistically significant increase in SSR (Brightening) took place over Europe, Mexico, Brazil, Argentina, Central and NW African areas, and some parts of the tropical oceans from the early 1980s to the late 2010s. On the other hand, during the same 35-year period, a strong and statistically significant decrease in SSR (Dimming) occurred over the western Tropical Pacific, India, Australia, Southern East China, Northern South America, and some parts of oceans. A statistically significant dimming at the 95% confidence level, equal to −0.063 Wm−2 year−1 (or −2.22 Wm−2) from 1984 to 2018 is found over the entire globe, which was more prevalent over oceanic than over continental regions (−0.07 Wm−2 year−1 and −0.03 Wm−2 year−1, statistically significant dimming at the 95% confidence level, respectively) in both hemispheres. Yet, this overall 35-year dimming arose from alternating decadal-scale changes, consisting of dimming during 1984–1989, brightening in the 1990s, turning into dimming over 2000–2009, and brightening during 2010–2018.

Solar radiation utilization of five upland–paddy cropping systems in low-light regions promoted by diffuse radiation of paddy season

Solar radiation affects crop productivity in farmland ecosystems. Global dimming has resulted in decreased incident global radiation over recent decades, with a huge subsequent effect on food security. Attempting to increasing utilization of radiation and production to increase output, especially in multiple cropping systems, is a significant problem in low-light regions. Here, five upland–paddy cropping systems were evaluated in a low-light region during 2016–2017 and 2017–2018: Garlic–rice (GR), wheat–rice (WR), broad bean–rice (BR), rapeseed–rice (RR), and potato–rice (PR). Solar radiation and crop-related indicators were investigated to determine radiation utilization. The results showed that annual global radiation was 4056.97. MJ·m−2 and 3985.43 MJ·m−2 in 2016–2017 and 2017–2018, respectively, 13.69%–26.25% of which was wasted during the fallow season. Furthermore, the seasonal distribution of global radiation was differed to study years. The ratio_dif in paddy season was greater than 75%, whereas in upland season was less than 55%. Additionally, the annual radiation utilization efficiency (RUE) values of the crops investigated in this study were 0.53%–0.80% and RUE during upland season were 0.30%–0.95%, compared to 0.99%–1.35% during paddy season. The ratio_dif during paddy season had a greater contribution to RUE than that of the upland season, whilst the ratio_dif had a positive relationship with RUE. Therefore, in the low light region the high radiation utilization of upland-paddy systems could primarily be attributed to the efficient utilization of diffuse radiation by rice, which had a high radiation interception, net photosynthesis and net assimilation rate. This increase in diffuse radiation will further promote the efficient use of radiation in low-light regions. Furthermore, planting the upland crops with long growth period (garlic) and high planting intensity (wheat and rapeseed) could take advantage of limited global radiation in low-light regions. Our study clarifies RUE magnitude and its causes in upland–paddy cropping systems in low-light regions, while also providing a theoretical reference for grain production prediction and crop RUE improvement within the context of global dimming.