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This study evaluates climate change impacts on crop production and water productivity of four major crops (wheat, barley, rice, and corn) in Iran's Zayandeh-Rud River Basin. Multi-model ensemble scenarios are used to deal with uncertainties in climate change projections for the study period (2015-2044). On average, monthly temperature will increase by 1.1 to 1.5°C under climate change. Monthly precipitation changes may be positive or negative in different months of the year. Nevertheless, on the annual basis, precipitation will decrease by 11 to 31% with climate change. While warming can potentially shorten the crop growth period, crop production and water productivity of all crops are expected to decrease due to lower precipitation and higher water requirements under higher temperature. Out of the four studied crops, rice and corn are more vulnerable to climate change due to their high irrigation water demand. So, their continued production can be compromised under climate change. This finding is of particular importance, given the locally high economic and food value of these crops in central Iran., (Copyright © 2012 Elsevier B.V. All rights reserved.)

As the climate crisis intensifies, it is becoming increasingly important to conduct research aimed at fully understanding the climate change impacts on various infrastructure systems. In particular, the water-electricity demand nexus is a growing area of focus. However, research on the water-electricity demand nexus requires the use of demand data, which can be difficult to obtain, especially across large spatial extents. Here, we present a dataset containing over a decade (2007–2018) of monthly water and electricity consumption data for 46 major US cities (2018 population >250,000). Additionally, we include pre-processed climate data from the North American Regional Reanalysis (NARR) to supplement studies on the relationship between the water-electricity demand nexus and the local climate. This data can be used for a number of studies that require water and/or electricity demand data across long time frames and large spatial extents. The data can also be used to evaluate the possible impacts of climate change on the water-electricity demand nexus by leveraging the relationship between the observed values. [ABSTRACT FROM AUTHOR]

Small agricultural reservoirs support water demands during dry spells. However, evaporative losses that are often overlooked in water accounting and management diminish the storage efficiency of these popular but un‐inventoried resources. We developed a predictive framework to identify the spatio‐temporal extent of small reservoirs (900–100,000 m2) and quantify their evaporative losses using a physically‐based model. Focusing on water‐stressed regions of Europe (Italy, Spain, and Portugal), our results indicate that the total number and cumulative area of small reservoirs in drier areas of Europe almost doubled in two decades from about 6,200 reservoirs with the cumulative area of 46 km2 in 2,000 to 11,800 reservoirs with the cumulative area of 93.5 km2 in 2020. We observed climate‐driven trends in the expansion of agricultural reservoirs and their evaporative losses which exceeded 72 million cubic meters during warm months (April to September) accounting for 38% of their total storage capacity. Plain Language Summary: Small agricultural reservoirs play a key role in supporting irrigation and local demands in a warming climate. However, evaporation diminishes their storage efficiency. We provide a physically‐based framework for estimating global abundance and evaporative losses from small reservoirs serving as a basis for improving water management and planning. To show the applicability of the proposed method, we focused on water‐stressed regions of Europe (Italy, Spain, and Portugal). We found that cumulative area of small reservoirs in the study area has reached to 93.5 km2 in 2020 with cumulative evaporative losses that may exceed 72 million cubic meters. The study offers new insights into the improved understanding of the role and efficiency of small water storage infrastructure in water planning strategies. Key Points: A physically‐based framework was proposed to identify the extent of small reservoirs (<0.1 km2) and quantify their evaporative lossesTotal number and cumulative area of small agricultural reservoirs in water‐stressed regions of southern Europe doubled in two decadesStrong correlations were found between expansion of agricultural reservoirs, air temperature and precipitation [ABSTRACT FROM AUTHOR]

By combining long-term ground-based data on water withdrawal with climate model projections, this study quantifies the compounding effects of human activities and climate change on surface water availability in Iran over the twenty-first century. Our findings show that increasing water withdrawal in Iran, due to population growth and increased agricultural activities, has been the main source of historical water stress. Increased levels of water stress across Iran are expected to continue or even worsen over the next decades due to projected variability and change in precipitation combined with heightened water withdrawals due to increasing population and socio-economic activities. The greatest rate of decreased water storage is expected in the Urmia Basin, northwest of Iran, (varying from ~ − 8.3 mm/year in 2010–2039 to ~ − 61.6 mm/year in 2070–2099 compared with an observed rate of 4 mm/year in 1976–2005). Human activities, however, strongly dominate the effects of precipitation variability and change. Major shifts toward sustainable land and water management are needed to reduce the impacts of water scarcity in the future, particularly in Iran's heavily stressed basins like Urmia Basin, which feeds the shrinking Lake Urmia. [ABSTRACT FROM AUTHOR]

Iran is currently experiencing serious water problems. Frequent droughts coupled with over-abstraction of surface and groundwater through a large network of hydraulic infrastructure and deep wells have escalated the nation's water situation to a critical level. This is evidenced by drying lakes, rivers and wetlands, declining groundwater levels, land subsidence, water quality degradation, soil erosion, desertification and more frequent dust storms. This paper overviews the major drivers of Iran's water problems. It is argued that while climatic changes and economic sanctions are commonly blamed as the main drivers of water problems, Iran is mainly suffering from a socio-economic drought—i.e. "water bankruptcy," where water demand exceeds the natural water supply. In theory, this problem can be resolved by re-establishing the balance between water supply and demand through developing additional sources of water supply and implementing aggressive water demand reduction plans. Nevertheless, the current structure of the water governance system in Iran and the absence of a comprehensive understanding of the root causes of the problem leave minimal hope of developing sustainable solutions to Iran's unprecedented water problems. [ABSTRACT FROM AUTHOR]

Highlights: [•] Addressing the major gap in previous climate change and hydropower research in California. [•] Simultaneous evaluation of climate change effects on high-elevation hydropower supply and pricing. [•] Estimating climate warming effects on high-elevation hydropower operations in California. [ABSTRACT FROM AUTHOR]

Given the important role of hydropower in peak electricity management, Middle Eastern countries are actively pursuing development of more hydropower resources by construction of large dams. Nonetheless, climate change is expected to affect the future productivity of hydropower by influencing the hydrologic cycle and different climate variables in the region. Although reactive plans to minimize climate change impacts on hydropower production have been implemented in the developed world, the developing world can still benefit from proactive actions. Studies of climate change impacts before and during implementation of hydropower projects can result in timely responses and adaptation to climate change with a potential of considerable cost savings. This study investigates the potential impacts of climate change on the hydropower systems in the Karkheh River Basin-the third largest river basin in Iran-in terms of potential for hydroelectricity generation. A simulation model is developed to examine how hydropower generation levels vary for different future climate change scenarios in this representative Middle Eastern basin. The obtained results suggest that the existing operation rules and design specifications, developed based on the historical climatic conditions, can lead to inefficient operations of the hydropower in the basin. Because of insignificant streamflow reductions in the short term, hydropower production may not change considerably in the near future. However, a serious hydropower generation deficit is expected in the midterm and long-term horizons in the Karkheh River Basin. Therefore, adaptation to the future climate change conditions and revision of the operation rule curves and design specifications are essential to optimal hydropower operations in this basin. [ABSTRACT FROM AUTHOR]

Abstract: In a recent article in this journal entitled “Game Theory and Climate Diplomacy”, DeCanio and Fremstad (2013) provide an interesting treatment of a range of simple game theoretic characterizations of international climate negotiations. The authors use the Nash and Maxi-min stability definitions to analyze 25 two-by-two ordinal games, which they recognize as “possible game-theoretic characterizations of climate negotiations between two players (e.g., Great Powers or coalitions of states)”. The authors' main conclusion that the Prisoner's Dilemma might not be the best description of climate negotiations game is consistent with the findings of others who have studied two-by-two conflicts over natural commons (Bardhan, 1993; Madani, 2010; Sandler, 1992; Taylor, 1987). Nevertheless, given the importance of the climate change issue, as well as the potential effects of our actions on the state of the environment and the well-being of future generations, I would like to address some gaps in their analysis, which result in it having limited usefulness for policy purposes. Of course, all models are simplified representations of reality, full of limitations. “Essentially, all models are wrong, but some are useful” (Box and Draper, 1987). So, “the practical question is how wrong do they have to be to not be useful” (Box and Draper, 1987). Models' limitations need to be carefully considered when interpreting them or applying their results to policy but some models are too simple to provide useful policy advice. [Copyright &y& Elsevier]

This paper explores the independent and combined effects of changes in temperature and runoff volume on California's water supply and potential water management adaptations. Least-cost water supply system adaptation is explored for two climate scenarios: 1) warmer-drier conditions, and 2) warmer conditions without change in total runoff, using the CALVIN economic-engineering optimization model of California's intertied water supply system for 2050 water demands. The warm-dry hydrology was developed from downscaled effects of the GFDL CM2.1 (A2 emissions scenario) global climate model for a 30-year period centered at 2085. The warm-only scenario was developed from the warm-dry hydrology, preserving its seasonal runoff shift while maintaining mean annual flows from the historical hydrology. This separates the runoff volume and temperature effects of climate change on water availability and management adaptations. A warmer climate alone reduces water deliveries and increases costs, but much less than a warmer-drier climate, if the water supply system is well managed. Climate changes result in major changes in reservoir operations, cyclic storage of groundwater, and hydropower operations. [ABSTRACT FROM AUTHOR]

Abstract: Cooperative game theory solutions can provide useful insights into how parties may use water and environmental resources and share any benefits of cooperation. Here, a method based on Nash and Nash–Harsanyi bargaining solutions is developed to explore the Federal Energy Regulatory Commission (FERC) relicensing process, in which owners of non-federal hydropower projects in the United States have to negotiate their allowable operations, with other interest groups (mainly environmental). Linkage of games to expand the feasible solution range and the “strategic loss” concept are discussed and a FERC relicensing bargaining model is developed for studying the bargaining stage (third stage) of the relicensing process. Based on the suggested solution method, how the lack of incentive for cooperation results in long delay in FERC relicensing in practice is explained. Further, potential effects of climate change on the FERC relicensing are presented and how climate change may provide an incentive for cooperation among the parties to hasten the relicensing is discussed. An “adaptive FERC license” framework is proposed, based on cooperative game theory, to improve the performance and adaptability of the system to future changes with no cost to the FERC, in face of uncertainty about future hydrological and ecological conditions. [ABSTRACT FROM AUTHOR]

California's hydropower system is composed of high and low elevation power plants. There are more than 150 high-elevation power plants, at elevations above 1,000 feet (300 m). Most have modest reservoir storage capacities, but supply roughly 74% of California's in-state hydropower. The expected shift of runoff peak from spring to winter due to climate warming, resulting in snowpack reduction and increased snowmelt, might have important effects on power generation and revenues in California. The large storage capacities at low-elevation power plants provide flexibility to operations of these units under climate warming. However, with climate warming, the adaptability of the high-elevation hydropower system is in question as this system was designed to take advantage of snowpack, a natural reservoir. With so many high-elevation hydropower plants in California, estimation of climate warming effects by conventional simulation or optimization methods would be tedious and expensive. An Energy-Based Hydropower Optimization Model (EBHOM) was developed to facilitate practical climate change and other low-resolution system-wide hydropower studies, based on the historical generation data of 137 high-elevation hydropower plants for which the data were complete for 14 years. Employing recent historical hourly energy prices, the model was used to explore energy generation in California for three climate warming scenarios (dry warming, wet warming, and warming-only) over 14 years, representing a range of hydrologic conditions. The system is sensitive to the quantity and timing of inflows. While dry warming and warming-only climate changes reduce average hydropower revenues, wet warming could increase revenue. Re-operation of available storage and generation capacities help compensate for snowpack losses to some extent. Storage capacity expansion and to a lesser extent generation capacity expansion both increase revenues, although such expansions might not be cost-effective. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for modeling high-elevation hydropower systems. Conservation of energy and energy flows (rather than water volume or mass flows) is used as the basis for modeling more than 135 high-elevation high-head hydropower sites throughout California. The unusual energy basis for reservoir modeling allows for development of hydropower operations models for a large number of plants to estimate large-scale system behavior without the expense and time needed to develop traditional streamflow and reservoir volume-based models in absence of storage and release capacity, penstock head, and efficiency information. Potential applications of the developed Energy-Based Hydropower Optimization Model (EBHOM) include examination of the effects of climate change and energy prices on system-wide generation and hydropower revenues. An extensive comparison of the EBHOM with a traditional hydropower optimization model used in California produced similar results and indicated good reliability of EBHOM's predictions. [ABSTRACT FROM AUTHOR]

Economically optimal operational changes and adaptations for California's water supply system are examined for a dry form of climate warming (GFDL CM2.1 A2) with year 2050 water demands and land use. Economically adaptive water management for this climate scenario is compared to a similar scenario with the historical climate. The effects of population growth and land use alone are developed for comparison. Compared with the historic hydrology, optimized operations for the dry climate warming scenario raise water scarcity and total operation costs by $490 million/year with year 2050 demands. Actual costs might be somewhat higher where non-economic objectives prevail in water management. The paper examines the economical mix of adaptation, technologies, policies, and operational changes available to keep water supply impacts to such modest levels. Results from this screening model suggest promising alternatives and likely responses and impacts. Optimized operations of ground and surface water storage change significantly with climate. Dry-warm climate change increases the seasonal storage range of surface reservoirs and aquifers. Surface reservoir peak storage usually occurs about a month earlier under dry-warm climate change. [ABSTRACT FROM AUTHOR]

A correction to the article "System Dynamics Evaluation of Climate Change Adaptation Strategies for Water Resources Management in Central Iran" in March 2017 issue is presented.

There is mounting evidence that human-made climate changes do project onto the natural modes of climate variability. As a result, hydro-climatic extreme events have become more intense and more frequent in the last decades. Yet, unraveling the role of climate change and climate variability in the occurrence of extreme events remains poorly known. Such information is critical to assess and manage disaster risks and improve adaptation and mitigation strategies to decrease the damages and costs to society. This study seeks to tease out the impact of anthropogenic climate change from natural climate variability on daily extreme rainfall events at 263 stations in Europe over an approximately century-long period from 1925 to 2015. The decadal oscillations of daily extreme rainfall in different seasons are determined using the quantile perturbation method and then tested for the presence of nonstationarity. The attribution analysis of significant extreme rainfall events based on the Monte Carlo method is performed by comparing the occurrence probability under natural forcing alone and under natural plus anthropogenic forcings. The results reveal a climate change footprint in the decadal oscillations of extreme rainfall, with significant upward trends ranging between 27% and 56% of the continental area in different seasons. From a spatial point of view, western Europe characterized by strong upward trends is the most hazardous region of the continent to extreme rainfall events. We also find that the extreme rainfall events under climate change have become twice as frequent as under natural forcing. The attribution of human-caused climate change to significant extreme rainfall events over Europe varies with seasons and is in the range of 35-52%. [ABSTRACT FROM AUTHOR]

Highlights • Joint analysis of human-landscape and climate drivers of lake shrinkage was performed. • Climate change is not the main cause of water level decline in Lake Urmia. • Agricultural vegetation expansion since 2000 has increased upstream water consumption. • Increased water consumption is the likely driver of Lake Urmia desiccation. Abstract Lake Urmia—a shallow endemic hypersaline lake in northwest Iran—has undergone a dramatic decline in its water level (WL), by about 8 m, since 1995. The primary cause of the WL decline in Lake Urmia has been debated in the scientific literature, regarding whether it has been predominantly driven by atmospheric climate change or by human activities in the watershed landscape. Using available climate, hydrological, and vegetation data for the period 1981–2015, this study analyzes and aims to explain the lake desiccation based on other observed hydro-climatic and vegetation changes in the Lake Urmia watershed and classical exploratory statistical methods. The analysis accounts for the relationships between atmospheric climate change (precipitation P, temperature T), and hydrological (soil moisture SM, and WL) and vegetation cover (VC; including agricultural crops and other vegetation) changes in the landscape. Results show that P, T, and SM changes cannot explain the sharp decline in lake WL since 2000. Instead, the agricultural increase of VC in the watershed correlates well with the lake WL change, indicating this human-driven VC and associated irrigation expansion as the dominant human driver of the Lake Urmia desiccation. Specifically, the greater transpiration from the expanded and increasingly irrigated agricultural crops implies increased total evapotranspiration and associated consumptive use of water (inherently related to the irrigation and water diversion and storage developments in the watershed). Thereby the runoff from the watershed into the lake has decreased, and the remaining smaller inflow to the lake has been insufficient for keeping up the previous lake WL, causing the observed WL drop to current conditions. [ABSTRACT FROM AUTHOR]

The uncertainty of a changing climate raises challenges for water infrastructure planning and design. Not accounting for nonstationarity may result in under-designed structures that fail too frequently, or over-designed structures that are economically inefficient. This concern is magnified by uncertainty in the long-term frequency and magnitude of future extreme events. Planning strategies that allow adaptations over a structure's life could improve both reliability and economic efficiency. This study develops a method to inform adaptive water infrastructure planning with uncertain hydrologic and other forms of nonstationarity, applied to levee system planning. A stochastic dynamic programming model including a Markov process is developed for infrastructure planning with uncertain nonstationarity in flood frequency. Bayes' theorem is used to update peak flow probabilities conditioned on observed past peak flows and to update expected residual flood damages over time. A levee system planning problem with a numerical example from California illustrates the approach to derive optimal levee heights over time, and economic values of adapting to uncertain nonstationary flood risk. The projected range of probabilistic hydrology scenarios affects the optimal results, particularly in later planning stages as hydrology scenarios diverge with time. Adaptive planning strategies allowing more levee upgrades over time slightly lowers the overall cost and provides better flood protection than one-time construction under nonstationary hydrology for any climate in the example. Compared to a known future nonstationary hydrology, incorporating uncertain nonstationary climate results in higher levees being planned for observed severe hydrology scenarios in later stages. The overall present value cost with uncertain nonstationary climate depends on rates of change in peak flow distribution parameters in future hydrology scenarios. [ABSTRACT FROM AUTHOR]

• Regional resource availability affects the desirability of an energy technology. • Some low-carbon technologies can lead to unsustainable outcomes. • Unintended impacts on other valuable resources reduces desirability. • Nuclear, geothermal and onshore wind are amongst the most desirable technologies across MENA. • Hydropower and biomass are not desirable across the region. Global warming urges governments to decarbonise their energy portfolios. Many governments have indistinctly transited away from fossil fuels towards renewable energies. However, a sustainable turnaround calls for limiting the overall impact of this transition on environmental resources and the economy. This study identifies the most desirable energy alternatives for the Middle Eastern and North African (MENA) countries based on their environmental and economic footprints using the Relative Aggregate Footprint (RAF) indicator. The RAFs of eleven widespread electricity generation technologies are computed for each country by considering the availability of four resources – energy, water, land, and the economy – which were weighted according to the national resource availability conditions. The results indicate that the MENA region must adapt their electricity mix to mitigate the impacts of climate change with respect to resource availability conditions, especially their scarce water resources. Due to the specificities of this region, deploying biomass and large-scale hydropower may lower greenhouse gases but significantly alter the impact on other valuable natural resources. Therefore, wind, geothermal, and nuclear power plants seem more desirable for a transition away from carbon-intensive technologies while their secondary effects on other resources (e.g. nuclear energy's possible water and environmental impacts) must be carefully considered. [ABSTRACT FROM AUTHOR]