The Lake Chad hydrology under current climate change

Scientific Reports, Journal Year: 2020, Volume and Issue: 10(1)

Published: March 26, 2020

Lake Chad, in the Sahelian zone of west-central Africa, provides food and water to ~50 million people supports unique ecosystems biodiversity. In past decades, it became a symbol current climate change, held up by its dramatic shrinkage 1980s. Despites partial recovery response increased precipitation 1990s, Chad is still facing major threats contemporary variability under change remains highly uncertain. Here, using new multi-satellite approach, we show that extent has remained stable during last two despite slight decrease northern pool. Moreover, since 2000s, groundwater, which contributes ~70% Chad's annual storage increasing due supply provided main tributaries. Our results indicate tandem with groundwater tropical origin supply, over not shrinking recovers seasonally surface volume. This study robust regional understanding hydrology changes region, giving basis for developing future adaptation strategies.

Language: Английский

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Impacts of 1.5°C Global Warming on Natural and Human Systems

Cambridge University Press eBooks, Journal Year: 2022, Volume and Issue: unknown, P. 175 - 312

Published: May 24, 2022

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Language: Английский

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Mechanisms and Impacts of Earth System Tipping Elements

Reviews of Geophysics, Journal Year: 2023, Volume and Issue: 61(1)

Published: Feb. 16, 2023

Abstract Tipping elements are components of the Earth system which may respond nonlinearly to anthropogenic climate change by transitioning toward substantially different long‐term states upon passing key thresholds or “tipping points.” In some cases, such changes could produce additional greenhouse gas emissions radiative forcing that compound global warming. Improved understanding tipping is important for predicting future risks and their impacts. Here we review mechanisms, predictions, impacts, knowledge gaps associated with 10 notable proposed be elements. We evaluate approaching critical whether shifts manifest rapidly over longer timescales. Some have a higher risk crossing points under middle‐of‐the‐road pathways will possibly affect major ecosystems, patterns, and/or carbon cycling within 21st century. However, literature assessing scenarios indicates strong potential reduce impacts many through mitigation. The studies synthesized in our suggest most do not possess abrupt years, exhibit behavior, rather responding more predictably directly magnitude forcing. Nevertheless, uncertainties remain elements, highlighting an acute need further research modeling better constrain risks.

Language: Английский

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Rainfall intensification in tropical semi-arid regions: the Sahelian case

Environmental Research Letters, Journal Year: 2018, Volume and Issue: 13(6), P. 064013 - 064013

Published: May 9, 2018

An anticipated consequence of ongoing global warming is the intensification rainfall regimes meaning longer dry spells and heavier precipitation when it rains, with potentially high hydrological socio-economic impacts. The semi-arid regions intertropical band, such as Sahel, are facing particularly serious challenges in this respect since their population strongly vulnerable to extreme climatic events. Detecting long term trends Sahelian regime thus great societal importance, while being scientifically challenging because datasets allowing for detection studies rare region. This study addresses challenge by making use a large set daily rain gauge data covering Sahel (defined extending from 20°W–10°E 11°N–18°N) 1950, combined an unparalleled 5 minute observations available 1990 over AMMA-CATCH Niger observatory.

Language: Английский

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Changes in climate extremes over West and Central Africa at 1.5 °C and 2 °C global warming

Environmental Research Letters, Journal Year: 2018, Volume and Issue: 13(6), P. 065020 - 065020

Published: May 11, 2018

In this study, we investigate changes in temperature and precipitation extremes over West Central Africa (hereafter, WAF domain) as a function of global mean with focus on the implications warming 1.5 °C 2 according Paris Agreement. We applied scaling approach to capture climate increase several subregions within domain: Western Sahel, Eastern Guinea Coast including Congo Basin.

Language: Английский

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Modelling climate change impacts on maize yields under low nitrogen input conditions in sub‐Saharan Africa

Global Change Biology, Journal Year: 2020, Volume and Issue: 26(10), P. 5942 - 5964

Published: July 6, 2020

Abstract Smallholder farmers in sub‐Saharan Africa (SSA) currently grow rainfed maize with limited inputs including fertilizer. Climate change may exacerbate current production constraints. Crop models can help quantify the potential impact of climate on yields, but a comprehensive multimodel assessment simulation accuracy and uncertainty these low‐input systems is lacking. We evaluated varying [CO 2 ], temperature rainfall conditions yield, for different nitrogen (N) (0, 80, 160 kg N/ha) five environments SSA, cool subhumid Ethiopia, semi‐arid Rwanda, hot Ghana Mali Benin using an ensemble 25 models. Models were calibrated measured grain plant biomass, N, leaf area index, harvest index in‐season soil water content from 2‐year experiments each country to assess their ability simulate observed yield. Simulated responses factors explored compared between Calibrated reproduced yield variations well average relative root mean square error 26%, although model prediction was substantial (CV = 28%). Model ensembles gave greater than any taken at random. Nitrogen fertilization controlled response rainfall. Without N fertilizer input, (a) benefited less increase atmospheric ]; (b) affected by higher or decreasing rainfall; (c) more increased because leaching critical. The intercomparison revealed that daily supply plays crucial role simulating impacts systems. input interactions have strong implications design robust adaptation approaches across low will be modified if intensify balanced nutrient management.

Language: Английский

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

Water, Journal Year: 2018, Volume and Issue: 10(6), P. 748 - 748

Published: June 8, 2018

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

Language: Английский

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Suitability of 17 gridded rainfall and temperature datasets for large-scale hydrological modelling in West Africa

Hydrology and earth system sciences, Journal Year: 2020, Volume and Issue: 24(11), P. 5379 - 5406

Published: Nov. 16, 2020

Abstract. This study evaluates the ability of different gridded rainfall datasets to plausibly represent spatio-temporal patterns multiple hydrological processes (i.e. streamflow, actual evaporation, soil moisture and terrestrial water storage) for large-scale modelling in predominantly semi-arid Volta River basin (VRB) West Africa. Seventeen precipitation products based essentially on gauge-corrected satellite data (TAMSAT, CHIRPS, ARC, RFE, MSWEP, GSMaP, PERSIANN-CDR, CMORPH-CRT, TRMM 3B42 3B42RT) reanalysis (ERA5, PGF, EWEMBI, WFDEI-GPCC, WFDEI-CRU, MERRA-2 JRA-55) are compared as input fully distributed mesoscale Hydrologic Model (mHM). To assess model sensitivity meteorological forcing during partitioning into evaporation runoff, six temperature used combination with datasets, which results evaluating 102 combinations rainfall–temperature data. The is recalibrated each combinations, responses evaluated by using situ streamflow remote-sensing from GLEAM ESA CCI GRACE storage. A bias-insensitive metric impact simulation spatial processes. process-based evaluation show that have contrasting performances across four climatic zones present VRB. top three best-performing TAMSAT, CHIRPS PERSIANN-CDR streamflow; RFE CMORPH-CRT storage; MERRA-2, EWEMBI/WFDEI-GPCC PGF temporal dynamics moisture; TAMSAT ARC GSMaP-std evaporation; evaporation. No single or dataset consistently ranks first reproducing variability all best not necessarily patterns. In addition, suggest there more uncertainty representing than their dynamics. Finally, some region-tailored outperform global thereby stressing necessity importance regional studies increasingly becoming an alternative measurements data-scarce regions.

Language: Английский

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Rainfall types over southern West Africa: Objective identification, climatology and synoptic environment

Quarterly Journal of the Royal Meteorological Society, Journal Year: 2018, Volume and Issue: 144(714), P. 1628 - 1648

Published: July 1, 2018

Southern West Africa (SWA) is characterised by a wide range of rainfall types, the relative importance which have never been quantified on regional level. Here, we use 16 years three‐dimensional reflectivity data from Tropical Rainfall Measuring Mission–Precipitation Radar (TRMM‐PR) to objectively distinguish between seven different types in three subregions SWA. Highly organized Mesoscale Convective System (MCS) events are dominating rain‐bearing systems They tend occur highly sheared environments as result mid‐level northeasterlies ahead cyclonic vortex. Their contribution annual decreases 71% Soudanian 56% coastal zone. MCSs SWA also propagate slower than their Sahelian counterparts and predominantly at start first rainy season. However, terms numbers, about 90% weakly classes, particularly small‐sized, reflective moderately deep (40 dBZ altitude <10 km) systems. Contrary MCSs, less convection typically occurs during after passage vortex within regime westerly anomalies, low wind shear moderate CAPE (convective available potential energy), bearing some resemblance what has termed “monsoon” or “vortex rainfall”. Combining TRMM‐PR system identification with infrared‐based cloud tracking reveals that over lasts for more >9 h, whereas intense be short‐lived, diurnal phenomena. This novel approach stresses relevance (wave) disturbances type lifetime convective thereby regionally, seasonally diurnally varying amount. The present study suggests further investigations into character well possible implications operational forecasting understanding variability

Language: Английский

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AMMA‐CATCH, a Critical Zone Observatory in West Africa Monitoring a Region in Transition

Vadose Zone Journal, Journal Year: 2018, Volume and Issue: 17(1), P. 1 - 24

Published: Jan. 1, 2018

Core Ideas AMMA‐CATCH is a long‐term critical zone observatory in West Africa. Four sites sample the sharp ecoclimatic gradient characteristic of this region. Combined measurements meteorology, water, and vegetation dynamics began 1990. Intensification rainfall hydrological cycles observed. The strong overall re‐greening may hide contrasted changes. Africa region fast transition from climate, demography, land use perspectives. In context, African Monsoon Multidisciplinary Analysis (AMMA)–Couplage de l'Atmosphère Tropicale et du Cycle eco‐Hydrologique (CATCH) regional was developed to monitor impacts global change on better understand its current future dynamics. organized into three thematic axes, which drive observation instrumentation strategy: (i) analyze evolution eco‐hydrosystems perspective; (ii) processes their variability; (iii) meet socioeconomic development needs. To achieve these goals, has gathered data since 1990 four densely instrumented mesoscale (∼10 4 km 2 each), located at different latitudes (Benin, Niger, Mali, Senegal) so as eco‐climatic that Simultaneous monitoring cover various components water balance provided new insights seemingly paradoxical eco‐hydrological changes observed Sahel during last decades: groundwater recharge and/or runoff intensification despite deficit subsequent with still increasing runoff. Hydrological role certain key landscape features are highlighted, well importance an appropriate description soil subsoil characteristics. Applications scientific results for sustainable issues proposed. Finally, detecting attributing identifying possible regime shifts hydrologic cycle next challenges need be faced.

Language: Английский

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