The human population is projected to reach more than 10 billion in the year 2100. Together with changing consumption pattern, population growth will lead to increasing food demand. The question arises whether or not the Earth is capable of fulfilling this demand. In this study, we approach this question by estimating the carrying capacity of current agricultural systems (KC), which does not measure the maximum number of people the Earth is likely to feed in the future, but rather allows for an indirect assessment of the increases in agricultural productivity required to meet demands.
We project agricultural food production under progressing climate change using the state-of-the-art dynamic global vegetation model LPJmL, and input data of 3 climate models. For 1990 to 2100 the worldwide annual caloric yield of the most important 11 crop types is simulated. Model runs with and without elevated atmospheric CO2 concentrations are performed in order to investigate CO2 fertilization effects. Country-specific per-capita caloric demands fixed at current levels and changing demands based on future GDP projections are considered to assess the role of future dietary shifts.
Our results indicate that current population projections may considerably exceed the maximum number of people that can be fed globally if climate change is not accompanied by significant changes in land use, agricultural efficiencies and/or consumption pathways. We estimate the gap between projected population size and KCto reach 2 to 6.8 billion people by 2100. We also present possible caloric self-supply changes between 2000 and 2100 for all countries included in this study.
The results show that predominantly developing countries in tropical and subtropical regions will experience vast decreases of self-supply. Therefore, this study is important for planning future large-scale agricultural management, as well as the critical assessment of population projections, which should take food-mediated climate change feedbacks into account.
Drought is among the most damaging, and least understood, of all "natural" hazards. Although some droughts last a single season and affect only small areas, the instrumental and paleoclimate records show that droughts have sometimes continued for decades and have impacted millions of square kilometers in North America, West Africa, and East Asia. To cross the spectrum of potential drivers and impacts, drought information systems have multiple sub-systems which include an integrated risk assessment, communication and decision support system of which early warning is a central component and output.
An early warning system is much more than a forecast - it is a linked risk information (including people's perception of risk) and communication system that actively engages communities involved in preparedness. There are numerous drought systems warning systems being implemented at different scales of governance. We draw on the lessons of over 21 drought early warning systems around the world, in both developing and developed countries and at regional, national and community levels. The successes illustrate that effective early warning depends upon a multi-sectoral and interdisciplinary collaboration among all concerned actors at each stage in the warning process from monitoring to response and evaluation. However, the links between the community-based approach and the national and global EWSs are relatively weak. Using the rich experience of information systems across the globe, this paper identifies pathways for knowledge management and action at the relevant scales for decision-making in response to a changing climate.
Using a multi-model ensemble of climate-change impacts over the Iberian Peninsula, we identified regions and cropping options for which the uncertainty levels of projected impacts on crop productivity were either high or low. The ensemble consisted of 10 members per combination of scenario, climate model, location and cropping option, and was used to quantify the uncertainty of impacts on crop yield CERES wheat and maize simulation models were linked to the control run and 1 scenario provided by 10 regional climate models (RCMs): control (1969–1990) and A2 future (2070–2100) climate.
The contribution of RCMs, locations and cropping options to uncertainty on yield projections was analysed. Differences between the sign of the response and 30 yr time series of projections generated by each member of the ensemble were compared. The largest response to A2 scenarios also resulted in the smallest uncertainty, and vice versa Low uncertainty was found for the sign of the yield response, which was mainly positive for spring and winter cropping options and negative for the summer option. Uncertainty was lower for A2 than for control projections. Uncertainty was largest in northern, coastal and mountain regions, and smallest for inland southern regions, and depended on seasonal cropping options. Minimum and maximum uncertainty were found for maize and irrigated spring wheat, respectively.
Water availability was the determinant for interannual variability and its uncertainty. Choice of RCM contributed less to uncertainty than choice of location, and choice of cropping option contributed more to uncertainty than both of these factors Interannual variability showed larger uncertainty than mean impact magnitude, and this uncertainty was larger than that of the sign of the yield response. Regions with high uncertainty could benefit from higher-resolution simulations.
Irrigated agriculture is the main source of water withdrawals, accounting for around 70% of all the world's freshwater withdrawals. The development of irrigated agriculture has boosted agricultural yields and contributed to price stability, making it possible to feed the world's growing population. Rapidly increasing nonagricultural demands for water, changing food preferences, global climate change, and new demands for biofuel production place increasing pressure on scarce water resources.
Challenges of growing water scarcity for agriculture are heightened by the increasing costs of developing new water, soil degradation, groundwater depletion, increasing water pollution, the degradation of water-related ecosystems, and wasteful use of already developed water supplies. This article discusses the role of water for agriculture and food security, the challenges facing irrigated agriculture, and the range of policies, institutions, and investments needed to secure adequate access to water for food today and in the future.
Climate change projections point to increasing air temperature and reduced precipitation in southern Portugal, which would affect farming systems. This study aims to assess the impacts of climate change on irrigated agriculture in southern Portugal. These impacts were assessed by combining climate model data with a soil water balance model and a numerical model for the design of irrigation systems. Meteorological data from two weather stations were used along with three climate models (HadRM3P, HIRHAMh and HIRHAMhh; 2071–2100).
The crop rotations studied included sugar beet–maize–tomato– wheat and sunflower–wheat–barley. Two adaptation measures were considered: (i) maintaining the current crop varieties; (ii) using new crop varieties. The results from the considered climate change scenarios indicated that the impacts of climate change on irrigation requirements depend on the adopted adaptation measures. On average, the seasonal irrigation requirements increased by 13–70% when new crop varieties were used and by -13 to 7% when the current crop varieties were maintained. The impacts of climate change on irrigation system design were considerable, with the design flow rate increasing by 5–24%.
Global demand for livestock products is expected to double by 2050, mainly due to improvement in the worldwide standard of living. Meanwhile, climate change is a threat to livestock production because of the impact on quality of feed crop and forage, water availability, animal and milk production, livestock diseases, animal reproduction, and biodiversity. This study reviews the global impacts of climate change on livestock production, the contribution of livestock production to climate change, and specific climate change adaptation and mitigation strategies in the livestock sector.
Livestock production will be limited by climate variability as animal water consumption is expected to increase by a factor of three, demand for agricultural lands increase due to need for 70% growth in production, and food security concern since about one-third of the global cereal harvest is used for livestock feed. Meanwhile, the livestock sector contributes 14.5% of global greenhouse gas (GHG) emissions, driving further climate change. Consequently, the livestock sector will be a key player in the mitigation of GHG emissions and improving global food security. Therefore, in the transition to sustainable livestock production, there is a need for: a) assessments related to the use of adaptation and mitigation measures tailored to the location and livestock production system in use, and b) policies that support and facilitate the implementation of climate change adaptation and mitigation measures.
Irrigated agriculture is crucial for food security and rural development in the Mediterranean region, but it will be significantly affected by climate change. Evaluating the present and future agroclimatic conditions and predicting the impacts on irrigation requirements for the dominant crops in the region may help to develop more appropriate adaptation strategies. This paper describes the expected changes in climate and assesses the irrigation requirement for key crops grown across the region, using a case study in a typical river basin in Spain. Milder but wetter winters and more extreme hot, dry summers are anticipated. Evapotranspiration, crop water requirements and irrigation needs for major crops are expected to increase by as much as 30% by the 2080s.
According to the Food and Agriculture Organization of the United Nations (FAO), there are around 300 million working animals worldwide. They play a fundamental role in human livelihoods through their contribution to financial, human and social capital, supporting between 300 and 600 million people globally, particularly in poorer areas, where animal energy represents a huge and extremely important sustainable power resource. Yet their recognition remains largely neglected, with animal traction being largely ignored by decision and policy makers and even by civil society at all levels, which compromises a real develo pment and improvement of this technology as well as animal welfare.
On the other hand, a collective ecological and economical consciousness and an increasing awareness of public opinion about the need to reduce the excessive industrialization and mechanization of agriculture and forestry has led some sectors of society to consider the (re)use of animal traction as a valid modern source of energy. Indeed, working animals optimally transform the consumed biomass in energy and natural fertilizer, which avoids soil degradation and contributes to a sustainable management of arable lands, forests and sensitive areas. The need to maintain biodiversity, reduce carbon emissions, encourage self-reliance and reduce consumption of resources also contributes to this trend.
This study aims at assessing the feasibility of deficit irrigation of maize, wheat and sunflower through an analysis of the economic water productivity (EWP). It focuses on selected sprinkler-irrigated fields in Vigia Irrigation District, Southern Portugal. Various scenarios of water deficits and water availability were considered. Simulations were performed for average, high and very high climatic demand.
The potential crop yields were estimated from regional climatic data and local information. Using field collected data on yield values, production costs, water costs, commodity prices and irrigation performance, indicators on EWP were calculated. Results show that a main bottleneck for adopting deficit irrigation is the presently low performance of the irrigation systems used in the considered fields, which leads to high water use and low EWP. Decreasing water use through deficit irrigation also decreases the EWP. Limited water deficits for maize are likely to be viable when the irrigation performance is improved if water prices do not increase much, and the commodity price does not return to former low levels.
The sunflower crop, despite lower sensitivity to water deficits than maize, does not appear to be a viable solution to replace maize when water restrictions are high; however it becomes an attractive crop if recently high commodity prices are maintained. With improved irrigation performance, wheat deficit irrigation is viable including when full water costs are applied, if former low prices are not returned to. However, under drought conditions full water costs are excessive. Thus, adopting deficit irrigation requires not only an appropriate irrigation scheduling but higher irrigation performance, and that the application of a water prices policy would be flexible, thus favouring the improvement of the irrigation systems.
Mediterranean regions are characterized by a large intra-annual and inter-annual variability in rainfall and associated hydrological regime patterns. Predictions of changes in climate indicate that mean precipitation and annual temperature will both increase, with a concentration of precipitation and the existence of extended and harsher drought periods with profound implications for river ecosystems. Our aim in this study was to predict the response of Mediterranean riparian vegetation to different climate change scenarios, using a dynamic riparian vegetation model that relates flow regime with riparian vegetation dynamics.
In our case study, mapped riparian patches were significantly distinct in between, and altitude, height above water table, patch age and stem diameter were the most important of the factors that distinguished succession phases. A floodplain vegetation model was calibrated and achieved a good strength of agreement between simulated and observed maps. Model results with the expected flow regime under the effect of climate change demonstrate that nonwoody sparsely vegetated areas expand outwards and mature succession patches expand inwards, whereas pioneer and young riparian patches decrease in area. Our results suggest that extreme climatic change in Mediterranean rivers will promote the disappearance of the pioneer and young succession stages of riparian woodlands, thus making efforts to conserve these ecosystems a challenging task.