Chapter 6: Special section on drought

Among the weather-related natural hazards, drought is probably the most complex and severe due to its intrinsic nature and wide-ranging and cascading impacts. It affects agricultural production, public water supply, energy production, transportation, tourism, human health, biodiversity, natural ecosystems, etc. Droughts are recurrent; they can last from a few weeks to several years, and can affect large areas and populations. The related impacts develop slowly, are often indirect and can linger for long times after the end of the drought. While the impacts result in severe economic losses, environmental damage and human suffering, they are generally less visible than the impacts of other natural hazards (e.g. floods and storms) that cause immediate and structural damages, which are clearly linked to the hazard and quantifiable in economic terms. Therefore, the drought risk is often underestimated and remains a "hidden" hazard. Proactive drought risk management is still not a reality in most parts of the world.

Drought-related fatalities mainly occur in poor countries. However, in wealthy countries, people suffer from indirect effects such as heat stress or dust, leading to a variety of health impacts. Examples are persistent unemployment, migration and social instability related to failures in public water supply, food insecurity and potential conflict.

Drought is likely to become more frequent and severe in the twenty-first century in many regions of the world. A better understanding of the physical processes leading to drought, its propagation, the societal and environmental vulnerability to drought and its impacts are more important than ever. The key challenge is to move to the widespread adoption of proactive risk management strategies. This includes the analysis of past trends and future projections of drought, as well as analysis of the societal and environmental exposure and vulnerability. All determine drought risk, which can be managed by developing policies and management plans that are adapted to the local context.

Droughts are a recurring feature and are defined with respect to the long-term average climate of a given region. They should be distinguished from aridity, a seasonally or fully dry climate (e.g. desert) and from water scarcity, a situation where the climatologically available water resources are insufficient to satisfy long-term average water requirements. A megadrought is a very lengthy and pervasive drought, lasting much longer than normal, usually a decade or more.

While a lack of precipitation often triggers drought, other factors, including more-intense but less-frequent precipitation, soil moisture conditions, poor water management and soil erosion, can also cause or enhance these droughts. Overgrazing, for example, led to elevated erosion and dust-storms that amplified the "Dust Bowl" drought of the 1930s over the Great Plains in North America. Droughts threaten human security because they undermine livelihoods, compromise culture and individual identity, and increase migration. As they can also undermine the ability of States to provide the conditions necessary for human security. Droughts may influence some or all the factors at the same time. Situations of acute insecurity, such as famine and sociopolitical instability, usually emerge from the interaction of multiple factors. The conflict in the Syrian Arab Republic is a clear example of how drought could accelerate instability. , For many populations that are already socially marginalized, resource dependent and have limited capital assets, human security will be progressively undermined. In such cases, sequences of smaller magnitude droughts can have disproportionate impacts.

Different drought types require different indicators for their characterization. The World Meteorological Organization (WMO) and the Global Water Partnership (GWP) published an overview on widely used drought indicators. The standardized precipitation index (SPI) and the standardized precipitation-evapotranspiration index (SPEI), , for example, are well known for meteorological drought analysis. Indicators related to soil moisture such as the drought severity index or the Palmer drought severity index aim to characterize drought impact in terms of plant water stress. Hydrological indicators such as flow percentiles are used to quantify the volume of water deficit in rivers and reservoirs. Finally, indicators based on remote sensing, such as the normalized-difference vegetation index or the fraction of absorbed photosynthetically active radiation, are used to monitor drought effects on vegetation.

Combined indicators that blend several physical indicators into a single indicator have recently been developed. The European Drought Observatory, for instance, uses the combined drought indicator to monitor drought impacts on agricultural and natural ecosystems.

To obtain an overview of the potential impacts of droughts, a core set of variables is needed to represent different aspects related to the water deficit. Frequency, intensity and duration are some of the key drought variables. Severity describes the accumulated deficit over the entire duration of an event, while intensity describes the average degree of the precipitation, soil moisture or water storage deficit during a drought. Both may determine the degree of associated impact.

For instance, the duration and area affected are linked to the propagation in time and space of the water deficit. Longer and more widespread events might trigger cascading effects, the magnitude of which is directly related to the water deficit. The timing of the onset, cessation and end of a drought are particularly relevant information during the growing season. The impacts of a drought may be felt after the drought has ended.

An emerging consideration in drought analysis is the occurrence of subseasonal (less than three months) drought events that can intensify or extend longer-term drought or background aridity. These "flash droughts"  refer to relatively short periods of warm surface temperature and anomalously low soil moisture. Based on the physical mechanisms associated with flash droughts, these events are classified into two categories: heat-wave and precipitation deficits.

Understanding the mechanisms behind low-frequency climate features like the El Nino Southern Oscillation is key to seasonal prediction of drought events. Though it is still incipient, reliable seasonal prediction with a reliable monitoring network and an appropriate risk assessment will allow for the development of EWSs.

Improvements in knowledge have reinforced the findings of the Fourth Assessment Report of IPCC, especially with respect to an increasing risk of rapid, abrupt and irreversible change with high levels of warming. These risks include increasing aridity, drought and extreme temperatures in many regions of the world. Despite the uncertainty in climate projections, several regions of the globe are likely to experience increased drought frequencies and/or intensities in the twenty-first century. These include countries in the Mediterranean, Southern Africa, South-Western North America and Central America.

A reduction in precipitation or changing precipitation patterns and greater evaporative demands related to higher temperatures are the underlying processes driving such changes. A temperature increase of 3C is estimated to bring current 100-year droughts (severe droughts that occur once every 100 years) to around 30% of the emerged lands on a 10-year basis.

These scenarios suggest that drought risk will increase for many economic sectors and vulnerable regions unless appropriate climate change mitigation and adaptation measures are taken. Many regions in the world with high population densities and vulnerable societies that rely on local agricultural production could experience significant losses because of droughts.

Studies after the IPCC Fourth Assessment Report indicate that there is medium confidence in a projected increase in duration and intensity of droughts in some regions of the world, including Southern Europe and the Mediterranean region, Central Europe, Central North America, Central America and Mexico, North-East Brazil and Southern Africa. Decreases in soil moisture are likely in several regions, particularly in Central and Southern Europe, and Southern Africa. For a range of scenarios, soil moisture droughts lasting four to six months double in extent and frequency, and droughts longer than 12 months become three times more common, between the mid-twentieth century and the end of the twenty-first century. A decrease in soil moisture can increase the risk of extreme hot days and heat-waves.

The term "risk" and the related terms of "hazard", "exposure" and "vulnerability" have been used and defined in different ways within the scientific community, with notable differences between the DRR and the climate change adaptation (CCA) communities. They base their analysis on two theoretical frameworks, commonly referred to as the outcome or impact approach (CCA community) and the contextual or factor approach (DRR community).

The outcome or impact approach is based on the relationships between stressor and response. Here, the endpoint of the analysis is the vulnerability (the more damage a society suffers, the more vulnerable it is). This approach relies on the use of quantitative measures of historical impacts as proxies for the vulnerability estimation. However, relying on historical impacts has several limitations, mainly because impacts are often available for short timescales only, or even unavailable, which inhibits the derivation of homogeneous global risk maps using this process. In addition, the number of affected people and the types of impact vary by region, thus hindering consistent broad-scale analyses.

The contextual or factor approach is based on intrinsic social or economic factors or dimensions that define the vulnerability. Here, the vulnerability is the starting point, allowing understanding why the exposed population or assets are susceptible to the damaging effects of a drought. It is more suitable for setting targets for risk reduction. This approach generally relies on combined risk determinants that have no common unit of measurement. The resulting values are not an absolute measure of economic loss or damage to the society or the environment, but a relative statistic that provides a regional ranking of potential impacts, which can serve to prioritize actions for reinforcing disaster management and adaptation plans.

Both approaches represent alternative but complementary ways for drought risk estimation at different scales. As drought impacts are context specific and vary geographically, regression models (i.e. the outcome approach) are important for developing preparedness plans and mitigation activities from local to national scales, while composite indicators (i.e. the contextual approach) can identify generic leverage points for reducing impacts at the regional to global scales.

For a global assessment, a contextual approach is adopted. This defines risk as a function of the natural hazard, the exposed assets and the inherent vulnerability of the exposed social or natural system. Following this definition, the risk of incurring losses from a drought depends on the combination of DS and the probability of occurrence, the exposed assets and/or people, and their vulnerability or capacity to cope with the hazard.

End users, water managers and policymakers rely on drought risk assessments to better protect populations from shocks and to develop management plans to reduce impacts. Therefore, drought risk assessments should include information tailored to the needs of specific users. This information should answer questions about where and which entities are more likely to be affected. As exposure and vulnerability vary between economic sectors (e.g. agriculture, public water supply, energy production, inland water transport, tourism and public health) and different ecosystems, drought risk assessments need to be sector specific.

This section presents an example of a global drought risk assessment with emphasis on agricultural and primary sector impacts, which are relevant at the global scale. The assessment is based on the conceptual approach proposed by UNDP. It includes the assessment of the hazard, the exposure and the societal vulnerability, which are then combined to arrive at an assessment of the risk for significant impacts due to droughts. The individual steps are explained in the following subsections.

6.4.1 Assessing the hazard

Precipitation can be used as a proxy indicator of the water available to the coupled human-environment system. The frequency and intensity of precipitation deficits, therefore, can represent the drought hazard for a given area. However, increasing temperatures and evaporative demand is now better understood to affect available water supplies.

6.4.2 Assessing the exposure

Meaningful information about the exposure is related to the entities, assets, infrastructures, agricultural land and people located in a drought-prone area. The model of drought exposure as applied for this GAR is computed and validated based on spatially explicit geographic layers. This approach to drought exposure is comprehensive and considers the spatial distribution of several physical elements (proxy indicators) characterizing agriculture and primary sector activities, namely: crop areas (agricultural drought), livestock (agricultural drought), industrial/domestic water stress (hydrological drought) and human population (socioeconomic drought).

This approach proposes a non-compensatory model to combine the different proxy indicators of drought exposure. Using this methodology, superiority in one indicator cannot be offset by an inferiority in another indicator. Thus, a region is highly exposed to drought if at least one type of asset is abundant there. For example, a region that is completely covered by rain-fed crops is fully exposed to drought, independent of the presence of other elements at risk.

6.4.3 Assessing the vulnerability

Vulnerability assessments are a key component of any drought risk estimation as they support the design of mid- and long-term preparedness actions to target sectors or more sensitive populations. Particularly, interventions to reduce drought impact should be oriented towards mitigating the vulnerability of human and natural systems.

In the present framework, vulnerability to drought is represented by a multidimensional model composed of social, economic and infrastructural factors. Social vulnerability is linked to the level of well-being of individuals, communities and society. Economic vulnerability is highly dependent upon the economic status of individuals, communities and nations. Infrastructural vulnerability is comprised of the basic infrastructures needed to support the production of goods and sustainability of livelihoods. This definition of vulnerability is in line with the framework proposed by UNISDR, where vulnerability is defined as a reflection of the state of the individual and collective social, economic and infrastructural factors of a specific region. Such factors may be viewed as the foundation on which local plans for reducing vulnerability and facilitating adaptation are built.

According to this theoretical framework, each factor is characterized by generic proxies that reflect the level of quality of different constituents of a society and its economy. This follows the concept that individuals and populations require a range of independent factors or capacities to achieve positive resilience to impacts and that no single factor is sufficient to describe the varied livelihood outcomes that societies need to cope with such disasters.

6.4.4 Assessing the drought risk

The three components of risk were aggregated following a multivariate and non-parametric linear programming algorithm (Data Envelopment Analysis). The values for each component are not an absolute measure, but a relative statistic that provides a regional ranking of potential impacts (hot spots) with which to prioritize actions to reinforce adaptation plans and mitigation activities.

The assessment presented above is targeted to the agricultural sector and other primary activities. However, the methodology can be implemented and re-calibrated for analysing the risk in other sectors, such as energy production (hydropower generation, and cooling of thermal and nuclear plants), navigation and transportation (waterways), public water supply or recreation, which should be part of any comprehensive drought risk management plan.

6.5.1 Uncertainty

Several factors of uncertainty must be considered in such analysis, as the metrics involved are partially subjective and conditioned by the data availability at a global scale. Agricultural drought can be quantified by several different indicators, each one able to provide a valid estimate of the different components of drought risk.

6.5.2 Scale considerations

Besides the highlighted differences in hazard, exposure and vulnerability among sectors, risk assessment is also dependent on the scale of analysis. This is due to the generally increasing detail of input data when moving to smaller spatial domains. As such, the presented methodology allows rescaling the analysis over different spatial domains and therefore obtaining adequate (useful) results at different scales of analysis. These can range from the farm level to the continent and the global levels as demonstrated above, thus allowing analysis of the spatial distribution of the drought risk within a given area of interest (e.g. farm, country, region, continent or global levels).

As this framework is data driven, more socioeconomic data at local levels is required to obtain reliable estimates. Wherever this information is available, it allows tailoring the analysis and setting adaptation strategies fitted to local requirements and specific sectors that might be adversely affected by droughts.

Combining the vulnerability with the hazard and the exposure shows that the drought risk is lower for remote regions, and higher for populated areas and regions extensively exploited for crop production and livestock farming, such as the Buenos Aires, Cordoba and Santa Fe provinces. Regions characterized by a lower or almost null exposure experience a lower drought risk. As the remaining regions are still subject to severe drought events, their risk increases as a function of the total exposed entities (mainly croplands) and their local coping capacity.

Drought conditions frequently remain unnoticed until water shortages become severe and adverse impacts on environment and society become evident. Drought impacts may be influenced by adaptive buffers (e.g. water storage, purchase of livestock feed, land and ecological conditions) or can continue long after precipitation has returned to normal (e.g. owing to groundwater, soil moisture or reservoir deficits). The slowly developing nature and long duration of drought, together with a large variety of impacts beyond direct and visible agricultural losses, typically make the task of quantifying drought impact difficult.

Impact of droughts can be classified as direct or indirect. Examples of direct impacts include limited public water supplies, crop loss and damage to buildings due to terrain subsidence and reduced energy production. Because of the dependence of livelihoods and economic sectors on water, most drought impacts are indirect. These indirect effects can propagate quickly through the economic system, including trade, affecting regions far from where the drought originates. Indirect impacts may affect ecosystems and biodiversity, human health, commercial shipping and forestry. In extreme cases, drought may result in temporary or permanent unemployment or even business interruption, and lead to malnutrition and disease in more vulnerable countries. Drought-related damage may further be classified as tangible (market related) or intangible (non-market related). The latter is particularly difficult to quantify, including, for example, ecosystem degradation or the costs of long-term adaptation measures.

In the few disaster databases that are publicly available, drought disasters are particularly poorly estimated or are underreported. The general lack of tangible damages combined with a prolonged duration make it extremely difficult to retrieve correct or attributable loss estimates. Given these data gaps, droughts are estimated at less than 7% of total losses from natural hazards since 1960. However, it should be noted that there is a significant gap between the reported and real drought impacts, which hinders their systematic quantification.

Developed and larger economies like Australia, Brazil, China or the United States of America suffer from economic and environmental consequences of droughts. Less developed countries face more direct or indirect impacts on the population. Economic damage from single drought events can be catastrophic, with a single event capable of causing billions of dollars of damage. In term of losses, the most severe events can affect the economy of an entire region or country. For instance, according to NatCatSERVICE data, the severe drought in California in 2006 caused losses of $4.4 billion, and during the 2013-2015 drought in midwestern United States of America, the reported losses were $3.6 billion. Estimates of impacts are however thought to be much higher than these numbers as they primarily reflect direct agricultural damage. The 2013-2015 drought that affected central eastern Brazil (mainly Sao Paulo, Minas Gerais and Rio de Janeiro) was linked to reported losses of about $5 billion. The 2010-2011 drought in the Horn of Africa is estimated to have caused up to a quarter of a million deaths, and to have left over 13 million people dependent on humanitarian aid. Approximately $1.3 billion was spent on drought-relief measures.

Among all economic activities, the agriculture sector has been one of the sectors most directly affected by drought. Impacts on health and water resources for non-agricultural uses are increasingly better understood. To identify trends in the economic impact of disasters on crops, livestock, fisheries and forestry, a review was conducted of 78 post-disaster needs assessments (PDNAs) undertaken in the aftermath of medium- to large-scale disasters in 48 developing countries in Africa, Asia and Latin America between 2003 and 2013. According to this GAR, agriculture absorbs on average about 84% of all the economic impact in these countries. Livestock is the second most affected subsector after crops, accounting for $11 billion, or 36% of all damage and losses reported in PDNAs, where almost 86% of these losses were caused by drought events. Missing from these estimates are losses due to livelihood disruption, migration and insecurity. Environmental conditions affect plants and their productivity during all phases of growth and development. Studies show that moisture stress in all growth stages reduced the grain yield significantly. Severe droughts are linked with significant reduction in yields of the main cereals and most other crops throughout the most drought-prone regions.

The health of human populations is sensitive to shifts in weather patterns and other aspects of climate change. These effects occur directly, due to changes in temperature and precipitation and in the occurrence of heat-waves and droughts. Human health may be affected indirectly by ecological disruptions related to climate change (e.g. crop failures or shifting patterns of disease vectors) or by social responses to climate change (e.g. displacement of following prolonged drought) and the elderly face disproportional physical harm from heat stress and drought.

Climate change is likely to increase the frequency and severity of meteorological and agricultural droughts in presently dry regions by the end of the twenty-first century. Particularly vulnerable are countries located in arid and semi-arid regions where water stress will be further exacerbated due to strain from overexploitation and degradation already tangible under the present conditions. Consequently, many other economic sectors and ecosystems are likely to be adversely affected by climate change. For instance, freshwater-dependent biota will suffer directly from changes in flow conditions and also from drought-induced river temperature increases linked to discharge reductions. Decreases in soil moisture and increased risk of agricultural drought are likely in drylands, and the agricultural risk in these areas is projected to increase by the end of this century. This is likely to lead to an increased risk of food insecurity, which is particularly relevant for poorer populations. In many countries, increased fire risk, longer fire season and more-frequent large, severe fires are expected because of increasing heat-waves in combination with drought.

Drought is a slow-onset hazard, often referred to as a creeping phenomenon. The absence of a precise, universally accepted definition of drought adds to the confusion. Definitions must be region specific because each climate regime has distinctive climatic characteristics. Drought impacts are non-structural and are spread over larger geographic areas and temporal scales than damage that results from other natural hazards such as floods, tropical storms and earthquakes. Drought risk drivers include non-meteorological factors, and are often spatially or temporally removed from drought impacts These characteristics of drought have hindered: development of accurate, reliable and timely forecasts; estimates of severity and impacts; and, ultimately, the formulation of drought management plans and implementation of appropriate risk reduction strategies. Similarly, local communities struggle to deal with the large temporal and spatial coverage usually associated with drought, resulting in secondary and tertiary impacts that may remain invisible to traditional risk assessments.

While it is impossible to control the occurrence of droughts, the resulting impacts may be mitigated through appropriate surveillance and management strategies in a drought management plan.

The proactive approach is based on short- and long-term measures and includes monitoring systems for a timely warning of drought conditions, the identification of the most vulnerable part of the population and tailored measures to mitigate drought risk and improve preparedness. The proactive approach entails planning necessary measures to prevent or minimize drought impact in advance.

Drought monitoring and early warning (Pillar 1) is the foundation of effective proactive drought policies to warn about impending drought conditions. It identifies climate and water resources trends and detects the emergence or probability of occurrence and the likely severity of drought and its impact. Reliable information must be communicated in a timely manner to water and land managers, policymakers and the public through appropriate communication channels to trigger actions described in a drought plan. That information, if used effectively, can be the basis for reducing vulnerability and improving mitigation and response capacities of people and systems at risk.

Vulnerability and impact assessment (Pillar 2) aims to determine the historical, current and likely future impacts associated with drought and to assess the vulnerability. Drought impact and vulnerability assessment aims to improve the understanding of the natural and human processes associated with drought and the impacts that can occur. The outcome of the vulnerability and impact assessment is a depiction of who and what is at risk and why.

The work related to drought mitigation, preparedness and response (Pillar 3) determines appropriate mitigation and response actions aimed at risk reduction, identification of appropriate triggers to phase in and phase out mitigation actions, particularly short-term actions, during drought onset and termination and, finally, identification of organizations to develop and implement mitigation actions. Triggers are defined as specific values of an indicator or index that initiate and/or terminate responses or management actions by decision makers based upon existing guidelines or preparedness plans. Triggers should link indices or indicators to impact.

To move from a reactive to a proactive approach, local or regional conditions must be taken into consideration, including the legislative and administrative framework as well as the local drought drivers. An effective drought management plan should provide a dynamic framework for an ongoing set of actions to prepare for, and effectively respond to drought, including: periodic reviews of the achievements and priorities; readjustment of goals, means and resources; and strengthening institutional arrangements, planning and policymaking mechanisms for drought mitigation.

A key decision support tool for crisis mitigation is embedded within the concept of early warning information systems across timescales. Efforts in drought early warning continue in countries such as Brazil, China, Hungary, India, Nigeria, South Africa and the United States of America. Regional drought monitoring activities exist or are also being developed in Eastern and Southern Africa and efforts are ongoing in West Asia and North Africa. Research and experience in several watersheds show that several paradoxes in multistate water management and governance across borders can militate against the accurate assessment of socioeconomic impacts and the effective use of scientific information for meeting short-term needs in reducing longer-term vulnerabilities.

These lessons include an expanded use of incentives for improving collaboration, water-use efficiency, demand management and development of climate services to inform water-related management as new threats arise.

Several cases show that changes in the management of climate-related risks (in this case, drought) may be most readily accomplished when: (a) a focusing event (climatic, legal or social) occurs, creating widespread public awareness and opportunities for action; (b) leadership and the public, the so-called "policy entrepreneurs", are engaged; and (c) a basis for integrating research and management is established. This latter dimension emphasizes the structure for developing the capacity to apply knowledge and to evaluate the consequences of actions among partners, to ensure the reliability and credibility of the projections of changes in the system outputs and to enable acceptable revisions on management practices in light of new information. Examples of end-to-end information systems in which monitoring and forecasting, risk assessment and engagement of communities and sectors are aligned across the weather-climate continuum are exemplified by the National Integrated Drought Information System (NIDIS) and the Famine Early Warning System Network (FEWSNet), which provide coordination of diverse regional, national and local data and information for supporting planning and preparedness. Owing to FEWSNet, there have been successful cases of drought risk interventions to prevent humanitarian crises, including the severe drought in Ethiopia in 2015-2016.

However, drought remains a "hidden risk". The microlevel actions involving households, communities and individual businesses are often underappreciated but are arguably the most important elements of drought risk mitigation. This is summarized as follows:

• More secure land tenure and better access to electricity and agricultural extension were found to facilitate the adoption of drought risk mitigation practices among agricultural households in Bangladesh. Similarly, access to secure land tenure, markets and credit played a major role in helping farmers cope with droughts in Morocco.
• Improved access to credit helped farming households in Ethiopia to cope better with drought impacts since they no longer needed to divest their productive assets. Moreover, as many rural households in Ethiopia tend to channel their savings into livestock, which may be wiped out during droughts, developing access to financial services and alternative savings mechanisms could also help to mitigate drought risk.
• Land-use change and modification of cropping patterns are frequently cited as ways to build resilience against droughts.
• Improved diversification of livelihoods by adopting off-farm activities and divesting of livestock assets.
• A strong asset base and diversified risk management options are among the key characteristics of drought-resilient households in Kenya and Uganda. These aspects were due primarily to the households having better education and greater knowledge of coping actions against various hazards. This allowed them to diversify their income sources.

Although drought insurance is an effective and proactive measure, the development of formal drought insurance mechanisms is hindered in many developing countries by obstacles such as high transaction costs, asymmetric information and adverse selection.

The experience of JRC, the Integrated Drought Management Programme (IDMP), NIDIS, FEWSNet and other information and risk management systems illustrates that early warning represents a proactive social process whereby networks of organizations conduct collaborative analyses and coordination. In this context, indicators help to identify when and where policy interventions are most needed, and historical and institutional analyses help to identify the processes and entry points that need to be understood if vulnerability is to be reduced. Taking local knowledge and practices into account promotes mutual trust, acceptability, common understanding, and community sense of ownership and self-confidence. As important as indicators are to such systems, it is also the governance context in which EWSs are embedded that needs further attention. A mix of centralized and decentralized activities is required, particularly for people-centred strategies at the so-called "last-mile".

EWSs are more than scientific and technical instruments for forecasting hazards and issuing alerts. They should be understood as sources of scientifically credible, authoritative and accessible knowledge. These integrate information about and from areas of risk that facilitate decision-making (formal and informal) in a way that empower vulnerable sectors and social groups to mitigate potential losses and damage from impending hazard events.

The costs of proactive drought management are usually lower than the costs of inaction, and can generate significant economic benefits. For example, one study estimated that every dollar spent by the United States Federal Emergency Management Agency (FEMA) on drought risk mitigation, , the country would save at least $2 on future disaster costs. Related actions to mitigate drought impacts include more secure tenure, better access to electricity, improved access to credits, land-use change and modification of cropping patterns, better use of groundwater resources and adoption of off-farm activities to diversify livelihoods.

Drought risk management can have substantial socioeconomic co-benefits, as some of the related actions build resilience against droughts and also against additional socioeconomic and environmental shocks. Regional and local networks that provide agricultural extension, precision farming, off-farm activities and higher education, for example, which are associated with stronger resilience to drought shocks, were identified as factors that also help address land degradation, facilitate poverty reduction and improve household food security.

Assessing the risk for drought-related impacts to society and environment is a difficult task. It is complicated by the creeping nature of the phenomenon, its often-large spatial extent and temporal duration, leading to cascading impacts that may affect areas distant from the drought and it may last long after the drought has ceased. Missing standardized data on past impacts (damage and loss) is a further complication. Finally, the interlinkages with other hazards such as wildfires, heat-waves and even floods and the combined risks need to be explored. These risk assessments need to be sector specific, requiring an adequate set of environmental and socioeconomic data related to the respective sectors.

Many hot spots that show fragility in the face of climate change also exhibit soil moisture and soil quality reduction combined with reduced adaptive capacity. Scenario planning (based on past, present, and projected events) may provide better understanding of whether and how best to use probabilistic information with past data and cumulative risks across climate timescales. There is a strong need to approach climate model outputs far more critically than at present, especially for impact assessment to support adaptation at the local level. Central to all of the above is a sustained network of high-quality monitoring systems.

The major assumption behind proactive action around drought is that present or upfront actions and investments can produce significant future benefits. No comprehensive study exists for drought. Some have outlined the advances to date in assessing benefits of action and the costs of inaction. In drought and other hazards, much more work needs to be done to realize what has been called the "triple dividend of resilience".

The benefits include:

• Avoiding losses when disasters strike.
• Stimulating economic activity from reduced disaster risk.
• Developing co-benefits, or uses, of a specific disaster risk management investment.

The need to explicitly acknowledge differing social values, to strengthen institutional mechanisms for collaboration, and to collect standardized data on drought impacts as a basis for reducing vulnerability and enhancing resilience needs to be acknowledged. How drought and climate change may play into future fragility will be an area of increasing research and security interest.

Despite the significant advances of the past century of drought research, in an increasingly interconnected world, several areas of concern for drought risk management are emerging:

• Uncertainties associated with climate change and its manifestation at all levels including cascading risks.
• Understanding the increasingly complex pathways through which drought affects filter (e.g. the water-energy-food nexus, socioecological buffers and thresholds).
• Assessing the costs of drought impacts, and the benefits of action and costs of inaction.
• Enhancing the role of technology, efficiency and community-based knowledge.
• Links to human security, globally networked risks and conflict that affect resilience.
• Emphasizing the role of governance, financing and decision-making in anticipating, assessing and acting on reducing and managing the impacts of complex risks.
• The need to explicitly acknowledge various social values and strengthening institutional mechanisms for collaboration, including data collection. How drought and climate change may play into future fragility will be an area of increasing research and security interest.

In the light of these challenges, UNISDR will publish a special report on drought risk in 2020. The foregoing discussion highlighted some of the key aspects and challenges to be discussed and further explored in this special report.

Local collection of disaster loss data in national risk management systems - from Ethiopia to the Gambia

This case study relates to the imperative to link risk management systems, seek local-level input and reinforce growing systems with policy, structure, governance and patience.

In 2014, Ethiopia began to undertake the challenging job of recording losses due to disaster events. This process is supported by UNISDR, based on a tool developed specifically to collect, validate and aggregate data at the lowest possible administrative unit.

In the case of Ethiopia, this means that data is being collected at the wereda level (the most locallevel administrative area). The country has nearly 700 weredas. Their data is then aggregated into one of around 70 zones, and the zone data is aggregated into one of 11 regions.

In collecting disaster event data and related losses at the local level, Ethiopia has joined a group of about 100 countries that are systematically recording disaster losses using the disaster loss accounting tool DesInventar. More importantly, Ethiopia has committed to a data-collection undertaking that would challenge the administrative governance capacities of any country. But it has done so knowing that, as well as being seismically active, its territory is exposed to hitherto uncounted small-scale, extensive disasters that sap development resources and undermine opportunities for the poorest people in the country to thrive. As Ethiopia has a large population (100+ million) and a GDP per capita in the bottom quintile of any global index, having an accurate understanding of the nature of these myriad localized losses will permit development decisions to better target resilience building.

At the time of writing, Ethiopia has around 15,000 records in its public database of disaster-related losses. It has another 10,000 records awaiting verification. This scale of data collection is exceptional and is indicative of the commitment of Ethiopia to: knowing its profile of disaster impacts; communicating to its population that every farm damaged, every localized flood or epizootic outbreak matters and will be counted; and sharing its experience in the interests of a better global understanding of risk.

Loss figures from Ethiopia's database are among those that populate the loss figures in Part II of this GAR. Without Ethiopia's immense effort, those figures would be less accurate and thus less valid. Ethiopia's model has inspired other countries in the region to begin accounting systematically for disaster losses. Since 2014, 19 more countries in Africa have begun the process of recording their losses using the same method.

One of the later countries to join this movement is the Gambia. Its process will be the same. The objective is to develop a system that facilitates the incorporation of risk information into public investment planning and decision-making. This will be done by first establishing a national disaster loss database to account for past losses, then assessing experienced losses against a handful of modelled risks, and then assessing budgetary spending against forecast losses to determine whether budgeting has been sufficient and appropriately targeted. This process is going on in 18 other countries around Africa as part of the same project.

The Gambia's database is much newer than Ethiopia's and therefore contains far fewer records. This is also a reflection of the size of the country, the exposure profile it faces and the reporting structures in place to gather information. But even though the Gambia has a smaller population, a more limited scope of hazards and fewer exposed assets than Ethiopia, its losses are just as important. The Gambia's National Disaster Management Agency knows that to manage losses, it needs to understand them and account for them. Through a series of platforms, data-collection conferences, and new regulations and plans, it has also committed to supporting institutionalization of data collection, to ensure that data collection continues as a parallel process even as the other elements of the project get under way.

Data collection of past losses is a necessary but not sufficient measure. Ethiopia and the Gambia have invested heavily in data collection and reflective processes of understanding what worked well in past circumstances and what could be improved in future. They are thinking about the regulatory, systemic and interconnected nature of managing their risks. Though the effects of climate change portend serious challenges for large parts of Africa, the countries that start today and plan for the long term are positioning themselves better to enable resilience and flexibility.