Water resources transfers through southern African food trade:water efficiency and climate signals

Temporal and spatial variability of precipitation in southern Africa is particularly high. The associated drought and flood risks, combined with a largely rain-fed agriculture, pose a challenge for water and food security in the region. As regional collaboration strengthens through the Southern Africa Development Community and trade with other regions increases, it is thus important to understand both how climate variability affects agricultural productivity and how food trade (regional and extra-regional) can contribute to the region's capacity to deal with climate-related shocks. We combine global hydrological model simulations with international food trade data to quantify the water resources embedded in international food trade in southern Africa and with the rest of the world, from 1986-2011. We analyze the impacts of socio-economic, political, and climatic changes on agricultural trade and embedded water resources during this period. We find that regional food trade is efficient in terms of water use but may be unsustainable because water-productive exporters, like South Africa, rely on increasingly stressed water resources. The role of imports from the rest of the world in the region's food supply is important, in particular during severe droughts. This reflects how trade can efficiently redistribute water resources across continents in response to a sudden gap in food production and water productivity. In a context of regional and global integration, our results highlight opportunities for improved water-efficiency and sustainability of the region's food supply via trade

Climate change and International River Boundaries: fixed points in shifting sands

The impacts of climate change will have far reaching consequences for transboundary water resources, particularly through the effects of changing frequency and intensity of extreme events, such as floods and their impacts on river channel systems. Watercourses have been used as boundaries throughout history for a variety of reasons, and as both a natural resource and political structure, they present a number of unique challenges. Despite academic studies looking broadly at the effects of changes in runoff on river ecosystems and their resources, less attention has been paid to the socio-political interactions and consequences for river functionality, in particular, as a boundary. We review the historical and legal role of International River Boundaries highlighting the paradox that exists between the stability needed for a boundary and the dynamism of fluvial landscapes in a changing climate. We draw attention to the fact that geopolitical concerns exist at other unstable border situations, such as ice-covered boundaries and lakes. We examine the knowledge gaps that exist in relation to understanding the physical impacts of climate change on terrestrial earth systems. We present an exploratory analysis of physical and political risk in Southern Africa that highlights two cases of potential risk. The paper ends with a discussion of actions to address the physical and social dimensions of this strategic issue

Global crop yield response to extreme heat stress under multiple climate change futures

Extreme heat stress during the crop reproductive period can be critical for crop productivity. Projected changes in the frequency and severity of extreme climatic events are expected to negatively impact crop yields and global food production. This study applies the global crop model PEGASUS to quantify, for the first time at the global scale, impacts of extreme heat stress on maize, spring wheat and soybean yields resulting from 72 climate change scenarios for the 21st century. Our results project maize to face progressively worse impacts under a range of RCPs but spring wheat and soybean to improve globally through to the 2080s due to CO2 fertilization effects, even though parts of the tropic and sub-tropic regions could face substantial yield declines. We find extreme heat stress at anthesis (HSA) by the 2080s (relative to the 1980s) under RCP 8.5, taking into account CO2 fertilization effects, could double global losses of maize yield (ΔY = −12.8 ± 6.7% versus − 7.0 ± 5.3% without HSA), reduce projected gains in spring wheat yield by half (ΔY = 34.3 ± 13.5% versus 72.0 ± 10.9% without HSA) and in soybean yield by a quarter (ΔY = 15.3 ± 26.5% versus 20.4 ± 22.1% without HSA). The range reflects uncertainty due to differences between climate model scenarios; soybean exhibits both positive and negative impacts, maize is generally negative and spring wheat generally positive. Furthermore, when assuming CO2 fertilization effects to be negligible, we observe drastic climate mitigation policy as in RCP 2.6 could avoid more than 80% of the global average yield losses otherwise expected by the 2080s under RCP 8.5. We show large disparities in climate impacts across regions and find extreme heat stress adversely affects major producing regions and lower income countries

Invention and diffusion of water supply and water efficiency technologies: insights from a global patent dataset

This paper identifies over 50 000 patents filed worldwide in various water-related technologies between 1990 and 2010, distinguishing between those related to availability (supply) and conservation (demand) technologies. Patenting activity is analysed – including inventive activity by country and technology, international diffusion of such water-related technologies, and international collaboration in technology development. Three results stand out from our analysis. First, although inventive activity in water-related technologies has been increasing over the last two decades, this growth has been disproportionately concentrated on supply-side technologies. Second, whilst 80% of water-related invention worldwide occurs in countries with low or moderate water scarcity, several countries with absolute or chronic water scarcity are relatively specialized in water efficiency technologies. Finally, although we observe a positive correlation between water scarcity and local filings of water patents, some countries with high water availability, in particular Switzerland or Norway, nevertheless appear as significant markets for water-efficiency technologies. This suggests that drivers other than local demand, like regulation and social and cultural factors, play a role in explaining the global flows of technologies. And finally, the extent to which innovation is "internationalised" shows some distinct patterns relative to those observed for innovation in technologies in general

Tracing the water-energy-food nexus : description, theory and practice

The ‘nexus’ between water, energy and food (WEF) has gained increasing attention globally in research, business and policy spheres. We review the premise of recent initiatives framed around the nexus, examine the challenge of achieving the type of disciplinary boundary crossing promoted by the nexus agenda and consider how to operationalise what has to date been a largely paper exercise. The WEF nexus has been promoted through international meetings and calls for new research agendas. It is clear from the literature that many aims of nexus approaches pre-date the recent nexus agenda; these have encountered significant barriers to progress, including challenges to cross-disciplinary collaboration, complexity, political economy (often perceived to be under-represented in nexus research) and incompatibility of current institutional structures. Indeed, the ambitious aims of the nexus—the desire to capture multiple interdependencies across three major sectors, across disciplines and across scales—could become its downfall. However, greater recognition of interdependencies across state and non-state actors, more sophisticated modelling systems to assess and quantify WEF linkages and the sheer scale of WEF resource use globally, could create enough momentum to overcome historical barriers and establish nexus approaches as part of a wider repertoire of responses to global environmental change

Fresh water goes global

Water management is a central responsibility of civil society. Major questions persist regarding practice, policy, and the underlying evidence and methods to inform both. Over the next 3 weeks, Science presents essays invited to debate key issues in freshwater research and management. This week: local versus global. When, and to what extent, should a global viewpoint replace, or work in tandem with, enduring localized perspectives

Co-benefits and trade-offs in the water–energy nexus of irrigation modernization in China

There are strong interdependencies between water use in agriculture and energy consumption as water saving technologies can require increased pumping and pressurizing. The Chinese Government includes water efficiency improvement and carbon intensity reduction targets in the 12th Five-Year Plan (5YP. 2011–2015), yet the links between energy use and irrigation modernization are not always addressed in policy targets. Here we build an original model of the energy embedded in water pumping for irrigated agriculture and its related processes. The model is based on the physical processes of irrigation schemes and the implication of technological developments, comprising all processes from extraction and conveyance of water to its application in the field. The model uses data from government sources to assess policy targets for deployment of irrigation technologies, which aim to reduce water application and contribute to adaptation of Chinese agriculture to climate change. The consequences of policy targets involve co-beneficial outcomes that achieve water and energy savings, or trade-offs in which reduced water application leads to increasing greenhouse gas (GHG) emissions. We analyze irrigation efficiency and energy use in four significant provinces and nationally, using scenarios based on the targets of the 12th 5YP. At the national scale, we find that expansion of sprinklers and micro-irrigation as outlined in the 5YP would increase GHG emissions from agricultural water use, however, emissions decrease in those provinces with predominant groundwater use and planned expansion of low-pressure pipes. We show that the most costly technologies relate to trade-offs, while co-benefits are generally achieved with less expensive technologies. The investment cost per area of irrigation technology expansion does not greatly affect the outcome in terms of water, but in terms of energy the most expensive technologies are more energy-intensive and produce more emissions. The results show that water supply configuration (proportion of surface to groundwater) largely determines the potential energy savings from reductions in water application. The paper examines the importance of fertigation and highlights briefly some policy implications

Transmission of climate risks across sectors and borders

Systemic climate risks, which result from the potential for cascading impacts through inter-related systems, pose particular challenges to risk assessment, especially when risks are transmitted across sectors and international boundaries. Most impacts of climate variability and change affect regions and jurisdictions in complex ways, and techniques for assessing this transmission of risk are still somewhat limited. Here, we begin to define new approaches to risk assessment that can account for transboundary and trans-sector risk transmission, by presenting: (i) a typology of risk transmission that distinguishes clearly the role of climate versus the role of the social and economic systems that distribute resources; (ii) a review of existing modelling, qualitative and systems-based methods of assessing risk and risk transmission; and (iii) case studies that examine risk transmission in human displacement, food, water and energy security. The case studies show that policies and institutions can attenuate risks significantly through cooperation that can be mutually beneficial to all parties. We conclude with some suggestions for assessment of complex risk transmission mechanisms: use of expert judgement; interactive scenario building; global systems science and big data; innovative use of climate and integrated assessment models; and methods to understand societal responses to climate risk. These approaches aim to inform both research and national-level risk assessment

Designing the next generation of climate adaptation research for development

Adaptation research has changed significantly in recent years as funders and researchers seek to encourage greater impact, ensure value for money and promote interdiscipinarity across the natural and social sciences. While these developments are inherently positive they also bring fresh challenges. This Perspective reviews experiences from the delivery of past and current adaptation research and reflects on the merits and limitations of the evolving adaptation research landscape. We propose five key areas that need to be changed in order to meet the needs of future adaptation research, namely: increasing transparency and consultation in research design; encouraging innovation in the design and delivery of adaptation research programmes; demonstrating impact on the ground; addressing incentive structures; and promoting more effective brokering, knowledge management and learning. As large international funding initiatives such as the Future Earth and the Global Challenges Research Fund start to take shape we underscore the importance of learning from past experiences and scaling-up of successful innovations in research funding models

Applications of interannual-to-decadal climate prediction: an exploratory discussion on rainfall in the Sahel Region of Africa

This perspective explores how climate services may potentially incorporate information emerging from the new science of interannual-to-decadal (I2D) climate prediction. The geographic focus is the Sahel region of West Africa, which has demonstrated prediction advances for rainfall on the I2D timescale, and vulnerability to climate hazards. The perspective draws on reviews of predictability and applications in the region and a national workshop in Sudan to explore applications. Decadal prediction is an emerging capability, to date being undertaken primarily as a learning process. However, for the multi-year forecast information, we identify a number of new dimensions that challenge product design and user uptake. Current experiments often present forecasts as the average conditions for a target first year, and then subsequent set of years raising a question of what a forecast of mean average conditions for years 2-5 represents in terms of climate to expect, and how annual updates to multi-year forecasts may be produced and communicated. Stakeholder consultations highlighted some of the concerns noted for existing seasonal forecasts, but now translated into terms for multi-year information, such as confidence in information, need for research on temporal downscaling (which may now include information on the risks of climate anomalies in the individual years that make up the forecast period), capacity development, and that communities would need to be convinced about effectiveness, alongside careful communication, especially in the context of multi-year planning. This perspective captures one of the first learning case studies on how I2D prediction may be explored in a given region, a first step towards climate services development that integrate I2D information