The intensification of thermal extremes in west Africa

Ringard, Justine; Dieppois, Bastien; Rome, Sandra; Diedhiou, Arona; Pellarin, Thierry; Konaré, A.; Diawara, Adama; Konate, Daouda; Djè, Bernard Kouakou; Katiellou, Gaptia Lawan; Sanda, Ibrah Seidou; Hassane, B.; Vischel, Théo; Garuma, Gemechu Fanta; Mengistu, Getahun; Camara, Moctar; Diongue, Abdou Kâ; Gaye, Amadou Thierno; Descroix, Luc

doi:10.1016/j.gloplacha.2015.12.009

Cited by 25 publications

(29 citation statements)

References 36 publications

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“…Other studies, e.g. Ringard et al for West Africa 24 , indicate similarities in trends in extreme temperatures between observations and simulations and an acceleration of the trend thereafter. For the higher RCP pathways, the trends tend to remain similar throughout the 21st century with little indications of decrease.…”

Section: Discussionsupporting

confidence: 55%

Historical and projected trends in near-surface temperature indices for 22 locations in South Africa

Kruger¹,

Rautenbach²,

Mbatha³

et al. 2019

S. Afr. J. Sci.

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Motivated by the risks posed by global warming, historical trends and future projections of near-surface temperature in South Africa have been investigated in a number of previous studies. These studies included the assessment of trends in average temperatures as well as extremes. In this study, historical trends in near-surface minimum and maximum temperatures as well as extreme temperature indices in South Africa were critically investigated by comparing quality-controlled station observations with downscaled model projections. Because climate models are the only means of generating future global warming projections, this critical point comparison between observed and downscaled model simulated time series can provide valuable information regarding the interpretation of model-generated projections. Over the historical 1951–2005 period, both observed data and downscaled model projections were compared at 22 point locations in South Africa. An analysis of model projection trends was conducted over the period 2006–2095. The results from the historical analysis show that model outputs tend to simulate the historical trends well for annual means of daily maximum and minimum temperatures. However, noteworthy discrepancies exist in the assessment of temperature extremes. While both the historical model simulations and observations show a general warming trend in the extreme indices, the observational data show appreciably more spatial and temporal variability. On the other hand, model projections for the period 2006–2095 show that for the medium-to-low concentration Representative Concentration Pathway (RCP) 4.5, the projected decrease in cold nights is not as strong as is the case for the historically observed trends. However, the upward trends in warm nights for both the RCP4.5 and the high concentration RCP8.5 pathways are noticeably stronger than the historically observed trends. For cool days, future projections are comparable to the historically observed trends, but for hot days noticeably higher. Decreases in cold spells and increases in warm spells are expected to continue in future, with relatively strong positive trends on a regional basis. It is shown that projected trends are not expected to be constant into the future, in particular trends generated from the RCP8.5 pathway that show a strong increase in warming towards the end of the projection period. Significance: Comparison between the observed and simulated trends emphasises the necessity to assess the reliability of the output of climate models which have a bearing on the credibility of projections. The limitation of the models to adequately simulate the climate extremes, renders the projections conservative.

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Section: Discussionsupporting

confidence: 55%

Historical and projected trends in near-surface temperature indices for 22 locations in South Africa

Kruger¹,

Rautenbach²,

Mbatha³

et al. 2019

S. Afr. J. Sci.

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“…e most severe e ects of global warming result from the frequency and severity of extreme events such as oods [1,2], droughts [3,4] and heat waves [5][6][7][8]. Severe, extreme and exceptional heat waves occurred worldwide, for example in 2003 in France [9][10][11], in 2010 in Russia [12,13] and recently in west Africa (i.e., Niger) in 2010 [14,15] with many drawbacks implying increased mortality, reduced labor productivity and human discomfort [16][17][18]. Because of its high vulnerability to climate change [19], Africa underwent many heatwaves events that are not o en noticed or documented [20,21].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, Russo et al [23] underlined that Africa experienced hotter, longer and more extent heat waves during the 1979-2015 period across all seasons than in the last two decades of the 20th century. Africa generally faces the occurrence of such peak temperatures and heat waves during the dry season (JFM), [15]. Particularly, the Sahel faces an important rise of International Journal of Geophysics 2 minimum temperatures compared with the maximum temperature during that season (i.e., JFM) since 1980 [14,24,25].…”

Section: Introductionmentioning

confidence: 99%

Twenty-First Century Projected Changes in Extreme Temperature over Côte d’Ivoire (West Africa)

Yapo

Diawara

Yoroba

et al. 2019

International Journal of Geophysics

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The projection of the future climate changes is of paramount importance inasmuch as it contributes to provide useful information for adaptation planning worldwide to local scales. This study investigated the future changes using four temperature related indices based on an ensemble of 14 CORDEX-Africa simulations at 0.44° × 0.44° of resolution under the RCP4.5 and RCP8.5 scenarios. These indices indicate moderate extremes over Côte d’Ivoire. The results show an increase in the warm extreme indices such as the warm spell days index (HWFI), very warm days frequency index (TX90P), and the warm nights frequency index (TN90P) over the entire country under both emission scenarios. The increase in these indices was higher under RCP8.5 and reached 85, 72, and 90% for HWFI, TX90P, and TN90P respectively. In addition, the magnitude of the changes is relevant along the coastal areas in the 2031–2060 and 2071–2100 periods. Moreover, the intra period extreme temperature range (ETR) shows future decrease following a south-north gradient with values in the range [−0.5; 1.5°C] over the country during January–March (JFM) and October–December (OND) seasons whereas an increase (~0.5°C) is projected for April–June (AMJ) and July–September (JAS) seasons, particularly in the central and northern parts. The minimum temperature increases faster than the maximum, except in AMJ and JAS in the central and northern regions. On the other hand, the changes in the indices based on the mean values of the reference period (1976–2005) are in concordance to the expected warming at the end of the twenty-first century with important trends. The projected changes are, however, subject to uncertainties, which are higher under RCP8.5 than under RCP4.5 scenarios. Overall, these changes are meaningful as all the 14 CORDEX-Africa simulations agree to an increase of warm extreme temperature.

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“…Intergovernmental Panel on Climate Change [] concluded that 21st century warming due to anthropogenic forcing will be large in Africa, which is likely to increase the number and duration and amplitude of heat waves, especially in arid and semiarid regions of West Africa [ Pachauri and Reisinger , ; Christensen et al , ; Stocker et al , ]. At the regional scale of the Central Sahel and Guinean zone, Ringard et al [] have already shown that the rising trends in TX and TN over the past 60 years are more pronounced than those of the other regions of the West African domain. These positive trends are consistent with Fontaine et al [] based on National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalyses [ Kalnay et al , ], who showed a significant warming (1°C–3°C) for the period 1979–2011 over Sahara and Sahel.…”

Section: Introductionmentioning

confidence: 99%

“…In boreal autumn and spring (October‐November‐December and April‐May‐June), the warming trends are larger in TN than in TX, which suggest a decrease in the daily temperature ranges as observed on the global scale [ Braganza et al , ]. This is, however, not verified in summer (July‐August‐September), when TX increases more rapidly than TN in the Sahel [ Rome et al , ; Ringard et al , ].…”

Section: Introductionmentioning

confidence: 99%

Trends of mean temperatures and warm extremes in northern tropical Africa (1961–2014) from observed and PPCA‐reconstructed time series

et al. 2016

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Trends in daily maximum (TX) and minimum (TN) temperatures and indices of warm extremes are studied in tropical North Africa, west of the eastern African highlands, from 1961 to 2014. The analysis is based on the concatenation and cross-checking of two observed databases. Due to the large number of missing entries (~25%), a statistical infilling using probabilistic principal component analysis was applied. Averaged over 90 stations, the linear trends of annual mean TX and TN equal respectively +0.021°C/yr and +0.028°C/yr. The frequency of very hot days (TX > 35°C) and tropical nights (TN > 20°C), as well as the frequency of daily TX and TN above the 90th percentile (p90) ("warm days" and "warm nights"), roughly follows the variations of mean TX and TN, respectively. Heat spells of TX or TN > p90 are often short (usually <2-3 days), and the interannual variation of their mean duration is noisier than for the other indices. Nevertheless, heat spells tend to last longer, with almost constantly positive anomalies since the mid-1990s. The trends in March-June, the warmest season across the Sahelian and Sudanian belts, show similar variations as annual means. Overall, the local-scale warming in annual temperatures, and in March-June, may be viewed merely as a simple shift of the probability distribution function of daily TX and TN. The correlations between the thermal indices and the 2 m temperatures suggest that the low-frequency (>8 years) variations may be viewed as a regional-scale fingerprint of the global warming, with largest correlations in the tropical Atlantic and Indian basins, while the high-frequency (<8 years) variations should be mostly viewed as a delayed remote impact of El Niño-Southern Oscillation (ENSO) events over the region, with warm (cold) anomalies tending to follow warm (cold) ENSO events.Several studies have analyzed the time variation of climate extremes at the global scale [Groisman et al., 1999;Frich et al.,

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The intensification of thermal extremes in west Africa

Cited by 25 publications

References 36 publications

Historical and projected trends in near-surface temperature indices for 22 locations in South Africa

Historical and projected trends in near-surface temperature indices for 22 locations in South Africa

Twenty-First Century Projected Changes in Extreme Temperature over Côte d’Ivoire (West Africa)

Trends of mean temperatures and warm extremes in northern tropical Africa (1961–2014) from observed and PPCA‐reconstructed time series

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