Land-Surface Characteristics and Climate in West Africa: Models’ Biases and Impacts of Historical Anthropogenically-Induced Deforestation

Sy, Souleymane; Noblet‐Ducoudré, Nathalie de; Quesada, Benjamín; Sy, Ibrahima; Diéye, Amadou Moctar; Gaye, Amadou Thierno; Sultan, Benjamin

doi:10.3390/su9101917

Cited by 25 publications

(22 citation statements)

References 77 publications

(103 reference statements)

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“…At global scale, projections of rainfall extremes are 2-2.5 times more dampened by future LCC than mean rainfall projections for at least two extreme indices (supplementary table S2, 'Global column' for PRCPTOT and R10mm versus P mean ). IPSL-CM5A-LR results clearly contrast with other model responses (figure 1, green triangle versus other symbols), as found in previous studies studying LCC/climate links (de Noblet-Ducoudré et al 2012, Pitman et al 2012, Sy et al 2017, Quesada et al 2017a. This model simulates local evapotranspiration increase in response to tropical deforestation (+0.60 W m −2 for IPSL-CM5A-LR latent heat flux changes above tropical deforested areas, i.e.…”

Section: Discussionsupporting

confidence: 67%

“…areas with future decrease in tree fraction, versus −0.18, −1.71, −1.10 and −2.40 W m −2 for CanESM2, HadGEM2-ES, MPI-ESM-LR and MIROC-ESM, respectively). Such local negative evapotranspiration/tree cover tropical feedback is however not supported by observational data (Spracklen et al 2018) and to simulate it correctly is critical in projecting accurate mean and extreme rainfall responses to LCC (Sy et al 2017).…”

Section: Discussionmentioning

confidence: 99%

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Anthropogenic land cover change impact on climate extremes during the 21st century

Quesada

2020

Environ. Res. Lett.

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Anthropogenic land cover change (LCC) can have significant impacts at regional and seasonal scales but also for extreme weather events to which socio-economical systems are vulnerable. However, the effects of LCC on extreme events remain either largely unexplored and/or without consensus following modelling over the historical period (often based on a single model), regional or idealized studies. Here, using simulations performed with five earth system models under common future global LCC scenarios (the RCP8.5 and RCP2.6 Representative Concentration Pathways) and analyzing 20 extreme weather indices, we find future LCC substantially modulates projected weather extremes. On average by the end of the 21st century, under RCP8.5, future LCC robustly lessens global projections of high rainfall extremes by 22% for heavy precipitation days (>10 mm) and by 16% for total precipitation amount of wet days (PRCPTOT). Accounting for LCC diminishes their regional projections by >50% (70%) in southern Africa (northeastern Brazil) but intensifies projected dry days in eastern Africa by 29%. LCC does not substantially affect projections of global and regional temperature extremes (<5%), but it can impact global rainfall extremes 2.5 times more than global mean rainfall projections. Under an RCP2.6 scenario, global LCC impacts are similar but of lesser magnitude, while at regional scale in Amazon or Asia, LCC enhances drought projections. We stress here that multi-coupled modelling frameworks incorporating all aspects of land use are needed for reliable projections of extreme events.

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Anthropogenic land cover change impact on climate extremes during the 21st century

Quesada

2020

Environ. Res. Lett.

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“…This decline is significant at a 5% significance level. These differences between the north and the southeast can be explained by the strong land surface heterogeneities, the topography, and the remote response of local precipitation to changes in vegetation dynamics [25,26].…”

Section: Annual and Seasonal Changes Of Precipitation And Evapotranspmentioning

confidence: 99%

“…The annual water balance is represented in Figure 4. A general water deficit can be seen (more than 180 mm), which means that the water losses through the process of evapotranspiration are These differences between the north and the southeast can be explained by the strong land surface heterogeneities, the topography, and the remote response of local precipitation to changes in vegetation dynamics [25,26].…”

Section: Annual and Seasonal Changes Of The Water Balance (P-et)mentioning

confidence: 99%

Impacts of 1.5 and 2.0 °C Global Warming on Water Balance Components over Senegal in West Africa

2019

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This study assesses the changes in precipitation (P) and in evapotranspiration (ET) under 1.5 °C and 2.0 °C global warming levels (GWLs) over Senegal in West Africa. A set of twenty Regional Climate Model (RCM) simulations within the Coordinated Regional Downscaling Experiment (CORDEX) following the Representative Concentration Pathways (RCP) 4.5 emission scenario is used. Annual and seasonal changes are computed between climate simulations under 1.5 °C and 2.0 °C warming, with respect to 0.5 °C warming, compared to pre-industrial levels. The results show that annual precipitation is likely to decrease under both magnitudes of warming; this decrease is also found during the main rainy season (July, August, September) only and is more pronounced under 2 °C warming. All reference evapotranspiration calculations, from Penman, Hamon, and Hargreaves formulations, show an increase in the future under the two GWLs, except annual Penman evapotranspiration under the 1.5 °C warming scenario. Furthermore, seasonal and annual water balances (P-ET) generally exhibit a water deficit. This water deficit (up to 180 mm) is more substantial with Penman and Hamon under 2 °C. In addition, analyses of changes in extreme precipitation reveal an increase in dry spells and a decrease in the number of wet days. However, Senegal may face a slight increase in very wet days (95th percentile), extremely wet days (99th), and rainfall intensity in the coming decades. Therefore, in the future, Senegal may experience a decline in precipitation, an increase of evapotranspiration, and a slight increase in heavy rainfall. Such changes could have serious consequences (e.g., drought, flood, etc.) for socioeconomic activities. Thus, strong governmental politics are needed to restrict the global mean temperature to avoid irreversible negative climate change impacts over the country. The findings of this study have contributed to a better understanding of local patterns of the Senegal hydroclimate under the two considered global warming scenarios.

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“…Pellarin [110] reached a similar conclusion and observed that the initiation, but also the path and behavior of MCS appear to be influenced by the soil moisture patterns during daytime, their path evolving preferentially on the edge of wet areas. Sy et al (2017) [111] showed that, although climate responses to land use changes seem to be relatively small, some atmospheric processes are influenced by LULCC.…”

Section: Main Trends Described In Recent Workmentioning

confidence: 99%

Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

Descroix

Guichard

Grippa

et al. 2018

Water

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Abstract:In the West African Sahel, two paradoxical hydrological behaviors have occurred during the last five decades. The first paradox was observed during the 1968-1990s 'Great Drought' period, during which runoff significantly increased. The second paradox appeared during the subsequent period of rainfall recovery (i.e., since the 1990s), during which the runoff coefficient continued to increase despite the general re-greening of the Sahel. This paper reviews and synthesizes the literature on the drivers of these paradoxical behaviors, focusing on recent works in the West African Sahelo/Sudanian strip, and upscaling the hydrological processes through an analysis of recent data from two representative areas of this region. This paper helps better determine the respective roles played by Land Use/Land Cover Changes (LULCC), the evolution of rainfall intensity and the occurrence of extreme rainfall events in these hydrological paradoxes. Both the literature review and recent data converge in indicating that the first Sahelian hydrological paradox was mostly driven by LULCC, while the second paradox has been caused by both LULCC and climate evolution, mainly the recent increase in rainfall intensity.

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Land-Surface Characteristics and Climate in West Africa: Models’ Biases and Impacts of Historical Anthropogenically-Induced Deforestation

Cited by 25 publications

References 77 publications

Anthropogenic land cover change impact on climate extremes during the 21st century

Anthropogenic land cover change impact on climate extremes during the 21st century

Impacts of 1.5 and 2.0 °C Global Warming on Water Balance Components over Senegal in West Africa

Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

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