Recent trends in the climate of Namaqualand, a megadiverse arid region of South Africa

Abstract

Namaqualand is especially vulnerable to future climate change impacts. Using a high-resolution (0.5°x0.5°) gridded data set (CRU TS 3.1) and individual weather station data, we demonstrated that temperatures as well as frequency of hot extremes have increased across this region. Specifically, minimum temperatures have increased by 1.4 °C and maximum temperatures by 1.1 °C over the last century. Of the five weather stations analysed, two showed evidence of a significant increase in the duration of warm spells of up to 5 days per decade and a reduction in the number of cool days (TX10P) by up to 3 days per decade. In terms of rainfall, we found no clear evidence for a significant change in annual totals or the frequency or intensity of rainfall events. Seasonal trends in rainfall did, however, demonstrate some spatial variability across the region. Spatial trends in evapotranspiration obtained from the 8-day MOD16 ET product were characterised by a steepening inland-coastal gradient where areas along the coastline showed a significant increase in evapotranspiration of up to 30 mm per decade, most notably in spring and summer. The increase in temperature linked with the increases in evapotranspiration pose significant challenges for water availability in the region, but further research into changes in coastal fog is required in order for a more reliable assessment to be made. Overall, the results presented in this study provide evidence-based information for the management of climate change impacts as well as the development of appropriate adaptation responses at a local scale.

Investigating changes in rainfall seasonality across South Africa: 1987–2016

“…Across the southwestern Cape region for shorter periods there is more consistency, with trends potentially reflecting a longer wet‐season with increases in autumn and spring rainfall totals (MacKellar et al ., 2014). Further north along the west coast, over longer and shorter periods, there is broad consistency with our results with most trends generally reflecting increases in autumn and spring totals (MacKellar et al ., 2014; Davis et al ., 2016; Kruger and Nxumalo, 2017b).…”

“…Although relatively little agreement exists with the changes in seasonal totals and the wet‐season timing, it is notable that results suggesting declines for autumn, winter and spring totals are broadly consistent with our results of a reduction in total wet‐season rainfall (Engelbrechet et al ., 2009; Sousa et al ., 2018; Ndebele et al ., 2020). Numerous studies, however, detect increases during some or all of these seasons (MacKellar et al ., 2014; Davis et al ., 2016; Kruger and Nxumalo, 2017b), indicating some inconsistencies. In agreement with our results, Dunning et al .…”

A Socio-Ecological Approach for Identifying and Contextualising Spatial Ecosystem-Based Adaptation Priorities at the Sub-National Level

“…In the NDM, rising temperatures consistent with historical trends [ 83 ] are likely, over time, to drive the southward expansion of the Desert Biome into the summer rainfall Nama Karoo biome, currently a commercially productive livestock farming system. The Succulent Karoo biome in the NDM appears stable under all climate change scenarios largely because its current climate envelope is so unique and internally diverse.…”

Water, justice, and wellbeing in the Kamiesberg, Namaqualand: Reflecting on local histories in the context of the Anthropocene

“…The total human population was probably limited to the thousands rather than the tens of thousands across approximately 50,000 km 2 (Hoffman & Rohde, 2007; Rohde & Hoffman, 2008). Most of “Little Namaqualand” (hereafter simply “Namaqualand”) was and still is a dry region, today receiving on average less than around 150 ml of rain a year (Cowling, Esler, & Rundel, 1999; Davis, Timm Hoffman, & Roberts, 2016). With its cooler, wetter climes, pasture and permanent springs, the Kamiesberg mountain range, about 450 km north of Cape Town, provided a vital refuge from the summer heat of the surrounding country, constituting a core hub in a seasonal round of movement of people and animals.…”