Trends in probabilities of temperature records in the non‐stationary climate of South Africa

Abstract

The temporal and spatial distribution of the frequency of breaking highest and lowest daily maximum and minimum temperature records over the period of 1951–2019 has been investigated for South Africa. Temperature records are station specific and defined as either larger or smaller than any previous values in a time series of specific year‐days. Daily maximum and minimum temperatures from homogenized time series of 25 weather stations in South Africa were analysed. Aspects considered to influence the frequency of record‐breaking events were the warming trend and variance. The study found that the record‐breaking frequencies of the highest daily maximum (high Tmax) and some high daily minimum temperature (high Tmin) records were higher than the theoretically expected number in a stationary climate. This was particularly apparent near the end of the analysis period. The ratio of highest maximum to lowest minimum temperature records was almost an equal 1:1 ratio near the start of the analysis period and increased to a about 4:1 in the last decade of the period. Focusing on the last decade, that is, 2010–2019 the study found that there is a different spatial pattern between the occurrence of high Tmax and high Tmin records. For high Tmax records the highest number were mostly recorded by stations over the central parts of the country (e.g., Kimberley, Glen College and Bloemfontein). In contrast, the highest number of high Tmin records were less confined spatially. Even when considering the general warming due to climate change, many more high temperature records are broken than expected in certain regions and on average. We deduce that the higher than expected numbers of high Tmax and high Tmin records in the latter part of the analysis period were mainly due to the variability in the warming trend with acceleration in the last decade.

Long-term temporal evolution of extreme temperature in a warming Earth

“…In these regions, extremes will continue to rise and reach unprecedented strengths in the future. This is true especially over continents and corresponds to the well-known fact that global warming is stronger over land than over the oceans or in coastal regions ([ 16 , 82 ]). However, we find a disagreement between the earth system models in terms of the total magnitude of the changes.…”

“…It has been observed that changes in extreme temperature are not taking place uniformly around the globe, but that they are instead showing a strong dependency on the geographic location and its climatic conditions. This is visible already on a regional level ([ 16 , 17 ]) and even more globally ([ 18 ]). Earth system model simulations predict this variability also to be present in the future development of Earth’s climate ([ 19 , 20 ]).…”

Changes in Extreme Daily Rainfall Characteristics in South Africa: 1921 – 2020

“…To investigate any abrupt changes in the mean α and β -parameters the differences in these means before and after every year were tested, starting in 1951. By observing changes from a decrease to an increase in the absolute value of the Student's t-test one can identify abrupt changes in the means (McBride et al, 2021). Years of abrupt change in the mean αparameter were 1975 and 1995, while for the β -parameter it was 1974-1975 (Fig.…”

The effect of climate change and agricultural diversification on the total value of agricultural output of farm households in Sub-Saharan Africa

“…Econometrically, the author suggests taking into account the non-stationarity of climate change, as is evident on the continent (Gosoniu et al 2009;Karambiri et al 2011;Djibo et al 2015;Garcia-Aristizabal et al 2015;De Paola et al 2018;McBride et al 2022). A reviewer of this manuscript highly recommended using variations from the mean for temperature and rainfall as key explanatory variables to capture the long-term variability of climate change.…”