A coupled human–natural system analysis of freshwater security under climate and population change

Identifying uncertainties in scenarios and models of socio-ecological systems in support of decision-making

Global water availability under high-end climate change: A vulnerability based assessment

Co-development of East African regional water scenarios for 2050

Water security and food security in the Indus basin are highly interlinked and subject to severe stresses. Irrigation water demands presently already exceed what the basin can sustainably provide, but per-capita food availability remains limited. Rapid population growth and climate change are projected to further intensify pressure on the interdependencies between water and food security. The agricultural system of the Indus basin must therefore change and adapt to be able to achieve the associated Sustainable Development Goals (SDGs). The development of robust policies to guide such changes requires a thorough understanding of the synergies and trade-offs that different strategies for agricultural development may have for water and food security. In this study, we defined three contrasting trajectories for agricultural system change based on a review of scientific literature on regional agricultural developments and a stakeholder consultation workshop. We assessed the consequences of these trajectories for water and food security with a spatially explicit modeling framework for two scenarios of climatic and socio-economic change over the period 1980–2080. Our results demonstrate that agricultural system changes can ensure per capita food production in the basin remains sufficient under population growth. However, such changes require additional irrigation water resources and may strongly aggravate water stress. Conversely, a shift to sustainable water management can reduce water stress but has the consequence that basin-level food self-sufficiency may not be feasible in future. This suggests that biophysical limits likely exist that prevent agricultural system changes to ensure both sufficient food production and improve water security in the Indus basin under strong population growth. Our study concludes that agricultural system changes are an important adaptation mechanism toward achieving water and food SDGs, but must be developed alongside other strategies that can mitigate its adverse trade-offs.

Climate change is a complex and contentious public issue, but the risk-management options available to us are straightforward and have well-characterized strengths and weaknesses.

The present paper evaluates the composite risk of anthropogenic and climate change on the future water status in Jordan during the period 2030–2050. The projected water status in the country is evaluated based on the more likely population growth and climate change scenarios. The most likely figure for the population of Jordan, excluding refugees from neighboring countries, in 2040 would be ∼15 million people. Given this likely projection, though conservative, annual water needs for the domestic sector alone are expected to be between 700 and 800 million m3, with the current level of water consumption. A rise in near surface air temperature by 2 °C and a drop in total precipitation by 15%, as projected by most Global Circulation Models, would diminish renewable water resources in the mountainous region by ∼ 25–40%, being more severe as aridity increases.1. IntroductionThere is almost a consensus among earth scientists that the buildup of greenhouse gases in the atmosphere is lea...

Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2 , (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.

Water security in the Global South is increasingly threatened by rapid socioeconomic changes, including urbanization, population growth, and the expansion of irrigated agriculture. These dynamics not only intensify competition for limited water resources but also amplify vulnerability to climate change impacts. The Sudano-Sahelian region, including the Sokoto Rima Basin (study area) in Nigeria, is particularly sensitive to these pressures, having experienced severe droughts in the 1970s and 1980s. This study adopts a participatory approach, leveraging stakeholder input to develop socioeconomic scenarios within the Shared Socioeconomic Pathways (SSPs) 4.5 and 8.5 frameworks. It projects future water use in the region and evaluates the combined effects of socioeconomic and climate change. While the CMIP6 GCMs agree on a wetter future climate for the region, uncertainty persists regarding the magnitude of these changes. Drivers of socioeconomic changes are better understood due to direct stakeholders involvement. Key findings indicate that by 2050, irrigated land, and population are expected to increase by 470%, and 200% respectively, relative to the reference period (1990–2004). This growth is projected to drive water demand up by 190%, outpacing the anticipated 160% increase in water availability due to climate-driven changes. The results underscore that socioeconomic changes pose a significant risk to water security and must be considered when planning climate change adaptation. Informed by stakeholder feedback, the study highlights adaptation strategies, including the adoption of water-efficient technologies, mechanized irrigation, and advanced seed technologies. Small-scale stormwater harvesting through dam construction is proposed as a viable strategy to conserve water and support municipal supplies during drought periods. This novel participatory based scenario development approach provides valuable insights into managing water resources under concurrent socioeconomic and climate challenges, with implications for policy and planning in water-scarce regions. 

The management of water resource in China has been under pressures due to rapid socioeconomic growth that escalates the demands in food, energy and domestic sectors, which rely on reliable water provision. Together with climate change, water security is expected to face greater uncertainty in the future. To support sustainable water resource management, this study established a system dynamic model to investigate the impacts of policy, socioeconomic and climate change on water security in China during 2025 to 2100. Five policy options related to carbon neutrality and water management, three socioeconomic and climate scenarios (SSP1-RCP2.6, SSP2-RCP4.5 and SSP5-RCP8.5) were considered. The results show that water demand and water resource will both be greater in the future. Under BAU, water demand will reach 514, 544 and 717 km3 while water resource will increase to 989, 992 and 1032 km3 in 2086-2100 under SSP1-RCP2.6, SSP2-RCP4.5 and SSP5-RCP8.5, respectively. Future water demand for food sector is expected to decrease slightly and then increase under SSP1-RCP2.6, while it shows continuous increase under SSP2-RCP4.5 and SSP5-RCP8.5 due to the changes of planted area, livestock and temperature. Water demand for domestic sector will decrease under three SSP-RCPs because the population will reach a peak around 2030 and then decrease with time. Water demand for energy is expected to decrease under SSP1-RCP2.6 while it will increase under other SSP-RCPs because of more energy demand under SSP2-RCP4.5 and SSP5-RCP8.5. China may face low water security pressure without policy intervention in the future especially under SSP5-RCP8.5. The analysis shows that bioenergy-oriented agriculture cannot mitigate water scarcity risks in China, while low-carbon agriculture strategies can potentially ensure water safety under carbon neutral goal. Water scarcity can be averted if we follow the development path of SSP1-RCP2.6 as well as apply interventions on water management combining with carbon neutral policies that focus on low-carbon agriculture and supplemented by low fossil energy.

Water is of vital and critical importance to ecosystems and human societies. The effects of human activities on land and water are now large and extensive. These reflect physical changes to the environment. Global change such as urbanization, population growth, socioeconomic change, evolving energy needs, and climate change have put unprecedented pressure on water resources systems. It is argued that achieving water security throughout the world is the key to sustainable development. Studies on holistic view with persistently changing dimensions is in its infancy. This study focuses on narrative review work for giving a comprehensive insight on the concept of water security, its evolution with recent environmental changes (e.g., urbanization, socioeconomic, etc.) and various implications. Finally, it presents different sustainable solutions to achieve water security. Broadly, water security evolves from ensuring reliable access of enough safe water for every person (at an affordable price where market mechanisms are involved) to lead a healthy and productive life, including that of future generations. The constraints on water availability and water quality threaten secured access to water resources for different uses. Despite recent progress in developing new strategies, practices and technologies for water resource management, their dissemination and implementation has been limited. A comprehensive sustainable approach to address water security challenges requires connecting social, economic, and environmental systems at multiple scales. This paper captures the persistently changing dimensions and new paradigms of water security providing a holistic view including a wide range of sustainable solutions to address the water challenges.

Climate change impacts on water security in global drylands

Water is of vital and critical importance to ecosystems and human societies. Issues like urbanization, population growth, socioeconomic change, evolving energy needs and climate change have put unprecedented pressure on utilization of freshwater resources. It is argued that achieving water security is the key to sustainable development. The focal point of water security evolves from ensuring reliable access of enough safe water for every person at an affordable price to lead a healthy and productive life along with maintaining the water-related ecosystem services for future generations. Although total water demand at global scale is well within available water resources, the shortages prevail at spatial and temporal scales. The constraints on water availability and water quality threaten secure access to water resources for different uses. Despite recent progress in developing new strategies, practices and technologies for water resource management, their dissemination and implementation have been limited. The chapter focuses on urban water security and their connections with practical issues dealing with real-world situations. This chapter sets the stage to understand the evolution of urban water security, its challenges and ways to achieve sustainable water management. A comprehensive sustainable approach to address water security challenges requires connecting social, economic and environmental systems at multiple scales. This chapter strives to capture the persistently changing dimensions and new paradigms of water security providing a holistic view including wide range of sustainable solutions to address the water challenges.

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Africa is considered to be the second driest continent in the world after Australia. Sub-Saharan Africa (SSA) is the whole of Africa except North Africa; SSA covers around 80% of Africa’s total land area with a population of around 0.9 billion people. The continued population growth poses a challenge to systems that supply services in SSA; for example, in 1950, less than 200 million people lived in Sub-Saharan Africa, but in 2016 the population in SSA has increased to around 1 billion. Since the beginning of the 21st century, there has been a rising sense of urgency about the need to address migration; movement of refugees and their displacement (Cross et al., 2006). There are many factors that influence the movement of people. This thesis examines some of these factors in depth to understand the tendency for migration both to urban from rural and from rural to urban – the latter being more important. Presently, 14 African countries (including 9 from SSA) are experiencing water stress, and it is predicted that the number of water stressed countries in SSA will increase to 25 countries by the year 2025 (Mejia et al., 2012; UN, 2008). SSA experiences rainfall fluctuations and rising temperatures that have been impacting the agricultural production over time. It is predicted that SSA may experience extreme rainfall events and such extreme precipitation may become more frequent and intense over time. Local rural water availability conditions may also face more challenges; for example, Nigeria water supply systems have failed to cope with the rapid population growth over time. In 1991, 79% (25 million) of Nigerian people living in urban areas had access to clean water, yet 17 years later it has fallen to 75%, but now 55 million people have access to fresh water. The literature reviewed showed a number of gaps in research with regards to water security. Essentially, this thesis investigates how water security, climate change and population growth are related to the people movement in and around SSA. This study uses quantitative type univariate and multivariate time series methodologies to investigate the links among the abovementioned variables. The main research aim of this major study as stated led to the examination, study and analysis of long term time series data concerning rainfall, temperature, populations; including their relationships to rural-urban and urban to rural migration time series data. The study developed univariate and multivariate time series models that are appropriate for trend studies, and prediction of the changes that may occur to the climatic and people movement variables in the future. The study identified associations and correlations between climatic and people movement variables. The findings of this study indicate that rainfall and temperature variabilities do indeed impact the movement of people in SSA in Somalia, Ethiopia and Democratic Republic of Congo in particular. The results of the time series analyses suggest that rainfall has a greater impact on rural-urban migration in Somalia, Ethiopia and Democratic Republic of Congo compared to that of the temperature; although a combined effect is also noted. The people movement in these countries responded to the unit shocks in rainfall or temperature. More importantly, the study notes that number of people leaving from rural areas outnumber those relocating to rural areas. This means that migration in selected countries and in SSA in general has net flows towards the cities. Due to limitations of the migration data availability, author used vital statistical method to indirectly measure net migration in selected countries. The study provides an essential breakthrough of the area of the climate change impact on rural urban migration in SSA. The findings can aid different levels of decision making authorities, research and educational institutions in the regions as well as regional and international organization in terms of what may be done to stem the flow away from rural areas. Hence, there is a need for more site specific research projects to further examine interactions and associations between climate change and human migration within SSA and member counties. Higher level studies in the future should seek funding from agencies to collect primary data from relevant government departments as well as climate related research institutions in SSA.

Water is an essential resource for social and economic development. The availability of this resource is constantly threatened by the rapid increase in its demand. This research assesses current (2010–2016), short- (2017–2040), middle- (2041–2070), and long-term (2071–2099) levels of water security considering socio-economic and climate change scenarios using the Water Evaluation and Planning System (WEAP) in Vilcanota-Urubamba (VUB) catchment. The streamflow data of the Pisac hydrometric station were used to calibrate (1987–2006) and validate (2007–2016) the WEAP Model applied to the VUB region. The Nash Sutcliffe efficiency values were 0.60 and 0.84 for calibration and validation, respectively. Different scenarios were generated for socio-economic factors (population growth and increased irrigation efficiency) and the impact of climate change to evaluate their effect on the current water supply system. The results reveal that water availability is much higher than the current demand in the VUB for the period (2010–2016). For short-, middle- and long term, two scenarios were considered, “Scenario 1” (RCP 4.5) and “Scenario 2” (RCP 8.5). Climate change scenarios show that water availability will increase. However, this increase will not cover the future demands in all the sub-basins because water availability is not evenly distributed in all of the VUB. In both scenarios, an unmet demand was detected from 2050. For the period 2071–2099, an unmet demand of 477 hm3/year for “Scenario 1” and 446 hm3/year for “Scenario 2” were estimated. Because population and agricultural demands are the highest, the effects of reducing the growth rate and improving the irrigation structure were simulated. Therefore, two more scenarios were generated “Scenario 3” (RCP 4.5 with management) and “Scenario 4” (RCP 8.5 with management). This socio-economic management proved to be effective in reducing the unmet demand up to 50% in all sub-basins for the period 2071–2099.