Climate Change Scenarios Research Articles

Increased offspring size and reduced gestation length in an ectothermic vertebrate under a worst-case climate change scenario

As global temperatures continue to rise, understanding the impacts of warming environments has become increasingly important. Temperature is especially relevant for ectothermic organisms which depend upon consistent and predictable annual temperature cycles for reproduction and development. However, additional research is required in this area to elucidate the potential impacts of climate change on future generations. To understand how projected increases in environmental temperatures may impact reproductive outcomes within natural populations of ectothermic vertebrates, we manipulated minimum ambient temperatures during gestation in Red-sided garter snakes (Thamnophis sirtalis parietalis). Wild snakes were collected in the Interlake region of Manitoba, Canada during their spring mating season and allowed to mate in controlled conditions. For the duration of gestation, mated females were placed into one of two ambient thermal conditions: temperatures emulating those found in the species’ natural habitat or temperatures with a consistent 5 °C increase to match end-of-century climate change projections. We recorded observations for each litter and all neonates resulting from controlled mating trials. We observed no difference in litter sizes or birth rates between thermal conditions. However, we observed a significant reduction in gestation length and significant increase to neonate body mass and body condition associated with increased ambient temperatures. These results suggest that increased minimum temperatures during gestation may confer reproductive benefits for the northern populations of this species even under the most extreme current modeled warming predictions. We discuss the broader implications of this effect, including possible negative ecological outcomes.

Impacts of Climate Change on Rainfall ‘Seasonality Index’ and Its Potential Implications on Water Savings and Reliability through Household Rainwater Tanks

This study depicts potential climate change impacts on annual rainwater savings from household rainwater harvesting using two different climate projection models; ACCESS 1.0 and CSIRO-Mk3.6. This paper also investigates potential changes in the relationships of ‘water saving efficiency’ and reliability with rainfall ‘seasonality index’ under the mentioned climate change scenarios. The annual water savings were calculated for three weather conditions: dry, average, and wet. Historical daily rainfall amounts provided by the Australian Bureau of Meteorology were used for three locations within the city of Brisbane (Australia). For the same locations, projected future daily rainfall amounts were collected from an online data portal facilitated by the Australian government. Potential annual water savings, water saving efficiency, and reliability values for the selected locations were calculated through a widely used tool, eTank, developed on water balance methodology at a daily scale. It was found that for the coastal location, Manly, the future water savings are not likely to change significantly. However, for the inland location, Sunnybank, the future water savings are expected to decrease under all the weather conditions through both the considered climate projections. For the far inner location, Oxley, the water savings are likely to decrease in the dry year, whereas in wet year, they are likely to increase. Also, it was found that the overall average relationship of SI–water saving efficiency is steeper for ACCESS 1.0 projected data compared to that produced through CSIRO-Mk3.6 data, and that significant differences exist among individual relationships for each location. The overall reliabilities calculated through the model projected data show lower values compared to the reliabilities calculated using historical data.

Projected impact of climate change on human health in low- and middle-income countries: a systematic review

Low- and middle-income countries (LMICs) contribute relatively little to global carbon emissions but are recognised to be among the most vulnerable parts of the world to health-related consequences of climate...

Evapotranspiration and Rainfall Effects on Post‐Storm Salinization of Coastal Forests: Soil Characteristics as Important Factor for Salt‐Intolerant Tree Survival

AbstractFlooding and salinization triggered by storm surges threaten the survival of coastal forests. After a storm surge event, soil salinity can increase by evapotranspiration or decrease by rainfall dilution. Here we used a 1D hydrological model to study the combined effect of evapotranspiration and rainfall on coastal vegetated areas. Our results shed light on tree root uptake and salinity infiltration feedback as a function of soil characteristics. As evaporation increases from 0 to 2.5 mm/day, soil salinity reaches 80 ppt in both sandy and clay loam soils in the first 5 cm of soil depth. Transpiration instead involves the root zone located in the first 40 cm of depth, affecting salinization in a complex way. In sandy loam soils, storm surge events homogeneously salinize the root zone, while in clay loam soils salinization is stratified, partially affecting tree roots. Soil salinity stratification combined with low permeability maintain root uptakes in clay loam soils 4/5‐time higher with respect to sandy loam ones. When cumulative rainfall is larger than potential evapotranspiration ETp (ETp/Rainfall ratios lower than 1), dilution promotes fast recovery to pre‐storm soil salinity conditions, especially in sandy loam soils. Field data collected after two storm surge events support the results obtained. Electrical conductivity (a proxy for salinity) increases when the ratio ETp/Rainfall is around 1.76, while recovery occurs when the ratio is around 0.92. In future climate change scenarios with higher temperatures and storm‐surge frequency, coastal vegetation will be compromised, because of soil salinity values much higher than tolerable thresholds.

Hurricane surge and inundation in the Bahamas, part 2: Flood risk assessment

AbstractA hurricane surge and inundation risk assessment has been carried out for Grand Bahama and Eleuthera in The Bahamas. 10,000 years of synthetic hurricane tracks were generated based on a statistical analysis of historical hurricanes from 1979 to 2020 inclusive. The surge and inundation were modelled using a hydrodynamic TELEMAC‐2D model covering sea around The Bahamas and the land of the two islands. Predictions of flood extents and depths were mapped for return periods of up to 1000 years for present day conditions and three climate change scenarios to 2100. The flooding experienced over Grand Bahama during Hurricane Dorian in 2019, was estimated to have a return period of up to approximately 450 years. Under the climate change scenarios the likelihood of flooding similar to Hurricane Dorian was estimated to be approximately 1.7 times more likely in 2050 and up to 3.4 times as likely in 2100 under a high greenhouse gas emissions scenario. The storm surge maps can be used by the Bahamas Department of Meteorology and other government agencies for emergency management, planning of infrastructure and building resilience in response to climate change.

Groundwater in the city of Pesaro (Marche, Italy): anthropic impact and interference with the urban environment

Groundwater in the urban area of Pesaro is a significant local resource, supplementing the main surfacewater supply from the external Metauro watershed. Nevertheless, since Pesaro’s groundwater is tapped from a coastal alluvial aquifer in a heavily anthropized environment, its use involves mutual impacts with the urban environment, which poses several constraints. Our work schematized the main interferences of groundwater with building works such as housing (i.e. foundations and underground works), hydraulic infrastructures, wells’ network development, and geoexchange projects. Moreover, the presence of a seawater wedge, historically intruding the aquifer, must be taken into account, alongside its potential evolution in changing climate scenarios. Contaminated sites were also analyzed, as they represent a critical issue when further groundwater withdrawals are planned. Due to these complex interactions, there is a need for renewed commitment to studying and monitoring the local water resource. This is also essential for promoting awareness among both citizens and the local government that its use will remain crucial for a long time.

Specific phytohormones levels in leaves and spikes of wheat explains the effects of elevated CO2 on drought stress at the flowering stage

This study aims to understand the combined impact of elevated CO2 and drought stress at flowering stage to explain the adaptation of bread wheat to future climate change scenarios. Four wheat genotypes with 24 replications of each were grown in two different greenhouses, maintaining 400 (ambient) and 800 (elevated) ppm levels of CO2. Irrigation was withheld at flowering to impose drought to 10 replications while 10 were allowed to grow normally. Daily water consumption was recorded until the pot-water of drought plants reached 10 % of the well-watered ones. This study was aided by the measurement of ecophysiology, phytohormones, and yield-related traits. In comparison to normal CO2, plants consumed the pot water quickly under elevated CO2. Further, the threshold value of the fraction of transpirable soil water, at which the relative transpiration is diverging from 1 was different at the two levels of CO2, and among genotypes. Drought significantly reduced plant water relations, gas exchange parameters, grain yield, and yield-related traits but enhanced osmotic adjustment, kernel abortion, and most of the phytohormones in leaves and spikes. Elevated CO2 though increased gas exchange parameters significantly under well-watered conditions but these parameters were significantly reduced under combined effect with drought and resultantly, lower yield-related traits were recorded. Moreover, we also identified a strong positive association between leaf trans-zeatin and a strong negative association of leaf and spike ABA and ACC with grain yield indicating that maintenance of a higher level of leaf trans-zeatin or lower levels of ABA and ACC can help plants to adapt better to the combination of elevated CO2 and drought.

Climate-responsive wada architecture: a bioclimatic design for climate change resilience

ABSTRACT With rising living standards and a growing global population, the energy consumption of buildings is predicted to soar. Energy efficiency and occupant comfort may both be enhanced by constructing buildings with climate-sensitive design principles in mind. The traditional architectural style of a given region, known as vernacular architecture, has changed throughout the years to accommodate the local climate. One example of a vernacular style of building that made use of climate-responsive design to produce energy-efficient and aesthetically pleasing structures is the Wada style, which is located in the Pune region of India. The performance of the traditional Wada House envelope and its thermal characteristics are being researched in this study. This study investigates the thermal performance of traditional Wada houses, utilizing simulation models, validation, and analyzing climate change scenarios for 2050 and 2080. Research shows that passive design principles are widely used in Wada architecture to control inside temperatures and cut down on energy usage. Insulation through thick walls and roofs, orientation to reduce solar heat gain, and natural ventilation are all part of these measures.

Integration of seasonal frequency domain electromagnetic surveys and geological data for assessing the integrity of earthen levee systems. The case study of the Panaro River (Northern Italy)

Floods rank among the most widespread and destructive natural hazards worldwide. The progressive degradation, impairment, and breach of earthen riverine levees can occur in both natural and anthropogenic environments, stemming from various scenarios or sequences of events. These may include hydraulic failure due to overtopping because of inadequate height, and structural failure occurring even prior to overtopping, due to insufficient geotechnical and hydraulic characteristics combined with external and internal erosion.Following the catastrophic flood of December 2020, caused by the collapse of a section of the levee system of the Panaro River (a tributary of the Po River, Northern Italy), local Authorities initiated a comprehensive investigation into the causes of the breach. Numerous factors, including geological, geomorphological, and ecological features, were found to have contributed to the progressive decrease of the levee integrity prior to and during the flood. This prompted a broader multidisciplinary study of the Panaro River levee system.The study expanded its focus to include the collapsed section (rebuilt in 2020), as well as an additional 30 km stretch of both the right and left levees north of Modena, totaling 60 km. Detailed geological and geophysical data were integrated into the analysis, with particular emphasis on evaluating the characteristics and integrity features of the levee system.This analysis was carried out using Frequency Domain Electromagnetic Methods (FDEM) on the top of the levees, previously calibrated using Electrical Resistivity Tomography (ERT), geological mapping, core logs, and Cone Penetration Tests (CPTs). The FDEM surveys were repeated in different environmental conditions, specifically in the dry 2021 summer season and in the wet 2023 spring season, during heavy rainfalls that caused disastrous floods in several areas of the Emilia-Romagna Region. Out of the 60 km surveyed in the study area, the comparison of the two datasets highlights an interval of about 4 km where the internal portion of the levees is characterized by relatively coarse-grained materials and higher permeability making it more prone to internal erosion phenomena. This paper describes and integrates the results of these investigations, drawing attention to the strengths and limitations of the FDEM method when applied to extensive surveys on earthen riverine levee systems. The proposed methodology contributes as well to maintenance and retrofitting efforts to reduce flood risk in the context of the present climate change scenarios.

Potential distribution of rice thrips (Stenchaetothrips biformis) in India under changing climate

Sudden outbreaks of agricultural pests are increasing in India due to the growing prominence of environmental issues like global warming, the occurrence of weather extremes, and hydrological extremes. Climate change impacts the developmental rates and population dynamics of agricultural pests. As rice is a staple food widely used in India, it often suffers intensive damage by various pests, leading to a considerable decrease in crop yield. One of the most common pests in rice fields in India and neighboring countries is the rice thrips (Stenchaetothrips biformis). However, the degree of pest infestation of rice crops under climate change scenarios is poorly known. Therefore, this study aimed to understand the potential geographical distribution of the rice thrips in India for future scenarios using the MaxEnt modeling framework. Future projections from global climate models (GCMs), such as HadGEM3-GC31 and MPI-ESMI-2, are used to predict the most affected regions in 2050 under three greenhouse gas emission scenarios: SSP1-2.6, SSP3-4.5, and SSP5-8.5. The results from the MaxEnt indicate that the southern and northeastern parts of India will be highly affected by rice thrips in 2050. The affected number of districts are found to be 256, 330 and 313 under SSP1-2.6, SSP3-4.5, and SSP5-8.5 scenarios, respectively. It has been observed that the maximum temperature is the most influential climatic parameter for the geographical distribution of rice thrips, followed by the annual mean and minimum temperatures. It can be concluded from these results that the elevated temperature enhances the growth and distribution of rice thrips.

Energy Efficiency and Sustainability in Food Retail Buildings: Introducing a Novel Assessment Framework

One of the primary global objectives is to decrease building energy consumption to promote energy efficiency and environmental sustainability. The large-scale food retail trade sector accounts for over 15% of total primary energy consumption in Europe, posing a significant challenge to the transition towards green energy. This study proposes a simple method for energy efficiency, environmental sustainability, and cost-saving assessment and improvement in large-scale food retail trade buildings. It aims to analyze the energy and environmental performance of building–plant systems, establishing an interactive network to assess intervention potential for the energy transition. The investigation focuses on the proper selection and analysis of the benefits of retrofit solution implementation, emphasizing potential energy savings in current and future climate change scenarios. Dynamic simulation with the Building Energy Model (BEM) was used to evaluate the impacts of building–plant system retrofit solutions, such as high thermal insulation, photovoltaic (PV) panels, Light Emitting Diode (LED) installation, waste heat recovery, and improvement in refrigeration units. The results show a reduction in annual energy consumption for the PV panel installation by up to 29% and lighting systems with high-quality LED to 60%. Additionally, CO2 emissions can be decreased by up to 41% by combining these two strategies.

Enhancing water management and urban flood resilience using Hazard Capacity Factor Design (HCFD) model: Case study of Eco-Delta city, Busan

This study evaluated future climate scenarios and the changes in urban flood resistance capacity in Busan Eco-Delta City using the hazard capacity factor design (HCFD) model. It analyzed the flood reduction effects of both gray and green infrastructure. Despite existing flood safety systems, there is a growing need to enhance urban flood resilience due to increasing heavy rainfall, unpredictable precipitation, and frequent typhoons driven by climate change. The HCFD model predicted urban flood volumes of Busan Eco-Delta City and analyzed the effectiveness of gray and green infrastructure in flood control. A stormwater management model (SWMM) simulated urban flood resistance capacity under the SSP1–2.6 climate change scenario. Results indicate that for an anticipated 500 mm rainfall over 3 h, green infrastructure can mitigate floods by 9 % to 17.6 %, while gray infrastructure can reduce flooding by 24 % to 32.1 %. The integration of gray and green infrastructure leads to an overall flood mitigation ranging from 47.1 % to 63.3 %. A notable contribution of this research is its predictive analysis of future flood scenarios using model-based scenario analysis and decision support algorithms, offering valuable insights into changes in urban flood resistance capacity and strategies for effective flood control decision-making.

Evaluating land use and climate change impacts on Ravi river flows using GIS and hydrological modeling approach

The study investigates the interplay of land use dynamics and climate change on the hydrological regime of the Ravi River using a comprehensive approach integrating Geographic Information System (GIS), remote sensing, and hydrological modeling at the catchment scale. Employing the Soil and Water Assessment Tool (SWAT) model, simulations were conducted to evaluate the hydrological response of the Ravi River to both current conditions and projected future scenarios of land use and climate change. This study differs from previous ones by simulating future land use and climate scenarios, offering a solid framework for understanding their impact on river flow dynamics. Model calibration and validation were performed for distinct periods (1999–2002 and 2003–2005), yielding satisfactory performance indicators (NSE, R2, PBIAS = 0.85, 0.83, and 10.01 in calibration and 0.87, 0.89, and 7.2 in validation). Through supervised classification techniques on Landsat imagery and TerrSet modeling, current and future land use maps were generated, revealing a notable increase in built-up areas from 1990 to 2020 and projections indicating further expansion by 31.7% from 2020 to 2100. Climate change projections under different socioeconomic pathways (SSP2 and SSP5) were derived for precipitation and temperature, with statistical downscaling applied using the CMhyd model. Results suggest substantial increases in precipitation (10.9 − 14.9%) and temperature (12.2 − 15.9%) across the SSP scenarios by the end of the century. Two scenarios, considering future climate conditions with current and future land use patterns, were analyzed to understand their combined impact on hydrological responses. In both scenarios, inflows to the Ravi River are projected to rise significantly (19.4 − 28.4%) from 2016 to 2100, indicating a considerable alteration in seasonal flow patterns. Additionally, historical data indicate a concerning trend of annual groundwater depth decline (0.8 m/year) from 1996 to 2020, attributed to land use and climate changes. The findings underscore the urgency for planners and managers to incorporate climate and land cover considerations into their strategies, given the potential implications for water resource management and environmental sustainability.

Seasonal wet–dry transition and denitrifying communities contributed to nitrous oxide emissions in the water-level fluctuating zone of the largest freshwater lake in China

The water-level fluctuating zone (WLFZ) is the alternating dry/wet zone in freshwater lakes, and plays a crucial role in nitrogen (N) biogeochemical cycling and nitrous oxide (N2O) emissions. However, N2O emission fluxes, the underlying microbial mechanisms, and their feedbacks to global warming in the extensive WLFZ of the freshwater lakes with dramatic water-level variations remain unclear. Here, we sampled through both wet and dry seasons and compared the N removal rates, N2O emission fluxes, composition and co-occurrence network properties of the denitrifying microbial communities of the WLFZ, continuously flooded, and non-flooded zones covered with the dominant plant (Carex. cinerascens) in Poyang Lake, the largest freshwater lake of China. We observed higher potential denitrification (1.129–5.657 nmol N g-1h−1) and anammox (0.047–0.756 nmol N g-1h−1) rates in the WLFZ for both wet and dry seasons than those in the other two zones. A large seasonal N2O sink-source transition (−2.297 and 0.297 μg m-2h−1 for wet and dry season, respectively) was observed in WLFZ. Moreover, the composition of nirK and nirS communities significantly varied in WLFZ between the wet and dry seasons. Especially, several keystone taxa (e.g., Mesorhizobium and Rhodanobacter) were enriched in the WLFZ and were responsible for denitrification and N2O emissions under drought stress in the dry season. Variations in denitrification rates and N2O fluxes were driven by pH, C and N substrates, as well as the co-occurrence network properties, including natural connectivity and small-world coefficients of the nirK and nirS communities. Our results suggested that WLFZ in freshwater lakes under future climate change scenarios would be a substantial N2O source and aggravate climate, which would result in the positive feedback.

Drosophila suzukii (Diptera: Drosophilidae) Population Dynamics and Infestation in a Raspberry Orchard of Loukkos Area, Morocco.

Raspberries (Rosales: Rosaceae) are considered to be one of most important crops in northwestern Morocco. However, this sector is seriously affected by the attack of Drosophila suzukii, which impairs the production and the export. Furthermore, the eco-ethology and population dynamics of D. suzukii under Moroccan conditions are still poorly understood. In Larache region, we monitored the population dynamics of D. suzukii adults using 4 traps baited with mashed ripe banana mixed with yeast, and reported the infestation levels during spring of 2022, 2023, and 2024 on raspberry cultivar Rubus idaeus var. Yazmin. Our results indicate that a maximum of 14, 20, and 28 D. suzukii adults per trap were caught weekly at the end of April 2022, in the middle of March 2023, and in the middle of April 2024, respectively. Furthermore, three peaks of D. suzukii adult flies were observed each year, whereas a total of six generations were predicted according to the accumulated degree-days. The male sex ratio of trapped D. suzukii was 1:0.32, 1:0.38, and 1:0.42 in 2022, 2023, and 2024, respectively. Raspberry fruit infestation reached a maximum of 76%, 75%, and 64% at the beginning of May 2022, middle of April 2023, and end of April 2024, respectively. Under the climate change scenario, knowledge of the eco-ethology of this insect and its population dynamics is essential for developing an IPM control strategy in Morocco, and further studies are ongoing to establish a biological and reasoned chemical approach based on degree-days.

Integrated modelling of fertilizer and climate change scenario impacts on agricultural production and nitrogen losses in Austria

The European Commission's Farm to Fork strategy aims at reducing nutrient losses and fertilizer use, but has been criticized for its expected negative impacts on European economy, agriculture, and food supply. We apply an integrated modelling framework to analyze potential effects of fertilizer reductions on land use, nitrogen losses, and agricultural output of two fertilizer and four climate change scenarios. The fertilizer scenarios comprise a uniform 20 % reduction of mineral N fertilizer (f20) and a combination of several fertilizer restrictions (fcm). The model results indicate that the restrictions in fertilization lead to decreases in crop production of 6 to 9 %, whereas intensive and extensive grassland production increases. N losses to air, water, and soil are substantially reduced by 9 % (f20) and 20 % (fcm), yet fall short of the intended 50 % reduction. The regional heterogeneity of the model results shows that tailored measures need to be elaborated by taking climate change developments, the regional heterogeneity of prevalent farming systems, and bio-physical conditions into account. Uniform measures applied to the national policy context fall short to attain policy targets cost-effectively. N emission capping, taxes or managerial measures such as crop rotational N balancing are options to be explored in future research.

An online tool with Google Earth Engine and cellular automata for seamlessly simulating global urban expansion at high resolutions

Projecting global urban expansion is crucial for environmental assessment under climate change scenarios. However, existing global future urban land products are typically provided at coarse resolutions (1 km) due to data and computing limitations. This hinders the accurate assessment of the impacts of global urban development at finer scales. Thus, we develop the first Cellular Automata (CA) online tool for simulating future global urban expansion in Google Earth Engine (GEE-CA), which can simulate future urban land change at a 30 m resolution under different SSP scenarios. GEE-CA enables seamless simulations of future urban land at high resolution through a partitioned parallel strategy. Seven large urban agglomerations are simulated under shared socioeconomic pathways as representative regions to present our fine-scale results. Comparatively, our datasets preserve significantly more spatial details than existing global urban land products. The improvement in resolution from 1 km to 30 m reduces errors by a range from 7.11% to 21.27% in the estimation of future urban area. So far, the proposed GEE-CA tool allows users to generate urban land projection maps for any defined region with a resolution as high as 30 m.

Potential Changes in Distribution of Major Conifers and Their Seed Mass across Siberia by the Mid-Twenty-First Century in a Warming Climate

Research highlights: At the turn of the 21st century, there were more forest territories found disturbed by both natural processes (climate change, wildfires, insect outbreaks, permafrost thawing, etc.) and anthropogenic interferences (air pollution, clearcuts, etc.). Seed collecting, then growing seedlings in forest nurseries, and then planting seedlings over lost forest areas are the forestry measures needed to restore the forest after disturbances. Goals were to construct bioclimatic models of ranges and seed mass of major Siberian conifers (Siberian pine (Pinus sibirica Du Tour), Siberian fir (Abies sibirica Ledeb.), Siberian spruce (Picea obovata Ledeb.), Siberian larches (Larix sibirica Ledeb., L. gmelini (Rupr) Rupr, and L. cajanderi Mayr.) and Pinus sylvestris L.) and predict their potential change in a warming climate by the mid-century. Methods: Multi-year seed mass data were derived from the literature, seed station data, and were collected in the field. Climate data (January and July data and annual precipitation) were derived from published Russian reference books and websites on climate. Bioclimatic indices (growing degree-days > 5 C, negative degree-days < 0 C, and annual moisture index) were calculated from January and July temperatures and annual precipitation for both contemporary and the 2050s (2040–2060) climates using the general circulation model INM-CM5-0 and two climate change scenarios, ssp126 and ssp585, from CMIP6. Our bioclimatic range models (envelope and MaxEnt models) and regression seed mass models for major conifers were built based on these bioclimatic indices. Additionally, their ranges were limited by the permafrost border, which divided the forest area into the permafrost-free zone, where five conifers are able to grow, and the permafrost zone, where only one conifer, Dahurian larch, is able to survive. Results: Under warmed climates, the ranges of all Siberian conifers would expand 1.5-fold due to the decrease in the permafrost zone, except Dahurian larch, which would lose 5–20% of its coverage due to permafrost retreat. Conifers shifting northward would be slower than predicted only by warmed climates because permafrost would thaw slower than climates would warm. Scots pine may expand by up to 60%, covering dryer lands in the south. Future climates were found to favor seed mass increase for major Siberian conifers and for heavier seed to shift northward. Our major conifers differ by the type of seed dispersal mode: zoochoric, animal (Siberian pine) and anemochoric, and wind-dispersed (other five trees). The seed masses of the five anemochoric conifers varied within the range of 1.5–15 g of 1000 seeds, which is about 40–50-fold less than that of zoochoric Siberian pine. Site climate explained about 28–65% of the seed mass variation for the five anemochoric trees and only 11% for Siberian pine (zoochoric tree). This finding needs additional research to explain the reasons. Conclusions: Warmed climates would favor the expansion of the ranges of major Siberian conifers and their seed mass to be heavier, which would support the high-quality seed production for forest well-being and its restoration in Siberia.

Changes in enzyme activity, structure and growth strategies of the rhizosphere microbiome influenced by elevated temperature and CO2

The impacts of global warming and increased CO2 levels on soil processes and crop growth are concerning. Soil enzymes in the rhizosphere, produced mainly by microbes, play a vital role in nutrients mobilization for plants. Nevertheless, a comprehensive understanding of how microbial communities in the rhizosphere respond to increased temperatures and CO2 levels, particularly in relation to nutrient acquisition, is still lacking. Addressing this problem, we grew soybeans under elevated temperature (ET, +2 °C) and CO2 levels (eCO2, +300 ppm), both individually and in combination (eCO2 + eT), in rhizobox mesocosms. Enzyme activity and microbial communities in soybean rhizospheres were investigated using soil zymography. eCO2 increased enzyme activity by 2.5 % to 8.7 %, while eT expanded the hotspot area from 1.8 % to 3.3 %. The combined factors amplified both the hotspot area by 5.3 % to 10.1 % and enzyme activity by 35.4 % to 67.3 %. Compared to ambient conditions, rhizosphere communities under eCO2 were predominantly comprised of r-strategist keystone taxa, including Acidobacteria, Proteobacteria, and Ascomycota. On the contrary, eT induced a shift in the microbial community towards K-selected taxa, characterized by an increased relative abundance of Basidiomycota and Actinobacteria. Furthermore, the combination of eCO2 and eT led to an increase in the relative abundance of key bacterial species (Acidobacteria, Proteobacteria, and Actinobacteria) as well as fungi (Ascomycota and Basidiomycota). These findings indicate the potential significance of enzyme hotspots in modulating responses to climate change. Changes in enzyme activity and hotspot area could indicate the alteration in microbial growth strategies. The treatments exhibited distinct changes in the composition of microbial communities, in network organization, and in the proportion of species designated as r or K-strategists. Overall, these findings highlight the combined effects of global change factors on bacterial and fungal communities, providing insights into their growth strategies and nutrient mobilization under climate change scenarios.

China's provincial optimum population sizes under SSP‐RCP scenarios

AbstractClimate change poses new challenges to achieving a balanced population distribution. Predicting the impact of development patterns using climate change scenarios can offer more precise insights into environmental and social risks. By adopting the possibility–satisfiability (P–S) model, this study investigates the optimum population sizes for the 31 provincial districts of China by 2035 and 2050 under seven shared socioeconomic pathway‐representative concentration pathway (SSP‐RCP) scenarios. Results indicate that under SSP2‐4.5 scenario, which maintains current development patterns, the optimum human population (OHP) ranges from 985 million to 717 million in 2035 and from 902 million to 623 million by 2050 at different P–S values, respectively. The SSP1‐1.9 and SSP1‐2.6 scenarios offer promising prospects by carrying the largest optimum population size. Therefore, China's future development depends on choosing a sustainable path that prioritizes the growth of the OHP. The optimum population sizes of provinces under unbalanced development routes SSP4‐3.4 and SSP4‐6.0 scenarios are mainly limited by economic development, while those of the regional competition route SSP3‐7.0 scenario are limited by both economic and climatic pressures. Under the fossil fuel route SSP5‐8.5 scenario, climate deterioration imposes severe constraints on optimum population size. The optimum population scales of the eastern coastal area with high urbanization levels and the northwest area with harsh environments are subject to natural conditions. In addition, the central and western regions encounter population size limitations due to insufficient economic development. Notably, China's population distribution remains concentrated in the east and sparse in the west, flanking the Hu Huanyong Line (Hu Line), with minimal expected changes in the future. By studying the spatial distribution of the optimum population under different SSP‐RCP scenarios, this study provides theoretical support for government decision‐making in the context of future climate change.