Drought In Recent Decades Research Articles

In-situ water retention monitoring system of an operational dike

The severe droughts in recent decades and the lack of regular flooding have caused considerable fissures to develop on clay embankments. Previous surveys in Hungary have identified the examined dike section as prone to desiccation cracks. It is essential to determine the possible extent of these desiccation cracks, as they degrade the dikes’ resistance against several failure mechanisms. A representative dike cross-section was equipped with a unique water retention monitoring system comprising 17 sensors, including 14 soil moisture and 3 water potential sensors. These devices were validated with laboratory measurements to obtain accurate results. The gravimetric water content (w) ranged from 8.3 % to 31.3 %, and the matric potential was recorded between 0.1 kPa and 2350.7 kPa over one and a half years. The study examined the differences in soil behaviour under pavement and turf cover, identifying common moisture content distribution patterns and areas of the cross-section prone to desiccation cracking. The uniqueness of the monitoring system lies in the fact that it was established in an operational embankment, which regulates the flow of a river. Furthermore, it was instrumented along the Tisza River, which is among Europe’s most significant watercourses. The results may help better understand the moisture content change in clay embankments and the role of the crest pavement in the moisture content distribution.

Analysis of recent trends and spatiotemporal changes of droughts over Serbia using high-resolution gridded data

The purpose of this study is to analyze the spatiotemporal variations in drought in Serbia over recent decades using the standardized precipitation evapotranspiration index (SPEI). The analysis is performed for time series of 1-, 3-, 6-, and 12-month SPEI indices (SPEI-01, SPEI-03, SPEI-06 and SPEI-12, respectively) calculated using the E-OBS gridded dataset with a horizontal resolution of 0.1° for the period of 1950–2022. In general, it was found that negative SPEI trends prevailed in Serbia for all months and all analyzed SPEI timescales, indicating a more frequent appearance of droughts in recent decades. Moreover, for a large majority of month-timescale combinations, the area with a negative trend was larger than the area with a positive trend. For several reasons, we focused on the SPEI for August. First, the SPEI for this month shows one of the most pronounced negative trends, which is rather consistent over different timescales and consistent in terms of the area over which the trend was found to be significant. Statistically significant negative trends of SPEI-03, −06 and − 12 for August were found over 11, 17 and 38% of the country area, respectively. To better understand the trends and changes in the SPEI for August, focusing on extreme and severe drought events, an innovative trend analysis (ITA) was applied. It was found that the occurrence of both extreme and severe SPEI drought categories has doubled over the last thirty years in comparison with the previous thirty-year period. Additionally, more frequent transitions from neutral and wet categories to dry categories were observed through an application of the Markov chain. Second, the special focus on SPEI-03, −06 and − 12 for August was motivated by the fact that we found a significant correlation between these index values and the annual maize production in Serbia, indicating that the SPEI for August can be useful for the assessment of drought impact on agriculture. To better understand interannual variability and long-term trends, this paper also explores the relations between the SPEI over Serbia and large-scale circulation patterns, together with general global and continental warming trends. Our findings indicate that drought changes over recent decades may be driven by the interplay of long-term warming and large-scale circulation patterns. In the context of climate change, especially climate projections, Serbia is situated in a region for which climate projections of mean precipitation change demonstrate weak signals and often with conflicting signs of change within multimodel ensembles. From this point of view, our results can be seen as a contribution to a better understanding of changes in extremes, in our case droughts, that can be hidden by inconclusive changes in the mean values. Finally, due to the similar situation in terms of precipitation and drought trends and changes, our results may be relevant for a wider region, and not only for Serbia.

Evaluation of satellite-based soil moisture for agricultural drought monitoring in the Brazilian semiarid region

The Northeast region of Brazil, particularly the Brazilian semiarid region (BSR), is frequently affected by drought events, such as the great drought that started in 2012 and is considered one of the most severe droughts in recent decades. Monitoring and quantifying this type of event is essential for decision-making and the adoption of impact mitigation strategies. In this study, remotely sensed soil moisture (SM) data from three products derived from Soil Moisture and Ocean Salinity (SMOS-CATDS and SMOS-IC) and Soil Moisture Active Passive (SMAP) were validated in the BSR using a dense network of in situ stations (N = 120) from 2015 to 2020. Subsequently, the best product was selected for the evaluation of agricultural drought, based on the Soil Water Deficit Index (SWDI), which was compared with the Atmospheric Water Deficit (AWD) obtained from in situ data (N = 50). After validation, SMAP was selected as the best product for estimating SM in the BSR, and SWDI-SMAP showed a strong temporal correlation with AWD. Based on these two indices, the results indicate the severity of drought in the BSR during the evaluated period, with significant social and economic impacts, highlighting the need for continuous monitoring, especially to support family farming, which is predominant in the region.

Drought impacts on the electricity system, emissions, and air quality in the western United States

The western United States has experienced severe drought in recent decades, and climate models project increased drought risk in the future. This increased drying could have important implications for the region's interconnected, hydropower-dependent electricity systems. Using power-plant level generation and emissions data from 2001 to 2021, we quantify the impacts of drought on the operation of fossil fuel plants and the associated impacts on greenhouse gas (GHG) emissions, air quality, and human health. We find that under extreme drought, electricity generation from individual fossil fuel plants can increase up to 65% relative to average conditions, mainly due to the need to substitute for reduced hydropower. Over 54% of this drought-induced generation is transboundary, with drought in one electricity region leading to net imports of electricity and thus increased pollutant emissions from power plants in other regions. These drought-induced emission increases have detectable impacts on local air quality, as measured by proximate pollution monitors. We estimate that the monetized costs of excess mortality and GHG emissions from drought-induced fossil generation are 1.2 to 2.5x the reported direct economic costs from lost hydro production and increased demand. Combining climate model estimates of future drying with stylized energy-transition scenarios suggests that these drought-induced impacts are likely to remain large even under aggressive renewables expansion, suggesting that more ambitious and targeted measures are needed to mitigate the emissions and health burden from the electricity sector during drought.

Overcoming Namibia’s worst drought in the last 40 years: Ethnographic insights from Okakarara constituency

In 2019, Namibia experienced one of the worst droughts in recent decades, significantly affecting its agricultural economy, especially the livestock production sector. In this context, there is limited literature about how pastoral farmers in the country’s communal agricultural areas navigated this severe dryness. This paper addresses this knowledge gap by introducing a case study involving Ovaherero pastoralists in the Okakarara constituency. Following a mixed-method approach, it describes the practices implemented by local households to keep their cattle herds alive, the challenges they experienced thereby, and the strategies used for recovering their livestock losses. The study reveals that essential drought-coping practices, such as livestock mobility along with various long-term risk reduction mechanisms, such as reservation of emergency pastures, and social institutions of exchange, are limited in the communities described in this research. The paper discusses the main reasons for these conditions and their implications for local farmers, considering that more frequent droughts of similar severity are projected for the coming years in the region.

Drought Analysis in Somalia Using GIS - Based on Reconnaissance Drought Index (RDI) and Standardized Precipitation Index (SPI)

As a result of climate change, Somalia has experienced severe droughts in recent decades because Somalia is a water-scarce country in East Africa with arid and semi-arid environments. In this study, drought in Somalia from 2010 to 2021 was investigated. For this purpose, the agroclimatological data consisting of precipitation, air temperature, and potential evapotranspiration (ETp) were obtained and calculated in DrinC software. The Reconnaissance Drought Index (RDI) and Standardized Precipitation Index (SPI) were used as meteorologically based to measure drought severity and analyse the variability of drought events in Somalia during the last decade. Most years experienced rainfall deficits and severe drought in the study area, but the worst years were 2010-2011 and 2016-2017. The results of the RDI and SPI variations showed that drought was most severe in 2016-2017 and 2010-2011, with the south-eastern region being the most severely affected. The results of this analysis should provide valuable guidance to future scientists, researchers, and national managers researching this topic.

Climate warming and summer monsoon breaks drive compound dry and hot extremes in India

Considering the severe impacts of compound dry and hot extremes, we examine the primary drivers of CDHEs during the summer monsoon in India. Using ERA5 reanalysis, we show that most of the CDHEs in India occur during the droughts caused by the summer monsoon rainfall deficit. Despite a decline in the frequency of summer monsoon droughts in recent decades, increased CDHEs are mainly driven by warming and dry spells during the summer monsoon particularly in the Northeast, central northeast, and west central regions. A strong land-atmospheric coupling during droughts in the summer monsoon season leads to frequent CDHEs in the Northwest and southern peninsular regions. Furthermore, regional variations in land-atmospheric coupling cause substantial differences in the CDHE occurrence in different parts of the country. Summer monsoon rainfall variability and increased warming can pose a greater risk of compound dry and hot extremes with severe impacts on various sectors in India.

Background climate conditions regulated the photosynthetic response of Amazon forests to the 2015/2016 El Nino-Southern Oscillation event

Amazon forests have experienced multiple large-scale droughts in recent decades, which have increased tree mortality and reduced carbon sequestration. However, the extent to which drought sensitivity varies across Amazonian forests and its key controls remain poorly quantified. Here, we analyse satellite remotely-sensed Solar Induced Fluorescence anomalies to investigate responses in Amazon forest photosynthetic activity to the 2015-2016 El Nino-Southern Oscillation (ENSO) drought. Using multivariate regression analysis, we examine the relative importance of ENSO-associated climate anomalies, background climate and soil characteristics in controlling basin-wide forest photosynthetic activity differences. Our model explains 25% of forest photosynthetic response and indicates background climate and soil conditions had a greater influence than the climatic anomalies experienced. We find marked sensitivity differences across Amazonia, with North-Western forests being the most sensitive to precipitation anomalies, likely relating to variation in forest species composition and background water stress. Such factors should be considered in climate change impact simulations.

Increasing and widespread vulnerability of intact tropical rainforests to repeated droughts

Intact tropical rainforests have been exposed to severe droughts in recent decades, which may threaten their integrity, their ability to sequester carbon, and their capacity to provide shelter for biodiversity. However, their response to droughts remains uncertain due to limited high-quality, long-term observations covering extensive areas. Here, we examined how the upper canopy of intact tropical rainforests has responded to drought events globally and during the past 3 decades. By developing a long pantropical time series (1992 to 2018) of monthly radar satellite observations, we show that repeated droughts caused a sustained decline in radar signal in 93%, 84%, and 88% of intact tropical rainforests in the Americas, Africa, and Asia, respectively. Sudden decreases in radar signal were detected around the 1997-1998, 2005, 2010, and 2015 droughts in tropical Americas; 1999-2000, 2004-2005, 2010-2011, and 2015 droughts in tropical Africa; and 1997-1998, 2006, and 2015 droughts in tropical Asia. Rainforests showed similar low resistance (the ability to maintain predrought condition when drought occurs) to severe droughts across continents, but American rainforests consistently showed the lowest resilience (the ability to return to predrought condition after the drought event). Moreover, while the resistance of intact tropical rainforests to drought is decreasing, albeit weakly in tropical Africa and Asia, forest resilience has not increased significantly. Our results therefore suggest the capacity of intact rainforests to withstand future droughts is limited. This has negative implications for climate change mitigation through forest-based climate solutions and the associated pledges made by countries under the Paris Agreement.

Assessment of CMIP5 and CORDEX-SA experiments in representing multiscale temperature climatology over central India

Abstract The central India region has been seriously affected by repeated droughts in recent decades due to climate change, which is the main reason for conducting this research. It is still uncertain how the numerous climate models could precisely estimate the future climate for central India. The study mainly focuses on the forcing global climate models (GCMs) and the regional climate models (RCMs). The models have been checked using the coefficient of correlation (r2), Nash-Sutcliffe efficiency (NSE) and an improved method, skill score (SS). The performance is also spatially checked on ArcGIS using the kriging interpolation. The bias-corrected GCMs performed more authentically than the CORDEX RCMs in signifying maximum and minimum temperatures for the Bundelkhand region in central India. Bias-corrected GCMs, EC-EARTH, CCSM4 and GFDL-ESM-2M affirmed the best models on multiple time scales for maximum and minimum temperature in the study region. Maximum NSE and r2 have been observed for seasonal minimum temperature. GCM-EC-EARTH has shown 97% to 98% accuracy, while GCM-GFDL-ESM-2M has demonstrated 84% to 97% accuracy among other selected models. The research outcomes will also assist policymakers in developing strategies and policies for the future climate of central India with the help of more precise projected climatic data.

Understanding spatiotemporal variability of drought in recent decades and its drivers over identified homogeneous regions of India

AbstractDrought is a recurring hydroclimatic extreme whose frequency and intensity have increased over India in recent decades, with a detrimental effect on regional water resources. This study addresses the spatiotemporal variability of drought and its plausible mechanism over India from 1951 to 2018. Firstly, six drought‐homogeneous regions are adequately ascertained by applying rotated empirical orthogonal function analysis using the Standardized Precipitation Evapotranspiration Index that captures most of the reported drought and regional hydroclimatic patterns. For the study period, a drying trend is witnessed across the regions though not significant, whereas in recent decades, northeast India (NEI) and some parts of the Indo‐Gangetic plain (IGP) exhibit higher drought frequency. This anomalous drying is attributed to a weakening of the monsoon circulation and accelerated warming caused by changes in the land‐use pattern. The interplay between El Niño Southern Oscillation and the Indian Ocean Dipole largely affects drought's interannual variability, which shows a modified response in recent decades. However, the long‐term decadal drought pattern is found to be strongly teleconnected with a newly discovered Southern Atlantic Oscillation (SAO) index, which reveals a statistically quite significant relationship (>50%) with drought variability. The positive phase of the SAO index is generally associated with drought across the regions except for IGP and NEI. Despite the recent overall wetting trend, drought frequency has enhanced over most of the regions, modulating the regional hydrological cycle.

Diagnosing Hawaii’s Recent Drought

Abstract Hawaii’s recent drought is among the most severe on record. Wet-season (November–April) rainfall deficits during 2010–19 rank second lowest among consecutive 10-yr periods since 1900. Various lines of empirical and model evidence indicate a principal natural atmospheric cause for the low rainfall, mostly unrelated to either internal oceanic variability or external forcing. Empirical analysis reveals that traditional factors have favored wetness rather than drought in recent decades, including a cold phase of the Pacific decadal oscillation in sea surface temperatures (SSTs) and a weakened Aleutian low in atmospheric circulation. But correlations of Hawaiian rainfall with patterns of Pacific sea level pressure and SSTs that explained a majority of its variability during the twentieth century collapsed in the twenty-first century. Atmospheric model simulations indicate a forced decadal signal (2010–19 vs 1981–2000) of Aleutian low weakening, consistent with recent observed North Pacific circulation. However, model ensemble means do not generate reduced Hawaiian rainfall, indicating that neither oceanic boundary forcing nor a weakened Aleutian low caused recent low Hawaiian rainfall. Additional atmospheric model experiments explored the role of anthropogenic forcing. These reveal a strong sensitivity of Hawaiian rainfall to details of long-term SST change patterns. Under an assumption that anthropogenic forcing drives zonally uniform SST warming, Hawaiian rainfall declines, with a range of 3%–9% among three models. Under an assumption that anthropogenic forcing also increases the equatorial Pacific zonal SST gradient, Hawaiian rainfall increases 2%–6%. Large spread among ensemble members indicates that no forced signals are detectable.

Hydrological Extremes in the Upper Yangtze River Over the Past 700 yr Inferred From a Tree Ring δ18O Record

AbstractOngoing global warming has a strong influence on regional hydrological cycles. The upper reaches of the Yangtze River (UYR) are highly vulnerable to extreme hydrological droughts and floods, but a lack of long‐term streamflow observations has limited our understanding on global warming influences. Here, we establish an annually resolved and absolutely dated tree‐ring oxygen (δ18O) isotope chronology and use it to reconstruct the summer streamflow history of the UYR between 1260 and 2017. The UYR experienced 79 extreme floods and 107 extreme hydrological droughts over this period. We found a trend toward dry conditions in the region with tendencies for an increased drought probability since around 1850s. Especially, the frequency of hydrological droughts in recent decades has been outside the envelope of natural variability of extreme hydrological droughts. The temporal evolution of hydrological extremes is closely linked to variability of the Indian summer monsoon (ISM) at decadal scales. The UYR has experienced more frequent droughts during dry spells and experienced more frequent floods during wet spells of the ISM. The recent increase in the frequency of hydrological droughts is consistent with the observed trend toward a weaker ISM and increasing temperatures. Weaker transport of low‐level moisture and greater evaporation caused by global warming have contributed to the increase in extreme hydrological droughts. Our results thus provide a long‐term context for observed hydrological changes and suggest that the UYR will experience more frequent and severe extreme events as a consequence of increasing greenhouse gas emissions.

The Guadalperal dolmen (Cáceres, Spain). Archaeological and heritage protection interventions

In 2019, the Iberian Peninsula suffered the worst drought in recent decades. The lack of rain and the water shedding to feed the rivers meant a clear reduction in water levels at Spanish reservoirs. This situation allowed previously flooded lands to re-emerge on the surface, and in many cases, they were accessible on foot, as happened at the Valdecañas reservoir (Cáceres). The Dolmen of Guadalperal, due to its spectacular nature aroused great expectation and attracted several curious visitors and the media, who understood that this was a unique opportunity to visit it. The responsible administrations therefore needed to act by protecting and archaeologically studying the site.

Multi-decadal analysis of water resources and agricultural change in a Mediterranean semiarid irrigated piedmont under water scarcity and human interaction

Mediterranean piedmonts are an important hydro-agricultural systems. They constitute the junction between the mountains, where the streamflow is generated, and the surrounding plains, where the water is used. In Morocco, these traditional systems extend largely along the High Atlas Mountains. Yet, changing conditions in the Mediterranean basin as well as recurrent droughts in recent decades remain poorly understood in terms of hydrological and agricultural impacts, particularly in traditional hydro-agro-systems. The combined effects of climate variability and ineffective management of water resource dynamics may lead to increased water scarcity in these regions. The present work aims to assess the effects of climate variability and associated agricultural changes on water resources in a traditional irrigated piedmont of the Moroccan High Atlas. To that end, a trend analysis, together with change points detection, was carried out on annual and monthly precipitation, and streamflow from 1965 to 2018. Then, the standardized precipitation index (SPI) was employed to identify meteorological droughts. Also, groundwater, and spring discharge data were analyzed and discussed from 1973 to 2021. SPI outcomes revealed three major droughts, in 1981–1988, 1999–2008, and 2013–2018. Although the precipitation data showed no significant trend, except for Tahannaout station, the average annual precipitation over the piedmont area decreased by 28%. Similarly, streamflow decreased significantly by almost 40% for all stations, as did the Abainou spring's discharge. Consistent with that, groundwater level has declined dramatically over the past decades in the downstream piedmont. These decreases in water cycle components were tightly aligned with droughts. Yet, irrigation diversions were maintained in both dry and wet periods. Paradoxically, this decrease in water resources was associated with an agricultural transition from seasonal crops (cereals) to perennial crops (olive trees). This conversion is likely to amplify the water shortage, leading to groundwater resources overexploitation to satisfy the growing agricultural demand.

Deep Learning for Vegetation Health Forecasting: A Case Study in Kenya

East Africa has experienced a number of devastating droughts in recent decades, including the 2010/2011 drought. The National Drought Management Authority in Kenya relies on real-time information from MODIS satellites to monitor and respond to emerging drought conditions in the arid and semi-arid lands of Kenya. Providing accurate and timely information on vegetation conditions and health—and its probable near-term future evolution—is essential for minimising the risk of drought conditions evolving into disasters as the country’s herders directly rely on the conditions of grasslands. Methods from the field of machine learning are increasingly being used in hydrology, meteorology, and climatology. One particular method that has shown promise for rainfall-runoff modelling is the Long Short Term Memory (LSTM) network. In this study, we seek to test two LSTM architectures for vegetation health forecasting. We find that these models provide sufficiently accurate forecasts to be useful for drought monitoring and forecasting purposes, showing competitive performances with lower resolution ensemble methods and improved performances over a shallow neural network and a persistence baseline.

Remote Sensing: Mapping of Drought Risk Areas in the Chichaoua Basin of the High Atlas (MarrakechMorocco) using the Vegetation Condition Index (VCI) using Landsat Data from 1984 To 2020

Drought is a complex natural phenomenon and does not have a precise definition. Thus, drought indicates the most frequent risk in the history of Morocco with negative consequences on the environment and the economy of the country. Indeed, the different regions of Morocco have experienced periods of intense drought in recent decades characterized by a decrease in rainfall and a trend towards higher temperatures. The Chichaoua watershed, which is part of the High Atlas with a semi-arid climate, has been exposed to drought episodes several times in recent years. Its effects can have negative impact on agriculture, water resources and immigration of the rural population. This study aims at characterizing the climatic drought at the level of the Chichaoua basin. It is based on the calculation of NDVI to have the calculation of the Vegetation Condition Index VCI, which also indicate the severe and sustainable nature of the drought in this area. This index was calculated using GIS, QGis and Arc Gis, and Landsat satellite imagery scenes. After a comparative study of these years from 1984 to 2020, the evolution of the VCI index was highlighted.

Water dynamics over a Western Patagonian watershed: Land surface changes and human factors

Warming trends in Patagonia and severe droughts in recent decades are still poorly understood in terms of their hydrological effects. The effects of climate change on water dynamics in addition to human water management could generate a future water scarcity scenario in one of the regions with the most abundant water resources of Chile. The aim of this work is to focus on assessing the impacts of warming trends on water dynamics in the Patagonian Simpson River watershed during the last two decades. We estimated anomalies in the main components of water balance such as precipitation (P), snow cover (SC), evapotranspiration (ET) and streamflows (Q) as well as surface variables and meteorological forcing (i.e. air temperature - Ta, solar radiation - RS, land surface temperature - LST). The processed data were obtained from remote sensing, reanalysis and in-situ data. We implemented a trend analysis for each variable in the period 2000-2019 at monthly, seasonal and annual scale. Results showed a warming trend in Ta and LST of about 1.2 °C and 2.1 °C, respectively, concentrated mainly in the autumn and winter seasons. Although P showed non-significant trends, Q diminished significantly at rates of more than 9.1 m3/s/decade, representing 36% of its historical mean. However, the decreases in Q are seen only in the maximum (spring) and minimum (summer) seasonal flows. These decreases are explained by significant increases in ET, led by a positive feedback of its drivers (LST, Ta and RS), which is directly linked to the impact of warming and an associated vegetation greenness in the watershed, as well as a decrease in SC during winter that feeds the Simpson River during spring and summer. The decrease in Q is reinforced by the intensification of water withdrawals in recent decades, as shown by an accelerated increase in water rights for agricultural and drinking uses. In a context of water scarcity and increasing and extreme droughts, this work contributes to further understanding water dynamics in western Patagonia, providing support for policy and decision-making when defining sustainable productive practices at watershed scale.

The Post-Sandstorm Rehabilitation of Rural Settlements Using Action Research Method; the Case of Sang Abad, Kerman Province

Deemed to be one of the most important problems in desert areas, sandstorms are among regularly-occurring disasters. They particularly affect rural areas due to their vulnerability, causing many economic, livelihood-related, physical, social, cultural, and environmental damages. Reagan County in Kerman province is known as one of the country’s most critical areas in this respect, with recent incidents causing 50 evacuations, and damages to a further 150 villages. Widespread droughts in recent decades have caused a lot of damage to the area’s nomadic communities such Sang Abad. Bearing in mind the frequent recurrence of the hazard, the rural settlements of this area are exposed to gradual decay. Exposure to local and regional sources of sandstorms, the high levels of vulnerability, and the poverty and deprivation necessitates the rehabilitation of the village. The action research method is used here. For two years, the researchers have participated in the reconstruction of Sang Abad village (August 2016 - September 2018). Devising a comprehensive and integrated reconstruction planning for the village, they have intervened in rehabilitation and reconstruction keeping in close contact with the residents. The findings have then gone through process of assessment and valuation obtained from the study of the action research methodology. Bearing in mind the differences between the method used here with those of mainstream approaches to reconstruction studies, the feasibility of using this method in future reconstruction studies is also examined. The results of evaluating rehabilitation and reconstruction activities in Sang Abad have shown the effectiveness of these activities in reducing sandstorm hazards. It also seems that rehabilitation of the economy and livelihood is one of the most critical reconstruction priorities in rehabilitation of rural settlements exposed to sandstorms and in particular Sangabad.

Causes of the long-term variability of southwestern South America precipitation in the IPSL-CM6A-LR model

Southwestern South America (SWSA) has undergone frequent and persistent droughts in recent decades with severe impacts on water resources, and consequently, on socio-economic activities at a sub-continental scale. The local drying trend in this region has been associated with the expansion of the subtropical drylands over the last decades. It has been shown that SWSA precipitation is linked to large-scale dynamics modulated by internal climate variability and external forcing. This work aims at unravelling the causes of this long-term trend toward dryness in the context of the emerging climate change relying on a large set simulations of the state-of-the-art IPSL-CM6A-LR climate model from the 6th phase of the Coupled Model Intercomparison Project. Our results identify the leading role of dynamical changes induced by external forcings, over the local thermodynamical effects and teleconnections with internal global modes of sea surface temperature. Our findings show that the simulated long-term changes of SWSA precipitation are dominated by externally forced anomalous expansion of the Southern Hemisphere Hadley Cell (HC) and a persistent positive Southern Annular Mode (SAM) trend since the late 1970s. Long-term changes in the HC extent and the SAM show strong co-linearity. They are attributable to stratospheric ozone depletion in austral spring-summer and increased atmospheric greenhouse gases all year round. Future ssp585 and ssp126 scenarios project a dominant role of anthropogenic forcings on the HC expansion and the subsequent SWSA drying, exceeding the threshold of extreme drought due to internal variability as soon as the 2040s, and suggest that these effects will persist until the end of the twenty-first century.