Development of an Updated Global Land In Situ‐Based Data Set of Temperature and Precipitation Extremes: HadEX3

Journal of Geophysical Research Atmospheres, Journal Year: 2020, Volume and Issue: 125(16)

Published: July 2, 2020

We present the second update to a data set of gridded land-based temperature and precipitation extremes indices: HadEX3. This consists 17 12 indices derived from daily, in situ observations recommended by World Meteorological Organization (WMO) Expert Team on Climate Change Detection Indices (ETCCDI). These have been calculated at around 7,000 locations for 17,000 precipitation. The annual (and monthly) interpolated 1.875°×1.25° longitude-latitude grid, covering 1901–2018. show changes these examining "global"-average time series comparison with previous observational sets also estimating uncertainty resulting nonuniform distribution meteorological stations. Both short long scale behavior HadEX3 agrees well existing products. Changes are widespread consistent global-scale warming. related daily minimum temperatures changing faster than maximum. Spatial linear trends over 1950–2018 less spatially coherent those indices. Globally, there more heavy events that intense contribute greater fraction total. Some use reference period calculating exceedance thresholds. between using 1961–1990 1981–2010. differences observed longer scales shown be result interaction warming climate. netCDF files and, where possible, underlying station available www.metoffice.gov.uk/hadobs/hadex3 www.climdex.org.

Language: Английский

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The Greening of the Sahara: Past Changes and Future Implications

One Earth, Journal Year: 2020, Volume and Issue: 2(3), P. 235 - 250

Published: March 1, 2020

In the future, Sahara and Sahelian regions could experience more rainfall than today as a result of climate change. Wetter periods, termed African humid occurred in past witnessed mesic landscape place today's hyperarid semiarid environment. Such large changes raise question whether near future might hold store similar environmental transformations, particularly view growing human-induced climate, land-use, land-cover changes. last decades, geoengineering initiatives (in form active re-greening projects Sahel) have been proposed significant effects on region. Here, we synthesize literature projected hydroclimate Sahelian-Saharan region associated feedbacks. We further address current state knowledge concerning Saharan afforestation their consequences. Our review underscores importance vegetation land-atmosphere-ocean feedback processes far-field impacts northern ecosystem

Language: Английский

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Rainfall trends in the African Sahel: Characteristics, processes, and causes

Wiley Interdisciplinary Reviews Climate Change, Journal Year: 2019, Volume and Issue: 10(4)

Published: June 4, 2019

Abstract Sahel rainfall is dynamically linked to the global Hadley cell and regional monsoon circulation. It therefore susceptible forcings from remote oceans land alike. Warming of enhances stability tropical atmosphere weakens deep ascent in Sahara nearby changes structure position shallow circulation allows more intense convective systems that determine seasonal rain accumulation. These processes can explain observed interannual multidecadal variability. Sea surface temperature anomalies were dominant forcing drought 1970s 1980s. In most recent decades, amounts have partially recovered, but rainy season characteristics changed: intermittent wetting concentrated late away west coast. Similar subseasonal subregional differences trends characterize simulated response increased greenhouse gases, suggesting an anthropogenic influence. While uncertainty future projections remains, confidence them encouraged by recognition mean depends on large‐scale drivers atmospheric circulations are well resolved current climate models. Nevertheless, observational modeling efforts needed provide refined changes, expanding beyond total accumulation metrics intraseasonal risk extreme events, coordination between scientists stakeholders generate relevant information useful even under uncertainty. This article categorized under: Paleoclimates Current Trends > Modern Climate Change

Language: Английский

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What can we know about future precipitation in Africa? Robustness, significance and added value of projections from a large ensemble of regional climate models

Climate Dynamics, Journal Year: 2019, Volume and Issue: 53(9-10), P. 5833 - 5858

Published: July 20, 2019

We employ a large ensemble of Regional Climate Models (RCMs) from the COordinated Regional-climate Downscaling EXperiment to explore two questions: (1) what can we know about future precipitation characteristics over Africa? and (2) does this information differ that derived driving Global (GCMs)? By taking into account both statistical significance change models' agreement on its sign, identify regions where projected climate signal is robust, suggesting confidence will change, those changes in statistics are non-significant. Results show that, when spatially averaged, RCMs median usually with GCMs ensemble: even though seasonal mean may differ, some cases, other (e.g., intensity, frequency, duration dry wet spells) same tendency. When robust (i.e., value averaged only land points it robust) compared between RCMs, similarities striking, indicating although uncertainty geographical extent, project consistent future. Potential added downscaling projections non-negligible fine-scale absent lower resolution simulations) found for instance Ethiopian highlands, RCM shows decrease contrast results. This discrepancy be associated better representation topographical details missing scale GCMs. The impact heterogeneity GCM–RCM matrix results has been also investigated; most indices, or non-significant, they so independently choice GCM. However, there especially Central Africa parts West Africa, uncertain, i.e. statistically significant but do not agree sign. In these clearly clustered according RCM, simple way subsampling model order reduce infer more result.

Language: Английский

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Decoupling of surface water storage from precipitation in global drylands due to anthropogenic activity

Nature Water, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 10, 2025

Abstract The availability of surface water in global drylands is essential for both human society and ecosystems. However, the long-term drivers change storage, particularly those related to anthropogenic activities, remain unclear. Here we use multi-mission remote sensing data construct monthly time series storage changes from 1985 2020 105,400 lakes reservoirs drylands. An increase 2.20 km 3 per year found primarily due construction new reservoirs. For old (constructed before 1983), conversely, trend minor when aggregated globally, but they dominate trends 91% individual dryland basins. Further analysis reveals that these bodies are linked factors—including human-induced warming water-management practices—rather than precipitation changes, as previously thought. These findings reveal a decoupling drylands, raising concerns about societal ecosystem sustainability.

Language: Английский

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Intensification of precipitation extremes in the world’s humid and water-limited regions

Environmental Research Letters, Journal Year: 2019, Volume and Issue: 14(6), P. 065003 - 065003

Published: April 25, 2019

Abstract Changes in precipitation totals and extremes are among the most relevant consequences of climate change, but particular regional changes remain uncertain. While aggregating over larger regions reduces noise time series typically shows increases intensity extremes, it has been argued that this may not be case water-limited regions. Here we investigate long-term annual aggregated world’s humid, transitional, dry as defined by their climatological water availability. We use globally complete observational datasets suitable for analysis daily data from global model simulations. show have increased humid since mid-20th century. Conversely, despite showing tendencies to increase, no robust can detected drier regions, part due large variability sparse coverage particularly driest Future simulations under radiative forcing indicate total more clear arid while likely increase than decrease on average both world. These results highlight increasing risk heavy world, including with implications related impacts through flooding or soil erosion.

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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Recent changes in the precipitation-driving processes over the southern tropical Andes/western Amazon

Climate Dynamics, Journal Year: 2020, Volume and Issue: 54(5-6), P. 2613 - 2631

Published: Feb. 1, 2020

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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Trends in hydrological extremes in the Senegal and Niger Rivers

Journal of Hydrology, Journal Year: 2018, Volume and Issue: 566, P. 531 - 545

Published: Sept. 5, 2018

Language: Английский

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