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Thicker snow cover in permafrost areas causes deeper active layers and thaw subsidence, which alter local hydrology and may amplify the loss of soil carbon. However, the potential for changes in snow cover and surface runoff to mobilize permafrost carbon remains poorly quantified. In this study, we show that a snow fence experiment on High‐Arctic Svalbard inadvertently led to surface subsidence through warming, and extensive downstream erosion due to increased surface runoff. Within a decade of artificially raised snow depths, several ice wedges collapsed, forming a 50 m long and 1.5 m deep thermo‐erosion gully in the landscape. We estimate that 1.1–3.3 tons C may have eroded, and that the gully is a hotspot for processing of mobilized aquatic carbon. Our results show that interactions among snow, runoff and permafrost thaw form an important driver of soil carbon loss, highlighting the need for improved model representation. Plain Language Summary: Snow cover is steadily disappearing as a result of climate change, but in areas that remain below 0°C we can still expect an increase in snow depth in the middle of winter. Since snow acts akin to a blanket, this warms the soil and accelerates the thaw of permafrost—thereby potentially contributing to carbon release from these frozen soils. Ice wedges, which are typical for permafrost landscapes, are particularly vulnerable to thaw because they hold a large amount of ice. When this ice melts, the surface sinks down, and soil carbon may be lost. In this study, we show how experimentally raised snow cover triggered the collapse of several ice wedges, not only through a warming effect of the snow but also due to an increase in the flow of water through the ice wedge network. As a result, we estimate that 1.1–3.3 tons of carbon were removed from this location, of which a portion could have entered the atmosphere as CO2. We emphasize the importance of studying the interactions among snow, runoff, and permafrost thaw to better understand how this may affect the release of greenhouse gases to the atmosphere. Key Points: A decade of raised snow depths led to strong local thaw subsidence, while increased runoff triggered the downstream collapse of ice wedgesThe abrupt thaw process mobilized about 1.1–3.3 tons of soil organic carbon in total, and dissolved organic carbon was degraded in the thermo‐erosion gullyFeedbacks linking changes in snow cover, surface drainage, and permafrost thaw are important drivers of thermokarst and soil carbon loss [ABSTRACT FROM AUTHOR]

The continuous growth of the world's population and the escalating demand for food raise serious concerns about the future of agriculture. According to FAO's estimates, agricultural product demand is expected to rise by 60% by 2030. However, the increasing use of chemical fertilizers has shown adverse effects on the environment and living organisms. In this context, biofertilizers offer a promising alternative to hazardous chemicals, supporting agricultural sustainability. Biofertilizers are known for their eco-friendly, non-toxic, and cost-effective nature, contributing to soil health, structure, and biodiversity preservation. Nevertheless, they face challenges, including poor shelf-life, on-field stability, sensitivity to fluctuating environmental conditions (such as temperature, radiation, and pH), limitations in long-term use, scarcity of beneficial bacterial strains, susceptibility to desiccation, and high required doses for large coverage areas. Commercially available microbe-based biofertilizers have not always met expectations in field conditions due to various reasons. While there have been advancements in biofertilizers to improve efficiency and popularity among farmers, the need to explore next-generation biofertilizers remains essential. This review primarily focuses on advanced and next-generation biofertilizers, such as PGPB (Plant Growth-Promoting Bacteria), fungal biofertilizers, nanobiofertilizers, and biofilm biofertilizers, aiming to address these challenges and propel sustainable agriculture forward. Highlights: Biofertilizers offer eco-friendly alternatives for sustainable agriculture. Advanced research improves manufacturing and application techniques. Novel microbial strains target specific nutrients. Biotechnological advancements enhance nutrient mobilization and stress tolerance. Key research priorities include selecting efficient biofertilizers and studying microbiological survival in stressed soil environments. [ABSTRACT FROM AUTHOR]

In 2020, anthropogenic methane (CH4) emissions decreased due to COVID‐19 containment policies, but there was a substantial increase in the concentration of atmospheric CH4. Previous research suggested that this abnormal increase was linked to higher wetland CH4 emissions and a decrease in the atmospheric CH4 sink. However, the impact of changes in the soil CH4 sink remained unknown. To address this, we utilized a process‐based model to quantify alterations in the soil CH4 sink of terrestrial ecosystems between 2019 and 2020. By implementing the model with various datasets, we consistently observed an increase in the global soil CH4 sink, reaching up to 0.35 ± 0.06 Tg in 2020 compared to 2019. This increase was primarily attributed to warmer soil temperatures in northern high latitudes. Our results emphasize the importance of considering the CH4 sink in terrestrial ecosystems, as neglecting this component can lead to an underestimation of both emission increases and reductions in atmospheric CH4 sink capacity. Furthermore, these findings highlight the potential role of increased soil warmth in terrestrial ecosystems in slowing the growth of CH4 concentrations in the atmosphere. [ABSTRACT FROM AUTHOR]

Microbial necromass carbon (MNC) accounts for a large fraction of soil organic carbon (SOC) in terrestrial ecosystems. Yet our understanding of the fate of this large carbon pool under long‐term warming is uncertain. Here, we show that 14 years of soil warming (+4°C) in a temperate forest resulted in a reduction in MNC by 11% (0–10 cm) and 33% (10–20 cm). Warming caused a decrease in the content of MNC due to a decline in microbial biomass carbon and reduced microbial carbon use efficiency. This reduction was primarily caused by warming‐induced limitations in available soil phosphorus, which, in turn, constrained the production of microbial biomass. Conversely, warming increased the activity of soil extracellular enzymes, specifically N‐acetylglucosaminidase and leucine aminopeptidase, which accelerated the decomposition of MNC. These findings collectively demonstrate that decoupling of MNC formation and decomposition underlie the observed MNC loss under climate warming, which could affect SOC content in temperate forest ecosystems more widespread. [ABSTRACT FROM AUTHOR]

Ecological similarity plays an important role in biotic interactions. Increased body size similarity of competing species, for example, increases the strength of their biotic interactions. Body sizes of many exothermic species are forecast to be altered under global warming, mediating shifts in existing trophic interactions among species, in particular for species with different thermal niches.Temperate rocky reefs along the southeast coast of Australia are located in a climate warming hotspot and now house a mixture of temperate native fish species and poleward range‐extending tropical fishes (vagrants), creating novel species assemblages. Here, we studied the relationship between body size similarity and trophic overlap between individual temperate native and tropical vagrant fishes.Dietary niche overlap between vagrant and native fish species increased as their body sizes converged, based on both stomach content composition (short‐term diet), stable isotope analyses (integrated long‐term diet) and similarity in consumed prey sizes.We conclude that the warming‐induced faster growth rates of tropical range‐extending fish species at their cool water ranges will continue to converge their body size towards and strengthen their degree of trophic interactions and dietary overlap with co‐occurring native temperate species under increasing ocean warming. The strengthening of these novel competitive interactions is likely to drive changes to temperate food web structures and reshuffle existing species community structures. [ABSTRACT FROM AUTHOR]

The scientific literature has many studies evaluating numerical weather prediction (NWP) models. However, many of those studies averaged across a myriad of different atmospheric conditions and surface forcings that can obfuscate the atmospheric conditions when NWP models perform well versus when they perform inadequately. To help isolate these different weather conditions, we used observations from the U.S. Climate Reference Network (USCRN) obtained between 1 January and 31 December 2021 to distinguish among different near-surface atmospheric conditions [i.e., different near-surface heating rates ( d T / d t ), incoming shortwave radiation (SWd) regimes, and 5-cm soil moisture (SM05)] to evaluate the High-Resolution Rapid Refresh (HRRR) Model, which is a 3-km model used for operational weather forecasting in the United States. On days with small (large) d T / d t , we found afternoon T biases of about 2°C (−1°C) and afternoon SWd biases of up to 170 W m−2 (100 W m−2), but negligible impacts on SM05 biases. On days with small (large) SWd, we found daytime temperature biases of about 3°C (−2.5°C) and daytime SWd biases of up to 190 W m−2 (80 W m−2). Whereas different SM05 had little impact on T and SWd biases, dry (wet) conditions had positive (negative) SM05 biases. We argue that the proper evaluation of weather forecasting models requires careful consideration of different near-surface atmospheric conditions and is critical to better identify model deficiencies in order to support improvements to the parameterization schemes used therein. A similar, regime-specific verification approach may also be used to help evaluate other geophysical models. Significance Statement: Improving weather forecasting models requires careful evaluations against high-quality observations. We used observations from the U.S. Climate Reference Network (USCRN) and found that the performance of the High-Resolution Rapid Refresh (HRRR) Model varies as a function of differences in near-surface heating and solar radiation. This finding indicates that model evaluations need to be conducted under varying near-surface weather conditions rather than averaging across multiple weather types. This new approach will allow for model developers to better identify model deficiencies and is a useful step to helping improve weather forecasts. [ABSTRACT FROM AUTHOR]

Increased atmospheric nitrogen (N) deposition and climate warming are both anticipated to influence the N dynamics of northern temperate ecosystems substantially over the next century. In field experiments with N addition and warming treatments, cumulative treatment effects can be important for explaining variation in treatment effects on N dynamics over time; however, comparisons between data collected in the early vs. later years potentially can be confounded with interactions between treatment effects and inter-annual variation in environmental conditions or other factors. We compared the short-term versus long-term effects of N addition and warming on net N mineralization and N leaching in a grass-dominated old field using in situ soil cores. We added new N addition and warming plots (3 years old) to an existing field experiment (16 years old), which enabled comparison of the treatment effects at both time scales while controlling for potential inter-annual variation in other factors. For net N mineralization, there was a significant interaction between plot age and N addition over the growing season, and for extractable inorganic N there was a significant interaction between plot age and warming over winter. In both cases, the directions of the treatment effects differed among old and new plots. Moreover, the responses in the new plots differed from the responses observed previously when the 16-year-old plots had been new. These results demonstrate how inter-annual variation in responses, independent from cumulative treatment effects, can play an important role in interpreting long-term effects on soil N cycling in global change field experiments. [ABSTRACT FROM AUTHOR]

Warming‐induced soil drought, especially in topsoil, may enlarge the spatial mismatch between nutrients and water along the soil profile, which impedes the uptake of not only water but also nutrients by trees. Therefore, coordinating the acquisition of soil water and nutrients along the soil profile is an important strategy for trees to cope with global warming.This study examined soil depth‐related changes in nutrient concentrations, biomass and morphology of fine roots in a Chinese fir plantation after 3 years of large‐scale manipulative soil warming.Soil warming (ambient +4°C) increased fine root nitrogen (N) concentrations but decreased fine root phosphorus (P) concentrations across soil depths. Warming did not affect total fine root biomass and its vertical distribution. At the 0–10 cm depth, warming increased specific root length (SRL), specific root area (SRA), fine root diameter (RD) and root length density (RLD) but reduced root tissue density (RTD). In the 40–60 cm layer, warming reduced RD, SRL and RLD while increasing RTD mainly for roots of the 1–2 mm diameter class.Synthesis. We concluded that roots of Chinese fir plantations could adapt to warming‐induced moderate water stress through contrasting depth‐related root morphological adjustments, probably to optimize the acquisition of both soil water and nutrients. The results of this study are crucial for understanding the adaptation strategies of subtropical forests under future climate conditions. [ABSTRACT FROM AUTHOR]

Soil pH significantly impacts microbial activity and community assembly, which in turn determines the temperature sensitivity (Q10) of soil respiration. Due to the high soil acidification in China, it is necessary to understand how soil acidification impacts Q10. Here, the Q10 of soil respiration was examined in a long-term field experiment (1982–present) with different soil pH caused by fertilization management. In this experiment, we selected treatments with neutral pH: (1) no crops and fertilization (CK); (2) crops without fertilization (NF); low pH with (3) crops with chemical fertilization (NPK); and (4) crops with chemical fertilization combined with wheat straw incorporation (WS). Under natural soil temperature changes, we observed that soil acidification lowered the Q10 value of soil respiration. Considering only temperature changes, the Q10 of soil respiration was strongly associated with microbial community composition, alpha diversity, and soil ammonium nitrogen. Considering the interaction between soil pH and temperature, warming strengthened the negative effect of soil pH on the Q10 of soil respiration, and the pathway through which soil pH mediated Q10 included not only microbial community composition, alpha diversity, and biomass but also the soil's available phosphorus. This work enhanced our insights into the relationships between Q10, temperature, and soil pH by identifying important microbial properties and key soil environmental factors. [ABSTRACT FROM AUTHOR]

The impact of anthropogenic global warming has induced significant upward dispersal of trees to higher elevations at alpine treelines. Assessing vertical deviation from current uppermost tree distributions to potential treeline positions is crucial for understanding ecosystem responses to evolving global climate. However, due to data resolution constraints and research scale limitation, comprehending the global pattern of alpine treeline elevations and driving factors remains challenging. This study constructed a comprehensive quasi‐observational dataset of uppermost tree distribution across global mountains using Google Earth imagery. Validating the isotherm of mean growing‐season air temperature at 6.6 ± 0.3°C as the global indicator of thermal treeline, we found that around two‐thirds of uppermost tree distribution records significantly deviated from it. Drought conditions constitute the primary driver in 51% of cases, followed by mountain elevation effect which indicates surface heat (27%). Our analyses underscore the multifaceted determinants of global patterns of alpine treeline, explaining divergent treeline responses to climate warming. Moisture, along with temperature and disturbance, plays the most fundamental roles in understanding global variation of alpine treeline elevation and forecasting alpine treeline response to ongoing global warming. [ABSTRACT FROM AUTHOR]

Kelps are in global decline due to climate change, which includes ocean warming. To identify vulnerable species, we need to identify their tolerances to increasing temperatures and determine whether tolerances are altered by co‐occurring drivers such as inorganic nutrient levels. This is particularly important for those species with restricted distributions, which may already be experiencing thermal stress. To identify thermal tolerance of the range‐restricted kelp Lessonia corrugata, we conducted a laboratory experiment on juvenile sporophytes to measure performance (growth, photosynthesis) across its thermal range (4–22°C). We determined the upper thermal limit for growth and photosynthesis to be ~22–23°C, with a thermal optimum of ~16°C. To determine if elevated inorganic nitrogen availability could enhance thermal tolerance, we compared the performance of juveniles under low (4.5 μmol · d−1) and high (90 μmol · d−1) nitrate conditions at and above the thermal optimum (16–23.5°C). Nitrate enrichment did not enhance thermal performance at temperatures above the optimum but did lead to elevated growth rates at the thermal optimum. Our results indicate L. corrugata is likely to be extremely susceptible to moderate ocean warming and marine heatwaves. Peak sea surface temperatures during summer in eastern and northeastern Tasmania can reach up to 20–21°C, and climate projections suggest that L. corrugata's thermal limit will be regularly exceeded by 2050 as southeastern Australia is a global ocean‐warming hotspot. By identifying the upper thermal limit of L. corrugata, we have taken a critical step in predicting the future of the species in a warming climate. [ABSTRACT FROM AUTHOR]

Flooding and climate warming lead to the increase of low‐molecular‐weight organic acid (LMWOA) inputs to soil. However, it is unclear what the effects of flooding and climate warming on soil nitrogen fraction transformation under LMWOA input are. Fluvisol was collected in the riparian zone of the Three Gorges Reservoir to conduct an incubation experiment with the treatments of three LMWOAs at five contents, two hydrological environments and two temperatures. Compared with LMWOA input of 0 mg kg−1, the soil nitrogen in ion exchangeable fraction (IEF‐N), strong oxidant extractable fraction (SOEF‐N) and non‐transformable nitrogen (NTF‐N) were increased by 35.77, 54.71 and 25.49 mg kg−1, respectively, under LMWOA input of 40 mmol kg−1. Soil nitrogen in the weak acid extractable fraction (WAEF‐N) was decreased by 117.41 mg kg−1. Microbial biomass nitrogen (MBN) was increased by 25.29 mg kg−1, and calcium carbonate (CaCO3) was decreased by 8.03 g kg−1. The contents of IEF‐N, NTF‐N and amorphous iron oxides were higher under the flooding environment than under the drying environment. In contrast, opposite results were observed for soil nitrogen in the strong alkali extractable fraction (SAEF‐N), SOEF‐N and MBN. IEF‐N and NTF‐N contents were higher at 20°C than at 30°C, and the contents of SOEF‐N and MBN were higher at 30°C than at 20°C. WAEF‐N was dissolved by LMWOA through CaCO3 dissolution. The dissolved WAEF‐N was partly transformed into SOEF‐N and NTF‐N by microbial assimilation and humification. Flooding desorbed SAEF‐N through the crystalline transformation of iron oxides. Flooding inhibited the transformation of IEF‐N to SOEF‐N and promoted the formation of NTF‐N, while warming did the opposite. The results provide a perspective of the bound state between soil and nitrogen for understanding the soil nitrogen cycling and help to assess the impacts of climate warming and flooding on soil nitrogen loss from soil to the surrounding water. [ABSTRACT FROM AUTHOR]

Field and laboratory studies on the effect of different systems of tillage on soil agrophysical properties, seed germination and productivity of maize (corn) demonstrate that tillage influences soil water content, penetration resistance and bulk density throughout the growing season. Faster soil warming and seed germination under the mouldboard plough influenced all stages of maize growth and development; minimal tillage was associated with lesser plant height, leaf area, number of cobs per 100 plants and 1000-grain weight, leading to an average yield shortfall of 0.37–0.88t/ha compared to the mouldboard plough. [ABSTRACT FROM AUTHOR]

Climate projections predict higher temperatures and more frequent hurricanes in the tropics. Tropical plants subjected to these stresses may respond by acclimating their physiology. We investigated tropical forest root respiration in response to in situ experimental warming and hurricane disturbance in eastern Puerto Rico. We measured mass-normalized root specific respiration, root biomass, and root traits at the Tropical Responses to Altered Climate Experiment (TRACE), where understory vegetation is warmed + 4 °C above ambient. Our measurements span 5 years, including before and after two major hurricanes, to quantify root contributions to ecosystem carbon fluxes. Experimental warming did not affect root specific respiration at a standard temperature of 25° (RSR25, mean = 3.89 nmol CO2 g−1 s−1) or the temperature sensitivity of root respiration (Q10, mean = 1.75), but did result in decreased fine-root biomass, thereby decreasing area-based estimations of ecosystem-level root respiration in warmed plots by ~ 35%. RSR25 of newer roots, which increased with increasing root nitrogen, showed greater rates 6 months after the hurricanes, but subsequently decreased after 12 months. Root specific respiration did not acclimate to higher temperatures, based on lack of adjustments in either Q10 or RSR25 in the warmed plots; however, decreased root biomass indicates the root contribution to soil carbon dioxide efflux was overall lower with warming. Lower root biomass may also limit nutrient and water uptake, having potential negative effects on carbon assimilation. Our results show that warming and hurricane disturbance have strong potential to affect tropical forest roots, as well as ecosystem carbon fluxes. [ABSTRACT FROM AUTHOR]

Climate change is predicted to cause milder winters and thus exacerbate soil freeze–thaw perturbations in the subarctic, recasting the environmental challenges that soil microorganisms need to endure. Historical exposure to environmental stressors can facilitate the microbial resilience to new cycles of that same stress. However, whether and how such microbial memory or stress legacy can modulate microbial responses to cycles of frost remains untested. Here, we conducted an in situ field experiment in a subarctic birch forest, where winter warming resulted in a substantial increase in the number and intensity of freeze–thaw events. After one season of winter warming, which raised mean surface and soil (−8 cm) temperatures by 2.9 and 1.4°C, respectively, we investigated whether the in situ warming‐induced increase in frost cycles improved soil microbial resilience to an experimental freeze–thaw perturbation. We found that the resilience of microbial growth was enhanced in the winter warmed soil, which was associated with community differences across treatments. We also found that winter warming enhanced the resilience of bacteria more than fungi. In contrast, the respiration response to freeze–thaw was not affected by a legacy of winter warming. This translated into an enhanced microbial carbon‐use efficiency in the winter warming treatments, which could promote the stabilization of soil carbon during such perturbations. Together, these findings highlight the importance of climate history in shaping current and future dynamics of soil microbial functioning to perturbations associated with climate change, with important implications for understanding the potential consequences on microbial‐mediated biogeochemical cycles. [ABSTRACT FROM AUTHOR]

Projections of West African Monsoon (WAM) precipitation are uncertain. To address this, an improved understanding of the mechanisms driving WAM precipitation change is needed to shed light on inter-model differences and aid model development. The full forcing of increased CO2 can be decomposed into different components such as the impact of ocean warming, or the direct radiative effect of increased CO2. This paper investigates such a decomposition, analysing the effect of a uniform 4K ocean warming whilst keeping atmospheric CO2 concentrations constant. The analysis highlights several mechanisms acting to decrease WAM precipitation over a range of timescales, from days after the abrupt ocean warming, to the long-term equilibrium response. The initial decrease in WAM precipitation is caused by warming and enhanced convection over the ocean, stabilising the atmosphere inland and disrupting the monsoon inflow at low levels. Later in the response (after about 5 days), the WAM precipitation is reduced through a strengthening of the shallow circulation over West Africa, associated with changes in the large-scale temperature gradients and a local warming of the atmosphere related to a soil moisture feedback mechanism over the Sahel. Finally, from around 20 days after the SST increase, the WAM precipitation is also reduced through changes in specific humidity gradients that lead to increased potency of dry air advection into the monsoon rainband. The analysis concludes by demonstrating that the processes affecting precipitation in the early stages of the response are also relevant to the long-term equilibrium response. [ABSTRACT FROM AUTHOR]

To help meet the need for the reuse of thermally desorbed soil from contaminated sites, this paper presents a laboratory simulation of the thermal desorption treatment of diesel-contaminated soils. The simulated treatment was based on the thermal desorption treatment of contaminated soil around chemical plants. X-ray micro-computed tomography and mercury pressure porosimetry were used to characterize changes in the pore structure of soil contaminated with diesel fuel and treated with thermal desorption. The changes in pore structure were rationalized in terms of macroscopic shrinkage of soil, matrix suction, particle gradation, and clay minerals. Additionally, permeability properties were explored. The main results were as follows: Thermal desorption altered the pore structure of the soil. With separate heating of different soil samples, the increase in heating temperature enlarged internal pore space, porosity, and average pore diameter, enhanced pore connectivity, and reduced tortuosity of the soil. Continuous heating of identical soil samples at intervals and progressively higher temperatures led to reductions in pore space, porosity, and pore average diameter as well as pore connectivity, and increased tortuosity. Matrix suction and clay minerals were the main factors responsible for changes in the pore structure. The mechanism of matrix suction was the main reason for very different trends in changes in the pore structure. Clay minerals were not influential until temperatures exceeded 400 °C. The permeability coefficients showed two very different trends with temperature under the two heating regimes. [ABSTRACT FROM AUTHOR]

Warming and precipitation fluctuations are changing desert ecosystems in global drylands. However, the effects of climate change on keystone species such as cryptogamic biocrust in drylands remain relatively under‐investigated, even though biocrusts play a vital role in desert ecosystems.We conducted a long‐term experiment (14 years) to simulate the responses of two main types of biocrusts to warming coupled with reduction in precipitation that was achieved by open‐top chambers (OTCs) to simulate the predicted warming and precipitation decreasing under climate change scenario. We also conduct a structural analysis to evaluate the resulting changes in desert ecosystem functioning (carbon and nitrogen cycling).Neither warming and corresponding rainfall reduction treatments had a negative effect on lichen species richness, but both treatments reduced lichen cover and biomass. The negative effects of warming on moss‐dominated crusts were much greater than those on lichen‐dominated crusts. Although mosses and lichens had varying degree responses to warming, the loss of mosses and decreased lichen cover and biomass, as well as the shortening of the wet time, resulted in a reduction in carbon and nitrogen fixation, soil enzyme activity and water‐holding capacity of biocrusts and topsoil. These impacts collectively change the water balance of drylands and weaken the hydrological and biogeochemical function of biocrusts.Synthesis and applications: Results from this long‐term experiment suggest that the ecosystem C and N cycling and water balance of global drylands may be highly impacted by climate change, in part because of the response of biocrusts, which contribute an important implication for both dryland restoration and earth system dynamics. [ABSTRACT FROM AUTHOR]

The permafrost region has accumulated organic carbon in cold and waterlogged soils over thousands of years and now contains three times as much carbon as the atmosphere. Global warming is degrading permafrost with the potential to accelerate climate change as increased microbial decomposition releases soil carbon as greenhouse gases. A 19-year time series of soil and ecosystem respiration radiocarbon from Alaska provides long-term insight into changing permafrost soil carbon dynamics in a warmer world. Nine per cent of ecosystem respiration and 23% of soil respiration observations had radiocarbon values more than 50‰ lower than the atmospheric value. Furthermore, the overall trend of ecosystem and soil respiration radiocarbon values through time decreased more than atmospheric radiocarbon values did, indicating that old carbon degradation was enhanced. Boosted regression tree analyses showed that temperature and moisture environmental variables had the largest relative influence on lower radiocarbon values. This suggested that old carbon degradation was controlled by warming/permafrost thaw and soil drying together, as waterlogged soil conditions could protect soil carbon from microbial decomposition even when thawed. Overall, changing conditions increasingly favoured the release of old carbon, which is a definitive fingerprint of an accelerating feedback to climate change as a consequence of warming and permafrost destabilization. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'. [ABSTRACT FROM AUTHOR]

The Central American Dry Corridor experienced five consecutive years of drought from 2015 to 2019. Here, we find that the severity of this drought was driven primarily by rainfall deficits in July–August. To determine if the magnitude of this event was outside the range of natural variability, we apply a statistical resampling method to observations that emulates internal climate variability. Our analyses show that droughts similar to the 2015–2019 event are possible, although extremely rare, even without anthropogenic influences. Persistent droughts in our ensemble are consistently linked to stronger easterly winds associated with the Caribbean Low‐Level Jet. We also examine the effects of temperature on soil moisture during this drought using the Palmer Drought Severity Index and show that anthropogenic warming increases the likelihood of severe deficits. Multi‐year droughts are likely to worsen by the end of the 21st century due to the compound effects of anthropogenic climate change. Plain Language Summary: Climate models project that Central America is one of the global hotspots for future decreases in precipitation as a result of human‐caused climate change. This is particularly concerning for the Dry Corridor region, which is already prone to frequent droughts and high levels of food insecurity among households. Much of this region experienced severe rainfall deficits between 2015 and 2019, provoking the question of whether or not this drought was caused by climate change or if it could have occurred because of natural climate variability alone. Using a statistical model, we show that while 2015–2019 was the driest period in the observational record, droughts as bad as this one are possible even without the influence of human‐caused climate change. We examine the additional role of temperature since it can modulate drought severity through its influence on soil moisture. We find warming temperatures increase the occurrences of greater soil moisture deficits. We also determine that the strength of the Caribbean Low‐Level Jet, which transports moisture from the Caribbean Sea into Central America, is strongly associated with persistent dry conditions in the region. Key Points: The 2015–2019 drought was severe, but it falls within the range of natural climate variabilityJuly–August deficits were the most significant drivers of overall droughtPositive easterly zonal wind anomalies associated with the Caribbean Low‐Level Jet are strongly linked to regional precipitation deficits [ABSTRACT FROM AUTHOR]

Climatic change conditions (elevated CO2 and warming) have been known to threaten agricultural sustainability and grain yield. Soil fungi play an important role in maintaining agroecosystem functions. However, little is known about the responses of fungal community in paddy field to elevated CO2 and warming. Herein, using internal transcribed spacer (ITS) gene amplicon sequencing and co-occurrence network methods, the responses of soil fungal community to factorial combinations of elevated CO2 (550 ppm), and canopy warming (+2 °C) were explored in an open-air field experiment for 10 years. Elevated CO2 significantly increased the operational taxonomic unit (OTU) richness and Shannon diversity of fungal communities in both rice rhizosphere and bulk soils, whereas the relative abundances of Ascomycota and Basidiomycota were significantly decreased and increased under elevated CO2, respectively. Co-occurrence network analysis showed that elevated CO2, warming, and their combination increased the network complexity and negative correlation of the fungal community in rhizosphere and bulk soils, suggesting that these factors enhanced the competition of microbial species. Warming resulted in a more complex network structure by altering topological roles and increasing the numbers of key fungal nodes. Principal coordinate analysis indicated that rice growth stages rather than elevated CO2 and warming altered soil fungal communities. Specifically, the changes in diversity and network complexity were greater at the heading and ripening stages than at the tillering stage. Furthermore, elevated CO2 and warming significantly increased the relative abundances of pathotrophic fungi and reduced those of symbiotrophic fungi in both rhizosphere and bulk soils. Overall, the results indicate that long-term CO2 exposure and warming enhance the complexity and stability of soil fungal community, potentially threatening crop health and soil functions through adverse effects on fungal community functions. [ABSTRACT FROM AUTHOR]

Side insertion horizontal transplanting sweet potato seedlings on mulch film is one kind of new planter pattern, which keeps the soil warm and moist restraining the infestation of pests and weeds, realizing dense transplanting and ensuring uniformity of sweet potato sizes. Therefore, a side insertion horizontal transplanting device for sweet potato seedlings on mulch film was designed, including the details and parameters of the reciprocating mechanism and the seedling clamping mechanism. Both the two mechanisms and the whole device were simulated and the test bench was built for field experiments to detect if this device can meet the agronomic requirements. The simulation results show that the designed device is in accordance with the agronomic requirements of horizontal transplanting, transplanting depth and transplanting length, and is potential for achieving rational close planting. The lateral length of the designed transplanting device is extended at about 90 mm compared with previous machine, which will promote the number of soil nodules of sweet potato seedlings and the growth of production enormously. The horizontal velocity of the transplanting claw is â?'17 mm/s when picking the seedling, the horizontal velocity of the transplanting claw 645 mm/s and the vertical velocity 83 mm/s when releasing the seedling. These data could ensure the accuracy requirements of horizontal transplanting trajectory. The field experiment results show the expulsion rate of sweet potato seedlings at 1.38%, the qualified rate of transplanting length and depth at 94.17% and 95.11% respectively, the average length and width of the mulch film breaking hole at 44.67 mm and 43.00 mm in several. The postures of the actual transplanted seedlings are consistent with the simulation results, meeting the requirements of horizontal transplanting with less damage to the mulch film. The designed transplanting device lays a foundation for the development of sweet potato seedlings side transplanting machine. [ABSTRACT FROM AUTHOR]

Adaptation of soil microbes due to warming from climate change has been observed, but it remains unknown what microbial growth traits are adaptive to warming. We studied bacterial isolates from the Harvard Forest Long-Term Ecological Research site, where field soils have been experimentally heated to 5°C above ambient temperature with unheated controls for 30 years. We hypothesized that Alphaproteobacteria from warmed plots have (i) less temperature-sensitive growth rates; (ii) higher optimum growth temperatures; and (iii) higher maximum growth temperatures compared to isolates from control plots. We made high-throughput measurements of bacterial growth in liquid cultures over time and across temperatures from 22°C to 37°C in 2-3°C increments. We estimated growth rates by fitting Gompertz models to the growth data. Temperature sensitivity of growth rate, optimum growth temperature, and maximum growth temperature were estimated by the Ratkowsky 1983 model and a modified Macromolecular Rate Theory (MMRT) model. To determine evidence of adaptation, we ran phylogenetic generalized least squares tests on isolates from warmed and control soils. Our results showed evidence of adaptation of higher optimum growth temperature of bacterial isolates from heated soils. However, we observed no evidence of adaptation of temperature sensitivity of growth and maximum growth temperature. Our project begins to capture the shape of the temperature response curves, but illustrates that the relationship between growth and temperature is complex and cannot be limited to a single point in the biokinetic range. IMPORTANCE Soils are the largest terrestrial carbon sink and the foundation of our food, fiber, and fuel systems. Healthy soils are carbon sinks, storing more carbon than they release. This reduces the amount of carbon dioxide released into the atmosphere and buffers against climate change. Soil microbes drive biogeochemical cycling and contribute to soil health through organic matter breakdown, plant growth promotion, and nutrient distribution. In this study, we determined how soil microbial growth traits respond to long-term soil warming. We found that bacterial isolates from warmed plots showed evidence of adaptation of optimum growth temperature. This suggests that increased microbial biomass and growth in a warming world could result in greater carbon storage. As temperatures increase, greater microbial activity may help reduce the soil carbon feedback loop. Our results provide insight on how atmospheric carbon cycling and soil health may respond in a warming world. [ABSTRACT FROM AUTHOR]

Summary: Below and aboveground vegetation dynamics are crucial in understanding how climate warming may affect terrestrial ecosystem carbon cycling. In contrast to aboveground biomass, the response of belowground biomass to long‐term warming has been poorly studied.Here, we characterized the impacts of decadal geothermal warming at two levels (on average +3.3°C and +7.9°C) on below and aboveground plant biomass stocks and production in a subarctic grassland.Soil warming did not change standing root biomass and even decreased fine root production and reduced aboveground biomass and production. Decadal soil warming also did not significantly alter the root–shoot ratio. The linear stepwise regression model suggested that following 10 yr of soil warming, temperature was no longer the direct driver of these responses, but losses of soil N were. Soil N losses, due to warming‐induced decreases in organic matter and water retention capacity, were identified as key driver of the decreased above and belowground production. The reduction in fine root production was accompanied by thinner roots with increased specific root area.These results indicate that after a decade of soil warming, plant productivity in the studied subarctic grassland was affected by soil warming mainly by the reduction in soil N. [ABSTRACT FROM AUTHOR]

Climate warming is altering plant and soil microbial communities, with important implications for ecosystem processes like litter decomposition. As warming alters plant community composition, the quality of litter will change. Further, shifts in microbial community activity and/or composition will alter microbial function. However, it is not yet completely understood how these shifts will interact to drive decomposition.We explored how changes in plant and microbial communities interact to influence litter decomposition using a 15‐year‐old grassland warming experiment. Previous studies within this system have shown that warming shifted the microbial community in ways that accelerate litter decomposition while simultaneously shifting the plant community in ways that may slow decomposition. Specifically, warming increased abundance of Sorghastrum nutans, while decreasing abundance of the previously dominant Schizachyrium scoparium. Using a series of lab‐based microcosm experiments, we examined the rate at which eight common grasses and, separately, varying abundances of S. nutans and S. scoparium decomposed. Using litter and soil from the warming experiment, we then incubated soils from warmed or control plots with different abundances of S. nutans and S. scoparium in a reciprocal design.We found S. nutans to be the slowest‐decomposing grass in our system. Further, decomposition slowed as S. nutans increased and S. scoparium decreased. When examining the interaction of plant and microbial communities, decomposition was generally greater early in our experiment as the relative abundance of S. scoparium increased. However, soil microbial community origin and litter composition interacted significantly. Specifically, decomposition increased with greater relative abundance of S. scoparium on soils derived from control plots, while litter composition did not shape rates of decomposition on soils from warmed plots. The influence of litter species on decomposition waned in the later stages of the experiment when decomposition was driven by microbial community origin.These results suggest that warming‐induced changes in microbial community function may interact with changes in plant litter composition to mitigate the impacts of warming on rates of decomposition. This emphasizes the importance of considering concurrent warming‐induced changes in both plant and microbial communities on ecosystem processes like decomposition. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

1. Non‐native species may be the cause of native species declines or an effect of habitat degradations that promote the former and damage the latter. Social insects are extraordinarily successful organisms, and non‐native social insects, such as ants, often are very successful invaders of novel habitats. 2. The red imported fire ant (Solenopsis invicta) and the Asian needle ant (Brachyponera chinensis) are widespread non‐native invaders in the eastern United States that bring ecological, economic and social impacts, but their putative effects on native ant communities may be concomitant with habitat degradation rather than inherent in their invasion. 3. Given this gap in understanding, our goal was to examine how experimental warming influenced native and non‐native ant communities. Specifically, we hypothesised that (a) non‐native ant abundance and species richness will increase in warmed plots and that (b) warming‐induced increases in the non‐native ant populations will correspond with decreases in native ant abundance and species richness. 4. To test these hypotheses, we used three levels of experimental forest edge soil warming (warming targeted at +0, +3, and +5°C above ambient soil temperature) in a mixed deciduous forest in the Georgia (USA) Piedmont. We used repeated pitfall trapping to investigate how the experimental warming influenced the composition of native and non‐native ant communities with a focus on how warming combined with S. invicta and B. chinensis invasion impacted native ant communities. 5. Our results suggest that experimental warming promoted the non‐native invasive ants, particularly S. invicta and B. chinensis. We also found that B. chinensis somewhat inhibited native ant communities, but not because of warming. The warmed environment benefited both non‐native invasive ants at the expense of native ants but, given that B. chinensis negatively impacted the native ants with far fewer workers than S. invicta, B. chinensis may pose a greater threat to native ant communities than S. invicta in a warmer world. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) has experienced an accelerated wintertime warming in recent decades under global warming, but consensus on its causes has not yet been reached. This study quantifies the processes of the warming through analyzing surface temperature budget and surface energy balance. It is found that increased diabatic heating (73%) and warm advection (27%) by an anomalous anticyclone southeast of TP are two primary processes determining the surface air warming. The former is caused by a significant increase of the TP skin temperature which warms the near surface atmosphere through increasing upward surface sensible heat flux. The land surface warming is attributed to increased absorbed radiation fluxes in which three processes are identified to be major contributors. While outside forcing which is primarily due to increased anthropogenic emissions of greenhouse gases contributes to the warming by 25% through increasing downward longwave radiation, two types of local positive feedbacks which are triggered by the land surface warming are found to contribute to most of the warming. One is the snow-albedo feedback which accounts for 47% of the surface warming by increasing surface absorption of incident solar radiation. The other is the moisture process feedback which accounts for 28% of the surface warming. The surface warming which works with increased soil water due to increased precipitation in the preceding seasons tends to promote surface evaporation and moisten the atmosphere aloft over the eastern TP, which, in turn, tends to increase downward longwave radiation and cause a further surface warming. [ABSTRACT FROM AUTHOR]

"Land radiative management" (LRM)—intentionally increasing land surface albedo to reduce regional temperatures—has been proposed as a form of geoengineering. Its effects on local precipitation and soil moisture over long timescales are not well understood. We use idealized cloud‐permitting simulations and a conceptual model to understand the response of precipitation and soil moisture to a mesoscale albedo anomaly at equilibrium. Initially, differential heating between a high‐albedo anomaly and the lower‐albedo surrounding environment drives mesoscale circulations, increasing precipitation and soil moisture in the surrounding environment. However, over time, increasing soil moisture reduces the differential heating, eliminating the mesoscale circulations. At equilibrium, the fractional increase in simulated soil moisture is up to 1.3 times the fractional increase in co‐albedo (one minus albedo). Thus, LRM may increase precipitation and soil moisture in surrounding regions, enhancing evaporative cooling and spreading the benefits of LRM over a wider region than previously recognized. Plain Language Summary: One way to reduce temperatures in a warming world is to increase the fraction of sunlight reflected by the land surface back to space (the "albedo"), for example, by painting surfaces white. However, changing albedo does not only change temperatures; it can also impact rainfall and soil moisture. Here, we show that increasing a region's albedo leads to increased rainfall and soil moisture in surrounding regions, where the albedo has not been changed, spreading the cooling effect over a wider area than previously recognized. Key Points: Land radiative management (LRM)—increasing land surface albedo to reduce temperatures—has been proposed as a form of geoengineeringWe use idealized cloud‐permitting simulations and a conceptual model to understand the hydrologic response to LRMLRM increases rainfall and soil moisture in surrounding regions, potentially extending its cooling benefits [ABSTRACT FROM AUTHOR]

Permafrost areas are sensitive to climate change and have a significant impact on energy and water cycles. Ground ice is a crucial component on the Qinghai–Tibetan Plateau (QTP). Understanding the environmental characteristics of ground ice is vital for accurately modeling its distribution and evolution. In this study, we analyzed 15 environmental characteristics of high ice-content permafrost sites. These attributes were extracted from 400 high ice-content permafrost datasets including 300 drilling boreholes and 100 thaw slumps collected throughout the entire plateau using large-scale remote sensing data and their products. The results are as follows: The mean annual air temperature in areas where high ice-content permafrost exists ranges from −5 to −3.5 °C, with an average warming rate of 0.08 °C/a. Additionally, there was an average increase in precipitation of about 25 mm/10a and an increase in soil moisture of about 4%/10a. Geomorphology strongly influences the occurrence of high ice content permafrost, with 85% of high ice-content permafrost development at altitudes between 4400 and 5100 m. Approximately 86% of high ice-content permafrost were developed in lowland or relatively flat areas, preferably in gently sloping and shady slope regions. Soils exhibit less variability in clay particles and more variability in silt and sand. Key indicators in the high ice content permafrost region include warming rate, active layer thickness, elevation, bulk density, soil thickness, clay content, precipitation, soil moisture, and NDVI. High ice-content permafrost is the result of a combination of environmental factors and is expected to undergo significant changes in the future. This study provides a foundation for comprehending the environmental changes in the high ice-content permafrost areas and modeling the distribution of ground ice. It underscores the urgent need to address the significant environmental changes faced by high ice-content permafrost regions. [ABSTRACT FROM AUTHOR]

Climate warming has been suggested to impact high latitude grasslands severely, potentially causing considerable carbon (C) losses from soil. Warming can also stimulate nitrogen (N) turnover, but it is largely unclear whether and how altered N availability impacts belowground C dynamics. Even less is known about the individual and interactive effects of warming and N availability on the fate of recently photosynthesized C in soil. On a 10‐year geothermal warming gradient in Iceland, we studied the effects of soil warming and N addition on CO2 fluxes and the fate of recently photosynthesized C through CO2 flux measurements and a 13CO2 pulse‐labeling experiment. Under warming, ecosystem respiration exceeded maximum gross primary productivity, causing increased net CO2 emissions. N addition treatments revealed that, surprisingly, the plants in the warmed soil were N limited, which constrained primary productivity and decreased recently assimilated C in shoots and roots. In soil, microbes were increasingly C limited under warming and increased microbial uptake of recent C. Soil respiration was increased by warming and was fueled by increased belowground inputs and turnover of recently photosynthesized C. Our findings suggest that a decade of warming seemed to have induced a N limitation in plants and a C limitation by soil microbes. This caused a decrease in net ecosystem CO2 uptake and accelerated the respiratory release of photosynthesized C, which decreased the C sequestration potential of the grassland. Our study highlights the importance of belowground C allocation and C‐N interactions in the C dynamics of subarctic ecosystems in a warmer world. [ABSTRACT FROM AUTHOR]

The alpine treeline is highly sensitive to temperature change, and treelines worldwide have been rapidly responding to temperature warming by increasing in tree density. However, often inconsistent or even conflicting results, regarding the response of tree recruitment to temperature change across regions, still challenge our profound comprehension of warming‐induced treeline dynamics. Here, we quantified the temperature sensitivity of tree recruitment within alpine treeline ecotones (i.e. the strength of relationship between tree recruitment and temperature change), and tested whether and how the temperature sensitivity changed along latitudinal gradients by examining 124 alpine treelines across North America and Asia. Our analyses demonstrated that temperature changes could significantly influence tree recruitment at treeline ecotones and the sensitivity of tree recruitment to temperature change was significantly and positively associated with latitude, showing that tree recruitment was more sensitive to temperature change at high latitudes than at low latitudes. Our findings highlighted the heterogeneous responses of tree recruitment at alpine treelines to temperature changes across latitudinal gradients, which should be incorporated into assessment models to improve future projections of global warming impacts across alpine ecosystems. [ABSTRACT FROM AUTHOR]

The uncertainty response of soil fungi community to climate warming in alpine agroecosystems will limit our ability to fully exploit and utilize soil fungi resources, especially in alpine regions. In this study, a warming experiment was conducted in one perennial leguminous agroecosystem [i.e., alfalfa (Medicago sativa)], perennial gramineous agroecosystem (i.e., Elymus nutans) and annual gramineous agroecosystem [i.e., highland barley (Hordeum vulgare L)] in Tibet since 2016 to investigate the response of soil fungi community to climate warming. Soils at two layers (i.e., 0–10 cm and 10–20 cm) were collected in August 2017 to estimate soil fungi community based on the ITS method. The α-diversity, community composition and functional group abundance of soil fungi in the leguminous agroecosystem were more sensitive to climate warming. The α-diversity of soil fungi in the perennial gramineous agroecosystem were more sensitive to climate warming, but topology parameters of soil fungi species cooccurrence network in the annual gramineous agroecosystem were more sensitive to climate warming. Compared with 0–10 cm, soil fungal α-diversity, community composition and functional group abundance at 10–20 cm were more sensitive to climate warming. The topological parameters of soil fungi species cooccurrence network at 0–10 cm in the gramineous agroecosystem were more sensitive to climate warming, but those at 10–20 cm in the leguminous agroecosystem were more sensitive to climate warming. Warming increased the differences of soil fungi α-diversity and functional composition. For the Medicago sativa agroecosystem, warming increased the abundance of soil pathogenic fungi but decreased the abundance of soil symbiotic and saprophytic fungi at 10–20 cm. Therefore, responses of the soil fungi community to climate warming varied with agroecosystem types and soil depth. Climate warming can alter the differences of the soil fungi community among agroecosystems. Changes in soil fungi community caused by climate warming may be detrimental to the growth of alpine crops, at least for perennial Medicago sativa in Tibet. [ABSTRACT FROM AUTHOR]

How root respiration acclimates to global warming remains unclear, especially in subtropical forests that play a key role in the global carbon budget. In a large‐scale in situ soil warming experiment, the occurrence of, and mechanisms controlling over, the acclimation of fine‐root respiration of Cunninghamia lanceolata during the fourth year of warming were investigated. Specific respiration rates (at reference temperature of 20°C; SRR20) were measured with exogenous glucose addition, uncoupler addition, or no addition, and root morphological and chemical traits were also measured. Warming decreased SRR20 by 18.4% only during summer, indicating partial thermal acclimation of fine‐root respiration under warming. Warming did not change fine‐root N concentration, showing no possible enzyme limitation on respiration. Warming decreased root soluble sugar/starch ratio in summer, and glucose addition increased respiration only under warming, indicating a warming‐induced substrate limitation on respiration. Uncoupler addition also stimulated respiration only under warming, showing a warming‐induced adenylate limitation on respiration. These findings suggest that thermal acclimation of root respiration in subtropical forests, which is at least partially constrained by substrate and adenylate use, is conducive to reducing ecosystem carbon emissions and mitigating the positive feedback between atmospheric CO2 and climate warming. SUMMARY STATEMENT: Fine‐root respiration of subtropical Chinese fir plantation showed partial thermal acclimation to warming only during summer and was limited by substrate and adenylate rather than enzyme capacity, which is conducive to mitigate the potential positive effect of warming on ecosystem carbon emissions. [ABSTRACT FROM AUTHOR]

Summary: Global nocturnal temperatures are rising more rapidly than daytime temperatures and have a large effect on crop productivity. In particular, stomatal conductance at night (gsn) is surprisingly poorly understood and has not been investigated despite constituting a significant proportion of overall canopy water loss.Here, we present the results of 3 yr of field data using 12 spring Triticum aestivum genotypes which were grown in NW Mexico and subjected to an artificial increase in night‐time temperatures of 2°C.Under nocturnal heating, grain yields decreased (1.9% per 1°C) without significant changes in daytime leaf‐level physiological responses. Under warmer nights, there were significant differences in the magnitude and decrease in gsn, values of which were between 9 and 33% of daytime rates while respiration appeared to acclimate to higher temperatures. Decreases in grain yield were genotype‐specific; genotypes categorised as heat tolerant demonstrated some of the greatest declines in yield in response to warmer nights.We conclude the essential components of nocturnal heat tolerance in wheat are uncoupled from resilience to daytime temperatures, raising fundamental questions for physiological breeding. Furthermore, this study discusses key physiological traits such as pollen viability, root depth and irrigation type may also play a role in genotype‐specific nocturnal heat tolerance. [ABSTRACT FROM AUTHOR]

The role of temperature advection in the Arctic lower troposphere under changing level of global warming is investigated using a large-ensemble climate simulation dataset. Taking the 30-year climatology of the non-warming simulation (HPB-NAT) as a reference, we examined the difference in temperature advection under changing basic states of the historical experiment (HPB) and 2 K and 4 K warming experiments (HFB-2K and HFB-4K) and decomposed them into terms related to dynamical changes, thermodynamical changes and the eddy term which is a covariance term related to the effect of sub-monthly transient eddies. Under the HPB experiment, it was found that the total change in advection hangs in a balance between the positive signal located along the sea-ice boundary in the North Atlantic and along the Eurasian continent driven by a stronger dynamical term and a negative signal in the thermodynamical term and eddy term. It is found that with the progression of global warming the dynamical term of advection increases due to changes in the large-scale atmospheric circulation, but the thermodynamical term and eddy term decrease due to weaker temperature gradient and increased sensible heat flux from the newly opened ice-free ocean, respectively. Atmospheric temperature advection terms related to large-scale atmospheric circulation partially cancels one another, and the relative importance of the eddy term diverging locally induced sensible heat from the newly opened ice-free ocean dominates as global warming progresses. [ABSTRACT FROM AUTHOR]

However, some gases (mainly methane) are buried in bottom sediments and become sequestered in gas hydrates forming large gas reservoirs. Meanwhile, heat insulation of tubing will keep the permafrost frozen over the whole well lifespan and prevent its degradation, as well as the ensuing dissociation of intrapermafrost gas hydrates and methane emission. Explosive gas emission is modeled for the case of the Yamal Peninsula, with regard to high gas contents in shallow permafrost which encloses ground ice, unfrozen intra-permafrost and sub-permafrost saline lenses (cryopegs), and hydrocarbon accumulations with related ascending gas-water fluids. [Extracted from the article]

Aim: Global warming and altered precipitation substantially affect soil carbon (C) pools and can, in turn, feed back into climate change. However, how soil C pools respond to the combined effects of warming and altered precipitation remains unclear. Location: Global. Time period: 1996–2021. Major taxa studied: Soil organic C pools. Method: A meta‐analysis was performed using 657 observations obtained from 34 published articles that focused on both individual and combined effects of warming and altered precipitation on soil organic C (SOC), dissolved organic C (DOC) and microbial biomass C (MBC) to quantify the responses of soil C pools. Results: Across all combined warming and increased precipitation experiments, SOC and MBC increased by an average of 4.0% and 15.4%, respectively. In contrast, warming combined with decreased precipitation led to a substantial decline in SOC and MBC by an average of 8.2% and 12.3%, respectively. The responses of DOC to combined warming and altered precipitation were marginal. The direction and magnitude of the responses to the combined treatment were more similar to those in the individual altered precipitation treatment than to those in the individual warming treatment. Furthermore, these combined effects were substantially influenced by altered precipitation magnitudes. Combined warming and altered precipitation had greater impacts on soil C pools than their individual treatments but were not substantially different from the sum of their respective individual effects, showing overall additive effects. The responses of soil C pools to combined warming and altered precipitation were observed to be more pronounced in grasslands than in forests. Main conclusion: The results demonstrated that altered precipitation regimes often dominated over warming in regulating soil C pools under combined warming and altered precipitation and improved our understanding of soil C cycles under climate change scenarios. [ABSTRACT FROM AUTHOR]

The soil freeze-thaw cycle in the permafrost regions has a significant impact on regional surface energy and water balance. Although increasing efforts have been made to understand the responses of spring thawing to climate change, the mechanisms controlling the global interannual variability of the start date of permafrost frozen (SOF) remain unclear. Using long-term SOF from the combinations of multiple satellite microwave sensors between 1979 and 2020, and analytical techniques, including partial correlation, ridge regression, path analysis, and machine learning, we explored the responses of SOF to multiple climate change factors, including warming (surface and air temperature), start date of permafrost thawing (SOT), soil properties (soil temperature and volume of water), and the snow depth water equivalent (SDWE). Overall, climate warming exhibited the maximum control on SOF, but SOT in spring was also an important driver of SOF variability; among the 65.9% significant SOT and SOF correlations, 79.3% were positive, indicating an overall earlier thawing would contribute to an earlier frozen in winter. The machine learning analysis also suggested that apart from warming, SOT ranked as the second most important determinant of SOF. Therefore, we identified the mechanism responsible for the SOT-SOF relationship using the SEM analysis, which revealed that soil temperature change exhibited the maximum effect on this relationship, irrespective of the permafrost type. Finally, we analyzed the temporal changes in these responses using the moving window approach and found increased effect of soil warming on SOF. In conclusion, these results provide important insights into understanding and predicting SOF variations with future climate change. [ABSTRACT FROM AUTHOR]

The climatic stressors that are affecting lake ecosystems, especially phytoplankton, are projected to become more intense with continued climate change (e.g., heatwaves, precipitation events). Concerns over the combined effects that multiple, coinciding stressors can have on phytoplankton necessitates investigating the impacts of different regional climate scenarios.A microcosm study was conducted to assess the responses of a phytoplankton assemblage containing a cyanobacterium (Anabaena flos‐aquae), a green alga (Chlorella vulgaris) and a diatom (Synedra) to a northwestern European summer scenario. Eutrophic microcosms were exposed to a full‐factorial design including a press temperature treatment scenario (ambient or warm) and a pulse precipitation treatment (no runoff simulation or runoff simulation).Warming scenarios had significant effects on the phytoplankton assemblage biomass, which supports our first hypothesis (H1: higher water temperatures under eutrophic conditions will support larger phytoplankton biomasses, especially cyanobacteria). By contrast, the extreme precipitation runoff event had minimal and short‐lived effects on the microcosm assemblage.Overall, the interaction between the two climate stressors was antagonistic. In contrast with our second hypothesis (H2: nutrient additions from extreme precipitation runoff will promote more productivity in higher temperature microcosms), the precipitation runoff event was not amplified by temperature.Our results indicate that the combined effect of two climate stressors on a phytoplankton community are not necessarily synergistic or multiplicative. Our findings on antagonistic interactions between climatic stressors necessitate future studies assessing variations of intensity and duration of the climatic stressors. [ABSTRACT FROM AUTHOR]

Background and Aims The response of subarctic grassland's below-ground to soil warming is key to understanding this ecosystem's adaptation to future climate. Functionally different below-ground plant organs can respond differently to changes in soil temperature (T s). We aimed to understand the below-ground adaptation mechanisms by analysing the dynamics and chemistry of fine roots and rhizomes in relation to plant community composition and soil chemistry, along with the duration and magnitude of soil warming. Methods We investigated the effects of the duration [medium-term warming (MTW; 11 years) and long-term warming (LTW; > 60 years)] and magnitude (0–8.4 °C) of soil warming on below-ground plant biomass (BPB), fine root biomass (FRB) and rhizome biomass (RHB) in geothermally warmed subarctic grasslands. We evaluated the changes in BPB, FRB and RHB and the corresponding carbon (C) and nitrogen (N) pools in the context of ambient, T s < +2 °C and T s > +2 °C scenarios. Key Results BPB decreased exponentially in response to an increase in T s under MTW, whereas FRB declined under both MTW and LTW. The proportion of rhizomes increased and the C–N ratio in rhizomes decreased under LTW. The C and N pools in BPB in highly warmed plots under MTW were 50 % less than in the ambient plots, whereas under LTW, C and N pools in warmed plots were similar to those in non-warmed plots. Approximately 78 % of the variation in FRB, RHB, and C and N concentration and pools in fine roots and rhizomes was explained by the duration and magnitude of soil warming, soil chemistry, plant community functional composition, and above-ground biomass. Plant's below-ground biomass, chemistry and pools were related to a shift in the grassland's plant community composition – the abundance of ferns increased and BPB decreased towards higher T s under MTW, while the recovery of below-ground C and N pools under LTW was related to a higher plant diversity. Conclusion Our results indicate that plant community-level adaptation of below ground to soil warming occurs over long periods. We provide insight into the potential adaptation phases of subarctic grasslands. [ABSTRACT FROM AUTHOR]

This manuscript reports the investigation of the polymorphic behaviour of fipronil using a systematic comparison of the thermochemical and structural properties of different crystal forms obtained in this study as well as those previously reported in literature. The analytical techniques employed include DSC, TGA, PXRD, SCXRD and hot stage microscopy. DSC proved particularly useful because it made it possible to differentiate between the two different crystal forms found in the as-received neat fipronil. The DSC scans revealed the presence of two polymorphs which had melting endotherms with peak maxima at ca. 196 °C and 205 °C, respectively. These polymorphs were successfully separated via sublimation and resulted in a metastable, lower melting polymorph in the sublimate and a thermodynamically stable, higher melting form in the sublimation residue. Clear evidence for the instability of the lower melting polymorph was found when the endotherms were examined under a range of heating rates. The proportion of the metastable form appeared to increase as the rate was increased, indicating that the metastable form underwent a solid–solid phase transition to the stable form at low heating rates. Recrystallization of fipronil from different solvents yielded five different forms. TGA curves revealed that all forms, except the acetone-derived one, were solvate pseudo-polymorphs that showed solvent loss between 60 and 100 °C. The acetone-derived sample was a hemihydrate that only started to show mass loss at 120 °C. SCXRD studies revealed that three of the five forms have similar structural characteristics, while the other two forms differ notably from each other and the rest of the structures. Despite these structural differences, all five forms exhibit near-identical intra- and intermolecular hydrogen bond networks. [ABSTRACT FROM AUTHOR]

There has been a severe shortage of water resources in Central Asia and agriculture has been highly dependent on irrigation because of the scarce precipitation in the croplands. Central Asia is also experiencing climate warming in the context of global warming; however, few studies have focused on changes in the amount of irrigation in Central Asia under future climate warming and their regional climate effects. In this study, we adopted the Weather Research and Forecasting (WRF) model to design three types of experiments: historical experiments (Exp01); warming experiments using future driving fields (Exp02); and warming experiments that involved increasing the surface energy (Exp03). In each type of experiment, two experiments (considering and not considering irrigation) were carried out. We analyzed the regional climate effects of irrigation under the warming of Central Asia by 2.0 °C through determining the differences between the two types of warming experiments and the historical experiments. For surface variables (irrigation amount; sensible heat flux; latent heat flux; and surface air temperature), the changes (relative to Exp01) in Exp03 were thought to be reasonable. For precipitation, the changes (relative to Exp01) in Exp02 were thought to be reasonable. The main conclusions were as follows: in Central Asia, after warming by 2.0 °C, the irrigation amount increased by 10–20%; in the irrigated croplands of Central Asia, the irrigation-caused increases (decreases) in latent heat flux (sensible heat flux) further expanded; and then the irrigation-caused decreases in surface air temperature also became enhanced; during the irrigation period, the irrigation-caused increases in precipitation in the mid-latitude mountainous areas were reduced. This study also showed that, in the WRF model, the warming experiments caused by driving fields were not suitable to simulate the changes in irrigation amount affected by climate warming. [ABSTRACT FROM AUTHOR]

Northeast China (NEC) is one of the main soybean-producing areas among the northern-latitude regions. Climate warming leads to frequent extreme disasters, and the threat of chilling damage to soybean production in NEC cannot be ignored. The study aimed to construct a dynamic disaster identification index based on the static evaluation of soybean after the disaster, taking into account the process of soybean chilling damage and using the historical disaster records to realize the dynamic prediction and analysis before the disaster. Taking soybean in NEC as the research object, chilling damage indicators of soybeans in NEC were constructed by dividing the mature regions, using daily temperature anomaly and negative temperature anomaly day data with the comprehensive consideration of the chilling damage intensity, duration, and temperature recovery. The results showed that the comprehensive indicators determined by the cumulative value of temperature anomaly—the cumulative days of negative temperature anomaly had better applicability in NEC than the single factor indicator. The indicator results were basically consistent with the historical disaster records, and the accuracy rate of the indicator verification reached 90.9%. Based on the analysis of the constructed indicators, the frequency of delayed chilling damage in NEC showed a fluctuating downward trend from 1961 to 2020. The station ratio of delayed chilling damage in NEC showed a fluctuating downward trend, with the most obvious downward trend occurring for severe damage, followed by moderate damage, and the least obvious trend observed for light damage. The scope of chilling damage gradually narrowed, with the frequency increasing from southeast to northwest. The high-risk areas of chilling damage were concentrated mainly in the northern part of Heilongjiang Province and the East Four Leagues. The risk of chilling damage in most areas of Jilin Province and Liaoning Province was relatively low. The study results provide basic support for the risk research of soybean chilling damage and for ensuring disaster monitoring and early warnings, and the risk assessment based on the chilling damage process has positive significance for adjusting agricultural structure and improving the distribution of soybean varieties. [ABSTRACT FROM AUTHOR]

Numerical modeling is a promising way to understand the characteristics of the thermo-mechanical (TM) coupled behaviors in rocks under high-temperature impact. This paper documents the thermo-mechanical response of Eibenstock granite (EG) through laboratory experiments and numerical simulations using a proposed TM coupled Grain-Based Model (GBM). Uniaxial compression and Brazilian tests of EG specimens after 400 °C and 600 °C heating–cooling cycles were undertaken. Based on the laboratory results, a newly developed TM coupled contact constitutive law considers mineral composition, heterogeneous temperature-dependent properties, reversible α ↔ β quartz-transitions, crack-slipping displacements with strength reduction, and real-time crack evolution. The models can well reproduce the real-time thermal expansion–contraction, microstructural changes, nonlinear stress–strain behavior, temperature-dependent strength, and the ultimate failure modes of thermal-damaged specimens. The P-wave velocities and the simulated thermal cracking revealed that the material contraction during cooling leads to a width reduction of the earlier heating-formed cracks. Newly induced microcracks are rare during cooling due to the released stress concentrations of the local mineral grains. The residual thermal strain, which results from microcrack formation and the growth of pre-existing microcracks, was simulated and used as a quantitative index of thermally induced damages. The damage degree of the 600 °C samples was up to six times higher than that of the 400 °C, leading to a stronger strength reduction upon mechanical loading and a higher concave stress–strain nonlinearity caused by micro-crack closing at the beginning of loading. In general, the GBM is able to simulate the TM coupled behavior of polycrystalline rocks in a realistic manner. Highlights: A joint constitutive law considering both temperature and crack-slipping is proposed. TM models considering a heating-cooling cycle are calibrated by laboratory tests. Real-time thermal-induced strains of granite specimens are reproduced. Concave stress-strain nonlinearity of thermally damaged granites is replicated. [ABSTRACT FROM AUTHOR]

Buildings are responsible for a large part of energy demand worldwide. To collaborate to reduce this demand, this paper aims to present a computational model to analyze the performance of an earth–air heat exchanger (EAHE) based on computational fluid dynamics using the ANSYS/Fluent® software in the simulations. This passive air conditioning system uses the soil as a heat exchanger, taking advantage of the fact that the temperature of the soil at a certain depth remains relatively constant, regardless of the weather conditions above the surface, promoting heating, cooling, or ventilation for buildings. The air temperature values obtained were compared with experimental data from sensors installed in an EAHE at the Federal University of Technology—Parana, Ponta Grossa/Brazil (25.1° South, 50.16° West) to validate the computational model. A high computational effort would be demanded to perform these simulations involving the whole soil domain and the climatic boundary conditions. In order to optimize the numerical analysis of EAHE, two reduced models for the soil and heat exchanger domains were verified. First, a constant temperature of 23.7 °C was imposed on the surface of the exchanger tube, corresponding to the average soil temperature at a depth of 1.5 m. Afterward, a reduced soil domain extending 0.5 m in all directions from the heat exchanger serpentine was considered. Likewise, constant temperatures were imposed on the upper and lower surfaces of the soil domain, also obtained experimentally. In both cases, the temperature values obtained through the fast simulations showed good agreement compared to the experimental values. Barely explored in the literature, the thermal behavior of the two identical indoor environments at the university was also compared, in which the climatized environment, with the EAHE working in a closed loop, obtained milder and smaller amplitude air temperatures. [ABSTRACT FROM AUTHOR]

Due to significant differences in biotic and abiotic properties of soils compared to those of sediments, the predicted underlying microbe-mediated mechanisms of soil carbon emissions in response to warming may not be applicable for estimating similar emissions from inland water sediments. We addressed this issue by incubating different types of sediments, (including lake, small river, and pond sediments) collected from 36 sites across the Yangtze River basin, under short-term experimental warming to explore the effects of climate warming on sediment carbon emission and the underlying microbe-mediated mechanisms. Our results indicated that under climate warming CO 2 emissions were affected more than CH 4 emissions, and that pond sediments may yield a greater relative contribution of CO 2 to total carbon emissions than lake and river sediments. Warming-induced CO 2 and CH 4 increases involve different microbe-mediated mechanisms; Warming-induced sediment CO 2 emissions were predicted to be directly positively driven by microbial community network modularity, which was significantly negatively affected by the quality and quantity of organic carbon and warming-induced variations in dissolved oxygen, Conversely, warming-induced sediment CH 4 emissions were predicted to be directly positively driven by microbial community network complexity, which was significantly negatively affected by warming-induced variations in pH. Our findings suggest that biotic and abiotic drivers for sediment CO 2 and CH 4 emissions in response to climate warming should be considered separately when predicting sediment organic carbon decomposition dynamics resulting from climate change. [ABSTRACT FROM AUTHOR]

While energy production is highly dependent on fossil fuels, which consider the main source of global warming, biofuels would play a significant impact in diminishing such warming. In this paper, biooils were extracted from inedible seeds (Jatropha and Castor) using different continuous devices (solvents, screw presses, and hydraulic press-machines), aiming to achieve the highest oil's yield of improved extraction properties at reduced time and energy. A wide range of engine speeds of 35, 60, 85, 110, and 135 rpm and preheating temperatures of 100, 125, 150, 175, 200, and 250°C were extensively studied to find their impact on the extraction properties. Results proved the ability of the screw press machine to extract the highest biooil yields from Jatropha and castor seeds. The optimum yield of Jatropha and castor were achieved at an extraction temperature range of 150-175°C at a motor speed of 135 rpm and a temperature range of 200-250°C at a motor speed of 35 rpm, respectively. Noteworthy, the yield of extracted castor oil is potentially solidified at low temperatures <100°C, leading oil samples to become like a dough. In contrast, lowering the temperatures of the Jatropha seeds improved the physical and chemical properties of the extracted oil. At a certain temperature (e.g., 100°C), the properties of both extracted and diesel oils are quite similar, which can be used directly in diesel engines. [ABSTRACT FROM AUTHOR]