Greater Drought Research Articles

Weird weather in Bristol during the Grindelwald Fluctuation (1560–1630)

The Grindelwald Fluctuation (1560–1630) was a cooling phase during the ‘Little Ice Age’ (c.1300–1850). Poor weather during the Fluctuation contributed to harvest failures, mass starvation and political crises across the globe. This paper examines information taken from Bristol chronicles that discuss some of the extreme weather events of the period. The entries support the notion that the Grindelwald Fluctuation featured some extraordinarily poor weather, such as great frosts, floods, severe storms, unseasonal snowfalls and droughts.

Analysis of Hydro-Meteorological Variables and Runoff Characteristics in the Sudano-Sahelian Ecological Zone of Nigeria

This study examines the impact of climate change on hydrologic resources of selected rivers and lakes in the Sudano- Sahelian Ecological Zone of Nigeria. Climatologically data acquired were rainfall, temperature and evaporation from Nigeria Meteorological Agency, Oshodi, Lagos. Similarly, the hydrological data of river discharge and lake levels were obtained from Nigeria Hydrological Services, Kaduna. We used the Standardised Anomaly Index to test for fluctuations in rainfall, temperature, runoff and water level in lakes. Mann Kendall statistics were used to examine the trends in the climate variables. Pearman correlation was adopted to test the relationship between runoff and the rainfall variables. The findings revealed a general downward trend in rainfall amounts in the 1970s and 1980s. The findings also detected an upward trend in the amount of rainfall from 1990 to 2019. The correlation results of rainfall attributes and runoff showed significant relationships in annual rainfall (r= 0.61), annual rain-days (r=0.61), rain days of heavy rainfall (r= 0.57) and wet season rainfall (r=0.54). These attributed when combined, revealed a 51% contribution to the overall regression with (r=0.51) at 95% probability level. The study concluded that the Sudano-Sahelian Ecological Zone of Nigeria experiencing an increase in the annual rainfall. The increase in rainfall point to the recovery of the rainfall from the great Sahelian drought of the 1970s and 1980s. The rise in the annual rainfall is a possible influencing factor to the frequent occurrences of flooding in recent time across the ecological zone.

50 years of woody vegetation changes in the Ferlo (Senegal) assessed by high-resolution imagery and field surveys

Woody vegetation dynamics in the Sahel have been debated since the great droughts of the 1970s–1980s. Here, we combined high-resolution satellite and aerial imagery, field inventory, and historical botanical records to study woody vegetation trends over the years 1965, 1980, 2008, and 2018 in the Ferlo, the Sahelian sylvo-pastoral zone of Senegal. While tree density has decreased from 1965 (14.8 trees ha−1) to 1980 (13.4 trees ha−1) and 2008 (11.9 trees ha−1), tree density has stabilized in 2018 (12.2 trees ha−1). The relatively moderate decrease in tree density over 50 years characterized by extensive human pressure and droughts, as well as the rather stable woody cover following the drought years after the 1980s, do not support narratives of widespread desertification in this region. However, we observed a shift in the composition of species. While the drought-resistant tree Balanites aegyptiaca showed a stable abundance, Acacia tortilis showed strong increases and other species like Sclerocarya birrea and Combretum glutinosum decreased. In addition, recent field surveys show that the ratio between shrubs and trees has increased towards more shrubs. The observed loss of species diversity combined with the increase of drought-resistant species is in line with current observations for savanna ecosystems in the context of an increased aridity.

LAND USE DATA IN THE MIDDLE MAULE RIVER SUB-BASIN: CLASSIFICATION AND COMPARISON BETWEEN 1999 AND 2019

Abstract. The use of satellite images is a modern strategy for the evaluation and prediction of various weather scenarios. In addition, this is a key tool for the development of environmental sciences. Since the end of the last decade, Chile has been suffering from a megadrought associated with climate change. In this context, this study proposes to evaluate the role of land use change in the Middle Maule River sub-basin, located in the Maule Region, Chile. This is an important sector characterized by a significant agricultural and hydroelectric contribution. To do so, this study performs a supervised classification of land cover through the usage of QGIS software and Landsat images for the years 1999 and 2019. The results show the growth of areas without vegetation due to a great drought facing the Central Zone of the country. Additionally, there is a decrease in available bodies of water. This article leaves open future research on the impact of the main economic activities of the region.

Drought in daily life: family farming and drought in rural communities in the “gerais” of Januária, MG

The Semiarid region of Minas Gerais experienced a severe drought between 2011 and 2018. In this area of already degraded water sources, scarce and concentrated precipitation contributed to reducing water for domestic and productive use. Considering the great drought as a scenario, this article seeks to understand the daily supply dynamics of rural families and analyze the arrangements made to ensure water supply in two communities of family farmers in the gerais region, vast plateaus of the Upper Middle São Francisco River. It investigated the topic using social research techniques (interviews and focus groups) and environmental research (analysis of sources and consumption) during the dry and rainy seasons over a year. The article reveals that in this "drought season", the existence of public programs to provide water and income ensured sufficient supply for the rural population. However, farmers needed to introduce adjustments and innovations in water management, consumption, and especially agriculture, in order to conserve, even on new bases, production systems and community organization.Keywords: family farming; semi-arid; water; drought; Minas Gerais.How to citeCRUZ, Gildarly Costa da; RIBEIRO, Eduardo Magalhães; ARAÚJO, Vanessa Marzano; ASSIS, Thiago Rodrigo de Paula. A seca no cotidiano: agricultura familiar e estiagem em comunidades rurais do gerais de Januária, MG. Estudos Sociedade e Agricultura, Rio de Janeiro, v. 28, n. 3, p. 700-720, out. 2020. DOI: https://doi.org/10.36920/esa-v28n3-9.Received on May 28, 2020. Accepted on August 21, 2020.

HaASR1 gene cloned from a desert shrub, Haloxylon ammodendron, confers drought tolerance in transgenic Arabidopsis thaliana

Abiotic stresses pose adverse impact on plant growth and development and exploring the stress tolerance genes from dominant species is still urgent. The desert shrub, Haloxylon ammodendron, a C4 and succulent xero-halophyte species, has great drought and salt tolerance. Here, we reported the isolation and functions analysis of HaASR1 (abscisic acid, stress, and ripening) from H. ammodendron. HaASR1 interacts with HaPrxQ and HaBADH and may function in preventing PrxQ and BADH from denaturation in plants under drought stress. Overexpression of HaASR1 reduces the sensitivity of Arabidopsis plants to exogenous ABA and decreases the endogenous ABA level through down-regulating ABA biosynthesis genes under drought stress, which making the plants display less inhibition of shoot growth and enhanced drought tolerance. Overexpression of HaASR1 significantly enhances photosynthetic capacity of Arabidopsis plants under drought stress by reducing H2O2 accumulation through up-regulating AtCAT2, AtAPX1 and AtPrxQ and maintaining relatively integrity of chloroplasts. Overexpression of HaASR1 also significantly improves water-retaining ability. Taken together, we propose that HaASR1 plays critical roles in plant drought stress adaptation by making the plants partially defective in ABA signaling and participating in drought tolerance regulation through nonstomatal pathways, enhancing ROS-scavenging ability and water-retaining ability, which is different from the functions of previously reported ASR genes from other plant species. This research also reveals that HaASR1 gene from the desert shrub, Haloxylon ammodendron, has potential application values in improving abiotic stresses of other plant species by genetic engineering.

A construção do espaço e da memória sonora da cidade de Sobral e da seca de 77-78 em Luzia-Homem

O presente artigo busca analisar o processo de construção da memória sonora do período da grande seca na cidade de Sobral entre 1877 até 1878 tendo como objeto de análise o romance naturalista-regionalista Luzia-Homem de Domingos Olímpio, a partir disso analisaremos a relação entre os conceitos de sonoridade, literatura, história e memória. A memória sonora é tida como um espaço de totalidade de sons que compõem a realidade, carregada de significados multicilturais e identitários compartilhados pelo grupo; neste sentido, encaramos a espaço da cidade como um espaço praticado e dinâmico. Os autores que embasam nossas considerações são: Schafer (2001), Chartier (2009), Pesavento (2005), Melo (2017), Lefebvre(2000) e Ricoeur (2007).

Prediction Skill of the 2012 U.S. Great Plains Flash Drought in Subseasonal Experiment (SubX) Models

AbstractRapid-onset droughts, known as flash droughts, can have devastating impacts on agriculture, water resources, and ecosystems. The ability to predict flash droughts in advance would greatly enhance our preparation for them and potentially mitigate their impacts. Here, we investigate the prediction skill of the extreme 2012 flash drought over the U.S. Great Plains at subseasonal lead times (3 weeks or more in advance) in global forecast systems participating in the Subseasonal Experiment (SubX). An additional comprehensive set of subseasonal hindcasts with NASA’s GEOS model, a SubX model with relatively high prediction skill, was performed to investigate the separate contributions of atmospheric and land initial conditions to flash drought prediction skill. The results show that the prediction skill of the SubX models is quite variable. While skillful predictions are restricted to within the first two forecast weeks in most models, skill is considerably better (3–4 weeks or more) for certain models and initialization dates. The enhanced prediction skill is found to originate from two robust sources: 1) accurate soil moisture initialization once dry soil conditions are established, and 2) the satisfactory representation of quasi-stationary cross-Pacific Rossby wave trains that lead to the rapid intensification of flash droughts. Evidence is provided that the importance of soil moisture initialization applies more generally to central U.S. summer flash droughts. Our results corroborate earlier findings that accurate soil moisture initialization is important for skillful subseasonal forecasts and highlight the need for additional research on the sources and predictability of drought-inducing quasi-stationary atmospheric circulation anomalies.

Nutritional muscular dystrophy in lambs reared on pasture in semiarid region of Brazil

This article presents important data on the diagnosis of nutritional muscular dystrophy (NMD) in sheep reared in the semiarid region of Northeast Brazil, with a focus on medical clinic data, nutritional management, anatomopathological aspects and quantification of serum selenium by highly sensitive analytical methodology. The semiarid region of Brazil is of great importance in the creation of small ruminants and many diseases that affect herds are related to failures in nutritional management, sanitary measures, periods of greater drought or low rainfall, little availability of native forage at certain times of the year and lack of supplementation with energy nutrients, proteins and minerals. The lack of publications on outbreaks of selenium deficiency demonstrates the importance of diagnosing in this area. The mean concentration of Se in the serum from the lambs was very low (2.52±1.02µg/L). The findings in the skeletal muscles are compatible with the characteristics observed in NMD, characterized by necrosis and calcification of myofibrils. In addition, necrotizing vasculitis in hepatic arterioles and hepatocellular coagulation necrosis in hepatocytes were observed, probably triggered by lipid peroxidation of cell membranes. The lambs from this outbreak, reared on pasture in the semiarid region, presented low serum Se concentration, with clinical and anatomopathological manifestation of NMD. Thus, supplementation with Se in the diet should be recommended regularly to avoid the appearance of new cases. Serum Se levels are useful indicators for the diagnosis of nutritional muscular dystrophy in lambs, associated with clinical and anatomopathological data.

Coinoculação do amendoim (Arachis hypogaea L.) com Bradyrhizobium e Azospirillum promove maior tolerância à seca

O uso de rizobactérias promotoras de crescimento pode ser uma estratégia de manejo para amenizar os efeitos da deficiência hídrica no crescimento e no desenvolvimento das plantas por modificar o metabolismo fisiológico e promover maior tolerância à seca. Este estudo teve como objetivo investigar os efeitos da inoculação das sementes com Bradyrhizobium japonicum e Azospirillum brasilense de forma isolada e combinada no crescimento e na indução da tolerância das plantas de amendoim (Arachis hypogaea L., cv. RUNNER IAC 886) à restrição hídrica. O delineamento experimental adotado foi o de blocos ao acaso em esquema fatorial 3 × 4, constituídos por três níveis de irrigação [100% da capacidade de retenção de água do solo (controle), 50% do controle (estresse moderado) e 25% do controle (estresse severo)] e por quatro tratamentos de inoculação [controle (sem inoculação), inoculação com B. japonicum, inoculação com A. brasilense e coinoculação das sementes com B. japonicum e A. brasilense, com quatro repetições. A restrição hídrica foi imposta no início do aparecimento do ginóforo, aos 40 dias após a emergência das plantas, por um período de 18 dias. As plantas expostas as condições de restrição hídrica severa tiveram redução de a altura da planta (32%), área foliar (44%), volume radicular (47%), matéria seca da parte aérea (35%) e na matéria seca das raízes (37%) quando comparadas às plantas em condições controle. A inoculação com B. japonicum e A. brasilense de forma isolada ou combinada melhorou a integridade da membrana plasmática em 7% e reduziu em 8% as perdas de água das folhas de amendoim expostas à deficiência hídrica. A inoculação com A. brasilense de forma isolada ou combinada com B. japonicum resultou em maior altura de planta (21%) e maior matéria seca das raízes (23%) quando comparado as plantas não inoculadas sob condições de restrição hídrica severa. Nossos resultados sugerem que inoculação com B. japonicum e A. brasilense de forma isolada ou combinada pode amenizar os efeitos adversos da deficiência hídrica, mantendo o crescimento e o acúmulo de matéria seca das plantas quando expostas à restrição hídrica. Portanto, o uso destas rizobactérias na cultura do amendoim pode ser uma alternativa de manejo em condições de cultivo sujeitas a ocorrência de deficiência hídrica por conferir maior tolerância das plantas à seca.

Análise da eficiência do uso da água na fruticultura irrigada do Vale do Açu no Rio Grande do Norte

O objetivo desse artigo é analisar a eficiência do uso da água na fruticultura irrigada do Vale do Açu/RN durante a grande seca que atingiu a microrregião no período de 2012-2015, em específico o caso dos produtores de manga e banana. Para tanto, foram usadas as técnicas de Data Envelopment Analysis (DEA) visando calcular os níveis de eficiência técnica e a eficiência de sub-vetor para medir a eficiência do uso da água. Os resultados da eficiência de sub-vetor apontam que, em média, 43% dos produtores de manga foram eficientes no uso da água. Os níveis de eficiência para os produtores de banana foram ainda mais baixos, alcançando apenas 28%. Portanto, os padrões de uso da água na fruticultura irrigada do Vale do Açu podem ser otimizados mantendo-se o mesmo nível de produção, exigindo uma ação efetiva nessa direção.

Extreme heat and drought in 1473 and their impacts in Europe in the context of the early 1470s

Droughts and heatwaves are both dangerous natural hazards with a potential significant impact on human societies. In order to understand these hazards, it is important to examine such extreme events in the past. During the years 1471 to 1474, warm and dry weather conditions are described in most parts of Europe. Until now, these extraordinary years have not been examined in depth. Moreover, in spring 1473, a great drought and heat occurred in Europe. This heatwave facilitated a fast phenological development. During the summer and the autumn, temperatures were unusually high, and extremely dry weather conditions continued. In many places, the harvest began remarkably early, and there was abundant wine of a good quality. Fruit trees even bloomed for the second time in autumn. The heat and drought had a considerable impact on the environment and also caused damage to agriculture and society, including water shortages, harvest failures and rising food prices. The weather conditions of the years from 1471 to 1474 were outstanding during the fifteenth century and the heatwave and drought, as well as impacts on environment, economy, and society in the year 1473, were comparable to—if not more severe—than those in the year 1540. Learning from past climate anomalies like the 1473 drought in Europe is important for evaluating more recent and future climate extremes under increasing anthropogenic pressure.

РОЛЬ ЦАРЯ ПЕПИ I В СТАНОВЛЕНИИ БУДУЩЕЙ СТОЛИЦЫ ЕГИПЕТСКОГО ГОСУДАРСТВА — МЕМФИСА

There is a common point of view in Egyptology that Memphis was a state capital since the earliest times and that its protecting gods were Ptah and his spouse Sekhmet. Arguing this concept, the author tries to find the reason why a pyramid city of Pepi I — Mennefer — became a core of the future capital. The main conclusion is following: Constructing his pyramid complex, Pepi I probably included into it a cult center of Habes where Bastet and Imhotep, a high priest of Ra, were worshiped. Imhotep, a companion of the king Djoser, was known as a priest and charmer who tamed the fiery forces of Sirius associated with Bastet, after which the great drought was over. To commemorate this, New Year celebration and the first sun calendar were established. Imhotep’s tomb became an important cult place, where ceremonies important for surviving of the Egyptian state were conducted. In the second half of the Old Kingdom period the Nile started to flood much less, which led to the decline of agriculture. Thus, the role of the cult center of Habes and Imhotep grew greatly. By including Habes, Pepi protected the dominion of his pyramid city from negative influence of Bastet and decreased flooding. The fact that Mennefer was a successor of the aforementioned cult center determined its capital functions in future.

O traço do personalismo das instituições assistenciais: doadores, doações e projeção social no Ceará oitocentista

In the nineteenth century, Brazil witnessed the emergence of the first welfare institutions. These became the platforms for provincial states to raise the status of their political and economic elite, naming them great benefactors. Men of local repute played active roles in building certain institutional spaces, employing practices that reinforced their social prestige not just among their peers and for their time, but also for the memory and history of the institutions with which they were involved. The building of three welfare institutions in the province of Ceará is problematized: Asilo de Mendicidade, Colônia Orfanológica Cristina, and Asilo de Alienados São Vicente de Paula, whose discourse and philanthropic actions were entangled with the great drought of 1877-1879.

Водоудерживающая способность хвои в популяциях основных лесообразующих видов хвойных в лесах таежной зоны Сибири

The limits of individual variation of trees by the water-retaining capacity of needles in populations of forest-forming coniferous species (Scots pine, Siberian pine, Siberian spruce and Siberian fir) growing in the conditions of the mountainous, middle and northern taiga of Central and Eastern Siberia were studied. It is found that among the compared evergreen species, Scots pine and Siberian pine are characterized by the highest intrapopulation variation in the rate of needles dehydration; Siberian spruce and Siberian fir are characterized by greater variability in the ability of needles to water absorption. However, in samples of the last twospecies, the share of trees with a low rate of water loss is quite large, even in wet habitats. In more drought-resistant pine species there is a smaller part of trees, which quickly evaporate moisture and have a high water capacity of needles. While a smaller part of trees of Siberian spruce and Siberian fir are less resistant to dehydration and differ by low water capacity of needles. While in Siberian spruce and Siberian fir a smaller part are trees less resistant to dehydration with low water capacity of needles. We revealed the significant differences between species in mixed stands and between geographic populations of species by water-retaining capacityof needles. The highest values of this indicator were obtained for Scots pine and Siberian spruce from Yakutia, as well as for old-growth trees of Siberian pine from the Western Sayan. The necessity of preserving old-growth stands and trees, characterized by the greatest drought resistance of needles, especially hygrophilous dark coniferous species in a changing climate is emphasized.The obtained data and correlations between the used features allow us to estimate one of the components of drought resistance of taiga populations of coniferous species and their intrapopulation diversity.For citation: Tikhonova N.А., Tikhonova I.V. Water Retaining Capacity of Needles in Populations of the Main Forest-Forming Coniferous Species in the Forests of the Taiga Zone of Siberia. Lesnoy Zhurnal [Forestry Journal], 2019, no. 5, pp. 83–94. DOI: 10.17238/issn0536-1036.2019.5.83Funding: The research is carried out within the framework of the budget project No. 0346-2016-0301 of the West-Siberian Branch of Sukachev Institute of Forest SB RAS and the Federal Research Center “Krasnoyarsk Science Center SB RAS” with the partial financial support from the Russian Foundation for Basic Research, the Government of Krasnoyarsk Territory, and the Krasnoyarsk Regional Fund of Science in the framework of the research project No. 18-44-240002.

Drought and the South African Imagination: Selected Readings

Both the work of a number of poets and novelists and the popular discourse of the late twentieth and early twenty-first centuries epitomise the fascination which drought continues to hold for the South African imagination. They also embody the environmental humanities principle that “environment” is inseparable from “society.” If, as has recently been argued, our literature is continuous with San orature, then our memory of drought covers millennia. A selective account of texts from the 1820s to the early twentieth century illustrates this continuity, as well as the complexity and controversy of the issue. In conclusion, 1933 was in popular memory the year of a “great drought,” anticipated by Francis Carey Slater and responded to by W. A. Kingon, C. M. van den Heever and, most powerfully, Eugène Marais.Keywords: Drought, South African literature, Eugène Marais

Quantitative scenarios for future hydrologic extremes in the U.S. Southern Great Plains

Decision‐makers using climate projection information are often faced with the problem of data breadth, complexity, and uncertainty, which complicates the translation of climate science products in addressing management challenges. Recently, the concept of climate scenario planning attempts to simplify climate information by developing a series of plausible future “storylines.” In some cases, however, these storylines lack quantitative detail on extremes that may be useful to decision‐makers. Here, we analyse a large suite of statistically downscaled climate projections from two methods to develop quantitative projections for hydrologic extremes (heavy precipitation and drought) across Oklahoma and Texas in the United States. Downscaled projections are grouped into four specific temperature/precipitation scenarios, including “Warm/Wet,” “Hot/Dry,” “Central Tendency,” and the full multi‐model ensemble average. The region is split into three sub‐domains spanning the region's west–east precipitation gradient, and projections are examined throughout the mid‐ and late‐21st century, using two emissions scenarios (“mid‐range” and “high”). Most scenarios project increased frequency and duration of moderate or greater drought across the whole domain, with the high‐emissions Hot/Dry projections showing the most severe examples. The Warm/Wet scenario also increases the frequency of dry months, particularly in the Southern High Plains, but does not discernably alter duration, and retains a similar frequency of pluvial (wet) periods. The mid‐range projections generally retain similar evolutions among scenarios, but they reduce drought intensity and project no change in drought/pluvial frequency with the Warm/Wet scenario. Notably, the occurrence of intense precipitation increases across all scenarios and emissions categories and does not significantly differ between any of the scenarios, including Hot/Dry versus Warm/Wet. Some observed differences in extreme precipitation magnitudes between the two downscaled data sets are briefly discussed.

Economics of Increasing Sorghum Productivity in Sub-Saharan Africa: The Mali Case.

Sorghum retains a crucial role in Sub-Saharan Africa for food and in the future feed. Unfortunately, the movement of sorghum technology onto farmers' fields in Sub-Saharan Africa has been slow in spite of substantial research since the great African drought of 1968-1973. What is necessary to get African sorghum yields and profitability up?After reviewing the situation of sorghum in the world, the USA, and Sub-Saharan Africa from 2007 to 2017 the results and the lessons of a twelve-year program in the Sahel of West Africa to introduce new sorghum technology and marketing strategies are the focus of the rest of the paper. In Mali, the program identified new technologies that were extended into a large number of farmers' associations. The Mali program then collaborated with two other agencies to scale up this pilot program. The pilot project demonstrated that yields with moderate fertilization, new varieties, and improved agronomic practices could be increased 50 to 100% and prices increased 30 to 50%. The 2012 military coup and then invasion of Al Queda from the north shut down both the pilot and the scaling up activities as the US government banned collaboration with Malian government agencies after the coup. The pilots were continued in Niger and Burkina Faso through 2014 and then with a Gates Foundation grant from 2014 to 2016. The pilot program in Mali responded to two of the three Second Generation problems identified. But more significantly the pilot project identified the lack of funds for responding to Second Generation problems as a major constraint for implementing a technology-marketing program in a low-income country.

Climate and the Global Famine of 1876–78

AbstractFrom 1875 to 1878, concurrent multiyear droughts in Asia, Brazil, and Africa, referred to as the Great Drought, caused widespread crop failures, catalyzing the so-called Global Famine, which had fatalities exceeding 50 million people and long-lasting societal consequences. Observations, paleoclimate reconstructions, and climate model simulations are used 1) to demonstrate the severity and characterize the evolution of drought across different regions, and 2) to investigate the underlying mechanisms driving its multiyear persistence. Severe or record-setting droughts occurred on continents in both hemispheres and in multiple seasons, with the “Monsoon Asia” region being the hardest hit, experiencing the single most intense and the second most expansive drought in the last 800 years. The extreme severity, duration, and extent of this global event is associated with an extraordinary combination of preceding cool tropical Pacific conditions (1870–76), a record-breaking El Niño (1877–78), a record strong Indian Ocean dipole (1877), and record warm North Atlantic Ocean (1878) conditions. Composites of historical analogs and two sets of ensemble simulations—one forced with global sea surface temperatures (SSTs) and another forced with tropical Pacific SSTs—were used to distinguish the role of the extreme conditions in different ocean basins. While the drought in most regions was largely driven by the tropical Pacific SST conditions, an extreme positive phase of the Indian Ocean dipole and warm North Atlantic SSTs, both likely aided by the strong El Niño in 1877–78, intensified and prolonged droughts in Australia and Brazil, respectively, and extended the impact to northern and southeastern Africa. Climatic conditions that caused the Great Drought and Global Famine arose from natural variability, and their recurrence, with hydrological impacts intensified by global warming, could again potentially undermine global food security.

Drought (scPDSI) reconstruction of trans-Himalayan region of central Himalaya using Pinus wallichiana tree-rings

Knowledge of the long-term frequency and intensity of drought events in an area is crucial since drought has adverse effects on natural ecosystems, food security, economy, society, and civilization. We developed a 405-year long (1611–2015C.E.) tree-ring chronology of Pinus wallichiana (Blue pine) from the Dolpo area of the trans–Himalayan region in Nepal to reconstruct drought variability in this remote region. Correlation analysis revealed significant positive relationships with February–August precipitation, but negative correlations with temperature. High positive correlations with the self-calibrated Palmer drought severity index (scPDSI) confirmed that moisture availability during the early growing season and full growing season is the primary limiting factor for Blue pine tree growth in the trans–Himalayan region. We used a linear regression model between our tree-ring record and regional climate data to reconstruct a 319-year long (1697–2015C.E.) February–August scPDSI series. This reconstruction accounts for 39.4% of the total variance in actual scPDSI over the calibration period (1957–2015C.E.). The reconstruction showed that the area was under slightly dry conditions for most of the reconstructed period, with below normal scPDSI values. An extreme drought was observed in the year 1707. Also, the years 1705, 1706, 1784, 1786, 1809, 1810, 1813, 1821, 1849, 1858, 1861, 1909, 1967, 2006, and 2009 experienced severe drought conditions. Consecutive years with moderate drought were 1702–1706, 1783–1789, 1796–1798, 1812–1814, 1816–1827, 1846–1848, 1856–1864, 1873–1877, 1879–1882, 1899–1901, 1908–1911, and 1967–1968. Three historic mega-drought events that occurred in Asia were also captured in our reconstruction: Strange Parallels drought (1756–1768), the East India drought (1790–1796), and the late Victorian Great Drought (1876–1878). Very few wet years (1776–1979, 1989, 1991, and 2003) were observed during the reconstruction period. Power spectrum analysis revealed drought variability at frequencies of 2.0–2.5, 3.0, 12.0, and 128 years, suggesting that drought in the region might be linked to broad-scale atmospheric-oceanic variabilities such as the El Niño-Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO). The results not only improve our understanding on regional drought variability, but are also helpful to make decisions on adaptation measures for protecting the marginal communities of the trans–Himalayan region from the anticipated adverse impacts of future droughts.