Vahid Karimi, Ezatollah Karami, Marzieh Keshavarz

1 Department of Agricultural Extension and Education, College of Agriculture, Shiraz University, Shiraz 71441-65186, Iran

2 Department of Agriculture, Payame Noor University, Tehran 19395-4697, Iran

REVIEW

Climate change and agriculture: Impacts and adaptive responses in Iran

Vahid Karimi1, Ezatollah Karami1, Marzieh Keshavarz2

1 Department of Agricultural Extension and Education, College of Agriculture, Shiraz University, Shiraz 71441-65186, Iran

2 Department of Agriculture, Payame Noor University, Tehran 19395-4697, Iran

The impacts of climate change on agriculture are still shadowed with uncertainty. However, climate change is expected to adversely affect Iran’s agricultural practices through changes in precipitation, temperature and carbon dioxide fertilization.Therefore, adaptation of this sector to the increasing weather events is imperative. This study is aimed to document the likely impacts of climate change on Iran’s agriculture and the current adaptation efforts made by government and farmers.The review of literature shows that changes in rainfall and water endowments will have signi ficant impacts on crop yield,crops’ water requirements and income and welfare of farm families. The extent of the changes in yield depends on the crop type, assumptions related to the CO2fertilization effect, climate scenarios and adaptation abilities. On adaptation, the government’s efforts have been distinguished in the improving agricultural productivity and irrigation development based on current technology, developing new technologies and policy reforms. Farmers’ adaptive responses have also been identi fied. Some conclusions and recommendations are offered to increase the adaptive capacity of farmers and reduce negative impacts of climate change.

climate change, agriculture, impacts, adaptation, Iran

1. Introduction

Despite the remaining uncertainty, it is widely accepted that climate is changing. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change,the atmospheric concentrations of the greenhouse gases,i.e., carbon dioxide (CO2), methane (CH4) and nitrous oxide(N2O), have increased to unprecedented levels in the last 800 000 years (IPCC 2013). An increase in the levels of GHGs (greenhouse gases) can lead to greater warming,which, in turn, can in fluence the world’s climate, leading to the climate change (VijayaVenkataRaman et al. 2012).While causes of climate change can be divided into two categories, namely, natural and man-made causes (Karami 2012), there is a strong evidence that most of the observed warming (of 0.1°C per decade) over the last 50 years can be attributed to human activities (Ravindranath and Sathaye 2003) such as the burning of fossil fuels and changes in land use (IPCC 2013). For instance, in 2009, agriculture directly accounted for 14% of global GHG emissions in CO2equivalents and indirectly accounted for an additional 17% of emissions when land use and conversion for crops and pasture were included in the calculations (IPCC 2013).Without additional efforts to reduce GHG emissions, the global average surface temperature will be very likely to rise in 2100 from 3.7 to 4.8°C compared to pre-industrial levels (IPCC 2014).

Under the Kyoto Protocol, most developed countries made binding commitments to modest - but not insigni ficant- net reductions in their emissions of six GHGs in the period of 2008 to 2012. Even if this goal is achieved through stringent worldwide mitigation actions to stabilize global GHG concentrations, some impacts will remain, at least in the short and medium terms, making adaptation imperative to reduce vulnerability and enhance resilience (Isoard 2011).Some areas such as northern Europe might bene fit to some extent from climate change, in the short and medium terms,e.g., by increasing crop yield, forest growth and increased tourism demand (Isoard 2011). However, the negative impacts of climate change will be so severe in arid or semiarid areas such as Iran (Parry et al. 2004).

Iran is one of the world’s water-scarce regions and is extremely vulnerable to the impacts of climate change due to its high dependency on climate-sensitive agriculture(Nassiri et al. 2006). Iran’s per capita freshwater availability was about 2 000 m3per capita per year in the year 2000. However, it is predicted that it will reduce to 1 500 m3per capita per year by 2030 due to the population growth (Yang et al. 2003). Therefore, it seems that the occurrence of probable climatic changes in this region has a disruptive impact on water resources. In addition, Iran has a broad spectrum of climatic conditions across regions with signi ficant rainfall (Abbaspour et al. 2009). While the northern part of the country is quite wet with frequent costly floods, the southern part is dry with large water scarcity. One of the largest climate changes is a decrease in precipitation that has occurred in northeastern Iran (Evans 2009). Changes in the timing of the maximum precipitation in northeastern Iran will affect the growing season and lead to adverse effects, in the long-term.

Climate change is expected to have different impacts on rainfall and temperature patterns across different regions and consequently on the spatial and temporal distributions of the various components of water resources. However,it is estimated that if the CO2concentration doubles by the year 2100, the average temperature in Iran will increase by 1.5–4.5°C. In turn, it will cause signi ficant changes in water resources, energy, agriculture and food production and forestry sectors (Amiri and Eslamian 2010) and aggravate current environmental challenges. It is therefore imperative for Iran to adapt to climate change.

As the major water consumer, agriculture is one of the most water vulnerable sectors to climate change in Iran.Despite the fact that the impacts of climate change on agriculture are still shadowed with uncertainty, there is a general consensus that Iran’s agricultural sector will be in fluenced signi ficantly (Nassiri et al. 2006). Climate change is expected to greatly affect agricultural practices through changes in precipitation, temperature, carbon dioxide fertilization, climate variability and surface water runoff.Moreover, dramatic population growth, associated with the reduction of productive land area and water resources,exerts extra pressure on the Iran’s agricultural sector.Therefore, there is a concern about the potential for climate change to disrupt Iranian farmers’ livelihoods and prevent the country from achieving sustainable development. To ensure sustainability of agriculture, studying the possible climate change impacts on this sector and adaptive responses are essential. This paper aims to review and analyze current understanding of climate change impacts on Iran’s agriculture and the present adaptation strategies employed by the government and farmers. Based on the literature review, discussions are provided and research gaps are addressed in order to fill these knowledge gaps in future studies.

2. Study area

Iran is located between 25° and 40°N and 44° to 63°E and has a total area of 1 648 000 km2(Abbaspour et al. 2009).This country contributes to a relatively heterogeneous climate. The area coverage of different types of climate in Iran is 35.5% hyper-arid, 29.3% arid, 20.2% semi-arid,5% Mediterranean and 10% wet (of the cold mountainous type) (Amiri and Eslamian 2010). Therefore, about 85% of Iran’s territory is dry with signi ficant water shortage, frequent droughts and a large reliance on groundwater resources.

Temperature varies between –20°C and +50°C while annual precipitation varies from less than 50 mm over the uninhabitable Eastern deserts to 1 800 mm over the Western Caspian Sea coast and Western highlands. However, Iran’s average rainfall is 250 mm, which is less than one-third of the global average (860 mm). This sparse precipitation is also unfavorable with respect to time and location. So that,most parts of the country receive less than 100 mm of rain per year (Madani et al. 2016).

Approximately 37 million hectares of Iran’s total surface is arable land. Of this, 18.5 million hectares are devoted to horticulture and field crop production (Keshavarz et al.2005). Also, about 47% of the arable land is irrigated using various traditional and modern techniques while the other 53% of the land is rain-fed (Salami et al. 2009). The major crops cultivated in Iran are wheat, barley, corn and rice.Wheat as the core commodity of Iranian food is grown on nearly 60% of the arable land. The average yield of irrigated and rain-fed wheat is approximately 3.0 and 0.95 tons per hectare, respectively (FAO 2016).

Iran is currently experiencing serious water problems.This country uses a considerable amount of groundwater for irrigation to compensate surface water de ficit. Currently,about 45% of the total water demand is satis fied through surface sources (Fig. 1) and the other 55% is from groundwater. Aggressive groundwater withdrawal has resulted in groundwater table decline in various regions.As a result, nearly 50% of the plains across Iran are in critical condition (Madani et al. 2016). Furthermore, owing to the traditional method of irrigation and water conveying systems, ef ficiency of irrigation water use varies between 15 and 36%. Therefore, a large fraction of diverted water is lost to evaporation and percolation (Abbaspour et al. 2009).

3. The impacts of climate change on Iran’s agricultural sector

3.1. Crop yield

In this section, major findings on the impacts of climate change on crop yields are discussed. In order to estimate crop productivity regarding the likely impacts of climate change, two distinct approaches are usually adopted, i.e.,statistical modeling and process-based crop modeling.Empirical crop models are statistical relationships derived from observations, which link crop yields in a given location to local climate variables. On the other hand, processbased crop modeling indicates physiological processes of crop growth and development as a response to climate.Therefore, it simulates the seasonal crop cycle and its different parts (Roudier et al. 2011). All reviewed findings(Tables 1 and 2) use a process-based crop modeling (e.g.,simple simulation model (SSM) and decision support system for agro-technology transfer (DSSAT)) that simulates the possible impacts of climate change, in the future. However,all models have not considered the same physiological approach and they have presented different levels of details.In particular, the positive effect of higher atmospheric CO2concentrations on crop photosynthesis has not been taken into account in some crop models.

Fig. 1 Distribution of surface water resources in Iran.

As indicated in Table 1, the simulation results on the impacts of climate change on crop yield depend on the climate change scenarios1The SRES-A1B scenario describes a world of rapid economic growth, a global population that peaks in mid-century and more ef ficient technologies based on a balanced energy mix. The SRES-A2 scenario indicates very heterogeneous world conditions with high population growth rate, slight economic development and slow technological change. The SRES-B1 de fines a convergent world with a global population that peaks in mid-century and rapidly changes in economic structures toward a service and information economy (IPCC 2007).(A1B, A2 or B1). Without considering adaptation strategies, the future impacts of climate change on the major crops will be signi ficant and climate change would limit crop production in many areas of Iran (Tables 1 and 2).

As Table 1 reveals, most of the Iranian studies are devoted to the investigation of the impacts of climate change on wheat production. Findings show that, except for Gorgan region, the impacts of climate change on rainfed wheat production in all other regions are negative (Table 1). Nassiri et al. (2006) reported that if the temperature increases by 2.7–4.78°C, the negative impacts of climate change on rainfed wheat will be about 18.0 and 24% by 2025 and 2050, respectively.

Furthermore, the impacts of climate change on irrigated wheat is expected to be higher in some scenarios (Table 1).For example, without any adaptive responses in Sistan and Baluchistan province, Valizadeh et al. (2014) concluded that wheat yield could be reduced by 10.60% by the 2020s under the A2 scenario, while the reduction of wheat yield will be 3.15% only under the B1 scenario in the same period(Table 1).

In addition, high negative impacts are expected for rainfed production as a result of long-term global climate change (about –5 to –57%). However, the impacts of climate change are expected to be lower in irrigated wheat production (Table 1; about +9.21 to –33.7%). For instance,according to the A2 scenario by the 2050s, the negative impacts of climate change on rainfed wheat can reach 50% (Table 1; Eyshi Rezaei and Bannayan 2012), which is much higher than that for irrigated wheat (–11.75%;Valizadeh et al. 2014). Furthermore, over time, the impacts of climate change on wheat yield will become more serious.For example, under the B1 scenario, wheat production will decline from 8.25% in the 2050s to 17.48% in the 2080s(Table 1; Valizadeh et al. 2014).

Table 1 Summary of the climate change impacts on wheat yield in Iran (without adaptation)

As indicated in Table 2, except chickpea, other investigated crops production are predicted to drop signi ficantly under climate change. While most of the crop simulation models excluded the CO2fertilization effect, Hajarpoor et al. (2014)revealed that with considering CO2fertilization effect, the impacts of climate change on chickpea yield will be positive(Table 2). However, Iran’s chickpea area and production have always been small.

Also, under the climate change scenario, the decrease in maize production is highly projected (Table 2). For example, Moradi et al. (2014) and Lashkari et al. (2012)indicated that without adopting any adaptation measures,maize production will reduce about 1.0 to 42.15% by the 2100s (Table 2). However, Hijmans (2003) considered the importance of including adaptation assumptions into the simulation and found that without any adaptation strategy,potato yield in Iran will be adversely affected by climate change (about –48.3%). With some adaptation measures,the impacts of climate change on potato crop are still possibly to be negative but the decrease is about 35% less(Table 2).

3.2. Water resources and crops’ water requirements

Scienti fic literature predicts that Iran’s water resources will experience signi ficant changes as a result of climate change.In this section, the major findings on the potential effects of climate change on water resources and crops’ water demand are reviewed. Climate change impacts on water resources have been studied on several rivers and lake basins by using historical hydro-meteorological data and runoff models in combination with the global warming scenarios.

Table 3 shows changes in the runoff for different periods.Findings reveal that nearly all regions are expected to experience a signi ficant decline in water resources (Table 3).Amiri and Eslamian (2010) investigated the long-term runoff change in 30 basins and concluded that reductions in precipitation combined with a general warming would result in increasing the runoff volume during winter and reducing it during spring and summer.

Moreover, the largest decline in water resources is projected under the A2 scenario (Table 3). For instance,Mohammadnejad (2010) predicted that the average annual runoff in Pishin Basin will decrease by 33% around 2040 under the A2 scenario, while the reduction of surface water resources will be 21.7% under the A1B scenario in the similar period (Table 3). Also, Vaghe fiet al. (2013)concluded that annual runoff will be approximately 44% and 18.5–48.8% less in 2025, under the B1 and A2 scenarios,respectively. Furthermore, the impacts of climate change are expected to be different in various regions of Iran.For example, based on the climate scenarios by 2025,Tashk, Bakhtegan and Maharlu lakes (Fars Province) will experience 5.67–15.15% reduction in runoff, while the Aras Basin’s runoff will witness a 2.7% decline. Also, the greatest runoff reduction is expected in the north provinces(e.g., Mazandaran and Qom) with a –11.29% and the highest increase is predicted in the northeast provinces(e.g., North Khorasan) (NCCO 2010). Additionally, over time, the climate change impacts on water resources will be signi ficantly increased. As indicated in Table 3, under the A2 scenario, runoff of Zayandeh-Rud Basin will decrease from 40–70% in 2010–2039 to 58–77% in 2070–2099(Massah Bavani and Morid 2005).

During the past two decades, an over-extraction of groundwater aquifers has caused a drawdown in the water table in most of the 600 aquifers especially in south and east regions (Motagh et al. 2008). Reducing the availability and the quality of groundwater resources is also expected as a result of climate change (Abbaspour et al. 2009; Cheshmi 2014). For instance, Cheshmi (2014) predicts that the Ramhormoz’ water tables (southern Iran) will decrease by 10 meters in the northwest to 30 meters in the southeast during the period of 2010–2040. Owing to the traditional method of irrigation and water conveying systems, alarge fraction of derived water is lost to evaporation and percolation. Therefore, without any adaptive responses,most of the country will suffer from water resources scarcity(Abbaspour et al. 2009). An additional aspect of the fragility of agricultural sector is the continuous degradation of the groundwater quality associated with climate change. Longterm salinization has been predicted by Toofan Tabrizi (2009)in Dayer aquifer, Booshehr Province. She concluded that under A1B, B2 and A2 scenarios by 2010–2040, decreased precipitation in Dayer region will signi ficantly increase the risk of water contamination. Increased saline irrigation water is expected to severely reduce crops yield.

Table 2 Summary of the climate change impacts on other crops yield in Iran

Table 3 Summary of the climate change impacts on water resources in Iran

On the other hand, agriculture specialists have estimated climate change impacts on the crop water requirements(Table 4). The impacts of climate change on water demand can be estimated by various indicators such as potential soil moisture de ficit (PSMD), CROPWAT water balance model and global irrigation model (GIM). However, most reviewed studies have assessed the net irrigation water requirement for the crop growth using crop coef ficient approach.

As revealed in Table 4, climate change (i.e., higher temperature) can greatly increase the irrigation water requirement. This is particularly true for cereals. The exception is Ashofteh et al. (2011) study while the other findings indicated the signi ficant increase of 7 to 40%in water consumption for cereal crops (Table 4). For example, Mirsane et al. (2011) concluded that in Qazvin Province, without any adaptation measure, cereal’ water requirements will increase about 30 to 40% by 2010–2039.Moreover, Shahkarami et al. (2007) revealed that assuming 75% probability in the 2080s, wheat and barley water requirements will increase by 27 and 25%, respectively,compared to the baseline crop water consumption.

Furthermore, the impacts of climate change on crops water demand will increase over time. For instance,considering 50% probability, wheat water requirementswill rise from 16.3% in 2010–2039 to 22.6% in 2060–2099(Table 4; Shahkarami et al. 2011). While increased water consumption can result in higher crop yield even under higher temperatures (Chen et al. 2010), without any adaptation strategy, lower crop yield is expected with global warming due to the severe water resources scarcity.

Table 4 Summary of the climate change impacts on crops’ water requirements in Iran (without adaptation)

3.3. Changes in income and welfare of farm families

Researchers have increasing concerns about the rising threats of climate change to income and consumption pattern of rural people that depend on natural capital for their livelihood. However, studies about the impacts of climate change on Iranian households’ economy are rare up to now and to the best of our knowledge, some indirect impacts of climate change on agriculture such as changes in agricultural prices and trade flows (i.e., agricultural import and export) have not been studied for the case of Iran. In this section, the few existing studies about economic impacts of climate change are reviewed.

The impacts of climate change on farm families’ income have been analyzed by Vaseghi and Esmaeili (2008) through its effects on wheat net revenue using the Ricardian model.This approach considers the net income of farming systems instead of focusing on crop yields and takes adaptation strategies into account, unlike most impact studies (Roudier et al. 2011). Results indicated that impacts of temperature and precipitation on farmers’ wheat net revenue are negative. Also, Khaleghi et al. (2015) projected that if climate change impacts were considered only (without adaptation), farmers’ income would deteriorate by 25.54,25.11 and 23.53% in 2025 under A1, A2 and B1 scenarios,respectively. However, the anticipated fall in farmers’ income is inconsistent with some economist’s analyses, which have shown that reduction of agricultural productions as a direct result of climate change would not necessarily lead to decreased farmers’ income due to increase in agricultural prices. It seems that studies, which have not considered market responses, tend to overestimate climate change impacts on farm families’ livelihood.

Moreover, the economic evaluations indicate that under A1, A2 and B1 scenarios by 2050, the added value of agricultural sector would reduce by 7.59–11.67% (Khaleghi et al. 2015). Furthermore, without offsetting strategies,climate change would cause 18 and 32% loss in GDP by 2040 and 2070, respectively (Hoseini et al. 2013). While Khaleghi et al. (2015) suggest that reduction of GDP can negatively affect poverty, other studies (e.g., Hoseini et al. 2013) make no attempt to investigate the impacts of climate change on rural poverty. Moreover, a number of recent studies state that the projected impacts of climate change on agricultural production are poor predictors of the poverty effects imposed by climate change as a result of heterogeneity in the ability of farm families to adapt(Skou fias et al. 2011). Furthermore, there are the range of physical, financial, social and hydrological factors behind increasing vulnerability to climate change (Keshavarz et al. 2017). These factors reduce farm families’ capacity of coping with climate change related risks. Low levels of human and physical capital, insuf ficient access to assets,weak institutional structures, inef ficient social capital and greater exposure to uncertainty in the physical and economic environment could reduce the adaptive capacity of farm families and increase their sensitivity to the impacts of climate change (Keshavarz et al. 2014).

From the socio-economic point of view, variations in the climate will affect the livelihood of rural households through their impacts on crop yield and farm income (Keshavarz et al. 2017). Poor farmers, pastoralists and producers that are unable to adapt to climate-related risks are usually considered as the most vulnerable to the effects of climate change. Also, upward price adjustments may negatively in fluence poor consumers, in urban areas (Table 5). This is because the density around the poverty line in the poor urban households is relatively high. Climate related poverty is a multidimensional phenomenon and has severe social and economic impacts on farm families, including(Keshavarz et al. 2013b):

? Economic impacts: such as loss of farm income and reduced income diversity, increased debt, increased on-farm workload and decreased options for off-farm employment.

? Basic needs: including food insecurity and health problems due to drought-related stresses and lack of income for adequate healthcare.

? Education: reduced household expenditure on education, which can especially affect younger members of families who may forego the opportunity to continue their education due to economic constraints.

? Marriage: an increase in the age of marriage and a change in mate selection criteria.

? Con flict and dependency: including increased family and social con flict, social isolation and increased dependency on government assistance.

? Emotional and psychological: including suffering from a sense of hopelessness, failure and loneliness.

Table 5 The impacts of climate change on households’ income(Khaleghi et al. 2015)

On the other hand, the frequency of climate-related shocks (i.e., drought) may keep poor farmers in a poverty trap. Poor farmers are obliged to reallocate their resources to cope with the consequences of climate variability and change instead of investing in food, health and educationrelated expenditures or other productive investments(Keshavarz et al. 2010, 2011, 2013a). Also, they may be trapped in a vicious circle. Their poverty makes them more vulnerable in the context of climate change. Due to their poverty, they will suffer more from negative consequences of environmental degradations and will trigger their poverty and vulnerability.

Declining crop yield and irrigation water resources will also reduce agricultural employment (NCCO 2010).Although economic reforms could lead to higher value crops and labor productivity, this transformation may not fully offset the loss of jobs that will occur as water scarcity rises (Jarvis and Pétraud 2013). Moreover, climate-related changes may have serious impacts on health, which is an important aspect of farm families’ welfare. Changes in weather elements may affect the prevalence of diseases or the level of the risk associated with the exposure to nontrivial weather changes (NCCO 2010).

4. Adaptive response to climate change

In order to improve the adaptive capacity of agricultural sector in the context of climate change, it is imperative for governments to undertake various adaptive actions. Also,it is necessary for farmers to choose appropriate adaptive strategies. If government and farmers are able to adapt adequately, it is possible that Iran’s agricultural sector can withstand changes in temperature and precipitation and maybe take advantages of climate change.

4.1. Response options from government

In order to mainstream climate change concerns, Iran has rati fied United Nations Framework Convention on Climate Change (UNFCCC2Iran submitted its Initial National Communication in 2003 and the second one in 2010.1996), the United Nations Convention to Combat Deserti fication (UNCCD 1997) and the Kyoto Protocol (2005). Also, climate change related issues are included in its development and economic objectives such as the 2025 Development Vision of Iran, the Fifth National Development Plan and the National Action Programs (NAP)under the UNCCD. Furthermore, the government has approved many climate change related policies and actions like development of GHG mitigation policies, adaptation programs, acquisition of technologies for adaptation to climate change, enhancement of the national capacity to use climate change observation systems and active participation in international and regional cooperation.However, national plans and policies are not yet being put into action (von Spannenberg and Hennum 2012). Also,despite being extremely vulnerable to the climate change impacts, designing agricultural adaptation plans has not received enough attention in Iran. While the impacts of climate change on agriculture make the need for certain types of adaptations imperative, many scholars believe that amongst the different adaptation options, plans and strategies that improve production under drought could help to avoid harmful climatic change. Iran’s government is considering a national strategy and action plan on drought preparation, management and mitigation in the agricultural sector to help farmers adapt to negative consequences of drought. A few examples are described below.

In discussion of institutional adaptation to drought, it is distinguished between three categories of adaptation, i.e.,improve agricultural productivity and irrigation development based on current technology, strengthen research and development for new technologies and make changes in the institutional environment within which the producer is operating (Hertel and Lobell 2014).

Adaptive responses based on the existing techn ologyThe simplest form of adaptation to drought is adaptation based on the current technology. This type of adaptive response tends to be attainable in a shorter time period and does not involve major new investments or response uncertainties (Hertel and Lobell 2014). Many adaptation strategies, which have been developed by Iran’s government, involve intensi fications of existing technologies or extensions of current support activities aimed to reduce the impacts of climate variability. For example, there is currently a strong interest in providing the crop insurance scheme for farmers. However, this program has suffered from low coverage rates and it has become increasingly unviable due to inequitable assessment of the individual losses and unfair indemnity payments (Karami et al. 2008). The other example is providing drought relief programs to protect those parts of the agricultural sector that have the least ability to cope (Morid et al. 2012). However, governmental drought assistance was found to have some administrative and logistic shortcomings in relation to the provision of funds, due to problems associated with determining the eligibility of the affected individuals to receive subsidized low-interest loans (Keshavarz and Karami 2013). Since the problems of poverty, unsustainable livelihood and natural resource degradation are raising as a result of drought(Keshavarz et al. 2013b) policies have emphasized on farm income diversi fication through integrating with other farming activities, such as livestock raising (NCCO 2010).These policies focus on the identi fication of main products and services and employment opportunities in rural areas(WAVA 2015).

On the other hand, for technologies that have already been developed, provision and transfer of high-quality information through extension systems are imperative.However, the case studies conducted in Fars Province,Southwest Iran, have indicated that there is not enough knowledge and information about advanced adaptation strategies due to the absence or ineffectiveness of extension programs (Keshavarz and Karami 2013; Karimi et al. 2017).In order to motivate farmers in taking actions to minimize the impacts of climate variability and change, the outreach of extension services should be enhanced. Keshavarz and Karami (2013) acknowledged that lack of a comprehensive drought management plan, including an effective earlywarning system and preparedness schemes, an ef ficient system for continuous assessment of drought impacts and dissemination of accurate information to reduce vulnerability,caused inef ficient use of information resources in the context of drought.

Table 6 Macro-level drought management strategies in Iran

A summary of macro-level drought management strategies in the Iran’s agricultural sector is provided in Table 6. As Table 6 shows, drought adaptation policy is context-speci fic and particularly concerns strategies that are directly or indirectly related to water issues (Keshavarz and Karami 2013). Also, the current policies provide weak incentives for a risk management. Investigation of drought management options in the agricultural sector (Table 6)con firms that the main response patterns during drought were technically and financially oriented to emergency schemes that relied on a crisis management approach.

Strengthen research and development of new technologiesThe second category of institutional adaptation involves development of new technologies.While application of the existing technologies and strategies,such as shifting planting dates, does not involve major new investments, more considerable bene fits will probably result from costlier adaptation strategies (Hertel and Lobell 2014).Also, they bear special risks due to uncertainty about drought occurrence and the performance of the new technology in various drought prone regions.

Although introduction of new technologies is conventional in agriculture, those particular technologies that would reduce the negative impacts of drought are considered in this paper. New crop seeds are the simplest innovation that can foster drought adaptation. With this purpose, Iran’s government has expanded breeding programs to develop drought and climate change tolerant inputs with more appropriate thermal time and vernalization requirements and with increased resistance to drought, water-logging,diseases and pests (NRIDR 2005). Also, technologies that facilitate earlier sowing have been introduced to help farmers avoid negative consequences of drought and extreme heats(WAVA 2015).

While new crop seeds facilitate adaptation to climate variability and change, agronomic innovations such as new methods of water harvesting that help reduce impacts of drought can also be bene ficial. In some regions, irrigation development is highly constrained by water availability(Forouzani and Karami 2010). Development of water saving technologies and automatic irrigation systems are planned in some regions in order to reduce water use in the agricultural sector (WAVA 2015). Furthermore, the potential bene fits of weather forecasting have led the government plans to invest in improved climate predictions at seasonal, 10-day and 3-day scales (Morid et al. 2012). However, even with improved climate forecasting, some signi ficant losses will be expected for asset poor farmers (Keshavarz et al. 2013b)who often rely on traditional risk sharing mechanisms such as local credit and informal networks.

Changes in the institutional environmentDealing with many impediments to climate change adaptation will require a comprehensive policy approach. Therefore, the third category of adaptation involves governmental policies that affect farmer decisions. Since some of these dynamic and comprehensive policies can help farmers to cope with the high level of uncertainty in the context of climate change,they can be an extremely important form of adaptation.For example, to change their farm management activities,farmers need to be convinced that scienti fic projections about climate change and its potential impacts are real and are likely to continue (Howden et al. 2007). This will be facilitated by policies that improve climate monitoring and early warning (Keshavarz et al. 2013b), implement regional adaptation plans and disseminate this information,effectively. However, risk management strategies have not received enough attention in Iran (Table 6).

Government policies can reduce the negative impacts of climate variability by anticipating the spread of risk through rural communities. Using vulnerability assessment,Iran’s government has identi fied high drought risk areas to devise actions that will limit drought related impacts.On the other hand, while Iran’s public policy has focused on increasing water supply on agricultural sector (NRIDR 2005), the opportunities for supply enhancement are decreasing. Therefore, construction of dams and other catchment facilities for surface water and the exploitation of groundwater aquifers in extremely drought sensitive regions are suspending (Zarrineh and Azari Najaf Abad 2014).Instead, major efforts have been made to increase treatment of wastewater (Sheidaei et al. 2016) and desalinization for use in agriculture (WAVA 2015). Also, the policy is changing to manage water demand. For example, redistribution of water rights is considered in some water scarce areas(Morid et al. 2012).

4.2. Adaptive responses from farmers

In addition to government, farmers have the central role in responding to climate change. As adaptation in agricultural systems substantially happens at the farm level, human adaption to climate change is the best investigated through addressing farmers’ adaptive responses in the context of climate change. However, the agricultural sector of Iran, in common with other sectors, is at an early stage in adaptation. Therefore, few of the observed farmers’adaptive responses to climate variability (i.e., drought) are reviewed in this section. A major challenge is that climate variability is a complex issue and demands complex responses. Empirical studies indicated that a wide variety of adaptation strategies were used by Iranian farmers in order to reduce the negative impacts of climate variability(Keshavarz et al. 2010; Keshavarz and Karami 2014). Also,farmers’ adaptive responses are varying across regions based on agro-ecological contexts, socio-economic factors,climatic impacts and existing infrastructure and capacity(Keshavarz et al. 2013b; Keshavarz and Karami 2014).

Investigation of farmers’ adaptive responses to climate variability in Iran has revealed that the most common strategy is increased diversi fication that involves changes in livelihood strategies and variations in crops (Keshavarz et al. 2010, 2013b). Keshavarz et al. (2013b) showed that some farm families had secured their livelihood by less weather-sensitive options such as off-farm works.While off-farm enterprises would be an effective income diversi fication option (Keshavarz and Karami 2014), it may require temporary migration of the farm family members(Keshavarz et al. 2013a), thereby removing their contribution to the farm (Keshavarz et al. 2013b).

Adoption of insurance and micro-credit supporting services are another typical adaptive response to climate variability. However, few studies exist yet of the adoption of crop insurance and drought reliefs by poor farmers(Ghalavand et al. 2012; Keshavarz et al. 2013b). Ghalavand et al. (2012) showed that wealthier farmers and those growing more drought sensitive crops are more likely to purchase crop insurance. Also, Keshavarz et al. (2013b)acknowledged that poor families, who usually suffer more from drought, are often least eligible or able to receive micro-credits and therefore borrow money from relatives or moneylenders.

Another common type of adaptation to climate variability is the adoption of agronomic management strategies that include changing planting schedule, adopting improved varieties, using conservation or minimizing tillage, changing cropping patterns and leveling land (Keshavarz et al. 2010;Keshavarz and Karami 2014). The severe droughts that occurred in recent decades and their negative impacts on water resources forced farmers to show a willingness to plant more drought resilient crop varieties. Keshavarz and Karami (2014) observed that the majority of farmers in Fars Province preferred to adopt drought resistant crop varieties in response to increasing water scarcity. Also,some farmers adjust seeding time according to short term weather forecasting information or adopt longer maturing verities in order to compensate for faster rates of crop development and reduce the impacts of climate variability(Keshavarz and Karami 2014). Furthermore, farmers in arid and semi-arid regions faced with drought are inclined to change crop pattern according to local climate conditions(Keshavarz et al. 2013b). They are willing to choose crops that are more adaptive under drought conditions. Using conservation or minimizing tillage and leveling land are other choice variables for farmers which may be affected by climate variability (Keshavarz et al. 2013b). These practices help to increase agricultural productivity through improving soil quality and adding organic matter to the soil. Practices like leveling land also help farmers to distribute irrigation water uniformly into their cropping field and therefore ef ficient use of available water resources.

Farmers also choose strategies like increased investment in irrigation infrastructure and adoption of water saving technologies to cope with drought conditions (Keshavarz et al. 2010, 2013b; Keshavarz and Karami 2014). This is especially true in areas that already suffer from water scarcity (i.e., diminished access to surface water). These farmers practice re-excavation of rivers, qanats3A qanat system comprises a series of well-like vertical access shafts connected through a gently sloping hand-dug underground channel that is used to extract and transport groundwater in arid areas., and canal,improving water transfer system or constructing water reservoir. Furthermore, drought vulnerable farmers turn to use groundwater to maintain or improve productivity. They utilize various types of water resources exploitation such as digging the irrigation well and deepening well (Keshavarz and Karami 2014). When faced with increasing water shortages, farmers also adopt water-saving technologies such as use cement to construct irrigation channel, apply plastic mulch or retain stubble to store water more ef ficiently,use surface level plastic irrigation pipe and utilize spray irrigation (Keshavarz et al. 2010).

5. Conclusion and policy implications

There is large uncertainty about the future of agricultural sector in the context of climate change. This paper has reviewed the likely impacts of climate change on agriculture and farmers in Iran. It also has documented the adaptive responses from government and farmers. The existing studies show that Iran’s total crop yield is projected to decrease in all scenarios. However, the extent of the changes in yield depends on the crop type, assumptions related to the CO2fertilization effect, climate scenarios and adaptation abilities. Also, it is predicted that climate change will contribute to reducing water resources in various regions of Iran. Moreover, reduction in precipitation and rising temperatures can greatly increase the irrigation water requirement. Economic studies reveal that as water availability declines, the welfare of farm families will also reduce.

Despite growing literature on the climate change impacts on Iran’s agricultural sector, there are still several research gaps that need to be addressed in the future. First, the majority of the studies analyzing the climate change impacts on crop yields focus on wheat crop. It is imperative to analyze the impacts of climate change on other crops, too.Second, most studies assess the impacts of climate change on crop yields and water resources, the economic impacts of climate change on rural communities are rarely studied in the literature. The economic analysis of the climate change impacts should be promoted. Third, agricultural production and demand for irrigation water are heavily in fluenced by socio-economic factors. Most studies did not include the role of socio-economic variables (i.e., adaptation). As a result,they cannot re flect the farmers’ adaptive responses well.The assumption that the current production context will be valid in the future is clearly flawed. Therefore, consideration of adaptation effects on agriculture production is imperative.Finally, the CO2fertilization effect is neglected in almost all studies. This may lead to overestimating the importance of climate change impacts when they are considered in isolation from CO2fertilization effect. Assessing the impacts of climate change on agriculture is necessary when the CO2fertilization effect is considered.

While assessing the potential impacts of climate change on agriculture is imperative, conducting research on the micro and macro-level adaptive responses to climate change is also important. However, there are few empirical studies about Iranian institutional and individual adaptations to climate change. To fill these knowledge gaps it is necessary to understand the processes of farmers’ decision making and adaptation, identify barriers that exist in the agricultural sector to implement adaptive strategies and develop approaches to mitigate these constraints.

Since this study builds on a vast range of studies, it provides insights into adaptation policy challenges and choices in response to climate change in Iran. The optimistic future of agriculture depends on whether this sector is able to mitigate negative impacts of climate change and manage irrigation water in a sustainable manner. This would require a set of actions that allow farmers access to the current technologies. Also, investing in research is imperative in order to enable land and water management to cope with uncertain future. With this regard, more efforts should be paid to investment in water conservation infrastructure, development of new technologies, investment in enhancing farmers’ capacity to adapt to climate change and investment in risk management. Furthermore, ensuring economic ef ficiency in water use and taking measures to promote water and soil conservation at the farm level are priority areas for action. Also, it is needed to evaluate the effectiveness and sustainability of water management strategies. For instance, the excessive exploitation of groundwater during drought is not sustainable and should be prohibited.

In addition to efforts to increase agricultural productivity,a set of policy measures which may not have tangible results in the short term (i.e., information and education programs) should be promoted. Unfortunately, in Iran, the problem of uncertainty about climate change impacts is exacerbated by the associated information de ficit. In this country, public institutions (e.g., extension systems) have inadequate investing in the production and dissemination of new information about climate change. While such information can help the inexperienced farmers to adapt more rapidly to climate variability and change and raise their agricultural productivity.

Also, it needs to be recognized that the effects of climate change on agriculture will be most severe for poor families and small scale farmers with minimal adaptive capacity.Although policies that develop financial incentive may result in short term gains, they can increase their vulnerability in the long term. Moreover, there is the possibility that public policies will reduce the welfare of poor farmers, even as they bene fit wealthier farmers with greater ability to respond effectively to climate change. Therefore, a set of actions will be required to relieve the expected severe pressures on poor farmers.

Abbaspour A C, Faramarzi M, Seyed Ghasemi S, Yang H. 2009.Assessing the impact of climate change on water resources in Iran. Water Resources Research,45, W10434.

Amiri M J, Eslamian S S. 2010. Investigation of climate change in Iran. Journal of Environmental Science and Technology,3, 208–216.

Ashofteh P S, Bozorg Haddad O, Massah Bavani A. 2011.Impact of climate change on water requirement of Aidoghmoush irrigation network. In: 21st International Congress on Irrigation and Drainage. International Commission on Irrigation and Drainage, Tehran.

Bannayan M, Eyshi Rezaei E. 2014. Future production of rainfed wheat in Iran (Khorasan province): Climate change scenario analysis. Mitigation and Adaptation Strategies for Global Change,19, 211–227.

Chen C, Wang E, Yu Q. 2010. Modelling the effects of climate variability and water management on crop water productivity and water balance in the North China Plain. Agricultural Water Management,97, 1175–1184.

Cheshmi A. 2014. The impact of climate change on groundwater resources using climatic, SPI indices and neural network NARX: A case study of Ramhormoz plain, Khozestan province, southern Iran. International Bulletin of Water Resources & Development,2, 54–70. (in Persian)

Evans J P. 2009. 21st century climate change in the Middle East. Climatic Change,92, 417–432.

Eyshi Rezaei E, Bannayan M. 2012. Rainfed wheat yields under climate change in northeastern Iran. Meteorological Applications,19, 346–354.

FAO (Food and Agriculture Organization of the United Nations).2016. FAOSTAT. Rome, Italy. [2017-1-14]. http://faostat3.fao.org/download/Q/QA/E

Forouzani M, Karami E. 2010. Agricultural water poverty index and sustainability. Agronomy for Sustainable Development,31, 415–431.

Ghalavand K, Koshteh K, Hashemi A. 2012. Agriculture insurance as a risk management strategy in climate change scenario: A study in Islamic Republic of Iran. International Journal of Agriculture and Crop Sciences,4, 831–838.

Hajarpoor A, Soltani A, Zeinali E, Sayyedi F. 2014. Simulating climate change impacts on production of chickpea under water-limited conditions. Agriculture Science Development,3, 209–217.

Hertel T W, Lobell D B. 2014. Agricultural adaptation to climate change in rich and poor countries: Current modeling practice and potential for empirical contributions. Energy Economics,46, 562–575.

Hijmans R J. 2003. The effect of climate change on global potato production. American Journal of Potato Research,80, 271–280.

Hoseini S, Nazari M R, Araghinejad S. 2013. Investigating the impacts of climate change on agricultural sector with emphasize on the role of adaptation strategies in this sector.Iranian Journal of Agricultural Economics and Development Research,44, 1–16. (in Persian)

Howden S M, Soussana J F, Tubiello F N, Chhetri N, Dunlop M, Meinke H. 2007. Adapting agriculture to climate change.Proceedings of the National Academy of Sciences of the United States of America,104, 19691–19696.

IPCC. 2007. Climate Change 2007: Synthesis Report.Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Core Writing Team, Pachauri R K,Reisinger A, eds., IPCC, Geneva, Switzerland.

IPCC. 2013. Summary for Policymakers. In: Stocker T F, Qin D, Plattner G K, Tignor M, Allen S K, Boschung J, Nauels A, Xia Y, Bex V, Midgley P M, eds., Climate Change 2013:The Physical Science Basis. Contribution of Working Group to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press,Cambridge, United Kingdom and New York, NY, USA.

IPCC. 2014. Summary for Policymakers. In: Edenhofer O,Pichs-Madruga R, Sokona Y, Farahani E, Kadner S,Seyboth K, Adler A, Baum I, Brunner S, Eickemeier P,Kriemann B, Savolainen J, Schl?mer S, von Stechow C,Zwickel T, Minx J C, eds., Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge,United Kingdom and New York, NY, USA.

Isoard S. 2011. Perspectives on adaptation to climate change in Europe. In: Ford J D, Berrang-Ford L, eds., Climate Change Adaptation in Developed Nations: From Theory to Practice.Springer, New York.

Jarvis L S, Pétraud J P. 2013. Climate change and increasing aridity: The fate of agriculture and rural communities in the Middle East and North Africa. In: Rosenberg International Forum on Water Policy. Aqaba, Jordan.

Karami E. 2012. Climate change, resilience and poverty in the developing world. In: Culture, Politics and Climate Change Conference. University of Colorado Boulder, USA.

Karami E, Zamani G, Keshavarz M. 2008. Factors contributing towards continuation of agricultural products insurance among Iranian farmers. Journal of Agricultural Economy and Development,62, 53–81. (in Persian)

Karimi V, Karami E, Keshavarz M. 2017. Vulnerability and adaptation of Iranian livestock producers to climate variability and change. Rangeland Ecology Management,https://doi.org/10.1016/j.rama.2017.09.006

Keshavarz A, Ashra fiS, Hydari N, Pouran M, Farzaneh E.2005. Water allocation and pricing in agriculture of Iran. In:Water Conservation, Reuse and Recycling: Proceedings of an Iranian-American Workshop. National Academy Press,Washington, D.C.

Keshavarz M, Karami E. 2013. Institutional adaptation to drought: The case of Fars Agricultural Organization. Journal of Environmental Management,127, 61–68.

Keshavarz M, Karami E. 2014. Farmers’ decision making process under drought. Journal of Arid Environments,108, 43–56.

Keshavarz M, Karami E, Kamgare-Haghighi A. 2010. A typology of farmers’ drought management. American-Eurasian Journal of Agricultural & Environmental Sciences,7,415–426.

Keshavarz M, Karami E, Lahsaeizadeh A. 2013a. Factors in fluencing the rural migrations resulting from drought: A case study in Fars province. A Quarterly Journal of Rural Development Studies,16, 113–127. (in Persian)

Keshavarz M, Karami E, Vanclay F. 2013b. Social experience of drought in rural Iran. Land Use Policy,30, 120–129.

Keshavarz M, Karami E, Zamani G H. 2011. Drought vulnerability of farm households: A case study. Iran Agricultural Extension and Education Journal,6, 15–32.

Keshavarz M, Karami E, Zibaie M. 2014. Adaptation of Iranian farmers to climate variability and change. Regional Environmental Change,14, 1163–1174.

Keshavarz M, Maleksaeidi H, Karami E. 2017. Livelihood vulnerability to drought: A case of rural Iran. International Journal of Disaster Risk Reduction,21, 223–230.

Khaleghi S, Bazazan F, Madani S H. 2015. The effects of climate change on agricultural production and Iranian economy. Journal of Research in Agricultural Economy,7,113–135. (in Persian)

Koocheki A, Nassiri M. 2008. Impacts of climate change and CO2concentration on wheat yield in Iran and adaptation strategies. Iranian Field Crops Research,6, 139–153. (in Persian)

Lashkari A, Alizadeh A, Eyshi Rezaei E, Bannayan M. 2012.Mitigation of climate change impacts on maize productivity in northeast of Iran: A simulation study. Mitigation and Adaptation Strategies for Global Change,17, 1–16.

Madani K, AghaKouchak A, Mirchi A. 2016. Iran’s socioeconomic drought: Challenges of a water-bankrupt nation.Iranian Studies,49, 997–1016.

Maddah V, Soltani A, Zeinali E, Bannayan M. 2015. Simulating climate change impacts on wheat production in Gorgan,Iran. Bulletin of Environment, Pharmacology and Life Sciences,4, 58–67.

Massah Bavani A, Morid S. 2005. The impact of climate change on water resources and agriculture production: A case study of Zayandeh-Rud basin. Research on Water Resources of Iran,1, 40–47. (in Persian)

Ministry of Jihad-Keshavarzi. 2013. Strategies for reducing drought impacts on agricultural sector. Department of Planning and Economic, Ministry of Jihad-Keshavarzi,Tehran. [2017-2-23]. http://www.maj.ir (in Persian)

Mirsane M S, Sohrabi Molla Youse fiT, Massah Bavani A,Bazrafshan J. 2011. Climate change and agricultural water demand: Assessing impact of uncertainties of AOGCM and downscaling methods. In: 21st International Congress on Irrigation and Drainage. International Commission on Irrigation and Drainage, Tehran.

Mohammadnejad B. 2010. Climate Change Imapct Assessment on Rainfall-Runoff Process: Case Study of Pishin Reservior Basin Iran. Sistan and Baloochestan Regional Water Company, Iran. (in Persian)

Moradi R, Koocheki A, Nassiri M. 2014. Adaptation of maize to climate change impacts in Iran. Mitigation and Adaptation Strategies for Global Change,19, 1223–1238.

Moradi R, Koocheki A, Nassiri Mahallati M, Mansoori H. 2013.Adaptation strategies for maize cultivation under climate change in Iran: Irrigation and planting date management.Mitigation and Adaptation Strategies for Global Change,18, 265–284.

Morid S, Moghaddasi M, Salavitabr A, Delavar M, Hosseini S, Fathian F, Ahmadzade H, Sahebdel S, Keshavarz A, Ghaemi H, Arshad S, Bagheri M, Agha Alikhani M.2012. Drought Risk Management Plan for Lake Urmia Basin: Summary Report. Working Group on Sustainable Management of Water Resources and Agriculture, Regional Council of Lake Urmia Basin Management.

Motagh M, Walter T R, Shari fiM A, Fielding E, Schenk A J.2008. Land subsidence in Iran caused by widespread water reservoir overexploitation. Geophysical Research Letters,35, L16403.

Nassiri M, Koocheki A, Kamali G A, Shahandeh H. 2006.Potential impact of climate change on rainfed wheat production in Iran. Archeves of Agronomy and Soil Sciences,52, 113–124.

Nazari M R. 2015. The Economic Impacts of Climate Change on Iranian Agricultural Sector. Technical Workshop Of Investigating Climate Change Related Challenges and Implementing the United Nations Framework Convention on Climate Change in Iran. Tehran. (in Persian)

NCCO (National Climate Change Of fice). 2010. Iran’s Second National Communication to UNFCCC. Department of Environment, Iran.

NRIDR. 2005. National report of the Islamic Republic of Iran on disaster reduction. In: World Conference on Disaster Reduction. January, 18–22. Kobe, Hyogo, Japan.

Parry M, Rosenzweig C, Inglesias A, Livermore M, Gischer G.2004. Effects of climate change on global food production under SRES emissions and socio-economic scenarios.Global Environment Change,14, 53–67.

Ravindranath N H, Sathaye J A. 2003. Climate Change and Developing Countries. Kluwer Academic Publishers,Dordrecht.

Roudier P, Sultan B, Quirion P, Berg A. 2011. The impacts of future climate change on West African crop yields: What does the recent literature say? Global Environmental Change,21, 1073–1083.

Salami H, Shahnooshi N, Thomson K J. 2009. The ecnomic impacts of drought on the economy of Iran: An integration of linear programming and macroeconometric modelling approaches. Ecological Economics,68, 1032–1039.

Shahkarami N, Morid S, Massah Bavani A, Agha Alikhani M. 2011. Risk analysis and integrated water resources management based adaptation strategies for Zayandeh-Rud irrigation system, Iran. In: 21st International Congress on Irrigation and Drainage. International Commission on Irrigation and Drainage, Tehran.

Shahkarami N, Morid S, Massah Bavani A, Fahmi H. 2007.Risk analysis of changes in crops water requirements under climate change in Zayandeh-Rud river basin. In:Technical Workshop of the Impacts of Climate Change on Management of Water Resources. Iran National Committee on Irrigation and Drainage, Tehran. (in Persian)

Sheidaei F, Karami E, Keshavarz M. 2016. Farmers’ attitude towards wastewater use in Fars province, Iran. Water Policy,18, 355–367.

Skou fias E, Rabassa M, Olivieri S. 2011. The Poverty Impacts of Climate Change: A Review of the Evidence. Policy Research Working Paper 5622. The World Bank.

von Spannenberg S L, Hennum A. 2012. Overview of Climate Change Financing Mechanisms in Iran, Iraq, Jordan,Lebanon, the Occupied Palestinian Territory, Syria and Yemen. The Global Mechanism of the United Nations Convention to Combat Deserti fication (UNCCD), Italy.

Toofan Tabrizi N. 2009. The impacts of climate change on fresh groundwater resources in coastal areas: A case study of Dayer plain, Kangan, Iran. MSc thesis, Tarbiat Modares University, Iran. (in Persian)

Vafa M N, Chehreh Negar A. 2001. Economic impacts of drought on agricultural sector and role of agriculture bank on supporting vulnerable farmers and herders. In: Amin S, Nazem Sadat M J, Kamgar Haghighi A A, eds., First Workshop on Drought related Problems in Fars Province.October, 19–20. College of Agriculture, Shiraz University,Iran. (in Persian)

Vaghe fiS A, Mousavi S J, Abbaspour K C, Srinivasan R,Yang H. 2013. Analysis of the impact of climate change on water resources components, drought and wheat yield in semiarid regions: Karkheh river basin in Iran. Hydrological Processes,28, 2018–2032.

Valizadeh J, Ziaei S M, Mazloumzadeh S M. 2014. Assessing climate change impacts on wheat production (a case study).Journal of the Saudi Society of Agricultural Sciences,13,107–115.

Vaseghi A, Esmaeili A. 2008. Investigation of economic impacts of climate change on agriculture sector of Iran:Ricardian model (a case study: Wheat). Journal of Science and Technology of Agriculture & Natural Resources,45,685–696.

VijayaVenkataRaman S, Iniyan S, Goic R. 2012. A review of climate change, mitigation and adaptation. Renewable and Sustainable Energy Reviews,16, 878–897.

WAVA (Working Group of Assessing Vulnerability of Agriculture,Animal Husbandry and Fishery’ Sectors). 2015. Assessing Vulnerability and Adaptation of Agricultural, Animal Husbandry and Fishery’ Sectors to Climate Change: A Case of Iran. Working Group of Assessing Vulnerability of Agriculture, Tehran, Iran. (in Persian)

Yang H, Reichert P, Abbaspour K C, Zehnder A J B. 2003.A water resources threshold and its implications for food security. Journal of Environmental Science and Technology,37, 3048–3054.

Zarrineh N, Azari Najaf Abad M. 2014. Integrated water resources management in Iran: Environmental, socioeconomic and political review of drought in Lake Urmia.International Journal of Water Resources and Environmental Engineering,6, 40–48.

23 February, 2017 Accepted 21 September, 2017

Correspondence Vahid Karimi, Tel: +98-71-32286072, E-mail:vakarimi69@gmail.com

? 2018 CAAS. Publishing services by Elsevier B.V. All rights reserved.

10.1016/S2095-3119(17)61794-5

Section editor HUANG Ji-kun

Managing editor WENG Ling-yun