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This paper presents the results of a detailed review of the research literature on how nomadic pastoralists are being affected by climate change, how they are adapting, and challenges with using traditional knowledge in adaptation. It focuses on research that investigates local, and particularly traditional, knowledge of water, pasture, their variability, and livestock. This knowledge underpins nomadic livelihoods, so is a foundation for effective adaptation. Changes in the total amount of precipitation, and particularly shifts in its timing, and increases in the frequency and intensity of extreme events, are having the greatest impacts on herding livelihoods. Herders in drylands worldwide face common adaptation challenges: declining traditional water sources and pasture degradation. Herders' adaptation strategies fall into five major categories: movement to areas with better water and pasture, improving seasonal access to water, improving seasonal access to feed, shifts in herd composition, and livelihood diversification. Movement is central to nomads' adaptation, yet, as climate change takes hold, restrictions on movement are increasing for both socio-economic reasons and climate reasons. Many papers emphasised the importance of combining traditional knowledge and current science to guide adaptation decision-making at household, locality, and national levels. There is widespread concern about the decline in traditional knowledge. All the papers reviewed emphasised the need to support passing on traditional know-how. Herder women's know-how, in particular, is marginalised in the research literature, so their traditional knowledge should be a focus in further research. Herders' adaptations are mostly localised, incremental, and have a relatively short-term focus. As nomadic pastoralism moves further outside the range of historical experience, the possibility of more profound transformations looms. [ABSTRACT FROM AUTHOR]

Semi-arid regions are known for erratic precipitation patterns with significant effects on the hydrological cycle and water resources availability. High temporal and spatial variation in precipitation causes large variability in runoff over short durations. Due to low soil water storage capacity, base flow is often missing and rivers fall dry for long periods. Because of its climatic characteristics, the semi-arid north-eastern region of Brazil is prone to droughts. To counter these, reservoirs were built to ensure water supply during dry months. This paper describes problems and solutions when calibrating and validating the eco-hydrological model SWIM for semi-arid regions on the example of the Pajeú watershed in north-eastern Brazil. The model was calibrated to river discharge data before the year 1983, with no or little effects of water management, applying a simple and an enhanced approach. Uncertainties result mainly from the meteorological data and observed river discharges. After model calibration water management was included in the simulations. Observed and simulated reservoir volumes and river discharges are compared. The calibrated and validated models were used to simulate the impacts of climate change on hydrological processes and water resources management using data of two representative concentration pathways (RCP) and five earth system models (ESM). The differences in changes in natural and managed mean discharges are negligible (< 5%) under RCP8.5 but notable (> 5%) under RCP2.6 for the ESM ensemble mean. In semi-arid catchments, the enhanced approach should be preferred, because in addition to discharge, a second variable, here evapotranspiration, is considered for model validation. [ABSTRACT FROM AUTHOR]

Irrigated areas, mainly in arid regions, are threatened by salinization processes. Climate change inducing temperature rise and rainfall depletion are expected to enhance these processes. Numerical models are often used to predict salinization in the root zone as well as water and solute fluxes reaching groundwater. Climatic data, mainly rainfall, have an important influence on the estimation of those fluxes. The present paper studies the impact of rainfall structure and climate change on soil and groundwater salinization. Soil samples were collected in three drip-irrigated plots in Korba semi-arid coastal plain in Tunisia during dry and wet seasons. Collected field data (water contents and soil salinities) are used to define the initial solute and flow conditions and to estimate the soil hydraulic parameters for numerical modeling. Daily rainfall structure and annual rainfall transition under both Markov Chain and climate change (RCP4.5 and RCP8.5) are assessed. Different climatic scenarios are then introduced as boundary conditions in HYDRUS-1D, to test the influence of rainfall on the salinity evolution in the soil profile and groundwater. Results show that both annual rainfall amounts and daily structure have an impact on soil concentrations and solute fluxes quantities reaching groundwater. The influence of rainfall paths is more important for larger unsaturated zone thickness when considering the dry and median rainfall conditions. Climate change scenarios show significant accumulation of salts in the root zone implying the imperative use of adequate irrigation practices. [ABSTRACT FROM AUTHOR]

Due to complexities of creating sea-level rise scenarios, impacts of climate-induced sea-level rise are often produced from a limited number of models assuming a global uniform rise in sea level. A greater number of models, including those with a pattern reflecting regional variations would help to assure reliability and a range of projections, indicating where models agree and disagree. This paper determines how nine new patterned-scaled sea-level rise scenarios (plus the uniform and patterned ensemble mean rises) influence global and regional coastal impacts (wetland loss, dry land loss due to erosion and the expected number of people flooded per year by extreme sea levels). The DIVA coastal impacts model was used under an A1B scenario, and assumed defences were not upgraded as conditions evolved. For seven out of nine climate models, impacts occurred at a proportional rate to global sea-level rise. For the remaining two models, higher than average rise in sea level was projected in northern latitudes or around populated coasts thus skewing global impact projections compared with the ensemble global mean. Regional variability in impacts were compared using the ensemble mean uniform and patterned scenarios: The largest relative difference in impacts occurred around the Mediterranean coast, and the largest absolute differences around low-lying populated coasts, such as south, south-east and east Asia. Uniform projections of sea-level rise impacts remain a useful method to determine global impacts, but improved regional scale models of sea-level rise, particularly around semi-enclosed seas and densely populated low-lying coasts will provide improved regional impact projections and a characterisation of their uncertainties. [ABSTRACT FROM AUTHOR]

Climate models agree that semi-arid regions around the world are likely to experience increased rainfall variability and longer droughts in the coming decades. In regions dependent on agriculture, such changes threaten to aggravate existing food insecurity and economic underdevelopment, and to push migration to urban areas. In the Brazilian semi-arid region, the Sertão, farmers' vulnerability to climate-past, present, and future-stems from several factors, including low yielding production practices and reliance on scarce and seasonally variable water resources. Using interpolated local climate data, we show that, since 1962, in the Bacia do Jacuípe-one of the poorest regions in the Sertão of Bahía state-average temperatures have increased ~ 2 °C and rainfall has decreased ~ 350 mm. Over the same time period, average milk productivity-the main rural economic activity in the county-has fallen while in Brazil and in Bahía as a whole milk productivity has increased dramatically. This paper teases apart the drivers of climate vulnerability of the Bacia do Jacuípe in relation to the rest of Bahía. We then present the results of a suite of pilot projects by Adapta Sertão, a coalition of organizations working to improve the adaptive capacity of farmers living in the semi-arid region. By testing a number of different technologies and arrangements at the farm level, Adapta Sertão has shown that interventions focused on balanced animal diets and efficient irrigation systems can help reduce (but not eliminate) the dependence of production systems from climate. They are thus viable adaptation strategies that should be tested at a larger scale, with implications for semi-arid regions worldwide. [ABSTRACT FROM AUTHOR]

In this paper we present an analysis of the direct impacts of climate change on the hydrology of the upper watersheds (range in elevation from 1,000 to 5,500 m above sea level) of the snowmelt-driven Limarí river basin, located in north-central Chile (30° S, 70° W). A climate-driven hydrology and water resources model was calibrated using meteorological and streamflow observations and later forced by a baseline and two climate change projections (A2, B2) that show an increase in temperature of about 3-4°C and a reduction in precipitation of 10-30% with respect to baseline. The results show that annual mean streamflow decreases more than the projected rainfall decrease because a warmer climate also enhances water losses to evapotranspiration. Also in future climate, the seasonal maximum streamflow tends to occur earlier than in current conditions, because of the increase in temperature during spring/summer and the lower snow accumulation in winter. [ABSTRACT FROM AUTHOR]

This paper compares precipitation, maximum and minimum air temperature and solar radiation estimates from the Hadley Centre's HadRM3 regional climate model (RCM), (50x50 km grid cells), with observed data from 15 meteorological station in the UK, for the period 1960-90. The aim was to investigate how well the HadRM3 is able to represent weather characteristics for a historical period (hindcast) for which validation data exist. The rationale was to determine if the HadRM3 data contain systematic errors and to investigate how suitable the data are for use in climate change impact studies at particular locations. Comparing modelled and observed data helps assess and quantify the uncertainty introduced to climate impact studies. The results show that the model performs very well for some locations and weather variable combinations, but poorly for others. Maximum temperature estimations are generally good, but minimum temperature is overestimated and extreme cold events are not represented well. For precipitation, the model produces too many small events leading to a serious under estimation of the number of dry days (zero precipitation), whilst also over- or underestimating the mean annual total. Estimates represent well the temporal distribution of precipitation events. The model systematically over-estimates solar radiation, but does produce good quality estimates at some locations. It is concluded that the HadRM3 data are unsuitable for detailed (i.e. daily time step simulation model based) site-specific impacts studies in their current form. However, the close similarity between modelled and observed data for the historical case raises the potential for using simple adjustment methods and applying these to future projection data. [ABSTRACT FROM AUTHOR]

Moisture conditions, especially those that occur as multi-decadal anomalies, have profound impacts on society, especially in arid and semi-arid regions. However, the lack of high-resolution climate data for the first millennium CE greatly limits our understanding of how moisture variations have influenced history. Here, we present an 1882-year (134–2015 CE) tree-ring chronology developed from Qilian juniper (Juniperus przewalskii Kom.) growing in the western Qilian Mountains, northwest China. The tree-ring index correlates significantly with the May–June self-calibrating Palmer Drought Severity Index (sc-PDSI) and can be used to reconstruct May–June moisture variations since 241 CE. The reconstruction reflects moisture conditions at the annual to multi-decadal time scales over the past two millennia. During the period from the third to eighth centuries, there were prominent interdecadal fluctuations, with the third century and the late fifth century being the wettest and driest periods during the reconstruction, respectively. The transition from the wet third century to the dry fifth century corresponded with key events in Chinese history, namely the demise of the Western Jin Dynasty and the chaotic Southern and Northern Dynasties. Thus, our reconstruction provides new evidence for the potential linkage between abnormal climate conditions and social changes in ancient times. [ABSTRACT FROM AUTHOR]

Investigating oasis effects of different oasis-town configurations is key to understanding the ecological stability of the oasis. However, previous studies have not considered the impacts of oasis–town configurations on oasis effects. In this study, the Weather Research and Forecasting (WRF) model was used to conduct a series of 1-km-resolution simulations of the Hami Oasis, Xinjiang of China, to examine how different oasis–town configurations influenced the oasis effects. The actual landscape and four hypothetical landscapes were considered. Results indicated that the WRF model effectively reproduced the trends of the surface temperature, 2-m air temperature, 2-m relative humidity, and 10-m wind speed. It was also found that the effects of the town on the oasis were substantially greater when the former was located at the center of the oasis, rather than on the margin. At 850 hPa, the center of the temperature field was downstream from that of the wind field, whereas both coincided at lower levels. When the size of the town was doubled, the convergence center over the town weakened the strength of the divergent low-level winds from the oasis. This facilitated the infiltration of dry air from the surrounding desert into the oasis, which is detrimental to the healthy development of the oasis. Placing a town at the margin of the oasis is therefore advantageous to the development of the cold island, whereas a town at the center of the oasis is beneficial to the comfort of the residents. [ABSTRACT FROM AUTHOR]

Moving gender equality forward in climate-resilient agriculture: Introduction to the Special Issue on Gender Equality in Climate-Smart Agriculture: Approaches and Opportunities The authors found that governments in both Uganda and Tanzania have made positive progress in integrating gender in policies, development plans, and implementation strategies, with a general positive shift from gender-blind policy to integration of gender as a cross-cutting issue. Coming out of an initiative to support farmers with more effective and timely climate information, the analysis presents research on gender trends in use and access to climate information services delivered through mobile phone platforms and underscores the necessity to collect sex-disaggregated data on and develop gender-responsive climate risk mitigation actions in Ghana. A case of two contrasting ecologies in India"); and (iii) development of indicators to measure gender equality results ("Does climate-smart village approach influence gender equality in farming households?. [Extracted from the article]

Inter-annual climatic variability over a large portion of sub-Saharan Africa is under the influence of the El Niño-Southern Oscillation (ENSO). Extreme variability in climate is a threat to rural livelihoods in sub-Saharan Africa, yet the role of ENSO in the balance between supply and demand of net primary productivity (NPP) over this region is unclear. Here, we analyze the impact of ENSO on this balance in a spatially explicit framework using gridded population data from the WorldPop project, satellite-derived data on NPP supply, and statistical data from the United Nations. Our analyses demonstrate that between 2000 and 2013 fluctuations in the supply of NPP associated with moderate ENSO events average ± 2.8 g C m yr. across sub-Saharan drylands. The greatest sensitivity is in arid Southern Africa where a + 1 °C change in the Niño-3.4 sea surface temperature index is associated with a mean change in NPP supply of −6.6 g C m yr.. Concurrently, the population-driven trend in NPP demand averages 3.5 g C m yr. over the entire region with densely populated urban areas exhibiting the highest mean demand for NPP. Our findings highlight the importance of accounting for the role ENSO plays in modulating the balance between supply and demand of NPP in sub-Saharan drylands. An important implication of these findings is that increase in NPP demand for socio-economic metabolism must be taken into account within the context of climate-modulated supply. [ABSTRACT FROM AUTHOR]

The response of West African climate zones to anthropogenic climate change during the late 21st century is investigated using the revised Thornthwaite climate classification applied to ensembles of CMIP5, CORDEX, and higher-resolution RegCM4 experiments (HIRES). The ensembles reproduce fairly well the observed climate zones, although with some notable discrepancies. CORDEX and HIRES provide realistic fine-scale information which enhances that from the coarser-scale CMIP5, especially in the Gulf of Guinea encompassing marked landcover and topography gradients. The late 21st century projections reveal an extension of torrid climates throughout West Africa. In addition, the Sahel, predominantly semi-arid in present-day conditions, is projected to face moderately persistent future arid climate. Similarly, the Gulf of Guinea shows a tendency in the future to experience highly seasonal semi-arid conditions. Finally, wet and moist regions with an extreme seasonality around orographic zones become less extensive under future climate change. Consequently, West Africa evolves towards increasingly torrid, arid and semi-arid regimes with the recession of moist and wet zones mostly because of the temperature forcing, although precipitation can be locally an important factor. These features are common to all multimodel ensembles, a sign of robustness, with few disagreements in their areal extents, and with more pronounced changes in the higher-resolution RCM projections. Such changes point towards an increased risk of water stress for managed and unmanaged ecosystems, and thus add an element of vulnerability to future anthropogenic climate change for West African water management, ecosystem services and agricultural activities. [ABSTRACT FROM AUTHOR]

Smallholder farming is among the most vulnerable sectors due to its great social and economic sensitivity. Despite future climate change, current climate variability is already an issue of concern that justifies adaptation efforts. In Brazil, the Semi-Arid Region is a climate hotspot, well known for both historic socioeconomic setbacks, and agriculture failures caused by dry spells and severe droughts. In 2010, the Brazilian government enacted the National Policy on Climate Change, which states as one of its key goals the identification of vulnerabilities and the adoption of adequate measures of adaptation to climate change. The improvement of vulnerability assessment tools is a response to the growing demand of decision makers for regular information and indicators with high spatial and temporal resolution. This article aims at undertaking a comparative assessment of smallholder farming's vulnerability to droughts. An integrated assessment system has been developed and applied to seven municipalities located in the Brazilian Semi-Arid Region (within the State of Ceará). Results show regional vulnerability contrasts driven by institutional and socioeconomic factors, beyond climatic stressors. [ABSTRACT FROM AUTHOR]

We examined if climate change in two dry ecosystems-Mediterranean (DME) and Semiarid (SAE)-would cause substantial reduction in the production of annual vegetation. Field measurements and computer simulations were used to examine the following six climate change scenarios: (1) rainfall amount reduction; (2) increases of 10 % in annual evaporation rate and 5 % in annual temperature; (3) increase in magnitude of rainfall events, accompanied by reductions in frequency and seasonal variation; (4) postponement of the beginning of the first rainfall event of the growing season; (5) long dry spells during the growing season; and (6) early ending of the growing season. The results revealed the following outcomes. a) Reduction by 5-35 % in annual rainfall amount did not significantly affect productivity in the DME, but a large (25-35 %) decrease in rainfall would change vegetation productivity in the SAE and lead to a patchier environment. b) Similar results were observed: when temperature and evaporation rate were increased; when the magnitude of rainfall events increased but their frequency decreased; and during a long mid-season dry spell. c) In both ecosystems, changes in the temporal distribution of rainfall, especially at the beginning of the season, caused the largest reduction in productivity, accompanied by increased patchiness. d) Long-term data gathered during the last three decades indicated that both environments exhibited high resilience of productivity under rainfall variability. These results imply that the response of dry ecosystems to climate change is not characterized by a dramatic decrease in productivity. Moreover, these ecosystems are more resilient than expected, and their herbaceous productivity might undergo drastic changes only under more severe scenarios than those currently predicted in the literature. [ABSTRACT FROM AUTHOR]

We examined both long-term climate variability and anthropogenic contributions to current climate change for Xinjiang province of northwest China. Xinjiang encompasses several mountain ranges and inter-mountain basins and is comprised of a northern semiarid region and a more arid southern region. Climate over the last three centuries was reconstructed from tree rings and temperature series were calculated for the past 50 years using weather station data. Three major conclusions from these analyses are: (1) Although temperature varied considerably in Xinjiang over the last 200 years, it was non-directional until the last 50 years when a substantial warming trend occurred; (2) The semiarid North Xinjiang was representative of the northern hemisphere climate, while the more arid South Xinjiang resembled the southern hemisphere climate, meanwhile, (3) The entire Xinjiang province captured the global-scale climate signal. We also compared human contributions to global change between North and South Xinjiang, including land cover/land use, population, and greenhouse gas production. For both regions, urban areas acted as heat islands; and large areas of grassland and forest were converted to barren land, especially in North Xinjiang. Additionally, North Xinjiang also showed larger increase in population and greenhouse gas emissions mainly associated with animal production than those in South Xinjiang. Although Xinjiang province is a geographically coupled mountain–basin system, the two regions have distinct climate patterns and anthropogenic activities related to land cover conversion and greenhouse gas production. [ABSTRACT FROM AUTHOR]

Abstract Herein, we calculate an aridity index, D, based on annual precipitation, P, and measured evaporation, PET, from ϕ20 evaporation pans: D = P/PET. The data were collected between 1951 and 1999 at 295 meteorological stations operated by the Chinese Meteorological Administration. On the basis of the index, three climatic regions are recognized in China: an arid zone in which D ≰ 0.20, a semi-arid zone with 0.20 < D ≰ 0.50, and a humid zone in which D > 0.50. Temporal fluctuations of the climate boundaries are substantial, and differ significantly regionally, and have the shifting features in the same direction in some areas and in opposite directions in others over the past 50 years. The semiarid zone lies along the border of the monsoon, and is thus highly susceptible to environmental change in China. In the period from the late 1960s to the early 1970s, the climate became drier in most parts of the regions of northern China. Moreover, the drought has an increasing trend. The fluctuations of climatic boundaries and the alternation from drier to wetter climate have substantial inter-decadal features. The main factors affecting the fluctuations in climate boundaries are the East Asian summer monsoon, the Indian Monsoon, the plateau monsoon in Tibetan Plateau, the westerly circulation, and the West Pacific Subtropical High. The different types of circulation and the strength of these circulations result in regional and temporal differences in aridity. Inter-decadal variations of the dry- and wet climate boundary fluctuations and of the arid and humid climate result from the inter-decadal changes of East Asian summer monsoon, Indian Monsoon, plateau monsoon, westerly circulation, and West Pacific Subtropical High. The anomalous general atmospheric circulation in the Northern Hemisphere during the late 1960s to the early 1970s is the cause of the remarkable change in arid and humid climate in China. Major natural disasters produced by arid and humid change are drought and flood disasters. They cause enormous economic losses to agriculture and industry. Furthermore, the loss has a substantial increasing trend. More than 110 cities are in severe water-deficiency conditions because of shortage of water resource in China. Drought has been a limiting factor of economic and social development in China. [ABSTRACT FROM AUTHOR]

Abstract The arid and semi-arid regions account for approximately 30% of the world total area and are inhabited by approximately 20% of the total world population. Issues of present and future climate variability and change on agriculture and forestry in the arid and semi-arid tropics of the world were examined and discussion under each of these issues had been presented separately for Asia, Africa and Latin America. [ABSTRACT FROM AUTHOR]