Impact of precipitation and increasing temperatures on drought trends in eastern Africa

The last few years have seen an explosion of interest in extreme event attribution, the science of estimating the influence of human activities or other factors on the probability and other characteristics of an observed extreme weather or climate event. This is driven by public interest, but also has practical applications in decision-making after the event and for raising awareness of current and future climate change impacts. The World Weather Attribution (WWA) collaboration has over the last 5 years developed a methodology to answer these questions in a scientifically rigorous way in the immediate wake of the event when the information is most in demand. This methodology has been developed in the practice of investigating the role of climate change in two dozen extreme events world-wide. In this paper, we highlight the lessons learned through this experience. The methodology itself is documented in a more extensive companion paper. It covers all steps in the attribution process: the event choice and definition, collecting and assessing observations and estimating probability and trends from these, climate model evaluation, estimating modelled hazard trends and their significance, synthesis of the attribution of the hazard, assessment of trends in vulnerability and exposure, and communication. Here, we discuss how each of these steps entails choices that may affect the results, the common problems that can occur and how robust conclusions can (or cannot) be derived from the analysis. Some of these developments also apply to other attribution methodologies and indeed to other problems in climate science.

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“…Williams et al 2015;Li et al 2017) or soil moisture and potential evaporation (e.g. Kew et al 2021 ).…”

Section: Event Definitionmentioning

confidence: 99%

“…Trends can also differ widely between different climate models (Hauser et al 2017). If the variable of interest is a hydrological or other physical impact variable, it is also better to use multiple impact models (Philip et al 2020b;Kew et al 2021).…”

Section: Model Evaluationmentioning

confidence: 99%

Pathways and pitfalls in extreme event attribution

et al. 2021

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“…8 Extreme weather has been wreaking havoc across East Africa interfering with Somalia's rain seasons, the main rainy season Gu (April to June) and the second rainy season Deyr (October to December) adversely impacting already fragile food security levels (see Supplementary B). 29,30 For the latter half of 2021, 2.7 million people across the country are estimated to face severe food insecurity and overstretched social support networks paired with diminishing levels of humanitarian aid, adding to the socio-economic impacts of the COVID-19 pandemic. 31 The drivers of migration are complex and interrelated with environmental factors being one of the many drivers.…”

Section: Environmental Vulnerabilitiesmentioning

confidence: 99%

Compound vulnerabilities exacerbate systemic risks of food security in Somalia

Thalheimer

Gaupp

Webersik

2021

Preprint

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The impacts of climate change are increasingly compounding around the world. Simultaneous extreme weather events threaten coping mechanisms such as migration, and food security in breadbasket regions. Systemic risk approaches offer a critical lens to guide risk-informed sustainable action both now, and in the future. This Analysis proposes a generic conceptual framework to address the nature of such risks. We combine data on weather-related displacement, food insecurity, and conflict to characterize compound vulnerabilities underlying systemic risks. Using an Systemic Risk Impact Pathways (SRIP) model, we illustrate intersections between systemic risk elements and compound vulnerabilities in Somalia, a country affected by recurring extreme weather, protracted armed conflict, political instability and displacement. We show how these dynamics have create a complex nexus of strains on the population and its ability to guarantee food security. Advancing a risk-informed sustainable development agenda, we recommend taking a systemic risk approach instead of a single hazard approach.

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“…Approximately 50% of inhabitants do not have access to water sources within a walking distance of 5km [40]. The erratic rainfall regime is considered a principal parameter linked to the viability of the mixed crop agroecosystem against the background of recurrent drought conditions [11]. As in most of East Africa, small-scale mixed crop farming is the primary livelihood in Kitui County, supporting food production among other benefits [11].…”

Section: Study Areamentioning

confidence: 99%

“…[72], [38], [41] and [11]. It is also in contrast with the key informant information that the March-April-May rain season, being the longer of the two seasons and essential in the farming calendar, has demonstrated unreliability in recent years.…”

Section: Annual and Seasonal Trendsmentioning

confidence: 99%

Uncertainty in Drought Identification Due to Data Choices, and the Value of Triangulation

Borona¹,

Busch²,

Krueger³

et al. 2021

Preprint

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Droughts are complex and gradually evolving conditions of extreme water deficits which can compromise livelihoods and ecological integrity, especially in fragile arid and semi-arid regions that depend on rainfed farming, such as Kitui West in south-eastern Kenya. Against the background of low ground-station density, 10 gridded rainfall products and four gridded temperature products were used to generate an ensemble of 40 calculations of the Standardized Precipitation Evapotranspiration Index (SPEI) to assess uncertainties in the onset, duration and magnitude of past droughts. These uncertainties were driven more by variations between the rainfall products than variations between the temperature products. Remaining ambiguities in drought occurrence could be resolved by complementing the quantitative analysis with ground-based information from key informants engaged in disaster relief, effectively formulating an ensemble approach to SPEI-based drought identification to aid decision making. The reported trend towards drier conditions in Eastern Africa was confirmed for Kitui West by the majority of data products, whereas the rainfall effect on the increasingly dry conditions was more subtle than annual and seasonal declines and greater annual variation, which warrants further investigation. Nevertheless, the effects of increasing droughts are already felt on the ground and warrant decisive action.

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Impact of precipitation and increasing temperatures on drought trends in eastern Africa

Cited by 45 publications

References 54 publications

Pathways and pitfalls in extreme event attribution

Pathways and pitfalls in extreme event attribution

Compound vulnerabilities exacerbate systemic risks of food security in Somalia

Uncertainty in Drought Identification Due to Data Choices, and the Value of Triangulation

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