Climate hazards in drylands: A review
Introduction
Deserts and semi-deserts, commonly referred to as drylands, are critical global environments for a number of reasons, not least because they cover about 40% of the world's land surface and are home to more than 2 billion people (Safriel et al., 2005). These areas encompass a wide variety of physical terrains including sandy deserts, temperate grasslands and savanna woodland but all have their aridity in common: they are characterised by limited water resources because precipitation is characteristically scarce and unreliable and evaporation is typically high. Most of the natural hazards that occur in drylands take place in a wide range of environments and are not therefore unique to drylands. However, some hazards assume a greater relative importance in drylands, notably those driven by the climate which determines the nature of dryland environments. The dryland system is shown in Table 1, categorised by degrees of aridity as defined by the aridity index, which is the ratio of precipitation to potential evapotranspiration (Middleton and Thomas, 1997). This scheme excludes high-latitude (polar) and mountainous drylands, although in this paper we follow Middleton et al. (2011) by including the dryland high-altitude plateaus of Tibet and the Altiplano-Puna.
Research on natural hazards and resulting disasters has focused on a number of physical environments, including coasts (e.g. Kron, 2012), mountains (e.g. Hewitt and Mehta, 2012) and small islands (e.g. Pelling and Uitto, 2001) but, as far as we are aware, synthesis of hazards research with a specifically drylands focus is not common (see Bryant, 2005, Smith, 2013), except for studies of particular types of hazard (e.g. Wiggs, 2011 on geomorphological hazards in drylands), particular dryland areas (e.g. Huho et al., 2011 on northern Kenya) or particular combinations of dryland hazards (e.g. Sternberg et al., 2009 on drought and extreme winter in Mongolia). The justification for this paper lies in the association between drylands and rural poverty and the particularly high levels of risk faced by the poor. Drylands are found on every continent but most drylands are located in developing countries and the majority of dryland inhabitants – some 90% – live in these countries (Safriel et al., 2005). Globally, about half of all dryland inhabitants are poor, about a billion people in total, dubbed the ‘forgotten billion’ because they have habitually been neglected in development processes (Middleton et al., 2011). Poverty is multi-dimensional, and reflects overlapping deprivations that members of a household experience. These can be assessed in measures of income, standard of living, health and education, indicators that are closely linked to human well-being (Alkire and Santos, 2010). Poverty is important when it comes to vulnerability or strength to cope with a disaster. This can be illustrated at the national scale by the conclusions of Gaiha and Thapa (2006) who found that people in low-income countries are four times more likely to die due to natural disasters and that the cost per disaster as a share of GDP is considerably higher in developing than in OECD countries.
Many people living in drylands depend directly upon a highly variable natural resource base for their livelihoods and this variability is driven primarily by climatic factors (Stringer et al., 2009). Principal among these is the variability of precipitation. Rainfall totals often vary greatly from year to year and over short geographical distances. Indeed, there is a well established relationship between declining rainfall levels and increasing variability in rainfall totals (Nicholls and Wong, 1990) and this relationship is particularly evident across the four dryland subtypes defined by the aridity index (Table 1). The livelihoods of most dryland inhabitants are based on herding in the drier areas and rain-fed cultivation in those less arid dryland regions, with many people also engaged in wild harvesting from common resources. Long experience of coping with the vagaries of their environment has engendered numerous strategies for managing risk and variability, but many dryland inhabitants remain vulnerable to natural perturbations, particularly those driven by the highly variable climate regimes that characterise drylands.
The importance of climate hazards for poor dryland inhabitants seems set to increase because several types of extreme climate event are likely to become more frequent, more widespread and/or more intense in most parts of the world during the twenty-first century (IPCC, 2012). Mitigation of the effects of climate hazards is therefore an essential component of any attempt to reduce poverty and improve environmental sustainability in the world's drylands.
Section snippets
Natural hazards in drylands
A wide range of natural hazards cause death, damage, and/or other types of losses (in combination referred to here as natural disasters) and these natural hazards can be classified in many different ways. A distinction can be made depending on the spatial scale of impact between small-scale hazard events (e.g. tornado, landslide, lightning strike) that may cause localised damage, injuring or killing a few individuals, and large-scale events (e.g. tropical cyclone, major drought, large volcanic
Drought
Globally, droughts are frequently described as the most damaging natural hazards in economic terms, collectively affecting more people than any other form of natural disaster (Keyantash and Dracup, 2002), and drought is the principal natural hazard faced by communities living in most drylands. Although droughts occur in virtually all climatic zones, it is probably fair to say that their effects are proportionally greater in drylands because of the naturally scarce availability of water in
Climate change and climate hazards in drylands
People have always been at risk from natural hazards, but the perception that the world is becoming a more hazardous place is widespread. Documenting the frequency of hazard events over time is not straightforward because of the paucity of reliable comprehensive, long-term worldwide databases of hazards or disasters. Nonetheless, an increase in disaster frequencies has been reported, with the time trends for climate-related disasters showing the greatest increase, well above all geological
The disaster risk-poverty nexus in drylands
Drylands and poverty are linked at various geographical scales, from the global and regional to the national and subnational (Middleton et al., 2011). The Millennium Ecosystem Assessment (MA) shows that people living in drylands lag behind the rest of the world in terms of human well-being and other indicators of development. For instance, the average infant mortality rate for all dryland developing countries is at least 23% greater than non-dryland countries (Safriel et al., 2005). The MA
Conclusions
Drylands are characterised by large numbers of people whose livelihoods are directly dependent on the physical environment. This environment is primarily driven by its variable climate and notable for numerous climate-related natural hazards that together result in a highly variable and generally low natural rate of provision of ecosystem services. Drylands also lag behind the rest of the world in terms of human well-being and other indicators of development. These traits are related via the
Acknowledgements
The authors thank the Leverhulme Trust, the British Academy and the Royal Geographical Society (with IBG) for research support and five anonymous referees for their comments. The idea for this paper originated at the 2010 Oxford Deserts Conference.
References (125)
- et al.
Deposition of 137Cs in Rokkasho, Japan and its relation to Asian dust
Journal of Environmental Radioactivity
(2007) - et al.
Fire effects on California chaparral systems: an overview
Environment International
(1991) Empirical regularities in the poverty–environment relationship of African rural households
World Development
(2000)- et al.
Effects of Asian dust storm events on daily mortality in Taipeh, Taiwan
Environmental Research
(2004) - et al.
Drought and saving in West Africa: are livestock a buffer stock?
Journal of Development Economics
(1998) - et al.
Life in sandy deserts: the scorpion model
Journal of Arid Environments
(1998) - et al.
Predicting locations sensitive to flash flooding in an arid environment
Journal of Hydrology
(2004) - et al.
A method to determine the effect of mineral dust aerosols on air quality
Atmospheric Environment
(2009) - et al.
Aeolian dust deposition on photovoltaic solar cells: the effects of wind velocity and airborne dust concentration on cell performance
Solar Energy
(1999) - et al.
Natural disaster risk in Asian megacities
Cities
(2011)
Australian dust storm: impact on a statewide air medical retrieval service
Air Medical Journal
The social experience of drought in rural Iran
Land Use Policy
Landscape–wildfire interactions in Southern Europe: implications for landscape management
Journal of Environmental Management
Wind erosion from cropland in the USA: a review of problems, solutions and prospects
Geoderma
Small island developing states: natural disaster vulnerability and global change
Environmental Hazards
The role of forest ecosystems in community-based coping strategies to climate hazards: three examples from rural areas in Africa
Forest Policy and Economics
Climate volatility deepens poverty vulnerability in developing countries
Environmental Research Letters
Long-term consequences of early childhood malnutrition
Oxford Economic Papers
Geohazard assessment of sand dunes between Jeddah and Al-Lith, western Saudi Arabia
Environmental Geology
Acute multidimensional poverty: a new index for developing countries
Solar power in the desert: are the current large-scale solar developments really improving California's environment?
The natural conditions of central Asian deserts
Do natural disasters affect human capital? An assessment based on existing empirical evidence
Climate change and sustainable livelihood of rural people in Mongolia
Livestock responses to drought and severe winter weather in the Gobi Three Beauty National Park, Mongolia
Journal of Arid Environments
Living with wildfires: what science can tell us
Human population growth and the demographic transition
Philosophical Transactions of the Royal Society
Poverty and the Environment: What the Poor Say: An Assessment of Poverty–environment Linkages in Participatory Poverty Assessments
Aerial dispersal of fungi on the global and continental scales and its consequences for plant disease
Science
Natural Hazards
Soil contamination and persistence of pollutants following organophosphate sprays and explosions to control red-billed quelea (Quelea quelea)
Pest Management Science
The increasing exposure of cities to the effects of volcanic eruptions: a global survey
Environmental Hazards
Dust storms in southwestern plains area
Monthly Weather Review
Do global warming targets limit heatwave risk?
Geophysical Research Letters
A study of windborne sand and dust in desert areas
The Chronic Poverty Report 2004–05
Are natural disasters increasing?
CRED CRUNCH
Drought under global warming: a review
WIREs Climate Change
Estimating bird damage to rice in Africa: evidence from the Senegal River Valley
Journal of Agricultural Economics
Changes in hot days and heat waves in China during 1961–2007
International Journal of Climatology
Observed variability and trends in extreme climate events: a brief review
Bulletin of the American Meteorological Society
Food, fibre and forest products
Extreme weather in the Peruvian high Andes
Water and the Rural Poor: Interventions for Improving Livelihoods in Sub-Saharan Africa
Cross-boundary and cross-level dynamics increase vulnerability to severe winter disasters (dzud) in Mongolia
Global Environmental Change
Prevalence of skin reactivity to coccidioidin and associated risks factors in subjects living in a northern city of Mexico
Archives of Medical Research
Natural disasters, vulnerability and mortalities — a cross-country analysis
Heat waves and heat days in an arid city in the northwest of México: current trends and in climate change scenarios
International Journal of Biometeorology
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