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Abstract Archaeological studies typically describe arid areas as extremely unpleasant areas for human occupation and use. Without suggesting that arid areas are pleasant places, however, this paper provides a reassessment of the meaning of aridity for an area showing a vast amount of evidence of (past) human activities. Several climatic proxy data suggest that at the transition between the late Bronze Age and the Early Iron Age (around c. 1300-1100 BC) the southern Levant witnessed more arid conditions, while after 1100 BC relatively moist conditions would have prevailed. In drylands, small changes in temperature and water availability can have large effects on subsistence options. Building on cooperation between an archaeologist and a water scholar, this paper offers an approach to study how people in the past were able to craft a livelihood in the arid environments in the southern Levant and elsewhere. Focusing on the Zerqa area, the paper explores the potential of this cooperation by studying effects of climatic changes at the transition from the Late Bronze Age to the Iron Age through a modelling approach. Changes in temperature and moisture availability were simulated, showing that increased aridity could have been met by either naturally available water (especially groundwater) or artificially added water (although the timing appears to be crucial). While the model approach under discussion offers an approximation of the past, it shows the potential impact of climatic changes on the subsistence of past communities. It shows that details can mean the difference between survival or collapse. Highlights • Modelling provides boundaries for thinking about ancient resilience. • Rainfed crop yields could be sustained with irrigation, even in the frequent dry years. • Increasing aridity might have been a trigger for expanding the irrigation system. • The Zerqa Triangle was affected by the LBA crisis, yet continuity is visible as well. • Aridity did not necessarily bring crisis, even in arid areas like the Zerqa Triangle. [ABSTRACT FROM AUTHOR]

Abstract: In many parts of the world the boundaries between grassland and shrubland biomes have changed substantially over the course of the last century. Many are projected to shift further from being grass-dominated to shrub-dominated by 2050 under global climate change and land use change projections. This paper used long-term surveys and repeat photography to assess vegetation change at the shrubland-grassland ecotone in semi-arid, South Africa. Changes in several climate variables as well as in the cover of grasses and dwarf shrubs over three time periods (1962, 1989 and 2009) were investigated at eight localities within a broad 500 km ecotone between the Grassland and Nama-karoo biomes. Results showed that for most sites grass cover has increased and that dwarf shrub cover has decreased over time. This contradicts earlier views which warned against the expansion of dwarf shrublands in response to over-grazing as well as more recent views which suggest that more mesic biomes in the Karoo Midlands will contract in response to climate-induced aridification. The decline in stocking densities and more conservation-friendly land management practices together with an increase in large wet events in the Nama-karoo biome may have contributed to the increase in grass cover. [Copyright &y& Elsevier]

Abstract: Australia has not always been arid, and the central desert was once well watered. This paper traces the changes in climate and vegetation, leading to the present aridity. At the beginning of the Cenozoic, continental Australia had a warm and humid climate, and the vegetation was mainly meso–micro-thermal (warm to cool temperate) rainforest. Central Australia experienced seasonal rainfall and there may have been limited aridity in the northwest. By the mid–late Eocene, rainforest in central Australia was restricted to the well-watered valley bottoms, with sclerophyll vegetation on the slopes and ridges. In the latest Eocene–earliest Oligocene, there was an abrupt cooling of ocean waters and the diversity of megathermal angiosperms decreased. The early–mid-Miocene was warm–humid and there was a considerable diversity of forest types. Woodlands and Casuarinaceae forests became more common. Central Australia was seasonal, with a very warm season of high evaporation. In Western Australia, regular flows in the palaeodrainage systems had stopped by the mid-Miocene and this marked the first major step towards aridity. The late Miocene was cool and dry, with a major reduction of rainforests and an increase of Eucalyptus/casuarinaceous sclerophyll forests in inland southeastern Australia. Regular burning became a feature of the eucalypt forests. Rainforest persisted, however, along the east coast and highlands of Australia. Central Australia became more arid with dry woodland and chenopod shrublands. Rainforests continued to decrease during the Pliocene and grasslands developed in central northern Australia. By the early Pleistocene, the modern climatic regime had been established, but precipitation was higher than today. Cycles of open, shrubland/grasslands/herbfields and wooded vegetation accompanied the arid glacial and humid interglacial cycles (respectively). About 0.5Ma, there was a change to a drier climate, but it was still wetter than today. The last glacial period was particularly harsh, and the present interglacial period is drier than the previous interglacial. Aridity has thus increased in a number of steps, following the first major step towards aridity in the early Miocene. Distinctive elements of the vegetation can be traced back to times when the arid zone was humid and supported rainforest. The elements, which have remained in arid regions, are the few that could tolerate or adapt to the drier climates. The taxa, which could not cope with these changing conditions, were eliminated from the arid regions. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to illustrate the importance of variation in water availability to temporal variation in vegetation dynamics in arid and semi-arid ecosystems. We hypothesize that fine-scale pulses of precipitation interact with longer scale variation in climate and weather to generate temporal variation in plant community composition. Arid and semi-arid regions exhibit great temporal variability in water availability as a result of variation in climate and weather at multiple scales and vegetation-soil water feedbacks. The scales of variation include: shifting climate regimes over centuries and decades, inter-annual variation in weather patterns, seasonal differences in winter and summer precipitation, and within-season variability in precipitation frequency and magnitude. In arid and semi-arid regions, pulses of rainfall are separated by intervening dry periods of variable lengths. This situation results in fluctuating availability of water that limits plant production and controls other ecological processes, such as rates of nutrient cycling. In some semi-arid and arid systems, temporal variation in water availability may create positive feedbacks that facilitate encroachment of C3 woody plant species into areas formerly dominated by C4 grasses. Our ability to predict these complex shifts in vegetation composition may be improved by including temporal variation in climate, weather, and ecosystem processes. [Copyright &y& Elsevier]

Dryland smallholders are faced with the challenges of achieving resilience and agricultural sustainability. This is in addition to constraints such as lack of capital, inputs, and often poor extension services. The risk of extreme weather events poses a great challenge to food security in drylands as the impacts of climate change increases. This paper examines the challenges faced by smallholders and the limitations of traditional farming systems in Sudano-Sahelian zones amidst climate change and emerging armed conflicts with special focus on the Sudano-Sahelian Nigerian drylands. The review reports three key findings as follows: first, smallholders have been active in managing short-term environmental risks and challenges by using local knowledge to improve production and short-term resilience. Secondly, concerns about potential longer-term climatic changes such as longer droughts, desertification, the impact of the drying of the Lake Chad, armed conflicts and extreme weather events could hinder resilience. Third, an increasing rainfall variability, soil/nutrient degradation and farming systems adopted could limit or undermine resilience strategies, especially if new environmental challenges exceed those previously experienced. This review suggests a need for additional research into innovative drylands' sustainability and resilience practices in response to a changing climate linked to other social challenges. • Drylands smallholders are resilient to changes in the climate they have experienced. • Production is restricted by new social challenges. • Climate change, and other challenges will limit food security. • Current adaptation not sufficient if new environmental challenges emerge. • More innovative strategies should be researched into for resilience. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to examine the beef value chain and identify climate change adaptation and investment options in the semi-arid areas of northern Kenya. The research uses an innovative approach to value chain analysis, namely the three-step Value Chain Analysis for Resilience in Drylands (VC-ARID) that considers the specific characteristics of semi-arid systems. All the respondents interviewed along the value chain have perceived changes in rainfall, temperature and climate extremes – especially drought – over the past 15 years and have experienced the impacts of these changes on their livestock. The findings show that pastoralist producers need to invest in fattening programmes at their ranches or via feedlots to increase the quality of the beef they produce. There is significant potential to improve the fattening stage in the value chain, since it would contribute towards meeting demand in the expanding high-end markets that require finished, top-quality meats. • Pastoralists beef value chain is more informal, traditional, extensive pastoralism. • Private ranches value chain is formal and incorporates fattening of livestock. • Pastoralists rely on mobility for coping with climate risk. • Climate change has negatively impacted on semi-Arid livestock production. • There is potential to improve and expand the fattening stage of the value chain. [ABSTRACT FROM AUTHOR]