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 nineteenth 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 nineteenth 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“We knew from our previous research that historical documents held huge potential for reconstructing the climate of the past.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.
The Climate Change article can be read at http://link.springer.com/article/10.1007/s10584-015-1550-8
For more information on Professor Nash’s research, go to Past Human and Environment Dynamics research group.