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Abstract This contribution provides an introduction to a sequence of five papers (CCE I- CCE V) that describe the impact of the Warm Anomaly of 2014–15 and El Niño 2015–16 on the pelagic food web of the southern California Current Ecosystem. These contributions analyze the influence of these two warm water perturbations on satellite-based measures of ocean fronts, export efficiency out of the euphotic zone, copepod egg production, mesozooplankton community structure, and a synthesis of primary production, mesozooplankton grazing, and gravitational fluxes of organic carbon. [ABSTRACT FROM AUTHOR]

Global warming and rare weather caused by climate change continue to affect ecosystems, human health, and economic systems, which pose serious climate risk challenges for humanity. To address and adapt to climate change risks and to facilitate the process of achieving carbon peaking and carbon-neutral targets, the financial industry has become more concerned about the information spillover effects of extreme climate events on green financial products. Therefore, this paper adopts the Southern Oscillation Index (SOI) to describe climate change and investigates the influence of the SOI on the volatility of the NASDAQ OMX Green Economy Index (OMX-GEI) under a variant of the Double Asymmetric GARCH-MIDAS (DA-GM-X) model. The results show that the SOI provides relevant information for OMX-GEI volatility forecasting and the DA-GM-X model yields outstanding forecasting performance in statistical and economic terms. This conclusion indicates that considering SOI and its asymmetry changes can significantly improve the prediction accuracy of econometric models. Also, several robustness tests confirm our findings. Overall, the findings of this paper suggest that to achieve the two-carbon goal and combat climate change, governments should pay more attention to policy formulation that combines environment, climate, health, energy, and economy, and actively promote green, low-carbon, and sustainable energy development globally. [ABSTRACT FROM AUTHOR]

Monthly rainfall data for Blue Nile Basin (BNB) were obtained from the Ethiopian Meteorological Authority (1950–2018). Long-term trends in the BNB annual and monthly rainfall are investigated in this study. The challenges of the paper were to explore the impact of climate change on the study area using sound practical methods. The paper used the widely used statistical methods to find precisely the significance of the impact of climate change rainfall variability and distribution both spatially and temporally in the BNB. The statistical significance of the trend in the study is calculated by the Mann-Kendall (MK) test. Data were analyzed using the coefficient of variation, anomaly index, and precipitation concentration index. The coefficient of variation is high in Kiremt rainfall which implies more inter-annual variability of Bega rainfall than Kiremt (Coefficient of Variation (CV): Bega˃ Belg˃ Kiremt season). Based on Precipitation Concentration Index (PCI) value, the number of moderate concentration years (89.9%) has been increasing through time and the study area has encountered successive years of drought. The results showed that the annual, Bega, Belg, and Kiremt precipitation over the whole of BNB is significantly decreasing except Bega season with a magnitude of 36.38, 3.8, 7.8, and 24.7 mm per decade respectively. The rainfall in the study area is characterized by a high CV. Moreover, prolonged droughts have become common which adversely affects the agricultural system. It was also found that very low values of rainfall anomalies that correspond to severe droughts were associated with El Niño Southern Oscillation (ENSO) events. [ABSTRACT FROM AUTHOR]

A declining trend in Indian summer monsoon precipitation (ISMP) in the latter half of the 20th century is a scientifically challenging and societally relevant research issue. Heavy aerosol loading over India is one of the key factors in modulating the ISMP. Using the state-of-the-state-of-the-art chemistry-climate model, ECHAM6-HAMMOZ, the impacts of South Asian anthropogenic sulfate aerosols on the Indian summer monsoon precipitation were investigated against: (1) 2010 La Niña (excess monsoon), (2) 2015 El Niño (deficit monsoon) in comparison to (3) normal monsoon 2016. Sensitivity simulations were designed with 48% enhancement in South Asian SO 2 emissions based on a trend estimated from Ozone Monitoring Instrument (OMI) satellite observations during 2006–2017. The model simulations showed that sulfate aerosols reduce ISMP by 27.5%–43.3 %, while simulations without sulfate loading enhanced ISMP by 23% in 2010 La Niña and reduction by 35% in 2015 El Niño. This paper reports that sulfate aerosols loading over India reduce precipitation by aerosol-induced direct and indirect effects by inducing atmospheric cooling, weakening in the convection, and reduction in moisture transport to Indian landmass. This paper emphasizes the necessity of alternate use of energy to reduce sulfate aerosol emissions to solve water issues in South Asia. [Display omitted] • Sulfate emission reduces Indian summer monsoon precipitation through aerosol-radiation and aerosol-cloud interactions. • Over 27% of the summer monsoon rainfall deficit in a normal year are linked to Asian anthropogenic sulfate emissions. • Sulfate-induced rainfall reduction is the maximum for La Niña year. • SO 2 loading increases atmospheric stability and weakens moisture transport to India. [ABSTRACT FROM AUTHOR]

El Niño/Southern Oscillation (ENSO) mainly occurs in the tropical Pacific Ocean every a few years. But it affects the climate around the world and has a dramatic impact on the development of ecology and agriculture. The analysis and prediction of ENSO become particularly important for meteorology and disaster management. However, due to insufficient data, spring predictability barrier (SPB), and model uncertainty, traditional analysis models face challenges. To address these issues, researchers begin to apply deep learning (DL) technologies to ENSO research, exploring the impact of ENSO on the world's extreme climate changes. In recent years, deep learning-based methods have obtained impressive progress with more accurate and effective predictions of ENSO. In this paper, we summarize the attempts of DL technologies in predicting ENSO. We first introduce the properties of ENSO, followed by the architecture introduction of DL technologies and their application to ENSO. We then investigate the potential of DL technologies for ENSO prediction from various aspects, including model evaluation metrics, prediction algorithms, overcoming SPB and prediction uncertainty. Finally, we provide discussions on the future trends and challenges of using DL technologies for ENSO prediction. [ABSTRACT FROM AUTHOR]

Understanding the interactions among climate change, carbon emission allowance trading, crude oil and renewable energy stock markets, especially the role of climate change in this system is of great significance for policy makers, energy producers/consumers and relevant investors. The present paper aims to quantify the time-varying connectedness effects among the four factors by using the TVP-VAR based extensions of both time- and frequency-domain connectedness index measurements proposed by Antonakakis et al. (2020) and Ellington and Barunik (2021) [8,48]. The empirical results suggest that, firstly, the average total connectedness among climate change, carbon emission allowance trading, crude oil and renewable energy stock markets is not so strong for the heterogenous fundamentals underlying them. Nevertheless, the time-varying total connectedness fluctuates fiercely through May 2005 to September 2021, varying from about 8% to 30% and rocket to very high levels during the global subprime mortgage crisis and the COVID-19 pandemic. Furthermore, the total connectedness mainly centers on the short-term frequency, i.e., 1–3 months. Secondly, climate change is generally the leading information contributor among the four factors, although not particularly strong, and its leading role also performs mainly on the short-term frequency (1–3 months). Thirdly, renewable energy stock market and crude oil market show tight interactions between them and they are the two major bridges of information exchanges across various time frequencies (horizons) in this system. Finally, we confirm the evidence that the primary net connectedness contributor and receiver switch frequently across different time frequencies, implying that it is extremely essential for policy makers, energy producers/consumers and investors to make time-horizon-specific regulatory, production/purchasing or investment decisions when facing the uncertain effects of climate change on the interactions among carbon emission allowance, crude oil and renewable energy stock markets. [ABSTRACT FROM AUTHOR]

• First high-accuracy prediction of global SST at 0.25° spatial resolution and 2 time scales (daily and monthly) based on deep learning. • Fully consider the spatiotemporal correlations in historical time series by attention mechanism to improve prediction accuracy. • Superior to widely-adopted deep learning models (3D-CNN, ConvLSTM, and LSTM) and numerical model (HYCOM). • Applicable to climate change sensitive area. Sea Surface Temperature (SST) is an essential parameter of the ocean–atmosphere system, so accurately predicting the future SST is of great significance. To address the low prediction accuracy due to insufficient consideration of spatiotemporal correlations in existing machine learning models, this paper proposes an Effective Attention Model (EAM) to achieve daily global SST prediction (predicting the SST of the next 15 days using those of the past 15 days) and monthly global SST prediction (predicting the SST of the next 12 months using those of the past 12 months). The EAM adopts an attention mechanism to avoid information redundancy and improve prediction accuracy. This is the first work to realize high-accuracy global SST prediction with a high spatial resolution of 0.25° on two time scales (daily and monthly) based on deep learning. Experiments show that (1) the prediction results have a consistent global spatiotemporal distribution with the ground truth, with the Root Mean Squared Difference (RMSD) of daily prediction ranging from 0.212 to 0.932 ℃ and the RMSD of monthly prediction ranging from 0.666 to 0.782 ℃. The EAM is superior to the deep learning models (ConvLSTM, 3D-CNN, and LSTM) and the numerical model (HYCOM); (2) Besides global prediction, the EAM also achieves good performance in a climate change sensitive area (Niño 3.4 sea area), with the lowest RMSD of 0.231 ℃. This study may not only benefit the research on climate events (El Niño and La Niña) but also serve to predict other marine disasters (such as heat waves and storms). In the future, the proposed attention module can also be adapted to other prediction scenarios such as meteorology. [ABSTRACT FROM AUTHOR]

• Climate change and dengue nexus have increased in recent time. • Dhaka and Chittagong Hill Tracts are dengue and malaria research hotspots. • A weak connection was observed between dengue incidents, ENSO, and IOD. • No association between malaria cases and SST was identified in this paper. Climate change is a significant risk multiplier and profoundly influences the transmission dynamics, geographical distribution, and resurgence of vector-borne diseases (VBDs). Bangladesh has a noticeable rise in VBDs attributed to climate change. Despite the severity of this issue, the interconnections between climate change and VBDs in Bangladesh have yet to be thoroughly explored. To address this research gap, our review meticulously examined existing literature on the relationship between climate change and VBDs in Bangladesh. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, we identified 3849 records from SCOPUS, Web of Science, and Google Scholar databases. Ultimately, 22 research articles meeting specific criteria were included. We identified that the literature on the subject matter of this study is non-contemporaneous, with 68% of studies investing datasets before 2014, despite studies on climate change and dengue nexus having increased recently. We pinpointed Dhaka and Chittagong Hill Tracts as the dengue and malaria research hotspots, respectively. We highlighted that the 2023 dengue outbreak illustrates a possible shift in dengue-endemic areas in Bangladesh. Moreover, dengue cases surged by 317% in 2023 compared to 2019 records, with a corresponding 607% increase in mortality compared to 2022. A weak connection was observed between dengue incidents and climate drivers, including the El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). However, no compelling evidence supported an association between malaria cases, and Sea Surface Temperature (SST) in the Bay of Bengal, along with the NINO3 phenomenon. We observed minimal microclimatic and non-climatic data inclusion in selected studies. Our review holds implications for policymakers, urging the prioritization of mitigation measures such as year-round surveillance and early warning systems. Ultimately, it calls for resource allocation to empower researchers in advancing the understanding of VBD dynamics amidst changing climates. [ABSTRACT FROM AUTHOR]

Ornithogenic sediment may contain important paleoecological information concerning past bird population dynamics. In this paper, we analyse the distribution of n -alkanes and polycyclic aromatic hydrocarbons (PAHs) in two sedimentary profiles collected from abandoned penguin colonies at Cape Bird, Ross Island, Antarctica. The geochronology of the sediment profiles was determined using 210Pb and AMS 14C dating techniques, and spans the past 1500 years. We observe low levels of n -alkanes (0.93–2.67 μg g−1) and PAHs (20.5–46.8 ng g−1) concentrations dominated by short-chain n -alkanes, low-molecular-weight and alkyl PAHs. Principal Component Analysis (PCA) shows that the PC 1 scores for n -alkanes and PAHs are significantly correlated with the input intensity of penguin guano and penguin bioelements. Using these proxies in combination with Generalized Additive Model (GAM), we reveal that breeding penguin population growth reaches a historical peak during the Medieval Climate Anomaly (MCA) prior to 1550 CE. This growth in population size corresponds to the extent of sea ice cover and the activity of the local atmospheric-ocean circulation. Warming induced by El Niño and the positive phase of the Southern Annular Mode, along with the expansion of ice-free zones and increased oceanic nutrient and food availability, are considered primary factors contributing to the growth of breeding penguin populations. Additionally, variations in sea ice extent and Amundsen Sea Low significantly influence penguin population dynamics. Our study suggests that n -alkanes and PAHs may be valuable organic proxies for reconstructing historical changes in breeding penguin populations, with the local sea ice extent and atmospheric-oceanic circulation exerting a major influence on Antarctic penguin population dynamics. [Display omitted] • n -Alkanes and PAHs can function as proxy indicators for historical penguin guano input. • PC 1 scores for n -alkanes and PAHs correlate with guano input intensity metrics and bioelements. • Penguin population significantly increase in mid Cape Bird during the Medieval Climate Anomaly. • Atmospheric-ocean circulation influences penguin population dynamics. [ABSTRACT FROM AUTHOR]

The periodicities of the climate change have long been explored by researchers not only because they reflect the inherent characteristics of the climate systems, but also because they are the foundations of climate-change predictability. This paper reports the periodicities of the hydroclimate variations reconstructed from a lacustrine sequence at Tiancun section (TC section) in the Luoyang Basin within the Central Plains of China and the sequence covers the first half of the Holocene. Our reconstruction shows that the hydroclimate variations at the TC section during the period from ∼10,135 and ∼ 5890 cal. yr BP were well corresponding with the effective soil moisture variations recorded by the stalagmite δ13C sequence at the Magou Cave. This corresponding relationship suggests that when the effective soil moisture increases (i.e., more negative δ13C values), the ratio of evaporation over precipitation in the paleolake at the TC section decreased, resulting in lower CaCO 3 content. It also suggests that when the effective soil moisture increases, more inflowing water entered the paleolake, resulting in coarser sediments. Our reconstruction also shows that the hydroclimate variations or lake level variations in the Luoyang Basin were characterized by millennial-scale quasi-periodicities that were most likely paced by the changes in ITCZ (Inter-tropical Convergent Zone) position and also by alterations in ENSO-like phase. And, both (ITCZ and ENSO) were most likely regulated by the solar activity. Our further analysis shows that the hydroclimate in the Luoyang Basin also experienced centennial-scale variations. Specifically, the grain size data express the following cycles: 692-year, 538-year, 217-year, 170-year and 123-year, all at the 99% confidence level. And, the CaCO 3 content data express the following cycles: 202-year, 184-year, 169-year and 85-year, all at the 99% confidence level. These cycles are approximately coincident with the widely-reported solar-activity cycles. • This paper reports the periodicities of the hydroclimate variations reconstructed from a lacustrine sequence in the Central Plains of China and the sequence covers the first half of the Holocene. • The hydroclimate variations were primarily paced by changes in ITCZ position and also by alterations in ENSO-like phase. And, both (ITCZ and ENSO) were most likely regulated by solar activity. • The centennial-scale hydroclimate variations were approximately coincident with the widely-reported solar-activity cycles. [ABSTRACT FROM AUTHOR]

The establishment of Forest Management Units (Kesatuan Pengelolaan Hutan/ KPH) represents one of Indonesia's most significant forest governance reforms, covering the 120 million hectares of designated Forest Areas. Sharing features with the Landscape Approach, KPHs are expected to reduce deforestation and forest degradation through improved forest planning, oversight, open access avoidance, and fire prevention and response. This paper assesses the impact of KPHs on the reduction of forest loss, including forest loss due to fire, and the factors that influence this impact (e.g. KPH's primary objective, deforestation risk). We use remotely sensed data to estimate difference-in-differences models accounting for differences in baseline characteristics and multiple time periods. Our case study, Sulawesi Island, is primarily shaped by smallholder farmer land use, where KPHs can exert significant influence. We do not find evidence of an overall effect of KPHs on deforestation. However, we observe intriguing heterogeneous effects depending on the year, including significantly less deforestation in already-established KPHs during the El Niño years of 2015–16, and a notable impact on the reduction of forest loss due to fire in some early-established KPHs. These findings warrant further investigation. [ABSTRACT FROM AUTHOR]

El Niño-Southern Oscillation (ENSO) is a crucial factor in global climate change, which can lead to disasters such as floods, droughts, and heavy rainfall worldwide. Although accurate long-lead prediction of ENSO is essential, the intricate time-varying spatial correlations make it challenging. In this paper, we propose a novel deep learning architecture, called Adaptive Graph Spatial-Temporal Attention Network (AGSTAN), to model the extensive spatial–temporal interactions in ENSO. We first develop a dynamic spatial graph module with self-attention mechanism, wherein the structure is adapted to the characteristics of the evolving states. Furthermore, we introduce the long-term temporal sequence module to capture long-range dependency between time-series outputs and inputs, and generate accurate long lead predictions with only one forward step. To validate its efficacy and robustness, we conducted experiments on the simulated and historical climate datasets. Results showcase that AGSTAN possesses superior performance in ENSO prediction, outperforming contemporary deep learning models and boasting a 23-month forecasting horizon with heightened correlation and minimized bias. [ABSTRACT FROM AUTHOR]

• Long-term evolution trend of wind and waves in China's offshore was investigated. • A novel approach was proposed to evaluate wind-wave joint exploitation potential. • Joint utilization guarantee rate of wind and waves in China's offshore was 67 %–87 %. • AO, AMO and Niño 3.4 affected WS and H s from high to low latitudes, respectively. • Impact of ENSO on WS and H s in SCS could reach 3.92 m/s and 1.15 m, respectively. Assessing wind and waves resources and analyzing their evolution are crucial for the exploitation of wind and wave energy. This paper utilized ERA5 reanalysis data to investigate the distribution characteristics, long-term evolution, and influencing factors of wind speed (WS) and significant wave height (H s) in China's offshore regions. It showed that over the past 60 years, the Bohai Sea experienced a significant downward trend in WS (−0.632 cm/s/yr) and H s (−0.135 cm/yr). The Yellow Sea exhibited a downward trend in WS, but no change trend was observed in H s (p > 0.05). The H s in the East China Sea (ECS) and South China Sea (SCS) showed upward trends, increasing by 0.191 cm/yr and 0.262 cm/yr, respectively. The concept of energy utilization guarantee rate (EUGR) was introduced to evaluate the complementarity and synergy between wind and wave resources. The ECS and SCS were found to possess ample wind resources, with an EUGR of approximately 80 %. The combined EUGR of wind and wave energy in the Bohai Sea, Yellow Sea, ECS, and SCS amounted to 67.41 %, 72.29 %, 86.86 %, and 84.10 %, respectively. The southeastern coastal waters of China exhibited significant complementary and synergistic effects between wind and waves, making them suitable for the joint utilization of wind and wave energy. The distribution and evolution of wind and waves in China's offshore varied due to diverse climate conditions prevailing in different regions. From high to low latitudes, the Bohai Sea was mainly controlled by AO, while the Yellow Sea was jointly affected by AO and AMO; The ECS and SCS were mainly affected by AMO and Niño 3.4, respectively. During El Niño/La Niña years, the SCS exhibited a decrease/increase in WS and H s , with a lag of ∼3 months in response to ENSO. The variation amplitude of WS and H s could reach 3.92 m/s and 1.15 m, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a framework for topological feature analysis in time-dependent climate ensembles. Important climate indices such as the El Nino Southern Oscillation Index (ENSO) or the North Atlantic Oscillation Index (NAO) are usually derived by evaluating scalar fields at fixed locations or regions where these extremal values occur most frequently today. However, under climate change, dynamic circulation changes are likely to cause shifts in the intensity, frequency and location of underlying physical phenomena. In case of the NAO for instance, climatologists are interested in the position and intensity of the Icelandic Low and the Azores High as their interplay strongly influences the European climate, especially during the winter season. To robustly extract and track such highly variable features without a-priori region information, we present a topology-based method for dynamic extraction of such uncertain critical points on a global scale. The system additionally integrates techniques to visualize the variability within the ensemble and correlations between features. To demonstrate the utility of our VTK+TTK-based software framework, we explore a 150-year climate projection consisting of 100 ensemble members and particularly concentrate on sea level pressure fields. [Display omitted] [ABSTRACT FROM AUTHOR]

Latin America has the largest share of renewable energy for power generation in the world, but has historically been dependent on hydropower, and is vulnerable to long-term phenomena like the El Niño-Southern Oscillation (ENSO). The region is currently experiencing a steady increase in gas-based power generation along with a rapid growth in non-hydro renewables, mainly aimed at improving reliability. But exploiting complementarities between hydropower and other renewables could offer additional benefits. This paper investigates to what extent improved deployment of wind turbines and solar photovoltaic cells (PV), aimed at complementing existing hydropower, could mitigate the impacts of ENSO in Latin America. We use a meteorological reanalysis dataset to model the variations in wind-, solar- and hydropower throughout the entire 20th century and their association with different ENSO phases in the same period. A statistical algorithm is then used to identify locations at national and regional levels offering the maximal level of complementarity. The results show that adding 136 GW of wind- and solar-power with high-complementarity has the potential to cost-effectively compensate the fluctuations of hydropower and reduce the variability of renewable power not only during drought ENSO phases but also outside ENSO events. Benefits include: (i) an increase of up to 5-fold the minimum threshold of renewable power available every month, (ii) a reduction of up to 65% in the variability of renewable power generation, and (iii) reaching a levelized cost of electricity (LCOE) of 0.09–0.23 $/kWh, which is comparable to that of new gas plants. • An improved selection of wind- and solar-power to mitigate impacts of ENSO on hydropower is shown. • A meteorological reanalysis dataset to model variations in wind-, solar- and hydropower is used. • A statistical algorithm is employed to identify locations with maximal complementarity. [ABSTRACT FROM AUTHOR]

This paper explores the Holocene climatic dynamics of South Africa's southern Cape, a region that supports a large proportion of the Greater Cape Floristic Region and contains an array of important archaeological sites. While South African climates are generally characterised by marked rainfall seasonality, the southern Cape is currently situated at the interface between tropical and temperate climate systems, resulting in a largely aseasonal rainfall regime. This regime, however, is thought to have been particularly sensitive to past changes in late Quaternary boundary conditions, meaning that variability in either tropical or temperate systems could have significant environmental impacts. Evidence of past climate change, however, remains limited. We present a 9000-year record of hydroclimatic variability obtained from rock hyrax midden stable nitrogen records, from Papkuilsfontein, on the southern slope of the Anysberg Mountains. Resolved to an average 6-year resolution and spanning the period c. 9050 cal yr BP to 1990 CE, this is the highest resolution Holocene record from southern Africa and presents a unique opportunity for the detailed study of the primary drivers and spatial gradients of Holocene climate change in the southern Cape. The data indicate a long-term decrease in aridity across the Holocene and a pattern of variability that reveals remarkable similarities with records from the South African tropics and El Niño–Southern Oscillation proxies, highlighting the significance of tropical systems as drivers of Holocene climate change in the region. This substantially expands what has been previously considered to be the zone of tropical influence, extending from a coastal phenomenon associated with heat transport via the Agulhas Current to encompass much, if not all, of the Agulhas Plain south of the Cape Fold Mountains. These findings provide a valuable new climatic framework for contextualizing changes in ecological and archaeological records in the southern Cape, and contribute to a more comprehensive understanding of the spatio-temporal dynamics of climate systems in southern Africa. • Sub-decadal 9000-year record of aridity from South Africa's southern Cape. • Reveals dominance of tropical forcing across the southern Cape and Agulhas Plain. • ENSO variability indicated to be important driver of regional climate change. • Presents high-resolution framework for study of human-environment interactions. [ABSTRACT FROM AUTHOR]

To reveal the heterogeneity of risk spillovers of new global energy listed companies at different time and frequency scales and to further explore the external impact of risk spillovers from new energy listed companies through the construction of a spillover index model and complex network, this paper studies the risk spillover effect of new energy listed companies from three aspects: static, geographical and dynamic. The TVP-VAR model is constructed to study the impact of economic policy uncertainty, climate policy uncertainty, geopolitical risk, El Niño, and international crude oil prices on new energy listed companies. The results show that new energy listed companies have a more significant long-term risk spillover relationship and regional heterogeneity. Total is a systemically important company. In contrast to the findings of existing studies, we find that climate policy uncertainty increases the risk spillover effect between new energy listed companies in both the short and long terms. In addition, new energy listed companies' response directions, intensities, and speeds of risk spillovers to various external shocks at different time points differ • Explores the risk spillover from a time-frequency perspective. • The geographical spillover effect is considered. • The long-term spillover effect is the strongest and has regional heterogeneity. • EPU, CPU, GPR, SSTA, and WTI have an impact on new energy listed companies. • CPU will increase the risk spillover levels in both the short and long term. [ABSTRACT FROM AUTHOR]

Most studies on the relationship between global warming and El Niño-Southern Oscillation (ENSO) rely on simulation experiments, but they have produced contradictory results, which cannot guarantee the reliability of the experimental findings. To address this challenge, we approached the issue from the perspective of objective ENSO and global warming signals. The effects of global warming on ENSO are not limited to the Earth's surface, but also present in the atmosphere. While objective monitoring indices exist for surface global warming and ENSO signals, objective ENSO and global warming signals in the atmosphere are difficult to obtain. To obtain high-precision ENSO and global warming signals in the atmosphere, we propose using the strategy of ICA (Independent Component Analysis) combined with a non-parametric method. The results of the objective ENSO and global warming signals suggest that the global warming signal leads the ENSO signal by approximately three months and exhibits a clear positive correlation with the ENSO signal, especially the occurrence of strong ENSO events is closely related to global warming, indicating that global warming promotes the occurrence of ENSO events. Under the influence of global warming, the frequency and intensity of ENSO increase, the characteristics and complexity of ENSO atmospheric teleconnections may be altered, and there is a greater tendency for more destructive El Niño events to occur. Since the beginning of the 21st century, the probability of ENSO event has increased significantly. Furthermore, moderate or strong ENSO events tend to develop earlier, and extreme ENSO events not only develop earlier but also prolong their decay phase, leading to an extended lifespan of ENSO events. This paper investigates the effect of global warming on ENSO from the perspectives of objective ENSO and global warming signals, which well supplements the objective factual basis for the previous simulation experimental studies. • Most simulation studies on the relationship between global warming and ENSO cannot guarantee the authenticity ofresults • We investigated the relationship between global warming and ENSO from the perspective of objective signals. • To obtain ENSO and global warming signals, we proposed the strategy of ICA combined with a non-parametric method. • The results suggest that the global warming signal exhibits a clear positive correlation with the ENSO signal. • Under influence of global warming, frequency, lifespan, intensity and atmospheric teleconnections of ENSO may be altered [ABSTRACT FROM AUTHOR]

Coastal wetlands provide valuable ecosystem services and understanding their response to past climatic changes may help predict their possible future responses. In this paper, we obtained records of pollen, algae, sediment grain-size, and other environmental proxies, from a late Holocene sediment core (CFD-E) from the Caofeidian area, on the northwest coast of the Bay of Bohai, China. Our results indicate three major stages of environmental change. During Stage I (3500–2800 cal yr BP), arboreal pollen content was high (mostly >60%), especially for Pinus and Quercus , and the PCA sample scores on Axis 1 were negative indicating that regional vegetation was temperate broadleaved forest and the climate was wet. During Stage II (2800–2350 cal yr BP), the arboreal pollen content decreased substantially (mostly <40%), and the PCA Axis 1 sample scores were positive indicating a decrease in forest vegetation, grassland expansion, and a drier climate. During Stage III (2350–1400 cal yr BP), the arboreal pollen content increased again (mostly >40%), although it remained lower than during Stage I, indicating that forests expanded under a relatively humid climate while the wetland area decreased slightly. Our results also record the 2.8 ka and 2.4 ka events of monsoon weakening, which were characterized by increases in herbaceous pollen (indicating grassland expansion) and the drying of the regional climate. There are several differences in the regional expression of these two climatic events. During the 2.4 ka event, Chenopodiaceae pollen increased substantially (average of 42.0%), indicating the expansion of halophytes; whereas during the 2.8 ka event, an increase in Artemisia indicates the occurrence of a dry climate throughout the region. We suggest that the aridity during the 2.8 ka event was triggered by decreased solar activity and the resulting changes in the El Niño-Southern Oscillation, which weakened the East Asian summer monsoon. However, we suggest that the 2.4 ka event was driven by the weakening of the Atlantic Meridional Overturning Circulation. • Significant increase in halophytic vegetation during 3500–1400 cal yr BP • The 2.8 ka and 2.4 ka events were characterized by climate drying lasting ∼150 years. • During these two events the area of forest decreased and grassland expanded. [ABSTRACT FROM AUTHOR]

[Display omitted] • The drought pattern in China is closely related to the basin distribution and multiple teleconnection factors. • The intensity and frequency of drought in China exhibited an increasing trend. • The ENSO-AO had important positive effects in the major basins in China. • Multiple wavelet coherence helps identify the processes controlling drought changes. Due to increasing global warming and the frequent occurrence of severe drought risk in recent decades, many studies have investigated drought in China. However, the spatiotemporal heterogeneities of droughts are complicated, and a comprehensive analysis of the driving forces has not been thoroughly explored. In this paper, we studied the temporal and spatial patterns of drought in China from 1960 to 2018 and disclosed its relationship with multiple teleconnection factors on different time scales. The results show that (1) Drought in China has exhibited a fluctuating increasing trend over the past 59 years, with a standardized precipitation–evapotranspiration index (SPEI) rate of change of –0.12/10 a, and the most severe droughts occurred during 2000–2010. (2) There was a significant abrupt change in China's meteorological droughts induced by climate change around 1997. (3) The trend in China was characterized by drought in spring and autumn and humidification in winter, while the trend in the Southwest River Basin was characterized by drought. (4) A combination of factors can best explain the drought variations from basin to basin, and the El Niño-Southern Oscillation (ENSO)-Arctic Oscillation (AO) was most commonly the best predictor. The use of multiple wavelet coherence helps to identify the dominant drought change processes. [ABSTRACT FROM AUTHOR]

The Mindanao Dome (MD) upwelling system has important implications for the local and even the global air-sea interaction, but its changing process in hydroecological conditions and response mechanism influenced by ENSO cycle are still unclear. The evolution of MD upwelling process and the changes in hydro-climatic environments in MD region in three typical El Niño, La Niña, and normal years during ENSO event from 2010 to 2015 are analyzed. Results reveal that migration of surface water is the main factor controlling the changes in the intensity of the MD upwelling during this ENSO cycle but not the variations in wind stress curl. Massive westward accumulation (eastward movement) of surface warm water and strengthened (weakened) upwelling Rossby waves together induce the enhancement (weakness) of the MD upwelling during mature phase of 2015/2016 El Niño (2010/2011 La Niña) year. In addition, NECC and MD upwelling together control the biological activities in surface waters in MD region during this ENSO cycle. The meandering NECC and MD upwelling both strengthen (weaken) when 2015/2016 El Niño (2010/2011 La Niña) occur, which transport more (less) nutrients to surface sea from horizontal and vertical levels, respectively, leading to an increase (decrease) in surface Chl- a. Two synopsis mechanisms are proposed to illustrate the response mechanism of the MD upwelling evolution and eco-hydro-climatic variations in the MD region to 2015/2016 El Niño (2010/2011 La Niña) event, respectively. This paper highlights the prospect for the role played by ENSO cycle in local ecological effects and hydro-climatic evolution, which further has profound implications for understanding the influence of the global climate change on the ocean carbon cycle. • Surface water migration controlled the MD upwelling variation during ENSO cycle from 2010 to 2015. • Surface biological activity is controlled by NECC and MD upwelling during ENSO cycle. • Two conceptual maps of the oceanic process changes during El Niño and La Niña events are proposed. [ABSTRACT FROM AUTHOR]

• The oceanographic conditions before El Niño 2015–16 favored the generation of events. • Significative differences between species and ENOS conditions were detected in HAB duration. • The upwelling relaxing condition favors the retention of HABs while the upwelling produces the dispersion. • The simulations explain the low connectivity between bays. The bays of Tongoy and Guanaqueros are located in the Humboldt Current system, where Argopecten purpuratus has been the subject of intense aquaculture development. These bays lie in one of the most productive marine ecosystems on Earth and are dominated by permanent coastal upwelling at Lengua de Vaca Point and Choros Point, one of the three upwelling centers on the Chilean coast. Significantly, this productive system experiences a high recurrence of harmful algal bloom (HAB) events. This paper examines 9-year (2010–2018) samples of three toxic microalgal species collected in different monitoring programs and research projects. During this period, nine HAB events were detected in Guanaqueros Bay and 14 in Tongoy Bay. Among these, three HAB events were produced simultaneously in both bays by Pseudo-nitzschia australis , and two events produced simultaneously were detected in one bay by Alexandrium spp. and the other by Dinophysis acuminata. Before El Niño 2015–16, there were more HAB events of longer duration by the three species. Since El Niño, the number and duration of events were reduced and only produced by P. australis. HAB events were simulated with the FVCOM model and a virtual particle tracker model to evaluate the dynamics of bays and their relationship with HAB events. The results showed retention in bays during the relaxation conditions of upwelling and low connectivity between bays, which explains why almost no simultaneous events were recorded. [ABSTRACT FROM AUTHOR]

In this paper, the linkage of the sub-seasonal variability of North Atlantic blocking (NAB) to the interannual-to-decadal winter midlatitude North Atlantic jet (NAJ) is examined. The variability of NAJ in meridional position (strength) is characterized by the first (second) empirical orthogonal function (EOF) mode of the winter-mean 46-days low-pass filtered North Atlantic 500-hPa zonal wind. The composite reveals that NAB exhibits weak (strong) westward movement and small (large) zonal width during the north- (south-) shifted NAJ winters, which result in severe cold anomalies over the southern Europe (northern Eurasia and eastern North America) and are characterized by a precursor of the positive (negative) North Atlantic Oscillation. In contrast, the NAB event during the strong (weak) NAJ winters mainly originates from the intensification of a ridge over North Europe (Atlantic), which has short (long) lifetime, small (large) intensity, small (large) zonal width, and leads to weather influences similar to those during south (north-) shifted NAJ winters. The underlying mechanism of the sub-seasonal variability of NAB can be explained by the nonlinear multi-scale interaction model of atmospheric blocking from the perspective of the meridional potential vorticity gradient. It is further shown that the meridional position of NAJ exhibits significant interannual variability, which is associated with the El Nino/Southern Oscillation (ENSO) via the changes in the Walker Cell and the Atlantic Hadley circulation as well as the second EOF of surface sea temperature (SST) over the North Atlantic. The strength of NAJ shows significant interannual-to-decadal variability, which is mainly regulated by the first EOF mode of North Atlantic SST. • First and second dominant modes of North Atlantic zonal wind represent the variability of North Atlantic jet (NAJ). • North Atlantic blocking and associated continental cold anomalies may be modulated by the interannual-to-decadal NAJ variability. • The meridional shift (strength）of NAJ is linked to ENSO and interannual North Atlantic SST EOF2 (interannual-to-decadal SST EOF1) mode. [ABSTRACT FROM AUTHOR]

[Display omitted] • Seeing El Niño only as a disaster in Peru obscures its role as a phenomenon of opportunity for desert farming and fishing. • Education for disaster management can align with school curricula to enhance the role of youth and children in development. • Using storytelling methodologies innovatively in school curricula can contribute to better community resilience planning. • A digital curriculum on El Niño gave voice to children as development knowledge producers and communicators during COVID-19. This paper calls for greater attention to the role of youth and children as development actors in the context of education for disaster management. Drawing on debates in disaster studies and children's geographies, we explore the possibilities offered by everyday formal education spaces, often overlooked in disasters management practice, to engage children in disaster preparedness and resilience planning. Using the case study of Peru, we examine the extent to which national responses to the restrictions that the COVID-19 pandemic placed on in-person teaching, opened-up opportunities to engage with disaster management in new ways. We draw on the case of an innovative digital curricula that uses intergenerational storytelling about the El Niño phenomenon to investigate livelihood opportunities and climate change pressures in northern coastal Peru, exploring how the phenomenon benefits desert populations. We assess the role of participatory virtual learning in facilitating disaster knowledge and climate adaptation awareness among students and critically examine the youth subjectivities that are constructed through these processes. We conclude calling for greater engagement with children's formal education spaces in climate adaptation strategies, while cautioning against conceptualising children and young people as only 'adults in the making', rather than as impacted individuals with current agency and everyday capacities. [ABSTRACT FROM AUTHOR]

This paper serves as an introduction to the Deep-Sea Research II special issue entitled an ocean perspective on CMIP6 model evaluations, which reported the progress of CMIP6 (Coupled Model Intercomparison Project phase 6) emphasizing the ocean component. The six papers in this volume provided a series of evaluations, including ENSO (El Niño-Southern Oscillation) phase locking, Ningaloo Niño, global marine heat waves, freshwater flux-induced stratification over the central tropical Pacific, global sea levels, and AMOC (Atlantic meridional overturning circulation). To complement the papers in this volume and to present a general view of the performance of CMIP6 models in simulating sea surface temperature (SST) and sea surface salinity (SSS), the historical simulation biases from 48 and 46 CMIP6 models compared with observations are analyzed, respectively. Although not able to cover all the major aspects of model evaluation, this special issue has provided crucial information for model development and research based on climate models. [ABSTRACT FROM AUTHOR]

Abstract: The effects of El Nino and La Nina have been considered as the major variables in weather changes in the Middle East. This issue has been shown by regression indexes in a number of papers. The presented study has proven that the El Nino and La Nina should be added to the weather forecast variables because of their major effects. Weather forecasts could be influenced by some variables that have uncertainty, so the deterministic approaches may lead to incorrect predictions. The proposed algorithm can be used when some variables have uncertainty. In this study, a probabilistic approach has been chosen to show the effect of El Nino and La Nina on the monthly maximum temperature. Different ENSO Indices have been proposed for El Nino or La Nina occurrences but each of them has some deficiencies. In order to overcome the drawback of using one of the ENSO Indices, the fuzzy based analysis approach has been chosen in this paper. Data from Chabahar, one of the stations in the south of Iran, has been chosen for the algorithm to be applied on. MATLAB has been used to run the algorithm on the data. The results show that El Nino and La Nina lead to major effect on the amount of monthly maximum temperature in the south of Iran. [Copyright &y& Elsevier]

Abstract: Grid computing is nowadays an established technology in fields such as High Energy Physics and Biomedicine, offering an alternative to traditional HPC for several problems; however, it is still an emerging discipline for the climate community and only a few climate applications have been adapted to the Grid to solve particular problems. In this paper we present an up-to-date description of the advantages and limitations of the Grid for climate applications (in particular global circulation models), analyzing the requirements and the new challenges posed to the Grid. In particular, we focus on production-like problems such as sensitivity analysis or ensemble prediction, where a single model is run several times with different parameters, forcing and/or initial conditions. As an illustrative example, we consider the Community Atmospheric Model (CAM) and analyze the advantages and shortcomings of the Grid to perform a sensitivity study of precipitation with SST perturbations in El Niño area, reporting the results obtained with traditional (local cluster) and Grid infrastructures. We conclude that new specific middleware (execution workflow managers) is needed to meet the particular requirements of climate applications (long simulations, checkpointing, etc.). This requires the side-by-side collaboration of IT and climate groups to deploy fully ported applications, such as the CAM for Grid (CAM4G) introduced in this paper. [Copyright &y& Elsevier]

Abstract: Much has been learned in the interpretation and use of climate information since the 1997/1998 El Niño event that garnered so much attention. Seasonal-to-interannual forecasts are now produced around the world. However, mismatches in their scales, specificity or communication (of forecast content and uncertainties) with decision-maker needs still hinder their use. More work is needed to improve a) the utility of models, b) access to observational and model/forecast data, c) understanding and communication of the opportunities and limitations of forecasts, and d) methods by which decision systems use climate predictions – both through modifications of decision systems and more tailored forecast information. This white paper discusses these issues and recent advances in providing climate information needed in effective climate risk management. The paper advocates for the establishment and/or strengthening of “chains of experts and communications” to better enable appropriate and effective dissemination, assimilation and further use and application of climate information. [ABSTRACT FROM AUTHOR]

Abstract: Over the past decade, soil moisture products derived from microwave remote sensing data have gained increasing attention for the monitoring of agricultural, hydrological and climate processes. ERS-1 and ERS-2 scatterometer-derived time series of data available since 1992 enable the user to analyze the change of soil moisture patterns over time and to monitor events deviating from the normal. In this paper, ERS scatterometer-derived soil moisture products are compared with known occurrences of heavy rain and drought related to the strong El Niño (EN) event of 1997/1998. We investigated globally if the typical EN-related short term climate changes can be depicted in soil moisture data. EN consequences and their manifestation in the data are presented for the Americas, Africa and Asia. Furthermore, the weather situation during the EN event in China is compared to the scatterometer-derived soil moisture data set in more detail. It could be observed that most EN-related climate variations on the different continents are clearly reflected by remote sensing soil moisture data. Heavy rain and drought conditions reported in daily media, science papers, and forecasts by the can be observed in anomaly data sets showing the deviation of soil moisture from the average. This also applies for the strong EN-related flood, which hit China in 1998 and following La Niña-related droughts. These analyses thus serve to demonstrate that information relevant to climatology is contained in the satellite scatterometer-derived soil moisture product, as well as in anomaly time series, derived from the existing soil moisture time series. Our procedure thus consisted of soil moisture time series calculation, soil moisture anomaly calculation, creation of time series and anomaly maps and the comparison of anomalies with meteorological data on three continents for the time period of outstanding El Nino years. The soil moisture data of TU Wien is available via the internet free of charge. [Copyright &y& Elsevier]

Abstract: In this paper, the relationship between flood/drought change in the Taihu Lake basin (TLB) and ENSO is investigated based on reconstructed flood/drought rank series (FD) and NINO-3.4 SST (DJF) data from 1857 to 2003. With the aid of empirical mode decomposition (EMD) method, the paper reveals that FD series and ENSO both contain strong inter-annual, decadal, multi-decadal and centennial signals, and have quite similar periodicities. The EMD method also obtains a monotonic trend for both series: the trend of FD series is upward, which suggests that flood trend is significant, and the trend of NINO-3.4 SST is also upward showing an increase of El Nino events. Continuous wavelet transform obtains similar oscillations for FD and NINO-3.4 SST series with those of EMD method. The results of cross wavelet and wavelet coherence suggest that there was stable in-phase relation between FD and NINO-3.4 SST from 1857 to 1950s, while this in-phase relation is not clear during recent decades. This conclusion is also verified by χ 2 test. These findings indicate weakening linkage between ENSO and flood/drought disasters in the TLB, which must be taken into account in the prediction of flood and drought disasters in the study area. [Copyright &y& Elsevier]

The interannual variability in streamflow presents challenges in managing the associated risks and opportunities of water resources systems. This paper investigates the use of seasonal streamflow forecasts to help manage three water resources systems in south-east Australia. The seasonal streamflow forecasts are derived from the serial correlation in streamflow and the relationship between El Nino/Southern Oscillation (ENSO) and streamflow. This paper investigates the use of ENSO and serial correlation in reservoir inflow to optimise water restriction rules for an urban township and the use of seasonal forecasts of reservoir inflow to help make management decisions in two irrigation systems. The results show a marginal benefit in using seasonal streamflow forecasts in the three management examples. The results suggest that although the ENSO–streamflow teleconnection and the serial correlation in streamflow are statistically significant, the correlations are not sufficiently high to considerably benefit the management of conservative low-risk water resources systems. However, the seasonal forecasts can be used in the system simulations to provide an indication of the likely increases in the available water resources through an irrigation season, to allow irrigators to make more informed risk-based management decisions. [Copyright &y& Elsevier]

El Niño-Southern Oscillation (ENSO) is the most predominant interannual variability in the tropics, significantly impacting global weather and climate. In this paper, a framework of low-order conceptual models for the ENSO is systematically derived from a spatially-extended stochastic dynamical system with full mathematical rigor. The spatially-extended stochastic dynamical system has a linear, deterministic, and stable dynamical core. It also exploits a simple stochastic process with multiplicative noise to parameterize the intraseasonal wind burst activities. A principal component analysis based on the eigenvalue decomposition method is applied to provide a low-order conceptual model that succeeds in characterizing the large-scale dynamical and non-Gaussian statistical features of the eastern Pacific El Niño events. Despite the low dimensionality, the conceptual modeling framework contains outputs for all the atmosphere, ocean, and sea surface temperature components with detailed spatiotemporal patterns. This contrasts with many existing conceptual models focusing only on a small set of specified state variables. The stochastic versions of many traditional low-order models, such as the recharge–discharge and the delayed oscillators, become special cases within this framework. The rigorous derivation of such low-order models provides a unique way to connect models with different spatiotemporal complexities. The framework also facilitates understanding the instantaneous and memory effects of stochastic noise in contributing to the large-scale dynamics of the ENSO. • A comprehensive conceptual modeling framework for ENSO is developed. • The framework provides a detailed analysis of spatiotemporal patterns. • Stochastic versions of established low-order oscillators are developed. • The rigorous derivation is provided for models with different complexity. • The framework helps understand the role of stochastic noise in ENSO dynamics. [ABSTRACT FROM AUTHOR]

Historically, La Niña events typically follow El Niño events, particularly in case of prolonged La Niña events that succeed strong El Niño events. However, the current triple-dip La Niña (CTD-La Niña) event during 2020–2023 occurred after a neutral event rather than a (strong) El Niño, which differs from the two historical triple-dip La Niña (HTD-La Niña; 1973–1976 and 1998–2001) events since 1950. Therefore, this paper aims to investigate the unique evolution and potential formation mechanisms of the CTD-La Niña event. Our results show that, in contrast to the HTD-La Niña, the CTD-La Niña event is not primarily influenced by tropical processes themselves. Instead, the consecutively in-phase (negative) North Pacific Meridional Mode and South Pacific Meridional Mode play a crucial role in initiating and sustaining the La Niña event of 2020–2023 through tropical-extratropical interactions. On one hand, their associated negative sea surface temperature (SST) anomalies extend toward the equatorial central Pacific each year from spring to summer, leading to negative SST and strengthening easterly surface wind anomalies in the equatorial Pacific. On the other hand, their related northeastern and southeastern wind stress can modify the wind stress curl over the equatorial Pacific, further intensifying the equatorward Ekman transport from the off-equator. These factors together provide favorable conditions for the re-occurrence of the La Niña event from 2020 to 2023. These findings may offer valuable insights into understanding the formation of long-lasting ENSO events. • The current triple-dip La Niña (CTD-La Niña) event during 2020–2023 occurred after a neutral event rather than an (strong) El Niño. • The consecutively in-phase (negative) NPMM and SPMM play a crucial role in initiating and sustaining the 2020–2023 La Niña event through tropical-extratropical interactions. • The NPMM made almost equally contributions in each consecutive year, whereas the SPMM started off relatively small in the first year and gradually strengthened thereafter to sustain the development of the CTD-La Niña event. [ABSTRACT FROM AUTHOR]

The 4.2 ka event was a period of global drought and climate cooling linked to the widespread disruption of Neolithic culture. However, the detailed climatic changes during this period are not completely understood. In this paper, we report a high-resolution pollen record for the Dayanghu wetland in the Zhejiang region of southeastern China, which we use to infer mean annual precipitation (MAP) fluctuations during the period spanning 4600–4000 calendar years before present (cal. yr BP). There was a long-term trend of decreasing MAP during this interval, consistent with weakening of the East Asian Summer Monsoon since the mid-Holocene. This trend was punctuated by episodes of relatively high MAP at 4350–4320, ca. 4260, and 4220–4200 cal. yr BP, and extreme droughts at 4200 and 4150 cal. yr BP. We propose that solar activity promoted El Niño events and contributed to dramatic MAP fluctuations in the Dayanghu wetland. La Niña events and negative-phase intervals of the Pacific Decadal Oscillation may have been responsible for the extreme drought at 4200–4150 cal. yr BP. In summary, we propose a close relationship between MAP and solar forcing, with short-term enhanced solar activity increasing the intensity of the East Asian Summer Monsoon and contributing to increasing decadal variability in the inner tropical Pacific, which ultimately leads to increased precipitation variability in southeast China. The results improve our understanding of the detailed climatic features of the 4.2 ka event. • High-resolution pollen record for ca. 4.2 ka for the Zhejiang region, China. • Pollen-based mean annual precipitation was quantitatively reconstructed. • Long-term droughts tended to occur during 4600–4000 cal. yr BP. • La Niña-dominated ENSO contributed to a catastrophic drought at 4200–4150 cal. yr BP. [ABSTRACT FROM AUTHOR]

Australia has long been observed to experience the ENSO (El Niño Southern Oscillation) of periodic alternation of flooding and drought. Australia has experienced consecutive years of the La Niña cycle of heavy rain and flooding. At some stage, this will revert to one or more years of drought, often severe. In previous years of drought, consideration was given to alternative water supply, including recycled wastewater. This paper reflects on the case of the previous period of El Niño drought in South East Queensland (SEQ), aiming to contribute to drought mitigation planning through reviving consideration of recycled water. • In depth case study on Queensland response to drought conditions. • Includes analysis of attempts to introduce other water sources, particularly recycled water for potable and non potable uses. • Examines reasons for failure and non-acceptance and uses comparisons with successful schemes to suggest policy changes for a way forward. [ABSTRACT FROM AUTHOR]

This paper investigates the persistent effects of negative shocks in utero and in infancy on low-income children's health and cognitive outcomes and examines whether timing of exposure matters differentially by skill type. Specifically, I exploit the geographic intensity of extreme floods in Ecuador during the 1997-1998 El Niño phenomenon, which provides exogenous variation in exposure at different periods of early development. I show that children exposed to severe floods in utero, especially during the third trimester, are shorter in stature five and seven years later. Also, children affected by the floods in the first trimester of pregnancy score lower on cognitive tests. Additionally, I explore potential mechanisms by studying health at birth and family inputs (income, consumption, and breastfeeding). I find that children exposed to El Niño floods, especially during the third trimester in utero, were more likely to be born with low birth weight. Furthermore, households affected by El Niño suffered a decline in income, total consumption, and food consumption in the aftermath of the shock. Falsification exercises and robustness checks suggest that selection concerns such as selective fertility, mobility, and infant mortality do not drive these results. [ABSTRACT FROM AUTHOR]

Abstract Precipitable water vapour (PWV) is a key factor in activities related to climate monitoring and the global hydrologic cycle. In this paper, the PWV time series with an accuracy of about 1.3 mm is obtained on a global scale using the zenith total delay (ZTD) derived from International GNSS Service (IGS). A theoretical error formula from ZTD to PWV reveals that the PWV error induced by errors in ZTD, surface pressure (P s) and weighted mean temperature (T m) is about 1–1.5 mm. P s and T m are two key factors during the conversion of ZTD to PWV, which can be derived from the Global Geodetic Observing System (GGOS) Atmosphere. The GPS-derived and radiosonde-derived PWV time series are compared at 97 collocated stations on a global scale, which shows the maximum/minimum/mean root mean square (RMS) errors and Bias of 1.8/0.6/1.3 mm and 2.6/2.9/4.0/5.2 mm, respectively with a data utilisation rate of 96.8%. By analysing the periodograms of GPS-derived PWV time series using the Lomb-Scargle method, preliminary result shows the various oscillations characteristics of PWV time series at different stations. Finally, the diurnal variations of PWV time series during the El Niño event of 2014–2016 are analysed and revealed an interesting climate signal. Highlights • Long-term PWV time series globally are obtained with the accuracy of about 1.3 mm. • A theoretical error formula from ZTD to PWV reveals that the errors in ZTD and Ps are about 1–1.5 mm. • Lomb-Scargle method is introduced to solve the issues of PWV time series caused by uneven sampling, or data with some gaps. • The diurnal variations in PWV time series during the El Niño event of 2014–2016 are analysed. [ABSTRACT FROM AUTHOR]

Abstract This paper aims to contribute to the ongoing conceptual development and practical pursuit of resilience, the ability to absorb and respond to shocks, in an agricultural and climate change context. It builds on work that aims to dissolve the nature-society dualism and naturalisation of power relations inherent in systems thinking by developing and extending a framework originally conceived to integrate research on biological and cultural diversity. The resultant 'biocultural' framework examines livelihood practices, institutions, knowledge and beliefs and is applied to a case study of cocoa communities in Ghana's Central Region. Drawing on data collected over three years spanning an El Niño Southern Oscillation (ENSO) related drought event, the analysis demonstrates the utility of an expanded conception of resilience that links livelihood practices, which define the impact and response to droughts, with the constituent knowledge, institutions and beliefs that shape those practices. The study focuses on two key factors that underpin cocoa farmers' resilience to climate shocks: access to wetlands and access to credit. We argue that particular characteristics of livelihood practices, knowledge, belief and institutions, and their interactions, can be both resilience enhancing and undermining, when viewed at different spatial, temporal and social scales. Although such contradictions present challenges to policy-makers engaging with climate resilience, the analysis provides a clearer diagnoses of key challenges to the resilience of agricultural systems and insights into where policy interventions might be most effective. Highlights • We explore the resilience of Ghanaian cocoa communities to climate shocks. • We use a framework that examines livelihood practices, institutions, knowledge and beliefs. • Characteristics of resilience can be contradictory across different spatial, temporal and social scales. • The analysis highlights the importance of attending to social differentiation among communities. [ABSTRACT FROM AUTHOR]

This paper aims at providing a descriptive view of the low-frequency sea-level changes around the northern Australian coastline. Twenty years of sea-level observations from multi-mission satellite altimetry and tide gauges are used to characterize sea-level trends and inter-annual variability over the study region. The results show that the interannual sea-level fingerprint in the northern Australian coastline is closely related to El Niño Southern Oscillation (ENSO) and Madden-Julian Oscillation (MJO) events, with the greatest influence on the Gulf Carpentaria, Arafura Sea, and the Timor Sea. The basin average of 14 tide-gauge time series is in strong agreement with the basin average of the altimeter data, with a root mean square difference of 18 mm and a correlation coefficient of 0.95. The rate of the sea-level trend over the altimetry period (6.3 ± 1.4 mm/yr) estimated from tide gauges is slightly higher than that (6.1 ± 1.3 mm/yr) from altimetry in the time interval 1993–2013, which can vary with the length of the time interval. Here we provide new insights into examining the significance of sea-level trends by applying the non-parametric Mann-Kendall test. This test is applied to assess if the trends are significant (upward or downward). Apart from a positive rate of sea-level trends are not statistically significant in this region due to the effects of natural variability. The findings suggest that altimetric trends are not significant along the coasts and some parts of the Gulf Carpentaria (14°S-8°S), where geophysical corrections (e.g., ocean tides) cannot be estimated accurately and altimeter measurements are contaminated by reflections from the land. [ABSTRACT FROM AUTHOR]

The present study investigates the relationship between extreme north-east (NE) monsoon rainfall (NEMR) over the Indian peninsula region and El Niño forcing. This turns out to be a critical science issue especially after the 2015 Chennai flood. The puzzle being while most El Niños favour good NE monsoon, some don’t. In fact some El Niño years witnessed deficit NE monsoon. Therefore two different cases (or classes) of El Niños are considered for analysis based on standardized NEMR index and Niño 3.4 index with case-1 being both Niño-3.4 and NEMR indices greater than +1 and case-2 being Niño-3.4 index greater than +1 and NEMR index less than −1. Composite analysis suggests that SST anomalies in the central and eastern Pacific are strong in both cases but large differences are noted in the spatial distribution of SST over the Indo-western Pacific region. This questions our understanding of NEMR as mirror image of El Niño conditions in the Pacific. It is noted that the favourable excess NEMR in case-1 is due to anomalous moisture transport from Bay of Bengal and equatorial Indian Ocean to southern peninsular India. Strong SST gradient between warm western Indian Ocean (and Bay of Bengal) and cool western Pacific induced strong easterly wind anomalies during NE monsoon season favour moisture transport towards the core NE monsoon region. Further anomalous moisture convergence and convection over the core NE monsoon region supported positive rainfall anomalies in case-1. While in case-2, weak SST gradients over the Indo-western Pacific and absence of local low level convergence over NE monsoon region are mainly responsible for deficit rainfall. The ocean dynamics in the Indian Ocean displayed large differences during case-1 and case-2, suggesting the key role of Rossby wave dynamics in the Indian Ocean on NE monsoon extremes. Apart from the large scale circulation differences the number of cyclonic systems land fall for case-1 and case-2 have also contributed for variations in NE monsoon rainfall extremes during El Niño years. This study indicates that despite having strong warming in the central and eastern Pacific, NE monsoon rainfall variations over the southern peninsular India is mostly determined by SST gradient over the Indo-western Pacific region and number of systems formation in the Bay of Bengal and their land fall. The paper concludes that though the favourable large scale circulation induced by Pacific is important in modulating the NE monsoon rainfall the local air sea interaction plays a key role in modulating or driving rainfall extremes associated with El Niño. [ABSTRACT FROM AUTHOR]

The Colombian power sector is highly dependent on hydroelectricity, making it vulnerable to both annual dry seasons and the droughts brought by the El Niño-Southern Oscillation (ENSO). One efficient way to reduce such vulnerabilities is by introducing renewable energies that may complement the availability of hydroelectricity. This paper explores the degree of complementarity between solar and wind resources in Colombia and the country's hydropower sector, on both annual and interannual scales. Various correlation analyses are performed over four climatic variables: water inputs (runoff), precipitation, solar radiation, and wind speed, plus the Oceanic Niño Index (ONI), which helps to characterize ENSO events. The analysis is carried out over different geographic locations and seasons. The results indicate that solar and wind resources, particularly those in the Caribbean Coast and the central Andes regions, complement the hydropower sector during both the dry seasons of the annual climatological cycle and ENSO's warm and cold phases. Also, they show that complementarity varies, not just with the type of sources and location, but also with the seasons of the year and ENSO's stage of development. This paper provides an enhanced perspective on the behavior of renewables and offers an alternative viewpoint for designing the future expansion of power systems. Image 1 • Annual and interannual complementarities between renewable energies are explored. • Solar and wind can complement hydropower during the annual dry seasons and ENSO. • The Caribbean Coast and Andes regions have the largest complementarity potential. • Complementarity varies through yearly seasons and ENSO's development stages. [ABSTRACT FROM AUTHOR]

There is a strong inter-annual and inter-decadal variability in time series of variables related to water abundance, such as intense precipitation, high river discharge, flood magnitude, and flood loss in China. Part of this variability can be random or chaotic, but it may well be that climate variability track plays an important role in the interpretation of the variability of water abundance. The principal aim of this review paper is to create a summary of literature-based information on links of various climate-variability drivers, i.e. natural oscillations in the ocean–atmosphere system, and the variability of characteristics of destructive water abundance in China, at a range of spatial scales (national, provincial, basin-based, municipal). The present paper reviews extensive pool of literature discussing the links between the two modes of oscillation in the ocean-atmosphere system (ENSO - El Niño -Southern Oscillation and PDO – Pacific Decadal Oscillation) and variability in time series of variables related to water abundance in China. This paper also reviews examples of extension of the database, with the help of proxies. It reviews interpretation of possible link of particular large flood events (e.g. the 1998 and the 2016 deluges) to climate variability. Also a range of issues of relevance to water management are reviewed, such as seasonal forecasting and non-stationarity of flood frequency. [ABSTRACT FROM AUTHOR]

Sediment load delivered by rivers is an important terrestrial factor in the evolution and productivity of coastal ecosystems and coastal morphology. As the strongest interannual climate signal, the El Niño Southern Oscillation (ENSO) is closely related to variations in the hydrological cycle at global and regional scales. However, the influence of ENSO on temporal variations in sediment discharge is poorly understood. In this paper, we examine periodic variations in sediment discharge to the South China Sea from the Pearl River since the 1950s using wavelet transform analysis (WT). Furthermore, we apply cross wavelet spectrum (XWT) and wavelet coherence (WTC) to investigate the linkages between ENSO and sediment variability. The WT results revealed that periodic oscillations in sediment discharge in the Pearl River occurred annually (1 yr) before the 2000s, interannually (2–8 yr) from 1960–2002, and decadally (10–16 yr) from 1975–1995. These periodic variations in the sediment load series had common spectrum power with the water discharge and precipitation series, indicating an important climatic control. The XWT and WTC results revealed significant impacts of ENSO on precipitation, water discharge and sediment load at interannual time scales of 2–4.6 yr from 1960–2002 with a shift of patterns of ENSO on sediment variability after the 1970s. In addition, an in-phase relation between sediment discharge and ENSO at time scales of 10–16 yr from 1975–1995 was detected, indicating that variations at decadal scales could be related to other climatic teleconnections such as the Pacific Decadal Oscillation. Compared with the spectrum structures of periodic variations in precipitation and water discharge and their relationship with ENSO, there was a loss of energy in the sediment load at annual time scales after 2002 that can be attributed to dam construction in the river basin. Our study provides perspectives on the connections between ENSO and sediment variability at different time scales, which is of practical and scientific importance for forecasting global hydrological processes and for river management. [ABSTRACT FROM AUTHOR]

Studies of contemporary populations have demonstrated an association between decreased dietary diversity due to resource scarcity or underutilization and an increase in diseases related to poor micronutrient intake. With a reduction of dietary diversity, it is often the women and children in a population who are the first to suffer the effects of poor micronutrient status. Scurvy, a disease of prolonged vitamin C deficiency, is a micronutrient malnutrition disorder associated with resource scarcity, low dietary diversity, and/or dependence on high carbohydrate staple-foods. The aim of this paper is to assess the potential impact of nutritional transition on the prevalence of diseases of nutritional insufficiency in an archaeological sample. Here, we report palaeopathological findings from an Early Formative Period transitional site located in coastal Northern Chile (Quiani-7). The subadult cohort from this site is composed of four perinates who exhibit a number of non-specific skeletal changes suggestive of a systemic pathological condition. One of these is associated with an adult female exhibiting diagnostic skeletal lesions of scurvy. We argue that the lesions exhibited by these perinates may represent maternal transmission of vitamin C deficiency but acknowledge that there are difficulties in applying current diagnostic criteria for scurvy to individuals this young. [ABSTRACT FROM AUTHOR]

In this paper, the spatial patterns and vertical structure of atmospheric temperature anomalies, in both the tropics and the extratropical latitudes, associated with the El Niño-Southern Oscillation (ENSO) and quasi-biennial oscillation (QBO) in the upper troposphere and stratosphere are investigated using global positioning system (GPS) radio occultation (RO) measurements from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Formosa Satellite Mission 3 mission from July 2006 to February 2014. We find that negative correlations between the atmospheric temperature in the tropics and ENSO are observed at 17–30 km in the lower stratosphere at a lag of 1–4 months and at a lead of 1 month. Out-of-phase temperature variation is observed in the troposphere over the mid-latitude band and in-phase behaviour is observed in the lower stratosphere. Interestingly, we also find that there is a significant negative correlation at a lag of 1–3 months from 32 km to 40 km in the mid-latitude region of the Northern Hemisphere. The atmospheric temperature variations over mid-latitude regions in both hemispheres are closely related to the QBO. There are also two narrow zones over the subtropical jet zone where the QBO signals are strong in both hemispheres, approximately parallel to the equator. Finally, we develop a new robust index to describe the strength of the ENSO and QBO signal. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the Holocene record of extreme flood events in the upper Minjiang River valley of the eastern Tibetan Plateau, China. Slackwater deposits (SWDs), the fine-grained sediments of palaeofloods, were identified within debris flow deposits at a tributary mouth and in channel expansions along the bedrock gorge. Eight palaeoflood SWDs were dated to between 6.0 ± 0.9 ka and 4.6 ± 0.9 ka using optically-stimulated luminescence analysis in combination with the minimum age model and represent at least two phases of palaeoflood events. The palaeoflood history in the upper Minjiang River Valley is consistent with the record of the mid-Holocene flood events in the mainstream of the Yangtze River. These mid-Holocene extreme flood events were closely related to strong ENSO activity and variability of the monsoon climate in the eastern Tibetan Plateau. In our study area, minimum palaeoflood discharges were estimated as 6500–7800 m3/s by the step-backwater method. These estimated discharges are less than the values inferred for the outburst flood that occurred in the upper Minjiang River Valley in 1933. Flood-inundation maps show that palaeoflood SWDs were deposited in low-velocity backwater zones. Our palaeoflood reconstructions are important for improving regional records of maximum flood and help to develop risk analysis for rare flood events. • Sedimentary characteristics of palaeoflood records in complex environment were identified. • Palaeoflood discharges were estimated to be 6500–7800 m3/s at the three study sites. • Palaeoflood results redefine the envelope curve of the regional maximum floods. • Response of mid-Holocene (6.0–4.6 ka) extreme flood events to climate variability. • Palaeoflood reconstructions help to develop risk analysis for rare flood events. [ABSTRACT FROM AUTHOR]

We revisit the classical Suarez–Schopf delayed oscillator. Special attention is paid to the region of linear stability in the space of parameters. By means of the theory of inertial manifolds developed in our adjacent papers, we provide analytical–numerical evidence for the existence of two-dimensional inertial manifolds in the model. This allows to suggest a complete qualitative description of the dynamics in the region of linear stability. We show that there are two subregions corresponding to the existence of hidden or self-excited attracting periodic orbits. These subregions must be separated by a curve on which homoclinic "figure eights", bifurcating into a single one or a pair of unstable periodic orbits, should exist. We relate the observed hidden oscillations and homoclinics to the irregularity theories of ENSO and provide numerical evidence that chaotic behavior may appear if a small periodic forcing is applied to the model. We also use parameters from the Suarez–Schopf model to discover hidden and self-excited asynchronous periodic regimes in a ring array of coupled lossless transmission lines studied by J. Wu and H. Xia. • The Suarez–Schopf delayed oscillator possesses two-dimensional inertial manifolds. • Hidden or self-excited oscillations appear in the region of linear stability. • Unstable periodic orbits are born after homoclinic "figure eight" bifurcations. • Chaos can occur if a small amplitude periodic forcing is applied. • Both irregularity theories of ENSO may be justified by means of the model. [ABSTRACT FROM AUTHOR]

Projections of an increase in drought frequency and intensity over the next century are expected to have severe implications for a number of globally important coastal ecosystems. In this paper, we present geochemical data from three sediment cores extracted from the main depositional basins of Lake St Lucia, Africa's largest estuarine system. Lake St Lucia is subject to extreme natural variations in salinity. The sedimentary record documents the evolution of the system from a relatively deep-water, open lagoon to a confined, shallow estuarine lake that today is highly sensitive to changes in freshwater supply. This is particularly evident in the northern portions of the system, where the presence of distinct halite-enriched horizons document episodes of prolonged drought. The lateral persistence of these halite layers, as revealed by seismic profiling, point to a system-wide onset of desiccation associated with a major shift in the regional hydroclimate. The most severe drought events identified, which may have lasted several years, occur at ~ 1100 and 1750 cal year BP, and are associated with known peaks in El Niño frequency and intensity. Our analyses suggest that past cycles of desiccation and hyper-salinity have been controlled by climatic changes related to ENSO intensification. This study provides a valuable new record from a key ENSO-sensitive region of the Southern Hemisphere. Our findings have important relevance for understanding ENSO variability across the Indo-Pacific region and the influence exerted on systems sensitive to changes in moisture balance. [ABSTRACT FROM AUTHOR]

Reconstructing Holocene changes in regional sea level is useful for understanding future sea-level scenarios. In this paper we examined the sedimentology, pollen, foraminifera, and organic matter properties of a well-dated profile from the Subei Basin that spans the last 6.7 ka. By integrating our findings with the archaeological record, we investigated mid- to late Holocene vegetation responses to relative sea-level fluctuations and considered the impact of climatic variations on cultural development. In the middle Holocene, the rapid and abrupt expansion of salt marsh vegetation (Chenopodiaceae, Cyperaceae, and Poaceae) suggests a relative rise in sea level. From 5.7 to 4.2 cal ka BP, lowland swamps were settled by Neolithic communities, as indicated by peak levels of microscopic charcoal and a significant rise in herbaceous pollen species, such as Cyperaceae, Typha , Myriophyllum , and Poaceae. From 4.2 to 3.7 cal ka BP, a major increase in Chenopodiaceae abundance and a δ13C excursion were observed along with a decrease in Cyperaceae and Poaceae levels, which revealed that human activity significantly decreased following the 4.2 ka climate event. Evidence suggests that the area under investigation experienced a relatively high sea level between 6.7 and 6.0 ka, a relative decrease in sea level between 6.0 and 5.7 ka, a steady sea-level condition between 5.7 and 4.2 ka, and gradual replacement by a freshwater marsh between 5.7 and 4.2 ka. The pollen and δ13 C records demonstrate that the relative sea level rose quickly from 4.2 to 3.7 ka, which could correspond to the 4.2 ka event. Enhanced El Niño-Southern Oscillation (ENSO) variance and intense climatic events in eastern China were the driving forces behind the mid-late Holocene relative sea-level shift. The rise in relative sea level eventually led to the collapse of the Qingdun and Jiangzhuang sites in the Subei Basin. Our results provide independent vegetation evidence of the simultaneous changes in relative sea level and variations in climate. • Vegatation and environment changes are investigated from ∼6700 cal a BP. • The significant relative sea-level rise in the Subei Plain during 4.2–3.7 cal ka BP. • The rise in relative sea level led to the collapse of the Qingdun site and Jiangzhuang site in the Subei Basin. [ABSTRACT FROM AUTHOR]

The majority of present-day and future global warming is related to various positive feedbacks in the climate system that tend to amplify the initial radiative forcing from increasing greenhouse gases in the atmosphere. One essential positive feedback is the rise in upper tropospheric water vapor (UTWV) or the specific humidity (SH) that acts as an intense greenhouse gas trapping in additional heat released from the Earth's surface. In this paper we expand on previous studies showing that the interannual variability of UTWV in the tropical and extratropical climates is strongly linked with the El Nino-Southern Oscillation (ENSO). We have expanded on previous studies by looking at the response of the long-term UTWV concentrations to the ENSO over a 41-year period (1979–2019) using the ERA5 reanalysis data. For the first time we look at the physical mechanism for the El Nino and La Nina connections to UTWV that is shown to be related to changes in deep convection over the central and eastern Pacific Ocean. In agreement with previous studies, we find that El Nino years have positive anomalies in UTWV, while in La Nina years there are negative anomalies in UTWV (±10%). • Distribution of SH in the tropics are linked to the ENSO. • La Nina shows negative anomalies in UTWV at all longitudes in the tropical region. • El Nino show positive anomalies in UTWV at all longitudes in the tropical region. • Source region for these changes in UTWV is clearly visible as the Pacific region. [ABSTRACT FROM AUTHOR]