Rain delays ‘predict droughts in hunger-prone regions’

Drought in Ethiopia
Families wait to fill jerry cans with clean water. Copyright: UNICEF Ethiopia/2016/Ayene, CC BY-NC-ND 2.0

Speed read

  • Researchers looked at whether the onset of rains could be used to predict droughts
  • Delays to the rainy season were linked to an increased risk of drought
  • Method can inform early warning systems in food-insecure regions

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[NAIROBI] Delays in the onset of the rainy season are a reliable early predictor of agricultural droughts in parts of Sub-Saharan Africa that are particularly prone to food insecurity, a new study shows.

According to the study, Sub-Saharan Africa has been experiencing increased acute food insecurity since 2015, with more than 100 million Africans estimated to have received emergency food assistance last year.

“Early indication of agricultural drought should help policymakers make decisions to mitigate the most adverse impacts of food insecurity and save lives.”

Shraddhanand Shukla, University of California Santa Barbara’s Climate Hazards Center

The study published in the journal PLOS ONE last month (20 January) assessed the relationships between onset dates of rains and droughts in East Africa, West Africa and Southern Africa.

“Since agricultural droughts often contribute to or worsen food insecurity, early indication of agricultural drought should help policymakers make decisions to mitigate the most adverse impacts of food insecurity and save lives and livelihoods,” says Shraddhanand Shukla, the study’s lead author and an associate researcher at the US-based University of California, Santa Barbara’s Climate Hazards Center.

Shukla adds that agencies such as the Food and Agriculture Organization of the United Nations that provide early warning on food insecurity have been monitoring rainy season onset as an indicator of droughts. This motivated his team to explore the accuracy of the method in Sub-Saharan Africa.

Researchers used satellite images of vegetation cover as measures of drought conditions in Sub-Saharan Africa and quarterly reports on food insecurity risks between April 2011 and February 2020, to assess how the conditions are linked to the onset date of the rainy season.

According to the study, a delay of about ten days from the median date of onset of the rainy season was linked to a higher likelihood of seasonal drought in food-insecure regions. A 20-day delay indicated a 50 per cent likelihood of drought in those regions.

“These results imply that the onset date can be used as an additional critical tool to provide alerts of seasonal drought development in the most food-insecure regions of Sub-Saharan Africa,” says the study.
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“Early warning systems using onset date as a tool can help trigger effective mid-season responses to save human lives, livestock, and livelihoods, and, therefore, mitigate the adverse impacts of drought hazards.”

The Climate Hazards Center is working on operational tools for providing agricultural drought forecasts based on predictions and observations of rainy season onset, Shukla adds.

Patricia Nying’uro a climate scientist at the Kenya Meteorological Department, tells SciDev.Net that the study provides good information as a starting point for drought response planning in Sub-Saharan Africa. But she adds that for the study to be useful, farmers must be better prepared.

“Gone are the days when rainfall seasons started and ended very reliably within a specific date (period), and farmers could plan around those dates. Farmers today need information on onsets, length of season as well as cessation in order to stretch resources or even plan accordingly,” explains Nying’uro, who is also the Kenya’s contact person for the Intergovernmental Panel on Climate Change.

This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.