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Integrated cross-sectoral impact assessments facilitate a comprehensive understanding of interdependencies and potential synergies, conflicts, and trade-offs between sectors under changing conditions. This paper presents a sensitivity analysis of a European integrated assessment model, the CLIMSAVE integrated assessment platform (IAP). The IAP incorporates important cross-sectoral linkages between six key European land- and water-based sectors: agriculture, biodiversity, flooding, forests, urban, and water. Using the IAP, we investigate the direct and indirect implications of a wide range of climatic and socio-economic drivers to identify: (1) those sectors and regions most sensitive to future changes, (2) the mechanisms and directions of sensitivity (direct/indirect and positive/negative), (3) the form and magnitudes of sensitivity (linear/non-linear and strong/weak/insignificant), and (4) the relative importance of the key drivers across sectors and regions. The results are complex. Most sectors are either directly or indirectly sensitive to a large number of drivers (more than 18 out of 24 drivers considered). Over twelve of these drivers have indirect impacts on biodiversity, forests, land use diversity, and water, while only four drivers have indirect effects on flooding. In contrast, for the urban sector all the drivers are direct. Moreover, most of the driver-indicator relationships are non-linear, and hence there is the potential for 'surprises'. This highlights the importance of considering cross-sectoral interactions in future impact assessments. Such systematic analysis provides improved information for decision-makers to formulate appropriate adaptation policies to maximise benefits and minimise unintended consequences. [ABSTRACT FROM AUTHOR]

The Yakima River Basin (Basin) in south-central Washington is a prime example of a place where competing water uses, coupled with over-allocation of water resources, have presented water managers with the challenge of meeting current demand, anticipating future demand, and preparing for potential impacts of climate change. We took a decision analysis approach that gathered diverse stakeholders to discuss their concerns pertaining to climate change effects on the Basin and future goals that were collectively important. One main focus was centered on how climate change may influence future salmon populations. Salmon have played a prominent role in the cultures of Basin communities, especially for tribal communities that have social, cultural, spiritual, subsistence, and economic ties to them. Stakeholders identified the need for a better understanding on how the cultural, spiritual, subsistence, and economic aspects of the Confederated Tribes and Bands of the Yakama Nation could be affected by changes in salmon populations. In an attempt to understand the complexities of these potential effects, this paper proposes a conceptual model which 1) identifies cultural values and components and the interactions between those components that could influence tribal well-being, and 2) shows how federal natural resource managers could incorporate intangible tribal cultural components into decision-making processes by understanding important components of tribal well-being. Future work includes defining the parameterization of the cultural components in order for the conceptual model to be incorporated with biophysical resource models for scenario simulations. [ABSTRACT FROM AUTHOR]

Most studies on the impact of climate change on regional water resources focus on long-term average flows or mean water availability, and they rarely take the effects of altered human water use into account. When analyzing extreme events such as floods and droughts, the assessments are typically confined to smaller areas and case studies. At the same time it is acknowledged that climate change may severely alter the risk of hydrological extremes over large regional scales, and that human water use will put additional pressure on future water resources. In an attempt to bridge these various aspects, this paper presents a first-time continental, integrated analysis of possible impacts of global change (here defined as climate and water use change) on future flood and drought frequencies for the selected study area of Europe. The global integrated water model WaterGAP is evaluated regarding its capability to simulate high and low-flow regimes and is then applied to calculate relative changes in flood and drought frequencies. The results indicate large `critical regions' for which significant changes in flood or drought risks are expected under the proposed global change scenarios. The regions most prone to a rise in flood frequencies are northern to northeastern Europe, while southern and southeastern Europe show significant increases in drought frequencies. In the critical regions, events with an intensity of today's 100-year floods and droughts may recur every 10-50 years by the 2070s. Though interim and preliminary, and despite the inherent uncertainties in the presented approach, the results underpin the importance of developing mitigation and adaptation strategies for global change impacts on a continental scale. [ABSTRACT FROM AUTHOR]

This study links climate change impacts to the development of adaptation strategies for agriculture in Europe. Climate change is expected to intensify the existing risks, particularly in southern regions, and create new opportunities in some northern areas. These risks and opportunities are characterised and interpreted across European regions by analysing over 300 highly relevant publications that appeared in the last decade. The result is a synthesis of the reasons for concern for European agricultural regions. The need to respond to these risks and opportunities is addressed by evaluating the costs and benefits of a number of technical and policy actions. The results highlight the importance of enhanced water use efficiency as a critical response to climate risks and the need for a more effective extension service. These results aim to assist stakeholders as they take up the adaptation challenge and develop measures to reduce the vulnerability of the sector to climate change. [ABSTRACT FROM AUTHOR]

Adaptation strategies are essential to manage water demand and ensure optimal use of available water resources under climate change. Identification and prioritization of adaptation options would greatly support decision-making in drought-prone Northwest Bangladesh. This study identified climate adaptation options by literature review and stakeholder consultation, then used multi-criteria analysis to evaluate and prioritize the options. The complexity of the options was also evaluated, specifically social, institutional, and technical obstacles to their local uptake. Seventy-two adaptation options were identified, spanning six sector categories. The options were further classified as in-system dependent, i.e., options that could be implemented by local actors, or as out-system dependent, i.e., options reliant on actions by external actors. Finally, they were defined as on-farm or off-farm strategies. Transboundary cooperation to increase surface water flows was ranked as the overall top-priority option, though this option is very complex and out-system dependent. Integrated water resources management and integrated crop management were the top-ranked options in the water management and crop production management sectors, respectively. Clustering scattered households and offering training programs in on-farm water management were the most and least complex measures, respectively. Stakeholders exhibited a clear preference for higher scale out-system dependent strategies, rather than in-system dependent options focused on changing the agricultural system itself to cope with climate change. Nonetheless, it is recommended that short-term and medium-term planning focus on opportunities to implement achievable adaptation measures within the local agricultural system. Investment in complex, externally dependent strategies is important for long-term planning. [ABSTRACT FROM AUTHOR]

Groundwater plays a critical supporting role in agricultural production in the California Central Valley (CV). Recent prolonged droughts (notably 2007–2009 and 2012–2016) caused dramatic depletion of groundwater, indicating the susceptibility of the CV's water supply to climate change. To assess the impact of climate change on groundwater storage in the CV, we combined integrated surface water and groundwater models with climate projections from 20 global climate models and thereby explore the vulnerability of CV groundwater under two climate scenarios RCP4.5 and RCP8.5. We found that groundwater has been declining over the past decades (3 km3/year on average during 1950–2009). In the absence of future mitigating measures, this decline will continue, but at a higher rate due to climate change (31% and 39% increase in loss rate under RCP4.5 and RCP8.5). The greatest loss (more than 80% of the total) will occur in the semi-arid southern Tulare region. We performed computational experiments to quantify the relative contribution of future crop water use and headwater inflows to total groundwater storage change. Our results show that, without management changes, continuing declines in future groundwater storage will mainly be attributable to ongoing overuse of groundwater. However, future changes in the seasonality of streamflow into the CV, (small) changes in annual inflows, and increased crop water use in a warmer climate will lead to 40–70% more annual groundwater losses than the current annual average, up to approximately 5 km3/year. [ABSTRACT FROM AUTHOR]

Evapotranspiration (ET) and water use efficiency (WUE) are critical indexes in water flux cycles of croplands, being affected by climate change. However, field studies addressing influence of experimental warming on ET and WUE in semi-arid cropland are highly deficient. A two-factor experiment, including soil temperature [ambient (C) and increased average 1.5 °C (T) at 5 cm soil depth] and nitrogen fertilizer (N) [without (N0) and with 315 kg N ha input (N1)], was conducted from 2010 to 2014 in North China Plain to measure ET and WUE of wheat-soybean/fallow rotation. In the N1 treatment, warming increased ET by 3 %, 22 %, 34 % and 16 % in wheat growing seasons of 2011, 2012, 2013 and 2014, respectively, compared with ambient temperature. N addition increased ET by 9 %, 22 %, 11 % and 27 % under ambient temperature, and by 14 %, 60 %, 45 % and 50 % under warming during the four wheat growing seasons. Warming reduced WUE by 15 %-45 % under N1. N addition increased WUE by 68 % under ambient temperature during 2010 to 2012, decreased WUE by 45 % under warming during 2011 to 2013. Warming did not alter ET and WUE in the N0 treatment during whole years. Under N1 treatment, the reduction in WUE with increasing soil temperature is likely due to the increased vapour pressure deficit (VPD). The study highlights the interactions between climate warming and N addition on hydrological cycles during wheat growth, contributing the understanding of how fertilized semi-arid cropland respond to climate change. [ABSTRACT FROM AUTHOR]

The human consequences of drought are normally addressed in terms of 'water scarcity' originating from human water use. In these terms, a common prediction to the next few decades is that population growth, not climate change, will be the dominant factor determining numbers living under such scarcity. Here we address the relative importance of increasing human caused extreme drought and increasing population for numbers of humans likely to be directly exposed in the future to such drought. Using the Standardized Precipitation Evapotranspiration Index (SPEI) in conjunction with an ensemble of 16 CMIP5 climate models we find that, by 2081-2100 under the high emissions scenario RCP 8.5, average worldwide monthly population exposed to extreme drought (SPEI < -2) will increase by 386.8 million to 472.3 million (+426.6% from the current 89.7 million). Anthropogenic climate change is responsible for approximately 230.0 million (59.5%) of that increase with population growth responsible for only 35.5 million (9.2%); the climate change-population growth interaction explains the remaining 121.1 million (31.4%). At the national level, 129 countries will experience increase in drought exposure mainly due to climate change alone; 23 countries primarily due to population growth; and 38 countries primarily due to the interaction between climate change and population growth. Given inherently large uncertainties, projections of future climate impacts should be accepted with caution especially those directed to the regional level, to future population trends, and, of course, where technological, social and security changes are possible. [ABSTRACT FROM AUTHOR]

Understanding cross-sectoral impacts is important in developing appropriate adaptation strategies to climate change, since such insight builds the capacity of decision-makers to understand the full extent of climate change vulnerability, rather than viewing single sectors in isolation. A regional integrated assessment model that captures interactions between six sectors (agriculture, forests, biodiversity, water, coasts and urban) was used to investigate impacts resulting from a wide range of climate and socio-economic scenarios. Results show that Europe will be significantly influenced by these possible future changes with between 79 and 91 % of indicator-scenario combinations found to be statistically significantly different from the baseline. Urban development increases in most scenarios across Europe due to increases in population and sometimes GDP. This has an indirect influence on the number of people affected by a 1 in 100 year flood which increases in western and northern Europe. Changes in other land uses (intensive farming, extensive farming, forests and unmanaged land) vary depending on the scenario, but food production generally increases across Europe at the expense of forest area and unmanaged land to satisfy increasing food demand. Biodiversity vulnerability and water exploitation both increase in southern and Eastern Europe due to direct effects from climate and indirect effects from changes in land use and irrigation water use. The results highlight the importance of considering non-climatic pressures and cross-sectoral interactions to fully capture climate change impacts at the regional scale. [ABSTRACT FROM AUTHOR]

Future changes of terrestrial ecosystems due to changes in atmospheric CO concentration and climate are subject to a large degree of uncertainty, especially for vegetation in the Tropics. Here, we evaluate the natural vegetation response to projected future changes using an improved version of a dynamic vegetation model (CLM-CN-DV) driven with climate change projections from 19 global climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). The simulated equilibrium vegetation distribution under historical climate (1981-2000) has been compared with that under the projected future climate (2081-2100) scenario for Representative Concentration Pathway 8.5 (RCP8.5) to qualitatively assess how natural potential vegetation might change in the future. With one outlier excluded, the ensemble average of vegetation changes corresponding to climates of 18 GCMs shows a poleward shift of forests in northern Eurasia and North America, which is consistent with findings from previous studies. It also shows a general 'upgrade' of vegetation type in the Tropics and most of the temperate zones, in the form of deciduous trees and shrubs taking over C3 grass in Europe and broadleaf deciduous trees taking over C4 grasses in Central Africa and the Amazon. LAI and NPP are projected to increase in the high latitudes, southeastern Asia, southeastern North America, and Central Africa. This results from CO fertilization, enhanced water use efficiency, and in the extra-tropics warming. However, both LAI and NPP are projected to decrease in the Amazon due to drought. The competing impacts of climate change and CO fertilization lead to large uncertainties in the projection of future vegetation changes in the Tropics. [ABSTRACT FROM AUTHOR]

Various frameworks related to climate change and adaptations that have been developed to date have notable benefits as well as significant limitations. It is not always practical to implement advanced climate change frameworks in situations with limited data availability. Social aspects, such as people's experience and perception, are often under-prioritized. Therefore, this study introduces an integrated framework linking social and physical aspects of climate change to assess its impacts on water resources and to evaluate differing adaptation options in poorly gauged basins. A case study of the Kali Gandaki River Basin (KGRB) in western Nepal is presented to demonstrate the applicability of this framework. Results of the study show that people of the mountainous Mustang district in the KGRB have perceived climate change or climate variability, its impacts on water resources, as well as other water-related issues and potential adaptations or responses. Furthermore, evaluation of people's perception using available physical data confirms the increase in temperature and average annual discharge in the Kali Gandaki River as well as poor water use, as a major problem at all levels in the basin. Despite increasing water availability, a concurrent increase in water use is difficult due to topographic constraints on irrigation development. However, the impacts of climate change are particularly severe in Mustang, owing to the fact that a large proportion of the population depends on a climate-sensitive livelihood like agriculture. Therefore, various adaptation options are identified in the agricultural sector, and one relevant option is further evaluated. The framework developed in this study has the potential to be further applied to other poorly gauged basins. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of climate change on sugarcane yield, water use efficiency, and irrigation needs in southern Brazil, based on downscaled outputs of two general circulation models (PRECIS and CSIRO) and a sugarcane growth model. For three harvest cycles every year, the DSSAT/CANEGRO model was used to simulate the baseline and four future climate scenarios for stalk yield for the 2050s. The model was calibrated for the main cultivar currently grown in Brazil based on five field experiments under several soil and climate conditions. The sensitivity of simulated stalk fresh mass (SFM) to air temperature, CO concentration [CO] and rainfall was also analyzed. Simulated SFM responses to [CO], air temperature and rainfall variations were consistent with the literature. There were increases in simulated SFM and water usage efficiency (WUE) for all scenarios. On average, for the current sugarcane area in the State of São Paulo, SFM would increase 24 % and WUE 34 % for rainfed sugarcane. The WUE rise is relevant because of the current concern about water supply in southern Brazil. Considering the current technological improvement rate, projected yields for 2050 ranged from 96 to 129 t ha, which are respectively 15 and 59 % higher than the current state average yield. [ABSTRACT FROM AUTHOR]

Projections of future climate change are plagued with uncertainties from global climate models and emission scenarios, causing difficulties for impact assessments and for planners taking decisions on adaptation measure. Here, we developed an approach to deal with the uncertainties and to project the changes of maize productivity and water use in China using a process-based crop model, against a global mean temperature (GMT) increase scale relative to 1961-1990 values. From 20 climate scenarios output from the Intergovernmental Panel on Climate Change Data Distribution Centre, we adopted the median values of projected changes in monthly mean climate variables for representative stations and driven the CERES-Maize model to simulate maize production under baseline and future climate scenarios. Adaptation options such as automatic planting, automatic application of irrigation and fertilization were considered, although cultivars were assumed constant over the baseline and future. After assessing representative stations across China, we projected changes in maize yield, growing period, evapotranspiration, and irrigation-water use for GMT changes of 1°C, 2°C, and 3°C, respectively. Results indicated that median values of projected decreases in the yields of irrigated maize without (with) consideration of CO-fertilization effects ranged from 1.4% to 10.9% (1.6% to 7.8%), 9.8% to 21.7% (10.2% to 16.4%), and 4.3% to 32.1% (3.9% to 26.6%) for GMT changes of 1°C, 2°C, and 3°C, respectively. Median values of projected changes in irrigation-water use without (with) consideration of CO-fertilization effects ranged from −1.3% to 2.5% (−18.8% to 0.0%), −43.6% to 2.4% (−56.1% to −18.9%), and −19.6% to 2.2% (−50.6% to −34.3%), which were ascribed to rising CO concentration, increased precipitation, as well as reduced growing period with GMT increasing. For rainfed maize, median values of projected changes in yields without (with) consideration of CO-fertilization effects ranged from −22.2% to −1.0% (−10.8% to 0.7%), −27.6% to −7.9% (−18.1% to −5.6%), and −33.7% to −4.6% (−25.9% to −1.6%). Approximate comparisons showed that projected maize yield losses were larger than previous estimates, particularly for rainfed maize. Our study presents an approach to project maize productivity and water use with GMT increases using process-based crop models and multiple climate scenarios. The resultant impact function is fundamental for identifying which climate change level is dangerous for food security. [ABSTRACT FROM AUTHOR]