A LONG-TERM link has been found between the El Niño weather pattern and droughts in southern Africa where crops are already under threat.
Research led by the University of Brighton, published online in the journal Climatic Change, used historical newspapers and materials written by colonial authorities and missionaries to identify variations in rainfall between 1836 and 1900 in the South African province of KwaZulu-Natal.
The study’s senior author, Professor David Nash of the University of Brighton’s College of Life, Health and Physical Sciences, said: “Given that this year’s Pacific El Niño event is likely to be the strongest ever recorded, these are potentially worrying times for the people of the subcontinent.”
The findings come on the heels of the World Food Programme and Food and Agriculture Organisation predictions that as many as 29 million people in southern African countries are food insecure and that that lower rainfall in the region will lead to reduced cereal yields and higher prices.
Professor Nash said: “Results indicate that the region was affected by severe or multi-year drought on eight occasions (1836-38, 1861-63, 1865-66, 1868-70, 1876-79, 1883-85, 1886-90 and 1895-1900). Six wetter than average periods were also identified (1847-49, 1854-57, 1863-65, 1879-81, 1890-91 and 1892-94). The timing of these events agrees well with independent reconstructions of 19th century rainfall for other parts of southern Africa, suggesting subcontinental scale variability.
“The timing of droughts shows a strong relationship with El Niño events, particularly during the latter half of the 19th century. Drought events were particularly severe during the rainy season immediately following an El Niño event.”
Professor Nash said combining the results of this study with other annually-resolved records of past climate from southern Africa and surrounding oceans shows that mean summer rainfall has been declining progressively over the subcontinent for the last 200 years.
“We knew from our previous research that historical documents held huge potential for reconstructing the climate of the past. What we never expected was the level of detail we would find in materials from KwaZulu-Natal. From newspapers such as the Natal Witness we could build up an almost weekly picture of the weather from across the region.
"Our work not only identifies rainfall variability in KwaZulu-Natal but also confirms that the link between El Niño and drought in southern Africa is long-standing.”
The research, funded by the Leverhulme Trust, was conducted in collaboration with the University of Nottingham, Hedmark University College (Norway), King’s College London and the University of Sussex.