Increase In Annual Precipitation Research Articles

The relative importance of driving factors of wildfire occurrence across climatic gradients in the Inner Mongolia, China

In recent decades, wildfire regimes have been changing in many parts of the world with significant differences among climatic regions. Thus, understanding the relationship between fires and driving factors in different climatic regions is important. We investigated the relative importance of wildfire drivers across climatic gradients using a Bayesian network model during 2001–2015 in the Inner Mongolia Autonomous Region (IMAR). Our results showed that regional-scale fire relative probability (FRP) on average increased in the IMAR, which was mainly attributed to increases in annual precipitation. However, changes in FRP and driving factors of wildfire occurrence varied among climatic regions. The FRP decreased at rates of −0.02/decade and −0.001/decade in the humid and semi-humid region, respectively, while increasing at an average rate of 0.05/ decade in the arid region. Temperature was recognized as the most influential driver of wildfires in the humid region, in which the relative importance of all driving factors remained relatively stable over time. In the semi-humid region, wildfires responded primarily to human activities, of which distance to railways was of greatest importance. The relative importance of distance to railways significantly increased over time, while the effects of temperature, humidity and elevation decreased considerably. Fractional vegetation cover (FVC) was the dominant factor controlling the wildfire occurrence in the arid region, in which the relative importance of precipitation significantly increased and the effect of settlements significantly decreased. Our study suggests that because of different driving factors of wildfires across climatic gradients, different fire prevention and management strategies are required. The optimal resource allocation for fire prevention should be adjusted according to the relative importance of wildfire drivers and spatiotemporal patterns of the FRP.

Global patterns and controls of soil nematode responses to nitrogen enrichment: A meta-analysis

Nematodes are important components of soil food webs and have important ecosystem functions. However, the responses of soil nematode communities to nitrogen (N) deposition have not been well assessed over large spatial scales. Here, we conducted a global-scale meta-analysis of the effects of N-addition regimes (N form, N addition approach, and N addition rate) and environmental factors (ecosystem type, soil depth, climate, and soil property) on the responses of soil nematodes to N addition. The results showed that N addition significantly increased the relative abundance of bacterial-feeding nematodes (23.54%), but decreased the relative abundance of plant-feeding nematodes (−20.24%) and omnivorous-predatory nematodes (−22.28%). Nitrogen addition, however, did not significantly affect total nematode abundance or the relative abundance of fungal-feeding nematodes. Understory N addition usually had larger effects on nematode abundance than canopy N addition. The responses to N addition increased with N addition rate in the case of bacterial-feeding nematode abundance, but decreased with N addition rate in the case of plant-feeding nematode and fungal-feeding nematode abundances. Nematode abundance in grasslands were more responsive to N addition than in forests or croplands, and the responses were affected by soil depth. The response ratios of bacterial-feeding nematodes to N addition decreased with increases in mean annual temperature and mean annual precipitation, while the response ratios of plant-feeding nematodes showed the opposite trend. Soil pH and organic carbon did not affect the response ratios of nematode parameters to N addition except plant parasite index. In summary, the responses of soil nematodes to N addition on a global scale were found to be affected by both N-addition regimes and environmental factors. We suggest that our understanding of how N deposition affects soil nematodes will be increased by additional studies of canopy N addition and of tropical ecosystems.

Use of maximum entropy (Maxent) niche modelling to predict the occurrence of threatened freshwater species in a biodiversity hotspot of Zimbabwe

AbstractGlobally, freshwater species are under threat from human mediated stressors. Therefore, there is an urgent need for methods to estimate population and species occurrences for conservation purposes. Here, we used a predictive species distribution model to determine the occurrence of three endangered species (Amietia inyangae, Chlorolestes elegans and Strongylopus rhodesianus) in Southern Africa (Eastern Highlands of Zimbabwe). The study revealed that the probability of occurrences for the three species increase with an increase in elevation and annual precipitation and decrease with an increase in annual mean temperature. Our results indicated that the highest probability of occurrences for A. inyange, C. elegans and S. rhodesianus is in the Nyanga, Stapleford and Chimanimani highland areas, with some probabilities of occurrence falling outside protected areas. Our findings suggest that the areas covered by protected areas may need to be revaluated. Our findings will be useful for managing threatened species.

Ensemble Temperature and Precipitation Projection for Multi-Factorial Interactive Effects of GCMs and SSPs: Application to China

Climate change has broadly impacted on the China areas. There will be severe challenges due to the variations of precipitation and temperature in the future. Therefore, a comprehensive understanding of the future climate change over China areas is desired. In this study, future annual precipitation and annual mean temperature under two SSPs over China areas were projected through multiple global climate models. Meanwhile, to explore the sources of uncertainty in projecting future climate change, the multi-factorial analysis was conducted through GCMs (five levels) and SSPs (two levels). This study can help us understand the possible changes in precipitation, temperature, and the potential extreme climate events over the China area. The results indicate that China would have more annual precipitation and higher annual mean temperature in the future. Compared with the historical period, the annual mean temperature would face a continuously increasing trend under SSPs. Regardless of SSP245 or SSP585, the growth rate of annual precipitation and annual mean temperature increase in the northern region (e.g., Northeast China, North China, and Northwest China) are higher than those in the southern parts (e.g., East China, South China, and Central China). The future temperature rise may increase the frequency of heat-related extreme climate events, which needs to be focused on in future research. Moreover, GCM was the main contributing factor to the sources of uncertainty in projecting future precipitation and SSP was the main factor for future temperature. Overall, climate change is an indisputable fact in China. The annual precipitation and annual mean temperature would increase to varying degrees in the future. Reducing the systemic bias of the climate model itself will undoubtedly be the top priority, and it would help to improve the projection and evaluation effects of relevant climate variables.

Forty Years of Increasing Precipitation is Correlated with Loss of Forbs in a Tallgrass Prairie

The effects of climate change on plant communities are already observable in many regions. In the tallgrass region of the Northern Great Plains, plant community composition may have shifted in response to increases in both annual precipitation and temperature. We compared community composition of a tallgrass prairie among three sampling periods (1978–1979, 1998, and 2014), spanning more than three decades, in order to better understand (1) temporal shifts in plant cover and (2) which environmental variables were correlated with these changes. Basal cover of Poa pratensis increased and basal cover of forbs declined over time. The shift from a forb-rich to grass-dominated prairie was positively correlated with higher levels of precipitation and soil moisture. Our study suggests that increased precipitation due to climate change has already altered plant community composition in the Great Plains.

Hydrological modelling of a snow/glacier-fed western Himalayan basin to simulate the current and future streamflows under changing climate scenarios

Himalayan rivers are the paramount source of water supply to millions of people in northern India for drinking, irrigation and hydropower generation. Several researches reported that the hydrological regime of these Himalayan rivers is vulnerable to climate change. In order to understand the hydrologic response of their headwaters and examine the climate change impacts on streamflow, a hydrological modelling study is carried out in the upper part of the Satluj river basin in western Himalaya by using a temperature index based SWAT (Soil Water Assessment Tool) model. The model performed well for both calibration (years 1986–2000) and validation (2001–2005) periods against the observed daily streamflow at Rampur (R2 ≈ 0.9 and NSE ≥ 0.85). The study reveals that having a larger snow covered area, the snowmelt runoff is the major contributor to the Satluj river discharge at Rampur that comes out to be about 68–71% of the average annual water yield of about 600 mm. The actual evapotranspiration comes out to be about 14% of precipitation. The water yield of the basin is about 50% of the precipitation, for which the major part is generated in early summer.Further, to study the climate change impact on future streamflow, the downscaled data of CORDEX CCSM4 under two Representative Concentration Pathways (RCP4.5 and RCP8.5) scenarios are used. The bias correction is applied at point level to remove biases from future time series of downscaled data and subsequently loaded into the SWAT model to simulate the future streamflows at the end of the century. The future climate variability in terms of precipitation and temperature exhibited that the climate in the region would become wetter and warmer. A 14% to 21% of increase in annual precipitation is predicted towards the end of the century from the current average annual precipitation of about 420 mm under RCP4.5 and RCP8.5, respectively. Similar to precipitation, the temperature will also be increased by 2.18 °C to 5.71 °C (in both the RCPs) than the current temperature values. The changed climate conditions in future are transformed into the possible range of stream flows using the SWAT model and found that the future climate would increase the streamflow by over 11%–19% at the end of the century under RCP4.5 and RCP8.5 scenarios, respectively. The outcome of this study can be used to develop the suitable strategies for sustainable water management in the region.

Resilience of Hydrologic Similarity Areas to extreme climate change scenarios in an urban watershed

ABSTRACT The water balance resilience to extreme climate change scenarios in Hydrologic Similarity Areas (HSA) is evaluated in the Belém catchment, Brazil. We used HadGEM2-ES statistically downscaled with the CMhyd tool under the Representative Concentration Pathways (RCPs) 2.6 and 8.5 to simulate climate scenarios. The AquaCycle model was used to simulate effects on the water balance. Climate modeling results show an increase in annual precipitation and average temperature, decreased rainy days, and increasing extremes. The water balance modeling demonstrated that the HSAs with higher percentages of impermeable surfaces present greater surface runoff and lower levels of infiltration and actual evapotranspiration increment in both RCP2.6 and RCP8.5. The differences among the HSA responses in the water balance are even more evident when analyzing the extreme events data series. Thereby, the results demonstrate that impermeable areas are less resilient to extreme events provided by climate change scenarios.

Snowfall and snowpack in the Western U.S. as captured by convection permitting climate simulations: current climate and pseudo global warming future climate

This study examines current and future western U.S. snowfall and snowpack through current and future climate simulations with a 4-km horizontal grid spacing cloud permitting regional climate model over the entire CONtinental U.S. for a 13-year period between 2001 and 2013. At this horizontal resolution, the spatiotemporal distribution of the orographic snowfall and snowpack is well captured partly due to the ability of the model to realistically simulate mesoscale and microphysical features such as orographically induced updrafts driving clouds and precipitation. The historical simulation well captures the observed snowfall and snowpack amounts and pattern in the western U.S. The future climate simulation uses the Pseudo-Global Warming approach, taking the climate change signal from CMIP5 multi-model ensemble-mean difference between 2070–2099 and 1976–2005. The results show that the thermodynamic impacts of climate change in the western U.S. can be characterized considering mountain ranges in two distinct geographic regions: the mountain ranges close to the Pacific Ocean (coastal ranges) and those in the inter-mountain west. Climate change out to 2100 significantly impacts all aspects of the water cycle, with pronounced climate change response in the coastal ranges. A notable result is that the snowpack in the Pacific Northwest is predicted to decrease by ~ 70% by 2100. Trends of this magnitude have already been observed in the historical data and in previous studies. The current Pseudo Global Warming future climate simulation and previous global climate simulations all suggest that these trends will continue to the point that most snowpack will be gone by 2100 in the Pacific Northwest for the most aggressive RCP8.5 climate scenario, even if annual precipitation increases by 10%. Future work will focus on extending the current convective permitting results to a full climate change simulation allowing for dynamical changes in the flow.

Influence of Earthquakes on Landslide Susceptibility in a Seismic Prone Catchment in Central Asia

Central Asia is one of the most challenged places, prone to suffering from various natural hazards, where seismically triggered landslides have caused severe secondary losses. Research on this problem is especially important in the cross-border Mailuu-Suu catchment in Kyrgyzstan, since it is burdened by radioactive legacy sites and frequently affected by earthquakes and landslides. To identify the landslide-prone areas and to quantify the volume of landslide (VOL), Scoops3D was selected to evaluate the slope stability throughout a digital landscape in the Mailuu-Suu catchment. By performing the limit equilibrium analysis, both of landslide susceptibility index (LSI) and VOL were estimated under five earthquake scenarios. The results show that the upstream areas were more seismically vulnerable than the downstream areas. The susceptibility level rose significantly with the increase in earthquake strength, whereas the VOL was significantly higher under the extreme earthquake scenario than under the other four scenarios. After splitting the environmental variables into sub-classes, the spatial variations of LSI and VOL became more clear: the LSI reduced with the increase in elevation, slope, annual precipitation, and distances to faults, roads, and streams, whereas the highest VOL was observed in the areas with moderate elevations, high precipitation, grasslands, and mosaic vegetation. The relative importance analysis indicated that the explanatory power reduced with the increase in earthquake level and it was significant higher for LSI than for VOL. Among nine environmental variables, the distance to faults, annual precipitation, slope, and elevation were identified as important triggers of landslides. By a simultaneous assessment of both LSI and VOL and the identification of important triggers, the proposed modelling approaches can support local decision-makers and householders to identify landslide-prone areas, further design proper landslide hazard and risk management plans and, consequently, contribute to the resolution of transboundary pollution conflicts.

CMIP6 Evaluation and Projection of Temperature and Precipitation over China

This article evaluates the performance of 20 Coupled Model Intercomparison Project phase 6 (CMIP6) models in simulating temperature and precipitation over China through comparisons with gridded observation data for the period of 1995–2014, with a focus on spatial patterns and interannual variability. The evaluations show that the CMIP6 models perform well in reproducing the climatological spatial distribution of temperature and precipitation, with better performance for temperature than for precipitation. Their interannual variability can also be reasonably captured by most models, however, poor performance is noted regarding the interannual variability of winter precipitation. Based on the comprehensive performance for the above two factors, the “highest-ranked” models are selected as an ensemble (BMME). The BMME outperforms the ensemble of all models (AMME) in simulating annual and winter temperature and precipitation, particularly for those subregions with complex terrain but it shows little improvement for summer temperature and precipitation. The AMME and BMME projections indicate annual increases for both temperature and precipitation across China by the end of the 21st century, with larger increases under the scenario of the Shared Socioeconomic Pathway 5/Representative Concentration Pathway 8.5 (SSP585) than under scenario of the Shared Socioeconomic Pathway 2/Representative Concentration Pathway 4.5 (SSP245). The greatest increases of annual temperature are projected for higher latitudes and higher elevations and the largest percentage-based increases in annual precipitation are projected to occur in northern and western China, especially under SSP585. However, the BMME, which generally performs better in these regions, projects lower changes in annual temperature and larger variations in annual precipitation when compared to the AMME projections.

VARIABILITY OF THE MAIN CLIMATIC INDICATORS IN THE TERRITORY OF THE VOLGA FEDERAL DISTRICT IN THE PERIOD 1966-2018

The spatio-temporal variability of air temperature and humidity, atmospheric precipitation in the Volga Federal District in 1966-2018 is considered. As a result of statistical processing of data from 20 weather stations, a clear warming trend in recent decades and a weak increase in annual precipitation are revealed, except for the south-east of the region. The annual variation of water vapor pressure and relative humidity is considered, statistics of the distribution of "dry" and "wet" days by stations in different months are carried out. Correlations between individual circulation modes (AO, NAO, SCAND, EAWR) and air temperature are revealed. It is shown that positive relationships are closer in winter with the AO and NAO indices than in summer. A sufficiently high negative correlation is established with the SCAND index in winter (r = -0,7), and with the EAWR index in summer (the correlation coefficient reaches a value of -0,6).

Responses of soil moisture to climate variability and livestock grazing in a semiarid Eurasian steppe

Soil water is vital for sustaining semiarid ecosystems. However, data on soil moisture have unlikely been continuously collected for a long time (e.g., >50 years), let alone under various combinations of climates and livestock grazing intensities. The objective of this study was to formulate and parameterize an ecohydrological model for predicting long-term variability of soil moisture, taking a typical Eurasian grassland located in northeast China as the testbed. The parameters were determined by extensive literature review, field reconnaissance, laboratory analyses of soil and grass samples, and model calibration using daily soil temperatures and soil moistures measured at four depths from 2014 to 2017. The model, driven by the daily climate data from 1955 to 2017, performed well in reproducing the measurements. Across the assessment years of 1960 to 2017, the daily soil moistures were predicted to vary from 0.02 to 0.38. Overall, the soil moistures at a shallower depth were smaller but had a wider range than those at a deeper depth, with a largest mean and a widest range around the 30 cm depth. Regardless of the depths, the soil moistures pulsed in beginning March and plateaued from May to September. Livestock grazing was precited to reduce top 1.5-cm soil moistures but increase moistures of the beneath soils. The optimal grazing intensity was determined to be around 3.0 cattle ha−1, above which wind erosion would become a concern. The grazing impacts on soil moisture were found to monophonically decrease with increase of evapotranspiration or annual precipitation of larger than 220 mm. For the years with an annual precipitation of less than 220 mm, such grazing impacts either increased or decreased with increase of precipitation, depending on the relative magnitude of evapotranspiration. Climate change will diminish soil moisture pulses in early spring, likely intensifying soil erosion by wind.

Impact of climate change on Swedish agriculture: Growing season rain deficit and irrigation need

Over 90% of Swedish agriculture is rainfed, and thus future climate change can pose a risk to agricultural production in coming decades. An overall increase in annual precipitation is predicted for northern Europe, but Sweden could still face an increasing need for irrigation, as shown by the drought summer of 2018. Adaptation of Swedish agriculture to include irrigated agriculture should thus be considered. To evaluate the theoretical need for irrigation, calculations were performed for different locations in Sweden, and for different soil-crop pairs at each location. In-situ weather data from a projected climate dataset created by the Swedish Meteorological and Hydrological Institute were used to evaluate changes in irrigation need over the period 1981–2050. The results showed an increasing need for irrigation of cereal crops during the early season (May–June), for two main reasons: i) A shift to an earlier start of the cropping period, leading to an earlier need for irrigation; and ii) a higher probability of dry spring weather, substantially increasing the irrigation requirement in dry years. Crops for which the growing season starts later (e.g., potatoes) showed an increasing need for irrigation during July. Crop development stages were predicted to occur earlier, leading to earlier harvesting, reducing the irrigation requirement in August. However, the calculation approach developed for this study may have underestimated the need for irrigation, which could be higher than reported here.

Projection of temperature and precipitation under SSPs-RCPs Scenarios over northwest China

Climate change significantly affects the environmental and socioeconomic conditions in northwest China. Here we evaluate the ability of five general circulation models (GCMs) from 6th phase of the Coupled Model Inter-comparison Project (CMIP6) to reproduce regional temperature and precipitation over northwest China from 1961 to 2014, and project the future temperature and precipitation during 2021 to 2100 under SSPs-RCPs (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0 and SSP5-8.5). The results show that the CMIP6 models can simulate temperature better than precipitation. Projections show that the annual mean temperature will further increase under different SSPs-RCPs scenarios in the 21st century. Future climate changes in the near-term (2021–2040), mid-term (2041–2060) and long-term (2081–2100) are analyzed relative to the reference period (1995–2014). In the long term, warming will be significantly higher than the near and mid-terms. In the long term, annual mean temperature will increase by 1.4°C, 1.9°C, 3.3°C, 5.5°C, 2.7°C, 3.8°C and 6.0°C under SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0 and SSP5-8.5, respectively. Spatially, warming in the Junggar Basin will be higher than those in the Tarim Basin. Seasonally, the maximum warming zone will be in the mountainous areas of Tarim Basin during spring and autumn, in the southern basin during winter, and in the east during summer. Precipitation shows an increasing trend under different SSPs-RCPs in the 21st century. In the long term, increase in precipitation will be significantly higher than in the near and mid-terms. Increase in annual precipitation in the long term will be 4.1% under SSP1-1.9, 13.9% under SSP1-2.6, 28.4% under SSP2-4.5, 35.2% under SSP3-7.0, 6.9% under SSP4-3.4, 8.9% under SSP4-6.0, and 27.3% under SSP5-8.5 relative to the reference period of 1995–2014. Spatially, precipitation increase will be higher in the south than the north, especially higher in mountainous regions than the basin under SSP2-4.5, SSP3-7.0, and SSP5-8.5. Seasonally, highest increase can be expected for winter, followed by spring, with significant increase in mountainous regions of southern Tarim Basin. Summer precipitation will reduce in Tian Shan and basins but will significantly increase in the northern margin of the Kunlun Mountain.

Increased frequency of extreme precipitation events in the North Atlantic during the PETM: Observations and theory

Climate model simulations of the PETM (Paleocene-Eocene Thermal Maximum) warming have mainly focused on replicating the global thermal response through greenhouse forcing, i.e. CO2, at levels compatible with observations. Comparatively less effort has gone into assessing the skill of models to replicate the response of the hydrologic cycle to the warming, particularly on regional scales. Here we have assembled proxy records of regional precipitation, focusing on the Mid-Atlantic Coasts of North America (New Jersey) and Europe (Spain) to test the response of the hydrologic system to greenhouse gas forcing of the magnitude estimated for the PETM (i.e., 2×). Given evidence that the PETM initiated during a maximum in eccentricity, this includes the response under neutral and extreme orbital configurations. Modeled results show excellent agreement with observations in Northern Spain, with a significant increase in both mean annual and extreme precipitation resulting from increased CO2 levels under a neutral orbit. The Mid Atlantic Coast simulations agree with observations showing increases in both overall and extreme precipitation as a result of CO2 increases. In particular, the development of sustained atmospheric rivers might be significantly contributing to the extremes of the eastern Atlantic, whereas extratropical cyclones are likely contributing to the extremes in the western Atlantic. With an eccentric orbit that maximizes insolation during boreal summer, there is a suppression of extreme precipitation events in the eastern Atlantic and an amplification in the western Atlantic, which may account for observations in the relative timing of the sedimentary response to the carbon isotope excursion associated with the PETM.

Assessing climate change impacts on streamflow and sediment load in the upstream of the Mekong River basin

AbstractAssessments of climate change impacts on streamflow and sediment processes are essential for developing science‐based sustainable watershed management plans. We assessed climate change impacts on streamflow and sediment load in the upstream of the Mekong River Basin, as a case study. Future climate scenarios including an ensemble‐mean climate scenario (EnM scenario) were generated based on 20 GCMs in CMIP5, using a stochastic weather generator (LARS‐WG) coupled with a distribution‐free shuffle procedure. The SWAT model was applied to simulate changes in streamflow and sediment load for the future period 2071–2100 under RCP8.5 with respect to the baseline period 1971–2000. Results show that mean monthly maximum and minimum temperature were projected to increase by all the 20 GCMs, with an ensemble‐mean increase of 4.6–5.7°C and 4.2–5.8°C across the 12 months, respectively. An increase in mean annual precipitation (3.4–55.8%) and streamflow (1.0–72.7%) was also projected by all GCMs. However, projected changes in sediment load were not consistent. One half of the GCMs projected an increase (5.2–53.2%) in annual sediment load while the other half projected a decrease (5.1%–43.2%). In each month, at least three‐quarters of the GCMs projected an increase in monthly streamflow. For monthly sediment load, an increase in May to July was projected by over half of the GCMs, while a decrease was projected by a majority of the GCMs for other months. Our results indicate large uncertainties in streamflow and sediment projections under climate change, demonstrating the need to use multi‐model ensembles in climate change impact studies. Moreover, it was found that the streamflow and sediment loads simulated using the EnM scenario were often close to the ensemble means simulated using the 20 GCMs, which implies that the single EnM scenario has the potential of effectively and efficiently estimating the ensemble means of projections in a multi‐model ensemble.

Temperature and precipitation projections for the Antarctic Peninsula over the next two decades: contrasting global and regional climate model simulations

This study presents near future (2020–2044) temperature and precipitation changes over the Antarctic Peninsula under the high-emission scenario (RCP8.5). We make use of historical and projected simulations from 19 global climate models (GCMs) participating in Coupled Model Intercomparison Project phase 5 (CMIP5). We compare and contrast GCMs projections with two groups of regional climate model simulations (RCMs): (1) high resolution (15-km) simulations performed with Polar-WRF model forced with bias-corrected NCAR-CESM1 (NC-CORR) over the Antarctic Peninsula, (2) medium resolution (50-km) simulations of KNMI-RACMO21P forced with EC-EARTH (EC) obtained from the CORDEX-Antarctica. A further comparison of historical simulations (1981–2005) with respect to ERA5 reanalysis is also included for circulation patterns and near-surface temperature climatology. In general, both RCM boundary conditions represent well the main circulation patterns of the historical period. Nonetheless, there are important differences in projections such as a notable deepening and weakening of the Amundsen Sea Low in EC and NC-CORR, respectively. Mean annual near-surface temperatures are projected to increase by about 0.5–1.5 $$^{\circ }$$ C across the entire peninsula. Temperature increase is more substantial in autumn and winter ( $$\sim $$ 2 $$^{\circ }$$ C). Following opposite circulation pattern changes, both EC and NC-CORR exhibit different warming rates, indicating a possible continuation of natural decadal variability. Although generally showing similar temperature changes, RCM projections show less warming and a smaller increase in melt days in the Larsen Ice Shelf compared to their respective driving fields. Regarding precipitation, there is a broad agreement among the simulations, indicating an increase in mean annual precipitation ( $$\sim $$ 5 to 10%). However, RCMs show some notable differences over the Larsen Ice Shelf where total precipitation decreases (for RACMO) and shows a small increase in rain frequency. We conclude that it seems still difficult to get consistent projections from GCMs for the Antarctic Peninsula as depicted in both RCM boundary conditions. In addition, dominant and common changes from the boundary conditions are largely evident in the RCM simulations. We argue that added value of RCM projections is driven by processes shaped by finer local details and different physics schemes that are introduced by RCMs, particularly over the Larsen Ice Shelf.

Impact of Climate Change on the Production of Coffea arabica at Mt. Kilimanjaro, Tanzania

Adapting coffee production to climate change is a significant challenge requiring a detailed understanding of local climatic change patterns and the consequences, both real and perceived, for coffee production. To this end, we examined changes in precipitation at Mt. Kilimanjaro over the last two decades and conducted twelve focus group discussions to obtain farmers’ perceptions on climate change, the impact of extreme weather events on coffee production and the potential of shade trees as an adaptation strategy. Despite an increase in total annual precipitation, farmers are still confronted with droughts due to a shift in seasons. We found a delayed onset of the main rainy season and showed that a positive Indian Ocean Dipole contributes to the increase in precipitation during the short rainy season. Farmers clearly described the impacts of drought or excess rainfall on coffee production during flowering, maturation, and harvest. Thus, adaptation strategies need to be tailored such that specific coffee development stages are buffered against the effects of droughts, shorter wet seasons, and less frequent but heavier rainfall events. To develop the potential of shade trees as an effective adaptation strategy, optimum shade density, specific tree species, and management practices need to be identified.

Climate Change and Sensitivity of Surface Water Resources in the Mekrou Sub-Watershed at the Yakrigourou Outlet (North Benin / West Africa)

The present work aims to contribute to a better understanding of the impacts of climate change on the availability of surface water resources in the Mékrou sub-basin at the Yakrigourou outlet in northern Benin. To achieve this objective, descriptive statistical methods were applied to hydro-climatological data. The historical data were taken from the Météo-Bénin database and from the General Directorate of Water in Benin. The simulation data are those of the HadGEM2-ES climate model under the RCP 4.5 and RCP 8.5 scenarios and then at horizons 50 (2041 to 2060) and 70 (2061 to 2080). The results show that the period from 1965 to 2018 is globally characterised by a strong irregularity of rainfall with a decreasing trend and a multiplication of dry years estimated at 54%. In the same way, the runoff decrease about 5.8 m³/s during the decade 2007-2016. Under the most pessimistic scenario (RCP8.5) and compared to the reference period (1971-1990), the HadGEM2-ES model predicts an increase in annual precipitation estimated at 8.29% by 2041-2060 and 13.83% by 2061-2080. As regards temperature, there could be an increase of 2.4°C by 2041-2060 and 3.7°C by 2061-2080. These climatic events affect the availability of surface water resources in the sub-basin.

全球木本植物叶片硅钙生态化学计量学特征

收集全球803种木本植物叶片硅（Si）、钙（Ca）数据，研究不同木本植物生活型（常绿植物以及落叶植物、针叶植物以及阔叶植物）叶片Si、Ca元素的化学计量学特征及其与纬度、气候因子（年平均温度，年平均降水量）间的关系。结果表明：（1）全球尺度上木本植物叶片Si、Ca含量存在较大变异性，且含量均低于中国境内的研究结果；（2）不同生活型树种间存在差异，针叶树叶片Si含量及Ca/Si显著高于阔叶树，落叶树叶片Si、Ca含量及Ca/Si均显著高于常绿树种；（3）随着纬度升高、年平均温度及年平均降水量的下降，全球尺度木本植物叶片Si、Ca含量显著升高，而Ca/Si显著下降；（4）不同生活型木本植物对气候因子的响应不同，除针叶及落叶树种的Ca含量外，其余各生活型树种Si、Ca含量与纬度及气候因子显著相关，随着纬度升高而升高，随年平均温度及年平均降水量的升高而降低，且随着年平均温度的降低，常绿及阔叶树种叶片Si含量下降速度显著高于落叶及针叶树种。研究结果能够为全球尺度生态化学计量学模型的发展提供数据基础，有助于更好地理解和模拟区域乃至全球尺度上纬度和气候因子对植物叶片Si、Ca含量的影响。;The ecological stoichiometric characteristics of silicon (Si) and calcium (Ca) play crucial roles in plant nutrient absorption, and thus impact the global biogeochemical cycle of Si and Ca. However, few were known about the stoichiometric characteristics of Si and Ca in the woody plant. In this study, using the collected data of Si and Ca of 803 woody plants in the world from the Plant Trait Database and published literature, the stoichiometric characteristics of Si and Ca in leaves of different woody plant life forms (evergreen plants, deciduous plants, coniferous plants and broad-leaved plants) and their relationships with latitude and climatic factors (mean annual temperature and mean annual precipitation) were investigated using the covariance analysis method. The results showed that:(1) the contents of Si and Ca in leaves of woody plants were highly variable at a global scale, and their contents were lower than those in China. In detail, the global geometric mean content of Si and Ca was 0.28 and 1.73 mg/g, respectively. (2) The contents of Si and Ca are varied among different life forms. The Si content and Ca/Si ratio of coniferous trees were significantly higher than those of broad-leaved trees, and the contents of Si, Ca in leaves of deciduous trees were significantly higher than those of evergreen trees; (3) With the increase of latitude and the decrease of mean annual temperature and precipitation, the contents of Si, Ca and Ca/Si in leaves of woody plants at the global scale increased significantly,while Ca/Si decreased significantly; (4) The responses of Si and Ca contents in leaves of different life forms to climate factors were varied. Except for Ca content of coniferous and deciduous trees, Si, Ca content in the life forms of evergreen plants and broad-leaved plants were significantly related to latitude and climate factors, and increased with the increase of latitude and decreased with the increase of mean annual temperature and precipitation. With the decrease of mean annual temperature, the decrease rate of Si content in leaves of evergreen and broad-leaved trees was significantly higher than that of deciduous and coniferous trees. From the perspective of ecostoichiometric characteristics, this study provides data basis for the development of ecological stoichiometric models at a global scale, and helps to better understand and simulate the effects of latitude and climate factors on the content of Si and Ca in plant leaves at regional and global scales.