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Exploring the evolution of vegetation cover and its drivers in the Ferghana Basin helps to understand the current ecological status of the Ferghana Basin and to analyze the vegetation changes and drivers, with a view to providing a scientific basis for regional ecological and environmental management and planning. Based on GIMMS NDVI3g and meteorological data, the spatial and temporal evolution characteristics of NDVI were analyzed from multiple perspectives with the help of linear trend and Mann–Kendall (MK) test methods using arcgis and the R language spatial analysis module, combined with partial correlation coefficients and residual analysis methods to analyze the impacts of climate change and human activities on the regional vegetation cover of the Ferghana Basin from 1982 to 2015. NDVI driving forces. The results showed the following: (1) The growing season of vegetation NDVI in the Ferghana Basin showed an increasing trend in the 34-year period, with an increase rate of 0.0044/10a, and the spatial distribution was significantly different, which was high in the central part of the country and low in the northern and southern parts of the country. (2) Temperature and precipitation simultaneously co-influenced the vegetation NDVI growth season, with most of the temperature and precipitation contributing in the spring, most of the temperature in the summer being negatively phased and the precipitation positively correlated, and most of the temperature and precipitation in the fall inhibiting vegetation NDVI growth. (3) The combined effect of climate change and human activities was the main reason for the overall rapid increase and great spatial variations in vegetation NDVI in China, and the spatial distribution of drivers, namely human activities and climate change, contributed 44.6% to vegetation NDVI in the growing season. The contribution of climate change and human activities to vegetation NDVI in the Ferghana Basin was 62.32% and 93.29%, respectively. The study suggests that more attention should be paid to the role of human activities and climate change in vegetation restoration to inform ecosystem management and green development.

In recent decades, global warming has had a significant impact on the streamflow across the Tibetan Plateau. As the largest tributary in the upper reaches of the Yangtze River, the Yalong river is known for its abundant hydropower resources, and the world’s largest multi-energy complementary base has been built in the Yalong River Basin. However, prudent water resource planning is limited by the lack of long-term, detailed and reliable streamflow records over the Yalong river basin. Here, we develop an October–June streamflow reconstruction for the Yalong River, based on composite tree-ring chronology of Picea likiangensis from seven sampling sites. The reconstruction goes back to 1480 CE, and accounts for 46.5% of the instrumental streamflow variance during 1962–2012. This record indicates that the Interdecadal Pacific Oscillation and the Atlantic Multi-decadal Oscillation were the major contributing factors to streamflow variations. A significant and stable correlation with temperature was found over the past few centuries on the interannual scale. Projections suggest that future climate change may lead to more frequent flood disasters in the Yalong River Basin.

Our understanding of pre‐modern El Niño Southern Oscillation (ENSO) variability is reliant on proxy records, often distant from the center of ENSO activity in the equatorial Pacific Ocean. Here, we assess the relationship between reconstructed soil moisture in four distant ENSO‐influenced regions over the past 400 years. A major breakdown in the teleconnection of regional drought conditions in Asia, Eastern Australia, and North America is identified around 1700 CE. The statistically significant decline in inter‐series correlations (p < 0.01) represents a previously unknown aspect of global hydroclimate dynamics. We hypothesize that the disruption was driven by ENSO weakening and/or by a large‐scale multi‐decadal reconfiguration of ocean‐atmosphere circulation. Data assimilation estimates of soil moisture from the same regions fail to produce results of the same magnitude, potentially due to an overreliance of ENSO influence on the boundaries of spatial covariance in the underlying climate models. Plain Language Summary The El Niño Southern Oscillation (ENSO) is a recurring change in sea surface temperatures in the tropical Pacific Ocean that affects climate across much of the globe. ENSO can influence drought conditions on land, all around the Pacific Ocean and beyond. Here, we use tree‐ring estimates of drought to see how coherent dryness and wetness in these regions have been over the past 400 years. Overall, the four regions we study are in agreement but there is a breakdown in the relationship around 1700 CE. During this period, drought conditions in inner Eurasia, eastern Australia, southeast Asia, and southwest North America were unconnected. Climate models for the past millennium highlight how rare such an event is. The breakdown in drought teleconnection we describe may represent an important component of ENSO that so far is not fully understood. Key Points Drought estimates based on tree rings in four El Niño Southern Oscillation (ENSO)‐influenced regions become disconnected in the early 17th century CE Data assimilation and climate model outputs fail to capture a disruption of similar magnitude Future ENSO‐driven drought teleconnections may include previously unknown variability

Historians and paleoclimatologists have long studied the connection between ecoclimatic changes and empire growth, transformation, and decline, but striking cases remain rare. Here, we introduce a tree-ring chronology from southern China to reconstruct changes in April-to-November water balance of the middle reaches of the Yangtze River over the last 464 years. The reconstruction supports a quantitative assessment of the spatiotemporal structure of the late Ming megadrought and potential effects on subsequent dynastic transitions. Our results indicate that the late Ming megadrought from 1625 – 1644 CE occurred in both the northern and southern parts of the East Asian monsoon region in China. However, variations in the onset, duration, and magnitude of this event differ between regions. The combination of factors such as Pacific sea surface temperature anomalies, weakened solar activity, and large-scale volcanic eruptions may have contributed to the occurrence of the late Ming megadrought. These factors are also identified as key drivers of interannual to decadal fluctuations in drought in the middle reaches of the Yangtze River. Our reconstruction provides an historical context for the development of adaptive measures to mitigate future drought impacts in the region.The late Ming megadrought across north-to-south China, lasting from 1625-1644 CE, was influenced by Pacific sea surface temperature anomalies, weakened solar activity, and volcanic eruptions, according to reconstruction of the Yangtze River's water balance using tree-ring chronology.

Over the past two decades, more frequent and intense climate events have seriously threatened the operation of water transfer projects in the Pacific Rim region. However, the role of climatic change in driving runoff variations in the water source areas of these projects is unclear. We used tree-ring data to reconstruct changes in the runoff of the Hanjiang River since 1580 CE representing an important water source area for China’s south-north water transfer project. Comparisons with hydroclimatic reconstructions for the southwestern United States and central Chile indicated that the Pacific Rim region has experienced multiple coinciding droughts related to ENSO activity. Climate simulations indicate an increased likelihood of drought occurrence in the Pacific Rim region in the coming decades. The combination of warming-induced drought stresses with dynamic El Niño (warming ENSO) patterns is a thread to urban agglomerations and agricultural regions that rely on water transfer projects along the Pacific Rim.

Evaluating long-term changes in precipitation resources is important for accurate hydrological evaluation and forecasting, water security and rational allocation of water resources. For this purpose in the Xinjiang Habahe area, tree-ring specimens were collected from Picea obovata , Larix sibirica , and Betula platyphylla to establish a tree-ring width chronology, which was used to analyse a correlation with the average temperature and precipitation per month for 1958–2016. Based on correlation coefficients for monthly temperature and precipitation with the chronology of tree-ring widths, radial tree growth was mainly restricted by precipitation, and tree-ring width chronology was significantly correlated with overall precipitation from the previous July to the next June ( r  = 0.641, P  < 0.01). The above results were used to establish a transformation equation, and the overall precipitation from the previous July to the following June from 1800 to 2016 in Habahe was reconstructed after adjusted degrees of freedom, and obtain an explanatory rate of the variation up to 41.1% (40.0%). In addition to the reliability of the reconstructed values, the stability of the conversion function was determined via the “leave-one-out” method, which is commonly used in research on tree rings, and by cross-checking the conversion function with the reduced error value (RE), product mean test ( t ), with a sign test (ST). During the last 217 years, there were nine dry periods: 1803–1829, 1861–1865, 1872–1885, 1892–1905, 1916–1923, 1943–1954, 1961–1966, 1973–1981, and 2005–2011; and 12 wet periods: 1830–1834, 1836–1860, 1866–1871, 1886–1891, 1906–1915, 1925–1930, 1934–1942, 1955–1960, 1967–1972, 1982–1996, 2000–2004, and 2012–2016. Comparisons of the reconstructions for neighboring regions and a spatial correlation analysis showed that the reconstructed sequence of the present precipitation data better represented the changes in precipitation in Habahe. Additionally, a power spectrum analysis revealed that precipitation over the past 217 years in Habahe Province exhibited 2–5 years of quasiperiodic variation. A power spectrum analysis and wavelet analysis indicated that El Niño-Southern Oscillation influenced the precipitation cycles. This reconstruction provides more information on high-frequency precipitation, which is an important supplement to the existing tree-ring reconstruction of precipitation in the study area. The reconstruction of regional high-resolution precipitation changes over the last several hundred years provides unique, important data for understanding regional differences in climate at the decadal-centennial scale.

Unstable environments intensify the frequency of extreme disasters. Long-term climate changes can lead to agricultural and ecological degradation that threatens population sustainability. To better understand past climatic events and consequences, here we present a reconstruction of the self-calibrating Palmer drought severity index (scPDSI) from September to August for the desert margins of northern China, dating back to 1742. The reconstruction accounts for 42.9% of the variation of meteorological data between 1951 and 2020. Our spatial correlation analyses showed significant correlations between scPDSI, runoff, and precipitation. Over the past 279 years, the study area has undergone nine dry and eight wet periods, with the most severe climate extremes between the 1850s and 1890s. This period of prolonged drought in northeastern China coincided with the combined impacts of climatic factors and human influences, contributing to the fall of the Qing Dynasty. Analysis of periodicity and anomalies in sea surface temperatures indicate a strong association between wet and dry cycles and El Niño-Southern Oscillations. Our findings offer insights into long-term dry and wet fluctuations at the desert margins in northern China and elucidate the relationship between drought and the dynamics of civilizations. They also highlight the potential impact of extremes in climate on modern society, especially under the four projected shared socioeconomic pathways climatic scenarios, which predict worsening droughts in northern China.

Rivers originating from the Andes Mountains are vital water sources for agricultural and societal needs in South America, yet are increasingly threatened by climate change. Here we reconstruct streamflow of the Negro River (Rió Negro) in northern Patagonia over the past 827 years using tree-ring records from the south-central Andes foothills. This reconstruction reveals an unprecedented decline in river flow in recent decades. Moisture from the El Niño–Southern Oscillation and the Southern Annular Mode provides a key water source, but temperature rise has increased atmospheric moisture demand and reduced availability. Antarctic amplification has further disrupted circulation patterns and accelerated warming, intensifying regional aridity. Since the 20th century, the Negro River has experienced a sustained flow reduction of approximately 10% per decade. Projections under various emission scenarios indicate continued decline, highlighting the urgent need for adaptive water management strategies to mitigate escalating water scarcity risks in the region. Climate change has led to a significant decrease in streamflow, particularly in the Negro River in the Andes, posing water scarcity risks and necessitating effective management strategies, according to streamflow reconstruction and tree-ring data analysis.

Anthropogenic climate change affects regional hydrological cycles and poses significant challenges to the sustainable supply of freshwater. The Central China water tower (CCWT) is the key source region feeding the Yangtze and Yellow Rivers, and its runoff is indispensable for the surrounding mega‐city clusters. Here we present a reconstruction of CCWT runoff depth (RD) back to 1595 CE, based on a new dendrochronological network including 100 tree‐ring sampling sites and an ensemble averaging approach that combines multiple regression models. Comparison of this reconstruction with similar records from six water tower regions along the Pacific Rim (Mongolian Plateau, Tibetan Plateau TP, Great Dividing Range, Southern and Northern Rocky Mountains, Andes Mountains) revealed that the CCWT provide the most stable water supply, while the TP to be most susceptible to extreme runoff events. Twenty‐first century projections indicate generally increasing runoff across most Pacific Rim water towers, whereas the Northern Rocky Mountains are projected to decline substantially. We attribute the differences in runoff variability and projected trends across Pacific Rim water towers to their distinct geographies and synoptic climatic conditions. The long‐term runoff reconstructions and projected changes highlighted in this study provide insights for adaptive management strategies in China and all other regions relying on supply from mountain water towers. Human‐caused climate change is creating major challenges for sustainable freshwater supply. The Central China Water Tower (CCWT), a key source for the Yangtze and Yellow Rivers, supports large populations and cities. In this study, we used tree‐ring data from 100 sites to reconstruct CCWT runoff depth back to 1595 CE, offering a long‐term view of water availability. We also compared CCWT runoff with records from six other Pacific Rim water towers, including the Mongolian Plateau, Tibetan Plateau (TP), Great Dividing Range, Northern and Southern Rocky Mountains, and Andes Mountains. The CCWT showed the most stable water supply over time, while the TP had more extreme fluctuations. Looking ahead, model projections suggest increasing runoff in most regions, but a decline in the Northern Rockies. These contrasting trends reflect differences in geography and climate patterns across regions. Our findings highlight the importance of understanding both past and future changes in mountain water resources and the need for region‐specific water management strategies in a changing climate. A new dendrochronological network of 100 tree‐ring sampling sites reconstructs Central China Water Tower (CCWT) runoff depth back to 1595 CE, revealing long‐term hydrological variability Comparative analysis of Pacific Rim water towers shows the CCWT provides the most stable water supply, while the Tibetan Plateau is more prone to extreme runoff events Twenty‐first century projections predict increased runoff across most Pacific Rim water towers, except the Northern Rocky Mountains, emphasizing the need for region‐specific water management strategies

Global warming has strongly influenced the hydroclimatic cycle in arid regions. Here, we established the dendrochronology of spruce on the northern and southern slopes of the Qilian Mountains in the Hexi Corridor based on tree-ring width. The correlation response analysis showed that the radial growth of Picea crassifolia in the study area was limited mainly by precipitation from July of the previous year to June of the current year. Therefore, we developed July–June precipitation reconstructions for the northern and southern slopes of the Qilian Mountains, respectively, based on the ensemble model from the simple linear regression and K-nearest neighbor. Our new reconstructions displayed that during the past 257 years, the northern Qilian Mountains experienced 39 and 38 extreme wet and dry years, and 5 wet and 6 dry periods, respectively, and the southern Qilian Mountains experienced 61 and 51 extreme wet and dry years, and 6 wet and 6 dry periods, respectively. Spatial correlation using CRU precipitation and scPDSI grid data revealed that our reconstruction contains the precipitation signal that is representative of an extensive region of north-central China. The precipitation reconstruction includes major cyclicities of 2–5 years in the north and 7 years in the south, and they document drought/famine events in the late nineteenth century and during the 1920s–1930s. Water vapor from the Pacific Ocean is identified as the main factor responsible for high precipitation events in the study area, while low precipitation events were influenced by continental air masses.