Various Scenarios Of Climate Change Research Articles

Future potable water supply demand projection under climate change and socioeconomic scenarios: A case of Gshba subbasin, Northern Ethiopia

This paper aims to quantify the subbasin’s potable water supply demand forecast from 2023 to 2050 under various scenarios of climate change and socioeconomic development. The variability of the climate and the resulting problems with urbanization threaten the availability of water resources, especially in less developed countries like Ethiopia. Thus, the main objective of this study is showing the necessary to determine the amount of water needed in advance, in order to comply with the availability of water resources within a specified future period under different scenarios. Our indicator-based approach used a multicriteria decision-making technique. Accordingly, several important variables were considered, including climatological, anthropological, demographic, socioeconomic, and economic variables, in addition to water engineering-related factors (e.g. Water losses). The method also considered a number of factors, such as unexpected and extreme temperature changes, and forecasting factors studied by the Ethiopian Ministry of Water and Energy. The projected population in the subbasin is estimated at 2.52 million, so the total projected water supply demand i.e., for domestic, non-domestic, industrial, commercial, public, and institutional is approximately 126.53 MCM/yr by 2050. Our results revealed how changes in both climatic and socioeconomic factors strongly influence future water resource system performance, and this will help the water services provider better prioritize the refurbishment of existing infrastructure and investment in new infrastructure, and more importantly, manage the subbasin effectively by introducing resilient adaptation options.

A framework to support the identification of critical habitat for wide-ranging species at risk under climate change

To recover species at risk, it is necessary to identify habitat critical to their recovery. Challenges for species with large ranges (thousands of square kilometres) include delineating management unit boundaries within which habitat use differs from other units, along with assessing any differences among units in amounts of and threats to habitat over time. We developed a reproducible framework to support identification of critical habitat for wide-ranging species at risk. The framework (i) reviews species distribution and life history; (ii) delineates management units across the range; (iii) evaluates and compares current and (iv) potential future habitat and population size and (v) prioritizes areas within management units based on current and future conditions under various scenarios of climate change and land-use. We used Canada Warbler (Cardellina canadensis) and Wood Thrush (Hylocichla mustelina) in Canada as case studies. Using geographically weighted regression models and cluster analysis to measure spatial variation in model coefficients, we found geographic differences in habitat association only for Canada Warbler. Using other models to predict current habitat amount for each species in different management units, then future habitat amount under land use and climate change, we projected that: (1) Canada Warbler populations would decrease in Alberta but increase in Nova Scotia and (2) Wood Thrush populations would increase under most scenarios run in Quebec, New Brunswick and Nova Scotia, but not in Ontario. By comparing results from future scenarios and spatial prioritization exercises, our framework supports identification of critical habitat in ways that incorporate climate and land-use projections.

StoPET v1.0: a stochastic potential evapotranspiration generator for simulation of climate change impacts

Abstract. Potential evapotranspiration (PET) represents the evaporative demand in the atmosphere for the removal of water from the land and is an essential variable for understanding and modelling land–atmosphere interactions. Weather generators are often used to generate stochastic rainfall time series; however, no such model exists for the generation of a stochastically plausible PET time series. Here we develop a stochastic PET generator, stoPET, by leveraging a recently published global dataset of hourly PET at 0.1∘ resolution (hPET). stoPET is designed to simulate realistic time series of PET that capture the diurnal and seasonal variability in hPET and to support the simulation of various scenarios of climate change. The parsimonious model is based on a sine function fitted to the monthly average diurnal cycle of hPET, producing parameters that are then used to generate any number of synthetic series of randomised hourly PET for a specific climate scenario at any point of the global land surface between 55∘ N and 55∘ S. In addition to supporting a stochastic analysis of historical PET, stoPET also incorporates three methods to account for potential future changes in atmospheric evaporative demand to rising global temperature. These include (1) a user-defined percentage increase in annual PET, (2) a step change in PET based on a unit increase in temperature, and (3) the extrapolation of the historical trend in hPET into the future. We evaluated stoPET at a regional scale and at 12 locations spanning arid and humid climatic regions around the globe. stoPET generates PET distributions that are statistically similar to hPET and an independent PET dataset from CRU, thereby capturing their diurnal/seasonal dynamics, indicating that stoPET produces physically plausible diurnal and seasonal PET variability. We provide examples of how stoPET can generate large ensembles of PET for future climate scenario analysis in sectors like agriculture and water resources with minimal computational demand.

Simulating the Effects of Agricultural Adaptation Practices onto the Soil Water Content in Future Climate Using SWAT Model on Upland Bystra River Catchment

The article presents predicted changes in soil water content in the Bystra river catchment (eastern Poland) for various scenarios of climate change and adaptation practices obtained on the basis of a SWAT model simulation for three regional climate models driven by the global climate model EC-EARTH for the years 2041–2050 and the RCP 4.5 and 8.5 RCP scenarios. Climate scenarios were put against five adaptation scenarios presenting changes in land use and protective measures compared against a zero scenario of BaU (Business as Usual) kept in the future climate. Adaptation scenarios 1–5 are modifications of Scenario 0 (S-0). The 0–5 scenarios’ analysis was based on comparing soil water content and total runoff, sediment yield, actual evapotranspiration. The first adaptation scenario (AS-1) assumes an increase in afforestation on soils from the agricultural suitability complex of soil 6–8 (semi-dry, permanent dry, semi-wet). The second adaptation scenario (AS-2) assumes the creation of a forested buffer for the Bystra River and its tributaries. The third adaptation scenario (AS-3) shows one of the erosion prevention practices, the so-called filter strips. The fourth adaptation scenario (AS-4) assumes the reduction in plowing on arable land. The fifth adaptation scenario (AS-5) involves increasing soil organic carbon to 2%. Simulations revealed that each of the adaptation scenarios 1, 2, 3, 5 does not generally contribute to increasing the water content in soil on BARL (spring crops), CANP (rape), WWHT (winter crops), CRDY (other crops) on arable lands (which together account for over 50% of the catchment area). However, they can contribute to the reduction in sediment yield, total runoff and changes in actual evapotranspiration. The adaptation scenario 4 (AS-4) shows a slight increase in the soil water content on Bystra catchment in the 2041–2050 perspective. Scenario 4 indicated a slight increase in total runoff and a decrease in sediment yield, which in combination with slightly higher water content reflects the protective role of plant residue mulch, lowering the evaporation from the bare soil surface during warm seasons. The no-till adaptation practice had the highest effect in positively affecting water balance at the catchment scale among the adaptation scenarios considered.

Methodological approach to assessing environmental risk (health risk) from air pollution in the Baikal region in a changing climate

The methodological approach to assessing the environmental risk (health risk) from atmospheric pollution in the Baikal region taking into account the changing climate was formulated. It is based on the US EPA's health risk assessment methodology and impurity concentration estimates by solving the adjoint equation for impurities transport and diffusion. The dynamics of health risk for the population of Irkutsk from atmospheric pollution PM10, PM2.5 due to emissions from possible sources located both in the Baikal region and beyond including sources of transboundary pollution in 1980-2050 under various scenarios of climate change was researched. A tendency for a moderate decrease in the considered risk over the past several decades was shown. In the forecast period until 2050, under both climate scenarios, significant changes in the risk were not noted. The spatio-temporal dynamics of the areas of PM10, PM2.5 sources location that create the increased health risk in relation to Irkutsk was studied. The results indicate the moderate narrowing of the increased risk zone for Irkutsk in the first half of the 21st century. In the period until 2050, the main impact on the population health in the Irkutsk area from emission sources located in the southwest, south and southeast is expected. In case of transboundary pollution, the main danger from sources in Kazakhstan, Mongolia, and China is expected. The results are important to develop proposals for ensuring safety for public health, developing health care and planning environmental protection measures in the Baikal and neighboring regions.

К оценке экологических рисков от загрязнения атмосферы Арк­тической зоны в условиях изменяющегося климата в ХХI в

The article formulates a methodological approach to assessing environmental risks from atmospheric pollution in the Arctic zone under a changing climate. It is based on the US EPA’s health risk assessment methodology and impurity concentration estimates by solving the adjoint equation for impurities transport and diffusion. The authors investigate the dynamics of health risk from atmospheric pollution PM10, PM2.5 in the areas of five arctic cities due to emissions from potential nearby and remote sources (including sources of transboundary pollution) in 1980—2050 taking into account various scenarios of climate change. The results indicate general tendency towards an increase in the danger of air pollution for humans in the forecast period until 2050 against the background of climate changes. The authors study the spatio-temporal dynamics in the location areas of PM10, PM2.5 sources that create the highest health risk in relation to Arkhangelsk. The results show the moderate narrowing of the high-risk zone in the first quarter of the XXI century and some upward trend in risk in the second quarter of this century. In the period up to 2050, the main impact on public health in the Arkhangelsk region is expected from emission sources located in the west and southwest. At the same time, the authors prove a tendency towards an increase in the influence of sources located in the southwestern and southern directions. In case of transboundary pollution, sources in the Scandinavian states, Baltics, the countries of Eastern and Central Europe, Ukraine and Belarus pose a danger. The results are important to develop proposals for ensuring the environmental safety in Arctic when planning the spatial development of the Russian Arctic zone and other country territories.

Hydrologic response of arid and semi-arid river basins in Iraq under a changing climate

Abstract An assessment of the total hydrologic response of arid and semi-arid river basins to various scenarios of climate change by considering evapotranspiration, streamflow, and snowmelt is essential for sustainable management of water resources. The Diyala River Basin in Iraq has been chosen as a typical case study of dozens of river basins in arid and semi-arid regions. Here, the Long Ashton Research Station-Weather Generator (LARS-WG), the Soil and Water Assessment Tool (SWAT), and the SWAT Calibration and Uncertainty Program (CUP) were used to evaluate the total response by considering three Representative Concentration Pathways (RCPs); RCPs 2.6, 4.5, and 8.5 over three periods, 2021–2040, 2041–2061, and 2061–2080. The results indicate that by the year 2080, the basin will experience a temperature increase by 6.6, 10.1, and 16.6% for RCP 2.6, RCP 4.5, and RCP 8.5, respectively. The corresponding reduction in precipitation will be 3.2, 6.4, and 8.7%, resulting in 38.8, 47.9, and 52.8% fall in streamflow for RCPs 2.6, 4.5, and 8.5, respectively. Due to the increase in temperature, an earlier and less contribution of snowmelt is expected in the projected streamflow. Our findings provide a useful reference and a guide to decision makers for developing adaption plans to sustainably manage water resources in the Diyala River Basin and other similar basins in arid and semi-arid regions.

Simulating tree growth response to climate change in structurally diverse oak and beech forests

This study aimed to simulate oak and beech forest growth under various scenarios of climate change and to evaluate how the forest response depends on site properties and particularly on stand characteristics using the individual process-based model HETEROFOR. First, this model was evaluated on a wide range of site conditions. We used data from 36 long-term forest monitoring plots to initialize, calibrate, and evaluate HETEROFOR. This evaluation showed that HETEROFOR predicts individual tree radial growth and height increment reasonably well under different growing conditions when evaluated on independent sites.In our simulations under constant CO2 concentration ([CO2]cst) for the 2071-2100 period, climate change induced a moderate net primary production (NPP) gain in continental and mountainous zones and no change in the oceanic zone. The NPP changes were negatively affected by air temperature during the vegetation period and by the annual rainfall decrease. To a lower extent, they were influenced by soil extractable water reserve and stand characteristics. These NPP changes were positively affected by longer vegetation periods and negatively by drought for beech and larger autotrophic respiration costs for oak. For both species, the NPP gain was much larger with rising CO2 concentration ([CO2]var) mainly due to the CO2 fertilisation effect. Even if the species composition and structure had a limited influence on the forest response to climate change, they explained a large part of the NPP variability (44% and 34% for [CO2]cst and [CO2]var, respectively) compared to the climate change scenario (5% and 29%) and the inter-annual climate variability (20% and 16%). This gives the forester the possibility to act on the productivity of broadleaved forests and prepare them for possible adverse effects of climate change by reinforcing their resilience.

Impact of COVID climate on global crisis and biodiversity

Climate change has created potential major threats to global biodiversity. The multiple components of climate change are projected to affect all pillars of biodiversity, from genes over species to biome level. Of particular concerns are “tipping points” where the exceedance of ecosystem thresholds will possibly lead to irreversible shifts of ecosystems and their functioning. As biodiversity underlies all goods and services provided by ecosystems that are crucial for human survival and wellbeing, this paper presents potential effects of climate change on biodiversity, its plausible impacts on human society as well as the setting in addressing a global crisis. Species affected by climate change may respond in three ways: change, move or die. Local species extinctions or a rapidly affected ecosystem as a whole respectively might move toward its particular “tipping point”, thereby probably depriving its services to human society and ending up in a global crisis. Urgent and appropriate actions within various scenarios of climate change impacts on biodiversity, especially in tropical regions, are needed to be considered. Foremost a multi sectored approach on biodiversity issues with broader policies, stringent strategies and programs at international, national and local levels is essential to meet the challenges of climate change impacts on biodiversity.

Spatial Assessment of Water-Use Vulnerability under Future Climate and Socioeconomic Scenarios within a River Basin

AbstractThis case study developed a framework to assess the spatial distribution of water-use vulnerability within a river basin under various scenarios of climate change, climate change adaptation...

Impact of Climate Change on the Diversity and Distribution of Enset (<i>Ensete ventricosum</i> (<i>Welw</i>) <i>Cheesman</i>) in Ethiopia: A Review

The aim of this review paper is to review the impact of climate change on diversity and distribution of enset in Ethiopia and to suggest the gabs for future research. Climate change impacts will disproportionately affect sub-Saharan African countries such as Ethiopia because their economies are highly dependent on climate-sensitive activities such as rain-fed agriculture. In Ethiopia, climate change and associated extreme events are causing significant damage to life, property, natural resources and the economy by affecting climate sensitive sectors such as agriculture. Of the influence of climate change in Ethiopia crop species diversity and distribution is the current issue to deal with. Big genetic erosion and limitation of production of crops toward the high lands parts of the country in general and enset in particular is under way. Species distributions are determined by a range of different factors, among which climate is one of the most important ones. Climate change based distribution of enset is currently observed in Ethiopia. In some part of the country the enset production is shifting to the high land areas due to the changing climatic conditions. Some of the clones are struggling for tolerance of the changing environment, while others shift toward higher altitude; the others are unable to withstand the changing climatic condition and are enforced to die. Recent climate change has become one of the main drivers of shifts in the geographical distributions and diversity of enset species in Ethiopia. Therefore, urgent and appropriate actions are needed within various scenarios of climate change impacts on biodiversity and species distribution of enset.

Comparison of daily flows simulated for the year 2060 on the Kaczawa River for various scenarios of climate change by simple time series analysis

In this paper a time series analysis for daily flow simulations according three climate change scenario for Kaczawa River a left side tributary of the Odra River in south-west Poland is presented. The flow sequences were simulated using the hydrological model MIKE SHE and the spatial SWGEN meteorological data generator. Meteorological data for the hydrological model were generated based on data from 24 meteorological stations and 35-year daily data from the Institute of Meteorology and Water Management of the National Research Institute (IMGW). Data were generated for future climate condition for 2060 according GISS Model E, HadCM3, and GFDL R15 scenarios as well for the present conditions. The year 2000 was used as a reference year. The results obtained on the basis of a simple time series analysis point to small changes in flows for current and simulated conditions for 2060 for the Kaczawa River.

Atmospheric deposition and exceedances of critical loads from 1800-2025 for the conterminous United States.

Atmospheric deposition of nitrogen (N) and sulfur (S) has increased dramatically over pre-industrial levels, with many potential impacts on terrestrial and aquatic ecosystems. Quantitative thresholds, termed "critical loads" (CLs), have been developed to estimate the deposition rate above which damage is thought to occur. However, there remains no comprehensive comparison of when, where, and over what time periods individual CLs have been exceeded. We addressed this knowledge gap by combining several published data sources for historical and contemporary deposition, and overlaying these on six CL types from the National Critical Loads Database (NCLDv2.5; terrestrial acidification, aquatic acidification, lichen, nitrate leaching, plant community composition, and forest-tree health) to examine exceedances from 1800 to 2011. We expressed CLs as the minimum, 10th, and 50th percentiles within 12-km grid cells. Minimum CLs were relatively uniform across the country (200-400eq·ha-1 ·yr-1 ), and have been exceeded for decades beginning in the early 20th century. The area exceeding minimum CLs peaked in the 1970s and 1980s, exposing 300,000 to 3million km2 (depending on the CL type) to harmful levels of deposition, with a total area exceeded of 5.8million km2 (~70% of the conterminous United States). Since then, deposition levels have dropped, especially for S, with modest reductions in exceedance by 2011 for all CL types, totaling 5.2million km2 in exceedance. The 10th and 50th percentile CLs followed similar trends, but were not consistently available at the 12-km grid scale. We also examined near-term future deposition and exceedances in 2025 under current air quality regulations, and under various scenarios of climate change and additional nitrogen management controls. Current regulations were projected to reduce exceedances of any CL from 5.2 million km2 in 2011 to 4.8million km2 in 2025. None of the additional N management or climate scenarios significantly affected areal exceedances, although exceedance severity declined. In total, it is clear that many CLs have been exceeded for decades, and are likely to remain so in the short term under current policies. Additionally, we suggest many areas for improvement to enhance our understanding of deposition and its effects to support informed decision making.

Slowing down the retreat of the Morteratsch glacier, Switzerland, by artificially produced summer snow: a feasibility study

Many large valley glaciers in the world are retreating at historically unprecedented rates. Also in the Alps, where warming over the past decades has been more than twice as large as the global mean, all major glaciers have retreated over distances of several kilometers over the past hundred years. The Morteratsch Glacier, Pontresina, Switzerland, is a major touristic attraction. Due to strong retreat, the lowest part of the glacier is getting out of sight from the gravel road that provided direct access to the glacier front. The Community of Pontresina has commissioned a preparatory study to find out if it is possible to slow down the retreat of the Morteratsch Glacier in an environmentally friendly way. In this article, we report on the outcome of such a study, based on a modeling approach. Our analysis is based on a 20-year weather station record from the lower part of the glacier, combined with calculations with a calibrated ice-flow model. We arrive at the conclusion that producing summer snow in the ablation zone over a larger area (typically 0.5 to 1 km2) may have a significant effect on the rate of retreat on a timescale of decades. We consider various scenarios of climate change: (i) no change, (ii) a rise of the equilibrium-line altitude (ELA) by 1, 2, and 4 m/yr. Projections of glacier length are calculated until the year 2100. It takes about 10 years before snow deposition in the higher ablation zone starts to affect the position of the glacier snout. For the case of modest warming, the difference in glacier length between the snow and no-snow experiments becomes 400 to 500 m within two decades.

Modeling the effect of land use and climate change scenarios on future soil loss rate in Kasilian watershed of northern Iran

Accelerated erosion processes caused by global climate and land use changes in many regions of the world constitute a major restrictive factor in their sustainability. This study proposes a method to estimate soil loss rate under changes in future land use and climate in Kasilian watershed of northern Iran within two periods. The first period is related to current climate and land use (1991–2010), and the second concerns climate and land use scenarios (2011–2030). Downscaling global climate model projections of future climate was applied at the regional scale. A statistical downscaling model was then used to downscale precipitation for three scenarios, i.e., 10% increase in rainfall, 10% decrease in rainfall, and unchanged rainfall. Next, cellular automata–Markov model was used for characterization based on two scenarios of land use future that were designed using suitability maps. The soil loss mean for the current period was found to be 6.3 t $${\text{ha}}^{ - 1} \;{\text{year}}^{ - 1}$$ , thereby indicating a low sustainability of soils. The results of simulated soil loss maps indicate a similar pattern in spatial distribution of loss rates compared with those of current periods, but the amount of risk has increased such that simulated erosion mean was 31–58% higher than the current period in all scenarios. Soil loss is thoroughly influenced by climate and land cover patterns in future. In other words, rainfall erosivity has increased by 20 MJ mm $${\text{ha}}^{ - 1} {\text{h}}^{ - 1} {\text{year}}^{ - 1}$$ , based on unchanged rainfall scenario and National Centers for Environmental Prediction data, simulated that cover management factor has increased by 35% compared with the current period. However, simulations indicated that land use changes may potentially induce much larger changes in erosion. The results also showed that soil loss is closely related to land use change and various scenarios of climate change and that revised universal soil loss equation is suitable model to investigate these relationships.

PRECIS-model simulated changes in climatic parameters under various scenarios in different agro-climatic zones of Punjab

In this study,the future simulated climatic data (temperature and rainfall) for the 21st century were downscaled using the regional climate model, viz., PRECIS model (Providing Regional Climates for Impact Studies) for different agro-climatic zones, i.e., Zone II (Ballowal Saunkhri), Zone III (Ludhiana, Amritsar, Patiala and Jalandhar) and Zone V (Bathinda) of Punjab. The corrected simulated data were then analyzed on the annual and seasonal basis to quantify the changes in maximum and minimum temperature and rainfall. The study showed that the maximum and minimum temperature and rainfall by the end of 21st century are likely to increase by 2.0 to 2.2 °C, 3.3 to 5.4 °C and 33 to 66% respectively in agro-climatic zone II; by 0.4 to 5.8 °C, 2.5 to 7.4 °C and 3 to 62% respectively in agro-climatic zone III and by 0.5 to 4.0 °C, 4.7 to 7.7 °C and 58 to 69% respectively in agro-climatic zone V at different locations of Punjab state under various scenarios of climate change. The trend analysis of these parameters revealed there is positive linear increasing trend under different scenarios in the Punjab state.

Identification of loggerhead male producing beaches in the south Atlantic: Implications for conservation

Concern over the potential impacts of increased temperature on marine turtles, which have temperature dependent sex determination, has resulted in an increase in research that predicts the sex ratio of marine turtle hatchlings under various scenarios of climate change. To accurately understand the projected impacts from global warming, it is necessary to understand the sex ratio baseline in advance of climate change. To address this, the primary sex ratio of loggerhead hatchlings, Caretta caretta, was estimated from incubation duration of 27,697 in situ nests from 21 nesting beaches used by two subpopulations of loggerhead turtles in Brazil over the last 25years. A strong female bias (94%) was observed in all the areas used by the northern loggerhead stock, Sergipe (SE) and Bahia (BA), whereas a more balanced sex ratio (53% female) was estimated at the regions used by the southern loggerhead stock, Espirito Santo (ES) and Rio de Janeiro (RJ). Both inter-annual (SE: 83% to 99%, BA: 79. % to 98%, ES: 33% to 81%, RJ: 18% to 81%) and inter-beach variabilities (SE: 91% to 98%, BA: 89% to 96%, ES: 47% to 69%, RJ: 28% to 55%) in mean female offspring were observed. These findings provide evidence of persistent female bias in Brazil, and importantly identify male producing beaches and months, which will guide management decisions.

On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

Abstract. Human activities have caused various changes to the Earth system, and hence the interconnections between human activities and the Earth system should be recognized and reflected in models that simulate Earth system processes. One key anthropogenic activity is water resource management, which determines the dynamics of human–water interactions in time and space and controls human livelihoods and economy, including energy and food production. There are immediate needs to include water resource management in Earth system models. First, the extent of human water requirements is increasing rapidly at the global scale and it is crucial to analyze the possible imbalance between water demands and supply under various scenarios of climate change and across various temporal and spatial scales. Second, recent observations show that human–water interactions, manifested through water resource management, can substantially alter the terrestrial water cycle, affect land–atmospheric feedbacks and may further interact with climate and contribute to sea-level change. Due to the importance of water resource management in determining the future of the global water and climate cycles, the World Climate Research Program's Global Energy and Water Exchanges project (WRCP-GEWEX) has recently identified gaps in describing human–water interactions as one of the grand challenges in Earth system modeling (GEWEX, 2012). Here, we divide water resource management into two interdependent elements, related firstly to water demand and secondly to water supply and allocation. In this paper, we survey the current literature on how various components of water demand have been included in large-scale models, in particular land surface and global hydrological models. Issues of water supply and allocation are addressed in a companion paper. The available algorithms to represent the dominant demands are classified based on the demand type, mode of simulation and underlying modeling assumptions. We discuss the pros and cons of available algorithms, address various sources of uncertainty and highlight limitations in current applications. We conclude that current capability of large-scale models to represent human water demands is rather limited, particularly with respect to future projections and coupled land–atmospheric simulations. To fill these gaps, the available models, algorithms and data for representing various water demands should be systematically tested, intercompared and improved. In particular, human water demands should be considered in conjunction with water supply and allocation, particularly in the face of water scarcity and unknown future climate.

Climate Change Impacts on Biodiversity—The Setting of a Lingering Global Crisis

Climate change has created potential major threats to global biodiversity. The multiple components of climate change are projected to affect all pillars of biodiversity, from genes over species to biome level. Of particular concerns are “tipping points” where the exceedance of ecosystem thresholds will possibly lead to irreversible shifts of ecosystems and their functioning. As biodiversity underlies all goods and services provided by ecosystems that are crucial for human survival and wellbeing, this paper presents potential effects of climate change on biodiversity, its plausible impacts on human society as well as the setting in addressing a global crisis. Species affected by climate change may respond in three ways: change, move or die. Local species extinctions or a rapidly affected ecosystem as a whole respectively might move toward its particular “tipping point”, thereby probably depriving its services to human society and ending up in a global crisis. Urgent and appropriate actions within various scenarios of climate change impacts on biodiversity, especially in tropical regions, are needed to be considered. Foremost a multisectoral approach on biodiversity issues with broader policies, stringent strategies and programs at international, national and local levels is essential to meet the challenges of climate change impacts on biodiversity.

Trait‐based climate change predictions of plant community structure in arid steppes

Summary Global climate change is possibly one of the most important challenges for current and future human populations due to its wide‐ranging effects on ecosystems. Global prediction models suggest that in some areas of the world (e.g. Northern Africa, Central America) an increase in aridity might strongly disturb agricultural production and affect food security. To counterbalance these negative effects, reliable predictive models are needed to anticipate ecosystem changes. We tested the ability of the Community Assembly by Trait‐based Selection (CATS) model that is based on the principle of maximum entropy and trait‐based environmental filtering, to predict actual and future plant community composition in the arid steppes of eastern Morocco. Specifically, we asked whether this model was adequate for predicting actual community composition, based on predicted community‐weighted mean (CWM) traits, and what would be the changes in community composition under various scenarios of climate change for the period 2080—2099. The CATS model could predict > 90% of actual community composition if the actual CWM traits were known but only ˜40% if the CWM values were predicted from estimated aridity and grazing values. The predictions of community composition for 2080—2099 suggested that, regardless of the climate change scenario considered, the dominant group in grazed and ungrazed sites would shift from ruderal species to stress‐tolerant sub‐shrubs, which would constitute up over 80% of total community composition in some cases. Synthesis. Our findings suggest that effects of climate change will strongly modify plant community structure in arid steppes, possibly accentuating the process of desertification, and reducing the pastoral value of the vegetation. Future research efforts should concentrate on the identification of strong trait–environment relationships to improve model predictions.