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Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The future risk for droughts and water shortages calls for substantial efforts by authorities to adapt at local levels. Understanding their perception of drought hazards, risk and vulnerability can help to identify drivers of and barriers to drought risk planning and management in a changing climate at the local level. This paper presents a novel interdisciplinary drought case study in Sweden that integrates soft data from a nationwide survey among more than 100 local practitioners and hard data based on hydrological measurements to provide a holistic assessment of the links between drought severity and the perceived levels of drought severity, impacts, preparedness, and management for two consecutive drought events. The paper highlights challenges for drought risk planning and management in a changing climate at the local level and elaborates on how improved understanding of local practitioners to plan for climate change adaptation can be achieved. [ABSTRACT FROM AUTHOR]

Background: Treeline ecotones of Mediterranean ecoregions have been affected by the increasing intensity and severity of droughts. Even though the effect of droughts on forest dynamics has been widely documented, knowledge is relatively scarce of how extreme climate episodes affect the hydraulic structure and, therefore, the physiology of woody plants. The Mediterranean Andes have experienced an uninterrupted period of drought since 2010, including an extremely dry year in 2019 with approximately 80% rainfall deficit. Here, we investigated shifts in wood anatomical and physiological traits of Kageneckia angustifolia, an endemic treeline species, in response to this drought period. Methods: We evaluated the xylem plasticity of three K. angustifolia populations across their natural distribution (31–35° SL) based on anatomical (vessel structure and distribution) and physiological (intrinsic water-use efficiency) variables in the tree rings. We focused on the period 2000–2020 that corresponds to before the megadrought (2000–2007), (ii) megadrought (2008–2018) and (iii) hyperdrought (2019–2020). The variables were annualized and analyzed by linear mixed-effects models. Results: Our results provide insights to the anatomical and physiological mechanisms underlying the resilience of treeline forests to persistent droughts in central Chile. We found that the extreme drought in 2019–2020 triggered shifts in vessel size and frequency that increased hydraulic safety. These significant shifts in vessel traits occurred in parallel with a decrease in pit aperture area and an increase in water-use efficiency, further increasing the resilience of K. angustifolia to extreme drought stress. Conclusions: Our results revealed coordinated shifts in vessel size and frequency and water-use efficiency in response to the megadrought, thereby reducing vulnerability to hydraulic failure. The apparent resilience of K. angustifolia to extreme droughts suggests that this adaptation to drought stress may increase its ability to tolerate novel climatic conditions of treeline environments of the Mediterranean Andes, although it is not clear whether these adaptations will be sufficient to persist in scenarios that predict intensification of climate stress. Finally, our results provide empirical evidence that integrating wood anatomical and physiological traits facilitates the understanding of resilience mechanisms that treeline forests develop in the face of increasing drought stress. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Atmospheric Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

NOAA has developed a global reference evapotranspiration (ET0) reanalysis using the UN Food and Agriculture Organization formulation (FAO-56) of the Penman-Monteith equation forced by MERRA phase 2 (MERRA2) meteorological and radiative drivers. The NOAA ET0 reanalysis is provided daily from January 1, 1980 to the near-present at a resolution of 0.5° latitude × 0.625° longitude. The reanalysis is verified against station data across southern Africa, a region presenting both significant challenges regarding hydroclimatic variability and observational quantity and quality and significant potential benefits to food-insecure populations. These data are generated from observations from the Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL) network. We further verified globally against spatially distributed ET0 derived from two reanalyses–the Global Data Assimilation System (GDAS) and Princeton Global Forcing (PGF)–and these verifications produced similar results, yet demonstrated wide regional and seasonal differences. We also present cases that verify the operational applicability of the reanalysis in long-established drought, famine, crop- and pastoral-stress metrics, and in predictability assessments of drought forecasts. [ABSTRACT FROM AUTHOR]

Droughts, or severe reductions of water flow, are expected to become more frequent and intense in rivers in many regions under the ongoing climate change scenario. It is therefore important to understand stream ecosystem functioning under drought conditions. We performed a meta-analysis of studies addressing drought effects on litter decomposition in streams (50 studies contributing 261 effect sizes) to quantify overall drought effects on this key ecosystem process and to identify the main moderators controlling these effects. Drought reduced litter decomposition by 43% overall, which can impact energy and matter fluxes along heterotrophic food webs. The magnitude of drought effects on litter decomposition depended on the type of drought (natural drought > human-induced drought), type of decomposer community (microbes + macroinvertebrates > microbes) under natural drought, climate (warm and humid > temperate and Mediterranean) under human-induced drought, and on litter identity. The magnitude of drought effects on litter decomposition also increased with the severity of the drought. The effects of ongoing climate change will likely be strongest in streams with abundant shredders undergoing natural drought, especially if the streams become temporary. The composition of the riparian vegetation may modulate the magnitude of drought effects on litter decomposition, which may have management applications. [ABSTRACT FROM AUTHOR]

The incidence of droughts and their intensity in recent times are affected by climatic variability and change, consequently affecting the agro-based economy of red and laterite zone (RLZ) India. In the present study, changing characteristics of meteorological droughts have been investigated over the sub-humid RLZ of West Bengal, India, using the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI). SPI and SPEI were computed over 1-, 3-, and 12-month time scales from monthly meteorological data from 1930 to 2019 to explore variations in drought frequency, intensity, duration, and spatial extent in the RLZ. It was observed that since the 1990s, the RLZ has been frequently affected by short-term extreme to severe drought, even in the wet-monsoon months. The frequency and intensity of droughts were observed to have increased in the recent period with a decrease in the duration. The Mann–Kendall test on the drought trend analysis of the region indicated a rising trend in monsoon months. The SPEI-monsoon was found to be more significantly correlated (r2 = 0.65) with the rainfed Kharif (monsoon)-rice production anomaly than the SPI. SPEI appeared to have a more pronounced impact on drought incidences in the region over the recent decades. Field surveys were conducted to validate the two recent drought occurrences and associated crop failure. A total of 95% of the farmers in the survey reported crop failure during the short-term meteorological droughts in monsoon months. It is therefore suggested to monitor changing patterns and extent of droughts, particularly in water-scarce RLZs, to design appropriate drought preparedness planning. [ABSTRACT FROM AUTHOR]

This study aims to reveal the relationship of the expansion of the salt-covered area of Lake Tuz in Turkey with the drought in the region and the change of the groundwater storage. The changes in the salt-covered area in Lake Tuz between 1985 and 2021 (37 years), which have been obtained by August satellite images, are compared with those in groundwater and the 12-month Standardized Precipitation–Evapotranspiration Index (SPEI) variations in the lake. The results show that the salt-covered area on the lake surface was most strongly correlated with the SPEI spring (−0.78, t test; p < 0.01) during the period of August 1985–2021, implying that the drought conditions in spring determines 62% of the salt-covered area on the lake in August. The groundwater storage (GWS) in June and July and the salt-covered area in August in Lake Tuz also depict a moderate correlation of −0.60 at 1% significance level from 1985 to 2021. The results illustrate that the SPEI and GWS values decreased, while the salt-covered area on the lake surface expanded in the Lake Tuz Basin over the past 37 years. The trends of the salt-covered area, SPEI, and GWS became especially pronounced after 1999, during which the SPEI change and similar changing trends appeared in the GWS and salt-covered area. These patterns of increase in drought severity and decreasing groundwater storage are expected to increasingly compromise the future of Lake Tuz and cause ecological and environmental problems in the near future. [ABSTRACT FROM AUTHOR]

The Upper Indus Basin (UIB) heavily depends on its frozen water resources, and an accelerated melt due to the projected climate change may significantly alter future water availability. The future hydro-climatic regime and water availability of the Hunza basin (a sub-basin of UIB) were analysed using the newly released Coupled Model Intercomparison Project Phase 6 (CMIP6) climate projections. A data and parameter parsimonious precipitation-runoff model, the Distance Distribution Dynamics (DDD) model, was used with energy balance-based subroutines for snowmelt, glacier melt and evapotranspiration. The DDD model was set up for baseline (1991–2010), mid-century (2041–2060) and end-century (2081–2100) climates projections from two global circulation models (GCM), namely EC-Earth3 and MPI-ESM. The projections indicate a substantial increase in temperature (1.1–8.6 °C) and precipitation (12–32%) throughout the twenty-first century. The simulations show the future flow increase between 23–126% and the future glacier melt increase between 30–265%, depending on the scenarios and GCMs used. Moreover, the simulations suggest an increasing glacier melt contribution from all elevations with a significant increase from the higher elevations. The findings provide a basis for planning and modifying reservoir operation strategies with respect to hydropower generation, irrigation withdrawals, flood control, and drought management. [ABSTRACT FROM AUTHOR]

Background: Worldwide, the arid regions have been experiencing cyclical droughts and devastation due to land desertification. A multi-criteria approach was proposed to establish the relationship between these pressures and assess their impact on the socio-economical, physical, and biological resources. This method was applied at local scale in the palm grove of Draa valley in southeastern Morocco. This paper aims to assess the socio-ecological impacts of drought and desertification, to develop a set of impact indicators of each phenomenon, and explore the relationship between drought and desertification. A framework of analysis was developed based on data collected from a survey using samples of 580 questionnaires: 290 for desertification and 290 for drought. A Likert scale data analysis was applied and rating scales varies from Low, Middle, High, and Very High impact. Results: The results depict that drought is considered a first-rate threat in this region. The findings indicated also a very strong link between drought and desertification. The area is currently suffering from drought followed by desertification and then inundation. Natural and human factors are in the origin of desertification. Conclusions: A set of variables and common variables of drought and desertification were proposed to understand their impacts on well-being. [ABSTRACT FROM AUTHOR]

Drought is an extreme event and its frequency is expected to increase in future under the imminent threats of climate change. The areas vulnerable to drought are increasing due to increase in the spatial extent and severity of droughts. This necessitates the need for development of an integrated framework for assessment of drought vulnerability, which will be vital for water resources management policies focused towards such vulnerable areas. An integrated drought vulnerability assessment framework has been developed considering the physical indicators that vary spatially, social indicators that vary spatially but their temporal variation may be at longer time-frames, and spatio-temporal drought indicators that vary spatially and temporally during various months during drought years. This framework has been tested for Bina basin located in the drought prone Bundelkhand region of Madhya Pradesh. The drought indicators used in the study include (i) Standardized Precipitation Index (SPI) for evaluating meteorological drought characteristics, (ii) Surface water Drought Index (SDI) for evaluating streamflow drought characteristics, and (iii) Groundwater Drought Index (GDI) for evaluating groundwater drought characteristics. Groundwater levels are being observed at quarterly (3 monthly) time step only. So the relationships between GDI and 3-m SPI, 6-m SPI, and 12-m SPI have been investigated. Based on the best correlation, the 12-m SPI can be used to represent the groundwater drought in Bina basin and has therefore been used to assess the monthly variability in the groundwater drought characteristics. The spatially varying physical indicators including basin reach (elevation band), land use pattern and soil type; the spatio-temporal drought indicators including soil moisture drought, surface water drought and groundwater drought, rainfall departure and number of consecutive dry days; and the spatially varying social indicators including infants and young children, illiterate population, marginal workers and rural population have been used for the development of a Drought Vulnerability Index (DVI). The integrated drought vulnerability assessment framework has been conceptualized on the basis of DVI. Four vulnerability classes have been defined and the study area falls in mild to moderate vulnerable class, based on the analysis carried out for the various drought years in the basin. Appropriate drought management plans and mitigation strategies need to be developed to target these vulnerable areas in Bina basin. [ABSTRACT FROM AUTHOR]

The influence of climate change on civil conflict and societal instability in the premodern world is a subject of much debate, in part because of the limited temporal or disciplinary scope of case studies. We present a transdisciplinary case study that combines archeological, historical, and paleoclimate datasets to explore the dynamic, shifting relationships among climate change, civil conflict, and political collapse at Mayapan, the largest Postclassic Maya capital of the Yucatán Peninsula in the thirteenth and fourteenth centuries CE. Multiple data sources indicate that civil conflict increased significantly and generalized linear modeling correlates strife in the city with drought conditions between 1400 and 1450 cal. CE. We argue that prolonged drought escalated rival factional tensions, but subsequent adaptations reveal regional-scale resiliency, ensuring that Maya political and economic structures endured until European contact in the early sixteenth century CE. The influence of climate on premodern civil conflict and societal instability is debated. Here, the authors combine archeological, historical, and paleoclimatic datasets to show that drought between 1400-1450 cal. CE escalated civil conflict at Mayapan, the largest Postclassic Maya capital of the Yucatán Peninsula. [ABSTRACT FROM AUTHOR]

Extreme or recurrent drought events are the principal source of stress on forests, impairing their overall health. They result in financial losses for forest owners and ecosystem service losses for society. Most of the forested area in the Grand-Est region, France, is covered by European beech, which is projected to decline in the future due to repeated drought events driven by climate change. Diversification is a management option that can reduce the drought-induced risk of dieback. Two types of diversification were separately and jointly analyzed: a mixture of beech species with oak species and a mixture of different tree diameter classes. Two types of losses were also considered: financial and in terms of carbon storage under different occurrences of drought events derived from climate change scenarios. We combined an individual-based model of forest growth with a forest economic approach (i.e., land expectation value or LEV), which we adapted to the stochastic context by developing a doubly-weighted LEV. The maximization of the LEV made it possible to identify the most effective adaptation strategies in terms of timber revenue and carbon storage by means of three different carbon values (i.e., market value, shadow price, and social cost). The results showed that diversification increases timber returns and reduces the loss in timber volume due to the drought-induced risk of forest dieback. However, diversification negatively affects carbon storage. Integrating the value of carbon storage increases the value of the forest stand, but only a high carbon value has a significant economic impact. [ABSTRACT FROM AUTHOR]

Climate extremes over the years have been a major concern for the globalized world. The hardest hit from these climate extremes are women farmers with low adaptive capacity. This study explored women farmers' perceived indices of occurrence and severity of observed climate extremes in rural Ghana. Employing the qualitative method approach, eight focus group discussions and 15 interviews were conducted with women farmers under Centre for Alleviation of Poverty, Environment and Child Support GROW Project. The study adopted the thematic analytical approach for the data analysis. The results of the study revealed that the occurrence of drought, flood and bush fires has been an annual phenomenon over the past decade. In terms of severity, women farmers also reported that climate extremes, when they occurred, were very intense, especially drought and bush fires. The results further indicated that rainfall and temperature variations were markedly observed with the prediction of rainfall in particular becoming extremely difficult. Evidently, women farmers observed that climate extremes were caused by deforestation, bush fires and neglect of veneration of ancestral spirits. Importantly, the study found that women have devised their own means of responding to climate extremes to include support networks, savings and spiritual assistance from ancestors for rain when there was prolonged drought. The study recommends the need for the Ministry of Food and Agriculture and the Ministry of Environment Science and Technology to forecast and display information on the yearly occurrence and severity of drought, flood and bush fires to complement women's local knowledge in decision making. [ABSTRACT FROM AUTHOR]

Due to extreme climate changes, plants are exposed to severe soil water content, i.e. flooding and drought. The aim of this study was to assess the effect of different soil water content on the nutritional potential of young Chinese cabbage (Brassica rapa ssp. pekinensis) on the level of phenolics, sugars, photosynthetic pigments and antioxidant capacity. Total phenolic acids were induced in plants grown under drought conditions. Both types of stress increased soluble sugars in Chinese cabbage but reduced total tannins. Plants grown under drought had more L-ascorbic acid than the control group; however, the concentration of ferulic acid and quercetin was reduced. On the other hand, excess of water increased the amount of sinapic and ferulic acid, main hydroxycinnamic acids in Chinese cabbage. Photosynthetic pigments were more susceptible to flooding (reduced amount) than drought, the only exception was chlorophyll b whose concentration was significantly higher in plants grown under drought. In addition, among all the measured parameters, chlorophyll b reacted most specifically against flooding (decreased) and drought (increased). Chinese cabbage grown under flooding had reduced amount of porphyrins compared to the one grown under normal and drought conditions, but showed higher antioxidant capacity (ABTS). Based on the results, the use of excess water could be considered as a possibility when growing young Chinese cabbage since it increased the concentration of antioxidants sinapic and ferulic acid and resulted in higher antioxidant capacity, recorded by ABTS assay, compared to control plants. [ABSTRACT FROM AUTHOR]

European Union's vulnerability to climate change stretches far beyond its borders because many of its economic sectors, such as meat and dairy, use raw materials sourced from far afield. Cross-border climate vulnerability is a relatively new subject in scientific literature, while of high societal and economic relevance. We quantify these climate vulnerabilities with a focus on drought risk and assessed them for 2030, 2050, 2085 and for RCP 2.6 and 6.0 climate scenarios. Here we find that more than 44% of the EU agricultural imports will become highly vulnerable to drought in future because of climate change. The drought severity in production locations of the agricultural imports in 2050 will increase by 35% compared to current levels of drought severity. This is particularly valid for imports that originate from Brazil, Indonesia, Vietnam, Thailand, India and Turkey. At the same time, imports from Russia, Nigeria, Peru, Ecuador, Uganda and Kenya will be less vulnerable in future. We also report that the climate vulnerabilities of meat and dairy, chocolate (cocoa), coffee, palm oil-based food and cosmetic sectors mainly lie outside the EU borders rather than inside. European Union's vulnerability to climate change stretches far beyond its borders. Here the authors find that more than 44% of the EU agricultural imports will become highly vulnerable to drought in future because of climate change. [ABSTRACT FROM AUTHOR]

Objective evaluation of the relationships among different types of droughts remains a challenging task due to the combined impacts of climate change and land surface modification caused by human activities. Based on the Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI) at the 3- and 6-month timescales, this study presents a systematic analysis of the relationships between the severity (S) and duration (D) of meteorological (MD) and hydrological droughts (HD) in the three catchments of the upper Huai River Basin in China. The relation between SPI and SRI is explored by the maximal information coefficient and the mutual entropy. The spatial propagation mechanism of MD is identified by the centroid trajectory, and the response of HD to MD is quantified by the model averaging method. The results indicate a drying (wetting) trend in the upstream (downstream) area, while the centroid trajectory of MD is found in the midstream area, but not associated with the large (or small) S and D simultaneously. There is a strong correlation (determination coefficient > 0.55) between SPI and SRI in all three subareas, particularly at the 6-month timescale. The increasing influences of human activities (e.g., regulation of water conservancy facilities) from upstream to downstream lead to a weaker correlation between SPI and SRI as well as a decreasing threshold of D for MD to trigger HD in downstream. By contrast, the drier climatic conditions are the main reason for the increasing threshold of S for MD to trigger HD from upstream to downstream. [ABSTRACT FROM AUTHOR]

While the literature on adaptation to drought has increasingly focused on investigating farmers' understanding of drought, no comprehensive study has been conducted on behavior determinants and farmers' adaptation strategies so far. To address this research gap, the current study was performed to investigate the effective factors and determinants on applying adaptation strategies by farmers in Iran. The statistical sample of the study included 430 farmers in East Azerbaijan province (located in northwest of Iran) selected through multistage sampling method. Study results after categorization of adaptation strategies (AS) first indicated that, the farmers under study suffer from a lack of high adaptation but in order to add more accuracy and grouping farmers' strategies in drought condition, exploratory factor analysis was applied in which they were categorized as self-control, active and integrated strategies. Next, structural equation modeling was adopted to study the effective factors on applying AS by farmers confronted with the drought. The results showed that, social, environmental, infrastructure, and economic factors exert a positively significant effect on selecting the AS whereas, human-related factors were proved to have an insignificant effect on adopting the AS. The results associated with structural equations indicated that, effective factors account for 93.3% of variance in application of AS which is a highly considerable rate. Indeed, these results revealed high importance of social factor, environmental factor, infrastructure factor and economic factors in applying the AS among the farmers. Therefore, our findings offered solutions as to how to reduce risks in farmers' activities during drought conditions to improve adaptation behavior of Iranian farmers. [ABSTRACT FROM AUTHOR]

Applying combined nonlinear indices is a useful approach in assessing drought condition. This study investigates a combined multivariate index (Joint Deficit Hydro-meteorological Index: JDHMI) in monitoring hydro-meteorological drought to determine whether the index could simultaneously reflect the complicated nonlinear behavior of precipitation and runoff in a watershed. The JDMI (JDHI) index is obtained on the basis of the joint marginal distribution of SPImod1,..., SPImod12 (SRImod1,..., SRImod12) using the empirical copula. The JDHMI then is computed by combining the JDMI and JDHI indices using a suitable theoretical copula. Furthermore, drought characteristics (severity-duration-magnitude) are extracted from the JDHMI and trivariate conditional return periods that are obtained from three-dimensional copulas in four different scenarios. Results of this study indicate that (1) multivariate copulas effectively reflect the complicated and nonlinear relationship between drought variables; (2) comparison between univariate and multivariate drought indices indicated that the JDHMI is slightly more sensitive to the historical events; and (3) spatial distribution of drought hazard is illustrated using conditional return period obtained in four different scenarios in Bandar-Sedij and Kole-Mehran watershed. Additionally, the conditional probabilities provide effective information for forecasting drought conditions. In this regards, on the basis of several specific values of S-D-M, it is estimated that the central and eastern parts of the region will experience frequent hydro-meteorological drought over next 18 years. Finally, due to the climatic changing in the recent years, findings of this study could be useful in reducing drought effects on the natural resources and also help decision-makers in developing water resources. [ABSTRACT FROM AUTHOR]

Drought has become one of the most serious meteorological disasters for agricultural production in many areas around the world, and the situation could be worse under the impact of climate change. To facilitate better adaptation planning, this study proposed a drought assessment framework integrating downscaling method, drought index, copula technique, and bivariate frequency analysis, and applied it to investigate the change of the drought characteristics and drought risks from the past to the future in Huang-Huai-Hai River basin (HRB), North China. Drought was firstly defined by standardized precipitation evapotranspiration index (SPEI) based on 1497 observed grid data from 1979 to 2004. Then, we constructed the joint distribution of drought duration and severity based on copulas to detect and quantify the drought risks. To address the effect of climate change, similar calculation process was applied to the future climate data, which was downscaled using delta change method from representative concentration pathway (RCP 8.5) of 12 general circulation models (GCMs). The study results suggested that, under climate change condition, most irrigation districts over HRB would generally experience lower frequency of drought events but with extended duration; some districts would have more serious drought, but majority would experience similar or even lower level of severity. In light of the mean joint occurrence probability, the irrigation district at the south part of Huai River basin would likely experience the highest increase of drought risks in near future (by 0.86%) and distant future (by 0.76%), while most of other districts over HRB would face low risk of serious drought risks. The obtained results offer useful information to agricultural managers or water resources authorities who are interested in the development of effective long-term adaptation strategies for drought management. [ABSTRACT FROM AUTHOR]

Reliable drought projections are crucial for the effective managements of future drought risk. Most of the existing drought projections over Southern Africa are based on precipitation alone, neglecting the influence of potential evapotranspiration (PET). The present study shows that inclusion of PET may alter the magnitude and robustness of the drought projections. The study used two drought indices to project potential impacts of global warming on Southern African droughts, focusing on four major river basins. One of the drought indices (SPEI: Standardized Precipitation Evapotranspiration Index) is obtained from climate water balance (i.e. precipitation minus potential evapotranspiration) while the other (SPI: Standardized Precipitation Index) is calculated from precipitation alone. For the projections, we analyzed multi-model regional climate simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX) at four specific global warming levels (GWLs) (i.e., 1.5 °C, 2.0 °C, 2.5 °C, and 3.0 °C) above the pre-industrial level and used the self-organizing maps to classify the drought projections into groups based on their similarities. Our results show that the CORDEX simulations give a realistic representation of all the necessary climate variables for quantifying droughts over Southern Africa. The simulations project a robust increase in SPEI drought intensity and frequency over Southern Africa and indicate that the magnitude of the projection increases with increasing GWLs, especially over the various river basins. In contrast, they project a non-significant change in SPI droughts at all the GWLs. The majority of the simulations clearly distinguish between the projected SPEI and SPI drought patterns, and the distinction becomes clearer with increasing GWLs. Hence, using precipitation alone for drought projection over Southern Africa may underestimate the magnitude and robustness of the projections. This study has application in mitigating climate change impacts on drought risk over Southern African river basins in the future. [ABSTRACT FROM AUTHOR]

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social benefits. Here, we combine high-resolution airborne LiDAR and optical data to track tree-level mortality rates for ~2 million trees in California over 8 years, showing that tree height is the strongest predictor of mortality during extreme drought. Large trees die at twice the rate of small trees and environmental gradients of temperature, water, and competition control the intensity of the height-mortality relationship. These findings suggest that future persistent drought may cause widespread mortality of the largest trees on Earth. Drought is intensifying due to climate change, impacting forests globally. Here, the authors track nearly 2 million trees through severe drought and show that tree height is the greatest predictor of mortality risk, suggesting that the tallest trees may be the most vulnerable. [ABSTRACT FROM AUTHOR]