Search Results (1,125)

We established a standardized tree-ring width chronology using 46 Mongolian pine (Pinus sylvestris var. mongolica) tree-ring cores from the Tuqiang Forestry Bureau in the northern Greater Khingan Mountains (GKM). The average minimum temperature from May to July was significantly positively correlated with tree-ring width, indicating that it is the main climatic factor affecting tree growth in the study area. Based on this, the average minimum temperature sequence from May to July for the past 164 years in this region was reconstructed, and its reliability and stability were verified using the leave-one-out method. The reconstruction results revealed four warm periods and two cold periods in the northern GKM over the past 164 years. The four warm periods were from 1891 to 1897, 1902 to 1909, 1923 to 1931, and 2003 to 2023, and the two cold periods were from 1864 to 1880 and 1953 to 1992. The results of multi-window spectrum analysis and wavelet analysis showed that the reconstructed sequence had periodicities of 2.2–5.3 years, 11 years, 39 years, and 52 years, suggesting that the minimum temperature changes may be influenced by El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and solar sunspot activities. Full article

A statistical study is conducted to understand how the Mascarene High (MH) of the southwest Indian Ocean affects the springtime climate of southeastern Africa, in response to global teleconnections. A temporal index of sea-level air pressure is formed and correlated with large-scale fields of sea temperature, winds, and rainfall in the period 1980–2024. The results suggests that the MH tends to intensify and shift westward during Pacific El Niño conditions via a standing wave train in the subtropical jet stream over the South Atlantic. As this happens, anticyclonic airflow draws moisture from the Mozambique Channel and drives it onto the Kalahari plateau via low-level jets over the Limpopo and Zambezi River valleys. The Sep–Nov rainfall increases ~1 mm/day across southern Africa, accompanied by cooler temperatures and lower potential evaporation. So the spring season starts with a smaller water deficit that could favor early-planted, short-cycle crops. Outstanding questions remain on the stability of Pacific teleconnections and coupling with the Indian Ocean Dipole. Full article

Climate change intensifies ecosystem vulnerability in mountainous regions, particularly in Northwestern Sichuan’s Terrestrial Ecosystems (TENS), where complex terrain amplifies impacts on biodiversity and carbon dynamics. This study assesses spatiotemporal ecological vulnerability using the IPCC exposure-sensitivity-resilience framework. We applied autoregressive modeling and a 5-year moving window to monthly NDVI, temperature, and precipitation data from 1983 to 2022. Results show vulnerability index (VI) increases latitudinally from south to north, driven by inverse temperature correlations. Longitudinally, VI forms a V-shaped pattern due to topographic and monsoon influences. Wetlands are most vulnerable (VI ≈ 0.48) from precipitation sensitivity, while forests show lowest vulnerability (VI ≈ 0.43) due to high resilience. Temporally, VI fluctuates nonlinearly with decline (1985–1994) under cool-humid conditions, increase (1994–2008) amid warmer-drier El Niño effects, and sharp decline (2008–2011) from La Niña and sand control initiatives. Spatially, 34.6% of areas exhibit decline-increase-decline-increase trends. Centroids of decreasing VI shift southwest-to-north, indicating recovery diffusion. Increasing VI centroids move northwest-central-north. These findings underscore ecosystem-specific adaptive management and conservation policies, especially in northern TENS, to mitigate accelerating climate pressures. Full article

This study examines how ENSO episodes affect maize price volatility transmission between the United States and South Africa. Using daily price data, from 1997 to 2024, for U.S. corn and South African white and yellow maize futures, the study employs GARCH models augmented with ENSO phase indicators and the Southern Oscillation Index (SOI) to determine volatility spillovers. The results show that South African maize prices respond to lagged US corn prices and exchange rate fluctuations, with price volatility of both white and yellow maize prices being more persistent during El Niño and La Niña events. This study integrates climate variability indicators, specifically different ENSO phases and the SOI, to investigate climate-driven volatility transmission between developed and emerging markets. Significant results were obtained when the Southern Oscillation Index was added in the volatility equations. Not only does the inclusion of ENSO indicators and SOI enhance the explanatory power of GARCH models beyond existing studies, it also provides evidence of climate-driven volatility spillovers between a developed and developing market. These findings highlight the role of climate variability in agricultural market dynamics and stress the need for proactive risk management strategies such as buffer stocks and climate responsive financial instruments to ensure food security and market resilience in Southern Africa. Full article

Coral reefs are increasingly impacted by marine heatwaves and global warming, with the 2023–2024 El Niño–Southern Oscillation (ENSO) event causing unprecedented thermal stress across the Eastern Tropical Pacific. This study assessed the effects of this event on coral reefs in the Gulf of Papagayo, Costa Rica. Sea surface temperatures exceeded the bleaching threshold for seven months, reaching a record 10.2 Degree Heating Weeks—twice the levels recorded during the 1997–1998 ENSO. Benthic and fish community surveys revealed severe coral mortality, particularly in Pocillopora-dominated reefs, with some sites losing over 90% of live coral cover. Resilience varied across sites, likely influenced by factors such as local water circulation, coral genetic diversity, symbiont type, and heterotrophic capacity. Reefs with higher genetic diversity and thermally tolerant Durusdinium symbionts showed partial recovery. Seasonal upwelling appeared to buffer thermal stress in some areas, potentially acting as a natural climate refuge. Bleaching also impacted reef fish communities, with a notable decline in invertebrate-feeding species on degraded reefs. These findings highlight the interplay between prolonged thermal stress, coral biology, and local oceanographic processes in shaping reef resilience. Identifying and protecting such climate refugia will be critical for coral conservation under future climate change scenarios. Full article

The northwest of Mexico has important zones for biodiversity conservation, denominated Priority Marine Regions (PMRs), and to study key oceanographic features related to ecological structure, it is necessary to understand environmental variability and observe climatic trends. Sea Surface Temperature (SST) is tightly associated with photosynthesis and serves as a control and driver for biological processes linked to the phytoplankton. Global climatic systems, like El Niño Southern Oscillation (ENSO), are responsible for the interannual and interdecadal variation in SST, since global circulation is modified by them. An important metric to assess phytoplanktonic biomass/photosynthesis is Chlorophyll a (Chl a), constituting the primary basis of the marine trophic web. The present study aims to examine the interannual oceanographic variability across 24 PMRs by employing monthly SST (°C) and Chl a (mg/m³) data derived from remote sensing instruments with spatial resolution of 4 km and 1 km from September 1997 to October 2018. We grouped the Priority Marine Regions into 18 main areas, based on a cluster analysis of Sea Surface Temperature. Significant differences were observed, showing higher SST levels during El Niño phase and higher Chl a concentration during La Niña phase, primarily in winter and spring, which will impact marine ecosystems. Full article

To mitigate the impact of north–south strip errors inherent in Gravity Recovery and Climate Experiment (GRACE) spherical harmonic coefficient solutions, this research develops a state-space model to generate a more robust solution. The efficacy of the state-space model is demonstrated by comparing its performance with that of conventional filtering methods and hydrological modeling schemes. The method is subsequently applied to estimate the GRACE Groundwater Drought Index in the California Central Valley basin, a region significantly affected by drought during the GRACE observation period. This analysis quantifies the severity of droughts and floods while investigating the direct influences of precipitation, runoff, evaporation, and anthropogenic activities. By incorporating the El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation, the study offers a detailed causal analysis and proposes a novel methodology for water resource management and disaster early warning. The results indicate that a moderate-duration flood event in 2006 resulted in a recharge of 19.81 km³ of water resources in the California Central Valley basin, whereas prolonged droughts in 2008 and 2013, lasting over 15 months, led to groundwater depletion of 41.53 km³ and 91.45 km³, respectively. Precipitation and runoff are identified as the primary determinants of local drought and flood conditions. The occurrence of ENSO events correlates with sustained precipitation variations over the subsequent 2–3 months, resulting in corresponding changes in groundwater storage. Full article

The El Niño–Southern Oscillation (ENSO) is one of the most important climate phenomena on Earth due to its impacts on the global atmospheric circulation. This paper conducts a comprehensive analysis of the spatiotemporal variations and characteristics of ENSO from 1950 to 2023. A number of indices, including the Oceanic Niño index, Modoki index, and the modified El Niño Modoki Index, were used to differentiate between various ENSO types and assess their respective impacts on the global climate. The analysis reveals notable changes in the frequency and intensity of ENSO events over the past seven decades. Notably, since 1990, the sea surface temperature anomalies (SSTAs) in the tropical Western Pacific regions have shifted westward by approximately 18 degrees longitude, potentially a result of global warming. During the same time period, the frequency and intensity of ENSO events have also changed, with an increase in the frequency of Central Pacific El Niño events and a decline in the frequency of Eastern Pacific El Niño events. The occurrence frequency of both Central and Eastern Pacific La Niña events has remained relatively stable but shows some variability. Based on the analysis results, this article also suggests potential improvement in data collection, which is critical to further understanding and verification of the spatiotemporal variations of ENSO events. Full article

The Mediterranean region is regarded as a hot spot on Earth because of its placement at the junction of many aerosols. Numerous studies have demonstrated that the North Atlantic Oscillation (NAO), which is closely related to the El Niño–Southern Oscillation (ENSO) phenomenon, influences the weather in the area. However, a recent study by the same author examined the ENSO effect on atmospheric processes in this area and discovered a slight but notable influence. This study builds on that earlier work, but it divides the Mediterranean region into four smaller regions during the same time span as the previous study, which is extended by two years, from 1980 to 2024. The division is based on geographical, climatological, and atmospheric process features. The findings demonstrate that volcanic eruptions significantly affect the total amount of aerosols. Additionally, the current study reveals that the Granger-causality test of the physical phenomena of solar activity, ENSO, and NAO indicates that all have a significant impact, either separately or in combination, on the atmospheric process over the four Mediterranean regions, and this effect can last up to six months. Moreover, a taxonomy of the different forms of aerosols across the four subregions is given. Full article

Climate projections suggest ecosystems could face drastic changes due to global climate change, including more severe and frequent droughts than those recorded in the last century. Paleoclimatic series provide more extensive information than that available with instrumental records, allowing for the analysis of trends and recurrence of extreme events over a longer time periods. The objective of this research was to reconstruct the precipitation variability for southwestern Chihuahua, based on the tree-ring records of Pinus arizonica Engelm. and to assess the influence of ocean atmospheric circulations like El Niño Southern Oscillation (ENSO) and the North American Monsoon (NAM) on both low- and high-frequency climate variability. We developed three dendrochronological series covering 214 years (1802–2015), 265 years (1750–2014) and 369 years (1647–2015), for the Talayotes (TAL), Predio Particular Las Chinas (PPC) and El Cuervo (CUE) sites, respectively. The 369-year regional chronology was significantly related to cumulative precipitation variability between January and September. Recurring droughts were observed at approximately 50-year intervals. This regional climate variability was significantly related (p < 0.05) to Niño 3 SST and PDSI (JJA) indices. Maximum and minimum extreme events reconstructed in the last 369 years were synchronized with ENSO events, both in the El Niño warm phase and the La Niña cold phase. These results suggest that P. arizonica tree rings record shared a common response to the regional climate that was significantly modulated by ENSO and the NAM. This is the first dendroclimatic study to reconstruct summer precipitation patterns in northern Mexico, which is valuable given the importance of this seasonal precipitation on the regional economy. Full article

China’s Yangtze and Yellow River Basins exhibit divergent drought patterns, yet the underlying mechanisms driving these differences remain underexplored. This study compares their drought characteristics from 1961 to 2022 using the Standardized Precipitation Index, Standardized Precipitation Evapotranspiration Index, and Palmer Drought Severity Index, and identifies their drivers through attribution models and interpretable machine learning. Our results reveal two distinct paradigms: the Yangtze Basin is characterized by high-frequency, over 14% in all seasons, short-duration droughts, reflecting a rapid hydrological response, while the Yellow River Basin experiences low-frequency, long-duration events indicative of strong soil moisture memory. Quantitative attribution demonstrates that atmospheric evaporative demand (VPD) plays a significantly greater role in the Yellow River Basin, contributing over 20% to soil drought, far exceeding its 14.4% contribution in the Yangtze Basin. Furthermore, their large-scale drivers differ fundamentally: the Yangtze Basin responds primarily to the Atlantic Multidecadal Oscillation (AMO) and Arctic Oscillation (AO), whereas the Yellow River Basin is mainly influenced by solar activity and the El Niño-Southern Oscillation (ENSO). These findings reveal that Yangtze drought is primarily driven by precipitation deficits, while Yellow River drought is a composite phenomenon amplified by evaporative demand. This distinction underscores the need for basin-specific water management strategies. Full article

This study presents a comprehensive analysis of key meteorological parameters at the Lenghu site, a premier astronomical observing location, with particular emphasis on understanding their variability patterns and long-term trends. The research systematically investigates regional distribution characteristics, periodic variations, seasonal changes, and the temporal evolution of critical atmospheric parameters that influence astronomical observations. Furthermore, this study explores the potential connections between these parameters and major climate oscillation patterns, including ENSO (El Niño–Southern Oscillation), PDO (Pacific Decadal Oscillation), and AMO (Atlantic Multidecadal Oscillation). Utilizing ERA5 (the fifth-generation atmospheric reanalysis from the European Centre for Medium-Range Weather Forecasts) reanalysis data, we examine the regional atmospheric conditions (82°–102° E and 31°–46° N) surrounding the Lenghu site from 2000 to 2023 (24 years). The analysis focuses on fundamental meteorological parameters: precipitable water vapor (PWV), temperature, wind speed at 200 hPa ($W_{200}$), and total cloud cover (TCC). For the Lenghu site specifically, we extend the temporal coverage to 1990–2023 (34 years) to include additional parameters such as high cloud cover (HCC) and total column ozone (TCO). The analysis reveals that the ENSO and PDO indices are negatively correlated with $W_{200}$. The AMO index has a positive correlation with PWV and a slight positive correlation with $W_{200}$, temperature, and TCO. Moreover, a comparative analysis of Lenghu, Mauna Kea, and Paranal reveals distinct variation trends across sites due to regional climate differences. Notably, while all observatory sites are affected by global climate change, their response patterns and temporal characteristics exhibit subtle variations. Full article

Climate change and the El Niño Southern Oscillation (ENSO) events have been increasingly linked to infectious disease outbreaks. While growing evidence has connected climate variability with systemic illnesses, the ocular implications remain underexplored. This study aimed to assess the relationships between ENSO-driven climate events and infectious diseases with ophthalmic consequences. A narrative review of 255 articles was conducted, focusing on infectious diseases influenced by ENSO and their associated ocular findings. 39 articles met criteria for full review, covering diseases such as dengue, zika, chikungunya, malaria, leishmaniasis, leptospirosis, and Rift Valley fever. Warmer temperatures, increased rainfall, and humidity associated with ENSO events were found to enhance vector activity and disease transmission. Ocular complications included uveitis, retinopathy, and optic neuropathy, but the specific disease findings varied by infectious disease syndrome. The climactic variable changes in response to ENSO events differed across diseases and regions and were influenced by geography, local infrastructure, and socioeconomic factors. ENSO event-related climate shifts significantly impact the spread of infectious diseases with ocular symptoms. These findings highlight the need for region-specific surveillance and predictive models that may provide insight related to the risk of ophthalmic disease during ENSO events. Further research is needed to clarify long-term ENSO effects and develop integrated strategies for systemic and eye disease detection, prevention, and management. Full article

Sugarcane yield plays a crucial role in food safety and biofuel production, and it is strongly influenced by climatic variations. In this context, this study applies canonical correlation analysis (CCA) to identify the climatic predictors, such as sea surface temperature, atmospheric pressure, and wind speed, that affect sugarcane yield from 1990 to 2019. Hierarchical cluster analysis applied to the performance of 58 municipalities in the eastern region of Pernambuco identified three distinct and homogeneous groups. An analysis of the CCA for the three sugarcane yield groups and climatic variables revealed that the first canonical function was significant with R = 0.82 and precision of 0.67 (p ≤ 0.05 at 95% confidence level), and that the sugarcane yield groups and climatic variables were different (Wilks’ lambda = 0.14), but they were associated. Climatic variables affected the three sugarcane productivity groups, with redundancy indices of 29.7%, 52.2%, and 59.9%. Climatic variables with positive canonical weights enhance performance, while those with negative weights decrease yields. The structural canonical loads and cross-loadings reveal that sea surface temperature plays a crucial role in determining sugarcane yield, potentially influencing precipitation and temperature patterns in the region. The sensitivity analysis confirms the stability of the canonical loads and the robustness of the results, demonstrating that this research can support yield forecasting, regional agricultural policy, and drought management. Identifying climate predictors, such as sea surface temperature, wind speed, and atmospheric pressure, enables the creation of accurate models to predict sugarcane productivity, assisting farmers in planning input management, irrigation during dry periods, and harvesting. Furthermore, climate data can inform policies that encourage sustainable agricultural practices and adaptation to climate conditions, strengthening food security and guiding the selection of more resilient sugarcane varieties, increasing production resilience. Full article

Longitudinal shifts in the zonal dipole associated with the El Niño–Southern Oscillation (ENSO) in the tropical Pacific have implications for the summer climate of Southern Africa. These features are studied via Empirical Orthogonal Function analysis applied to monthly standardized sea temperatures from 1 to 100 m in depth and spanning 1980–2024. The dipole exhibits two modes: central and east Pacific. The central mode has 4–7 yr oscillations, while the east mode has a periodicity of 3 yr and 8–14 yr, with a trend toward La Niña. Correlations are mapped with environmental fields around Southern Africa. During east-mode La Niña, there are low-level westerlies over the Kalahari Plateau that coincide with a warm-west Indian Ocean and neutral summer (Dec–Mar) weather conditions over Southern Africa. The weak climatic response across the Atlantic–Indian basins during east Pacific La Niña is linked to an isolated Walker cell that feeds tropical moisture into a trough over the dateline (180° W). It is the central mode that has greater influence over Southern Africa, by triggering global Walker cells that link with the Indian Ocean Dipole. Full article