Observed variability and trends in the microclimate of the midlands of KwaZulu‐Natal and its influence on fire danger

Abstract

ABSTRACTCurrent changes in global climate are likely to be evident at both the regional and the local scale. This study presents an investigation in climatic trends in the KwaZulu‐Natal (KZN) midlands, South Africa and seeks to assess the level of change in the microclimate and more specifically, the influence of a changing climate on fire danger. To this end, long‐term (1953–2015), historical daily meteorological data from the KZN midlands were analysed, using multitemporal regression analysis as well as time‐series analysis. Analysis indicated significant trends, to varying rates of change, across all sites. Over the last two decades, annual average air temperature was found to be increasing at a rate of between 1 and 3 °C century−1. Atmospheric water vapour pressure across the three sites also experienced significant levels of change. Decreases in total rainfall over the last two decades are of concern. Fire danger, calculated using the Lowveld fire danger index (LFDI), displayed significant rates of change. At two sites, annual average fire danger, over the last two decades, was found to be decreasing at a rate between roughly 5 and 10 FDI units century−1. The onset and length of the KZN midlands fire season has also undergone significant changes, as a response to changes in the microclimate. Sites experienced an overall decreasing trend in the onset of the fire season – indicative of an earlier start to the fire season, as well as an increase in fire season length. Results indicate that while the microclimate of the KZN midlands is changing, the rate of change differs from that of global and continental estimates.