Heat waves in spring from Senegal to Sahel: Evolution under climate change

Abstract

This study analyses the long-term (1950-2100) observed and projected changes in springtime (March-May) heat waves (HWs) in West Africa under climate change. To that end, 28 climate models participating to the fifth Coupled Model Intercomparison Project (CMIP5) are considered, after a statistical postcorrection of their biases. A multi-scale approach is proposed, covering the Sahel, Senegal, and three thermally-coherent zones within Senegal. HWs are defined as a sequence of at least three consecutive days above a moving 95th percentile of current temperature distributions. Climate change over Senegal translates into a general shift of the whole statistical distribution towards higher temperature values, with a general stability in the shape of the distribution. Ongoing mean warming could reach +5 C in 2100 under RCP8.5 scenario, implying that coastal Senegal could experience then a mean climate comparable to the hinterland parts today. HWs have increased in intensity, frequency and duration across Sahel and Senegal over the past years, such intensification being higher on recent decades. Future HWs over all regions present intrinsic properties that radically differ from those observed so far. The severity and length of HWs displayed stationary conditions until the late 1990s, but started increasing since then. Projected changes show marked and rapid increase in these variables, the amplitude of which is primarily RCP-dependent, and secondarily region-dependent. For both metrics, the largest changes occur over hinterland Senegal and Sahel. There, under RCP8.5 and after the 2070s, the whole spring season could be considered as a permanent HW lasting 3 months. Along the coast, by contrast, average temperatures are both weaker and more variable, causing more frequent threshold crossings and limiting the duration of HWs. The multi-scale approach used here highlights contrast within Senegal, which constitutes important information for public policy decision-makers and its inhabitants in terms of adaptation to climate change.

Recent Observed Changes in Extreme High‐Temperature Events and Associated Meteorological Conditions over Africa

“…Similarly, there is also an upsurge in the number of hot nights across the continent. However, the trends in the frequency of hot nights are higher than hot days, consistent with the results obtained in other studies conducted in West Africa (Ringard et al ., 2016), Senegal and Sahel (Moron et al ., 2016; Oueslati et al ., 2017; Sambou et al ., 2020, 2021), Asia‐Pacific countries (Choi et al ., 2009), Indo‐Pacific (Caesar et al ., 2011), and China (Shi et al ., 2018; Pi et al ., 2020). In accordance with previous studies (Omondi et al ., 2014; Gebrechorkos et al ., 2019), an increasing trend in warm days and nights in most parts of East Africa is found in this research.…”

“…Studies (Diffenbaugh and Ashfaq, 2010; Loikith and Broccoli, 2012; Lee and Lee, 2016; Hu and Huang, 2020; Joshi et al ., 2020; Pi et al ., 2020; Zhu et al ., 2020) indicate that large‐scale circulation is one of the most vital factors responsible for high‐temperature extremes. Regional and global climate models also show an increase in extreme heat events in the future (Vogel et al ., 2020; Almazroui et al ., 2021; Sambou et al ., 2021; Iyakaremye et al ., 2021b); however, the distribution of changes is not uniform worldwide. It will be impacted by variations in the large‐scale circulation of the atmosphere, exacerbated by the continuously increasing greenhouse gases in the atmosphere (Meehl, 2004).…”

Indoor temperature variability in the Sahel: a pilot study in Ouagadougou, Burkina Faso

“…The frequency and occurrence of the "Danger" and even "Extreme Danger" categories are expected to rise significantly in coming decades under climate change, raising the question of public health impacts of climate extremes, especially heat extremes and HWs (e.g. Ringard et al 2016;Moron et al 2016;Sambou et al 2021). The most underprivileged populations face the greatest difficulties in protecting themselves against deadly heat during such severe events, confirming that climate change enhances inequalities and differences between the most and least resilient households.…”

“…This warming, which is particularly marked during the hottest season, the northern-hemisphere spring (Oueslati et al 2017), is even accelerating and is now clearly discernible not only in mean temperature, but also across a wide range of derived thermal indicators (Moron et al 2016), including climate extremes like HWs (Ringard et al 2016;Barbier et al 2018;Sambou et al 2020). The fifth Intergovernmental Panel on Climate Change assessment report (IPCC 2013) concluded that anthropogenic warming will continue in Africa throughout the twenty-first century, leading to HWs of increased frequency, duration and severity (Russo et al 2014(Russo et al , 2016Diedhiou et al 2018;Sambou et al 2021).…”

Statistical modeling of monthly maximum temperature in Senegal

“…Sambou et al (2020) studied springtime heat wave occurrences over Senegal using data from 12 stations. Sambou et al (2021Sambou et al ( ) studied long-term (1950Sambou et al ( -2100 observed and projected changes in springtime heat waves in Sahel, Senegal, and three thermally-coherent zones within Senegal. Yet again none of these papers apply statistical models for extreme temperature in Senegal.…”