Climatic Oscillations Research Articles

Holocene stratigraphic architecture of a Mediterranean delta and implication for sediment budget evolution: Example of the Rhône delta

Deltaic systems evolve as a result of interactions between the hydroclimatic processes that occur in the catchment area and the coastal marine processes that reshape the coastline. The Holocene evolution of these environments is controlled by climate and anthropization, which are rarely considered in models of the evolution of deltaic systems. The Rhône delta has recorded the impact of climatic variations as well as the development and evolution of human societies over the Holocene period. This system underwent a post-glacial evolution controlled by global climatic warming punctuated by short periods of cooling, fluvial metamorphoses and a rapid marine transgression generated by the melting of the ice caps, followed by the initiation of delta progradation from around 7000 cal yr BP. Sedimentological and chronostratigraphic studies of 17 cores, supplementing an existing dataset on the deltaic plain and the prodelta, have enabled us to construct well-constrained stratigraphic correlations, making it possible to specify the spatio-temporal evolution of the Rhône delta. The variation in sedimentary fluxes was assessed for the different sequences identified, using 95 new core datings to constrain the sequential evolution of the different lobes. From the stratigraphic correlations on the delta and the estimated volumes of sediments exported out of the deltaic system, the total sediment volume between 11,700 cal yr BP and today is estimated at 126 billion m3. The variation of sediment fluxes has been adjusted according to the different phases of lobe progradation linked with the climate oscillations and the anthropic activity evolution during the Holocene. Taken together, these data highlight contrasting periods corresponding to the Roman period, the Little Ice Age and finally the ‘Anthropocene’, that can be compared to the main Mediterranean deltaic systems during the Holocene.

Recent global climate change effects: A study of Eleutheronema rhadinum in Chang-Yuen Ridge, Taiwan

This study investigated the potential effects of climatic oscillations on CPUE of Eleutheronema rhadinum (East Asian fourfinger threadfin), a commercially valuable fish species in East Asia. Fishery data from Chang-Yuen Ridge between 2015 and 2022 was analyzed in conjunction with four climatic oscillation indices that were lagged by up to 5 years. The results revealed a fluctuating CPUE associated with the 1-year-lagged Ocean Niño Index (ONI lag 1) and 1-year-lagged Southern Oscillation Index (SOI lag 1) suggesting a potential effect between climatic oscillation indices and East Asian fourfinger threadfin CPUE. These findings can provide insights into the association between East Asian fourfinger threadfin abundance and climatic oscillations in Chang-Yuen Ridge, Taiwan; the insights are valuable for fishery management amidst changing climate conditions.

Population structure and microscale morphological differentiation in a freshwater snail from the Chilean Altiplano

BackgroundThe diversity and population genetic structure of many species have been shaped by historical and contemporary climatic changes. For the species of the South American Altiplano, the historical climatic changes are mainly related to the wet events of great magnitude and regional influence that occurred during the Pleistocene climatic oscillations (PCOs). In contrast, contemporary climate changes are associated with events of lesser magnitude and local influence related to intensifications of the South American Summer Monsoon (SASM). Although multiple studies have analyzed the effect of PCOs on the genetic patterns of highland aquatic species, little is known about the impact of contemporary climate changes in recent evolutionary history. Therefore, in this study, we investigated the change in population structure and connectivity using nuclear and mitochondrial markers throughout the distribution range of Heleobia ascotanensis, a freshwater Cochliopidae endemic to the Ascotán Saltpan. In addition, using geometric morphometric analyses, we evaluated the concomitance of genetic divergence and morphological differentiation.ResultsThe mitochondrial sequence analysis results revealed the presence of highly divergent co-distributed and geographically nested haplotypes. This pattern reflects an extension in the distribution of groups that previously would have differentiated allopatrically. These changes in distribution would have covered the entire saltpan and would be associated with the large-scale wet events of the PCOs. On the other hand, the microsatellite results defined five spatially isolated populations, separated primarily by geographic barriers. Contemporary gene flow analyses suggest that post-PCO, climatic events that would have connected all populations did not occur. The morphometric analyses results indicate that there is significant morphological differentiation in the populations that are more isolated and that present the greatest genetic divergence.ConclusionsThe contemporary population structure and morphological variation of H. ascotanensis mainly reflect the post-PCO climatic influence. Although both markers exhibit high genetic structuring, the microsatellite and morphology results show the preponderant influence of fragmentation in recent evolutionary history. The contemporary genetic pattern shows that in species that have limited dispersal capabilities, genetic discontinuities can appear rapidly, erasing signs of historical connectivity.

Diversification of the terrestrial frog genus Anomaloglossus (Anura, Aromobatidae) in the Guiana Shield proceeded from highlands to lowlands, with successive loss and reacquisition of endotrophy

Two main landscapes emerge from the Guiana Shield: the highlands to the west called the Pantepui region and the Amazonian lowlands to the east, both harbouring numerous endemic species. With 32 currently recognized species, the genus Anomaloglossus stands out among Neotropical frogs as one that diversified only within the Guiana Shield both in the highlands and the lowlands. We present a time-calibrated phylogeny obtained by using combined mitogenomic and nuclear DNA, which suggests that the genus originates from Pantepui where extant lineages started diversifying around 21 Ma, and subsequently (ca. 17 Ma) dispersed during the Miocene Climatic Optimum to the lowlands of the eastern Guiana Shield where the ability to produce endotrophic tadpoles evolved. Further diversification within the lowlands in the A. stepheni group notably led to an evolutionary reversal toward exotrophy in one species group during the late Miocene, followed by reacquisition of endotrophy during the Pleistocene. These successive shifts of reproductive mode seem to have accompanied climatic oscillations. Long dry periods might have triggered evolution of exotrophy, whereas wetter climates favoured endotrophic forms, enabling colonization of terrestrial habitats distant from water. Acquisition, loss, and reacquisition of endotrophy makes Anomaloglossus unique among frogs and may largely explain the current species diversity. The micro evolutionary processes involved in these rapid shifts of reproductive mode remain to be revealed.

Refugia within refugium of Geranium yesoense varieties: a follow-up study using chloroplast genome sequencing data of specimens from Mt. Asama, Japan

Abstract Recent phylogeographical studies have revealed that refugia sometimes retain high levels of genetic heterogeneity due to multiple colonization events, a phenomenon defined as ‘refugia within refugium’. In previous research, we reported a complex genetic structure within the Geranium yesoense complex, an alpine plant found in an interglacial refugium at high elevation in Central Japan, probably resulting from multiple colonization and hybridization events. However, we were unable to evaluate instances of introgression due to limited sample size. In the present study, we performed additional chloroplast genome sequencing, along with Sanger sequencing of selected chloroplast DNA regions, to elucidate the phylogenetic relationships among the refugial populations. The chloroplast genome sequence of a sample from Mt. Asama (an important refugium) was nested within the northern lineage (i.e. var. yesoense and var. pseudopratense), and haplotypes from Mt. Asama and Mt. Ibuki were also grouped with those of the northern lineage. Although our previous study suggested hybridization events between northern and southern lineages (i.e. var. nipponicum) at Mt. Asama, haplotypes from the southern lineage were not detected at range margins. This suggests that directional introgression occurred in these regions. Overall, our results further support that genetic heterogeneity within these refugia was amplified by recolonization and hybridization during past climate oscillations.

Can the delayed effects of climatic oscillations have a greater influence on global fisheries compared to their immediate effects?

Climatic oscillations affect fish population dynamics, ecological processes, and fishing operations in maritime habitats. This study examined how climatic oscillations affect catch rates for striped, blue, and silver marlins in the Atlantic Ocean. These oscillations are regarded as the primary factor influencing the abundance and accessibility of specific resources utilized by fishers. Logbook data were obtained from Taiwanese large-scale fishing vessels for climatic oscillations during the period 2005-2016. The results indicated that the effect of the Subtropical Indian Ocean Dipole on marlin catch rates did not have a lag, whereas those of the North Atlantic Oscillation, Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation, and Indian Ocean Dipole had various lags. Pearson's correlation analysis was conducted to examine the correlations between atmospheric oscillation indices and marlin catch rates, and wavelet analysis was employed to describe the influences of the most relevant lags. The results indicated that annual atmospheric fluctuations and their lags affected the abundance and catchability of striped, blue, and silver marlins in the study region. This, in turn, may affect the presence of these species in the market and lead to fluctuations in their prices in accordance with supply and demand. Overall, understanding the effects of climatic oscillations on fish species are essential for policymakers and coastal communities seeking to manage marine resources, predict changes in marine ecosystems, and establish appropriate methods for controlling the effects of climate variability.

Hybrids as mirrors of the past: genomic footprints reveal spatio-temporal dynamics and extinction risk of alpine extremophytes in the mountains of Central Asia.

Hybridization is one of the key processes shaping lineage diversification, particularly in regions that experienced strong climate oscillations. The alpine biome with its rich history of glacial-interglacial cycles and complex patterns of species distribution shifts offers an excellent system to investigate the impact of gene flow on population dynamics and speciation, important issues for evolutionary biology and biodiversity conservation. In this study, we combined genomic data (DArTseq), chloroplast markers, and morphology to examine phylogenetic relationships and the permeability of species boundaries and their evolutionary outcomes among the alpine extremophilic species of Puccinellia (Poaceae) in the Pamir Mountains, a part of the Mountains of Central Asia biodiversity hotspot. We determined the occurrence of interspecific hybrids between P. himalaica and P. pamirica, which demonstrated almost symmetric ancestry from their parental species and did not show signals of introgression. According to our integrative revision, the natural hybrids between P. himalaica and P. pamirica should be classified as Puccinellia ×vachanica (pro species). Using approximate Bayesian computation for population history inference, we uncovered that P. himalaica hybridized with P. pamirica independently in multiple localities over the Holocene. Hybrids inherited the fine-scale genetic structure from their parental species, which developed these patterns earlier, during the Late Pleistocene. Hybridization had different consequences for the involved parental lineages, likely playing an important role in a continuing decline of P. himalaica in the Pamir Mountains over the Holocene. Our results show that P. himalaica should be considered a critically endangered species in the Pamir Mountains and could also be retreating across its entire range of distribution in High Mountain Asia. Using a comparative phylogeographic framework, we revealed the risk of extinction of a cold-adapted alpine species in a global biodiversity hotspot. This study highlights that genomics could unravel diversity trends under climate change and provides valuable evidence for conservation management.

Comparative and Historical Analysis of the Principles of Stimulating the Economy during the Crisis Period (Middle Bronze and Modern Times)

Introduction. The comparative analysis contained in the work is devoted to the limitations of the dependence of socio-political processes and economic conditions on historical and anthropogenic factors. Now we witness the instability of the global system, overheated by specific contradictions, phobias and crises. Falling stock indices, the threat of default, growing international problems, climate oscillations – all this forces society to look for a way out of the crisis. Purpose. Only at the level of transdisciplinary approaches can one calculate accurate and consistent data that allows one to develop fundamental knowledge of the subject in order to implement a predictive function for choosing a development concept and determining a management strategy. Materials and Methods. This study, carried out with the requirements of a retrospective analysis, draws attention to the most striking aspects of the economic policies of the Roosevelt administration in the 1930s, past experience and similar principles created from the sources of the era of the III Dynasty of Ur. Results. A real historical comparative analysis of various socio-economic models depending on natural and climatic changes. Methods for overcoming the crisis in the most difficult period of the Bronze Age (III Dynasty of Ur), caused by fluctuations in the Bond cycle, have been identified. Comparisons of the administrative forms regulating the national economy of the Third Dynasty of Ur and the state-monopoly capitalism of F. Roosevelt’s New Deal. Discussion and Conclusion. The author knows the meaning of the saying “Omne simile claudicat”. Despite the same nature of the crisis trends that led to an unexpected turn, in which the role of the government in the economic activity of society is manifested, the concept of stimulating the national economy in these two cases is equally similar. And if they are truly intended and repeated, then there are opportunities to consider them in the present or future as a leading concept for economic development.

An age-depth model for Lake Bosumtwi (Ghana) to reconstruct one million years of West African climate and environmental change

Situated within a 1.07 million-year-old meteorite crater, Lake Bosumtwi in Ghana stands as a pivotal location for comprehending climatic, ecological and environmental fluctuations within the sub-Saharan region of West Africa. The region's susceptibility to seasonal environmental shifts and climate oscillations is heightened by the annual movements of the tropical rain belt driven by atmospheric circulation. Yet, there is no satisfying age-depth model available for the entire sedimentary sequence strongly limiting our understanding of changes in this circulation pattern and associated (broad-scale) environmental responses during the last million years in the local to regional context of Lake Bosumtwi. To overcome this, we statistically examine the cyclicity in total natural gamma ray (NGR) data on a core from the lake's centre and create a cyclostratigraphic age-depth model. The calculated maximum age of 946 ka agrees well with the meteorite impact age (∼10 % offset). In order to refine this purely statistical approach, we also perform a correlative age-depth model using 33 tie points accounting for the complexity of climatic and environmental imprints to the NGR record that may exceed direct insolation related effects. Special attention is paid to the core's robustly dated (14C, OSL, U/Th) uppermost part covering the last 200 ka. Here, high NGR and co-varying K counts coincide with warm periods (except of the water-saturated and unconsolidated Holocene part) and the inverse for glacials and stadials. Based on this, we define tie points for correlating our NGR data to the age-depth model of a NE Atlantic SST record. Comparing our results to the correlation target, other global climate records and Sahara dust flux data reveals striking similarities and supports a proxy understanding with increased in wash of K-enriched terrigenous material from the crater rims in warm and moist periods (high NGR) and K-depleted dust input in stadials possibly contributing to low NGR values in addition to reduced input of K-enriched sediments from the crater rims. Our correlative age model results in precession amplitudes matching eccentricity well, providing further support especially because an over-tuning is unlikely with the used 33 tie points. Overall we provide crucial chronological context to numerous datasets along with environmental constrains that can be used to study the potential habitat availability of early anatomically modern humans in West Africa.

Weakened casual feedback loops following intensive restoration efforts and climate changes in a large shallow freshwater lake

Understanding how phytoplankton interacts with local and regional drivers as well as their feedbacks is a great challenge, and quantitative analyses of the regulating role of human activities and climate changes on these feedback loops are also limited. By using monthly monitoring dataset (2000–2017) from Lake Taihu and empirical dynamic modelling to construct causal networks, we quantified the strengths of causal feedbacks among phytoplankton, local environments, zooplankton, meteorology as well as global climate oscillation. Prevalent bidirectional causal linkages between phytoplankton biomass (chlorophyll a) and the tested drivers were found, providing holistic and quantitative evidence of the ubiquitous feedback loops. Phytoplankton biomass exhibited the highest feedbacks with total inorganic nitrogen and ammonia and the lowest with nitrate. The feedbacks between phytoplankton biomass and environmental factors from 2000 to 2017 could be classified into two groups: the local environments (e.g., nutrients, pH, transparency, zooplankton biomass)-driven enhancement loops promoting the response of the phytoplankton biomass, and the climate (e.g., wind speed)-driven regulatory loops suppressing it. The two counterbalanced groups modified the emergent macroecological patterns. Our findings revealed that the causal feedback networks loosened significantly after 2007 following nutrient loading reduction and unsuccessful biomanipulation restoration attempts by stocking carp. The strength of enhancement loops underwent marked decreases leading to reduced phytoplankton responses to the tested drivers, while the climate (decreasing wind speed, warming winter)-driven regulatory loops increased– like a tug-of-war. To counteract the self-amplifying feedback loops, the present eutrophication mitigation efforts, especially nutrient reduction, should be continued, and introduction of alternative measures to indirectly regulate the critical components (e.g., pH, Secchi depth, zooplankton biomass) of the loops would be beneficial.

Vegetation response to cold climate oscillations during the Holocene – preliminary results of the pollen analysis of the sediments of Lake Boczne (the Great Masurian Lakes District, NE Poland)

Vegetation response to cold climate oscillations during the Holocene – preliminary results of the pollen analysis of the sediments of Lake Boczne (the Great Masurian Lakes District, NE Poland)

Resolving Cenozoic climate pattern debate in East Asia: Insights from orbital-scale oscillations

Paleoclimate reconstruction and aeolian deposits in China indicate a major environmental reorganization – the formation of a nonzonal monsoon-dominated climate pattern – in East Asia in the late Oligocene and the early Miocene. In contrast, a zonal planetary-wind-dominated climate pattern has prevailed during the Paleocene and Eocene. However, this classical paradigm describing the climate transition has been questioned by recent studies. Here, our study emphasizes the importance of considering orbital-scale climate oscillations to better understand and reassess the paradigm. By examining the halite and mudstone sequence in the Jianghan Basin and conducting numerical experiments using the Norwegian Earth System model, we propose the concept of a “green Yangtze” phenomenon, which utilizes orbital-scale climate oscillations to reconcile the wet and dry environmental indicators in Eastern China during the Paleogene. It is essential to differentiate the Paleogene climate, characterized by intense orbital-scale wet and arid oscillations, from the Neogene monsoon-dominated climate. The classic paradigm remains valuable in understanding the long-term mean environment, albeit without capturing the orbital-scale details. Future research should focus on uncovering orbital-scale variations to enhance our understanding of climate evolution and dynamics in East Asia during the Cenozoic.

Impacts and risks of “realistic” global warming projections for the 21st century

The IPCC AR6 assessment of the impacts and risks associated with projected climate changes for the 21st century is both alarming and ambiguous. According to computer projections, global surface temperature may warm from 1.3 °C to 8.0 °C by 2100, depending on the global climate model (GCM) and the shared socioeconomic pathway (SSP) scenario used for the simulations. Actual climate-change hazards are estimated to be high and very high if the global surface temperature rises, respectively, more than 2.0 °C and 3.0 °C above pre-industrial levels. Recent studies, however, showed that a substantial number of CMIP6 GCMs run “too hot” because they appear to be too sensitive to radiative forcing, and that the high/extreme emission scenarios SSP3-7.0 and SSP5-8.5 are to be rejected because judged to be unlikely and highly unlikely, respectively. Yet, the IPCC AR6 mostly focused on such alarmistic scenarios for risk assessments. This paper examines the impacts and risks of “realistic” climate change projections for the 21st century generated by assessing the theoretical models and integrating them with the existing empirical knowledge on global warming and the various natural cycles of climate change that have been recorded by a variety of scientists and historians. This is achieved by combining the SSP2-4.5 scenario (which is the most likely SSP according to the current policies reported by the International Energy Agency) and empirically optimized climate modeling. According to recent research, the GCM macro-ensemble that best hindcast the global surface warming observed from 1980 to 1990 to 2012–2022 should be made up of models that are characterized by a low equilibrium climate sensitivity (ECS) (1.5 °C < ECS ≤ 3.0 °C), in contrast to the IPCC AR6 likely and very likely ECS ranges at 2.5–4.0 °C and 2.0–5.0 °C, respectively. I show that the low-ECS macro-GCM with the SSP2-4.5 scenario projects a global surface temperature warming of 1.68–3.09 °C by 2080–2100 instead of 1.98–3.82 °C obtained with the GCMs with ECS in the 2.5–4.0 °C range. However, if the global surface temperature records are affected by significant non-climatic warm biases — as suggested by satellite-based lower troposphere temperature records and current studies on urban heat island effects — the same climate simulations should be scaled down by about 30%, resulting in a warming of about 1.18–2.16 °C by 2080–2100. Furthermore, similar moderate warming estimates (1.15–2.52 °C) are also projected by alternative empirically derived models that aim to recreate the decadal-to-millennial natural climatic oscillations, which the GCMs do not reproduce. The proposed methodologies aim to simulate hypothetical models supposed to optimally hindcast the actual available data. The obtained climate projections show that the expected global surface warming for the 21st-century will likely be mild, that is, no more than 2.5–3.0 °C and, on average, likely below the 2.0 °C threshold. This should allow for the mitigation and management of the most dangerous climate-change related hazards through appropriate low-cost adaptation policies. In conclusion, enforcing expensive decarbonization and net-zero emission scenarios, such as SSP1-2.6, is not required because the Paris Agreement temperature target of keeping global warming < 2 °C throughout the 21st century should be compatible also with moderate and pragmatic shared socioeconomic pathways such as the SSP2-4.5.

Range dynamics of Walterinnesia morgani (Serpentes, Elapidae) during climatic oscillations in Iran

Reptiles have a crucial part in maintaining global biodiversity and the functioning of dynamic ecosystems, owing to their ecological roles and functions. Nevertheless, these organisms are susceptible to human-induced disruptions and the deterioration of their habitats, leading to their categorization as the third most endangered group of vertebrates on a global scale. Understanding the spatial distribution of reptiles is crucial due to their often specific habitat needs and limited vagility. Morgan’s black cobra (Walterinnesia morgani) is a secretive venomous snake species that has thus far received little attention in Iranian scientific literature. The aim of the present study was to determine the existing distribution pattern of the cobra and to speculate on how climatic changes might affect it. Maximum entropy modeling was used to examine a dataset consisting of 16 occurrence records gleaned from field observations and the literature. The niche of the species was predicted using current and future climate change forecasts and bioclimatic and topographical characteristics. The models predicted a future reduction in the wide distribution region of W. morgani in southern and western Iran. It was discovered that climatic factors like temperature range, precipitation dynamics, and river proximity all played a key role in shaping the pattern of distribution. The predicted suitable areas for W. morgani were dependent on water sources; however, future scenarios showed a decline in suitable habitats. This study underscores the importance of conservation efforts in light of the potential implications of climate change on this species. To further understand the range shifts and adaptive strategies of the species, further study of its ecology and dispersal dynamics is required.

Multilocus phylogeography of Italian Moorish geckos adds insights into the evolutionary history of European populations

AbstractGeckos of clade III of the Tarentola mauritanica species complex are widespread throughout southern Europe and northern Africa. We investigated the genetic variability of the Italian populations by performing a widespread sampling throughout the mainland and the two main islands of Sicily and Sardinia. We analysed 199 newly generated sequences of the mitochondrial 16S rRNA gene and 269 nuclear genotypes inferred from nine microsatellite loci from 307 individuals. We found 13 new mitochondrial haplotypes in Italy, whereas previous findings reported a single haplotype widespread throughout the country and in the rest of Europe, which currently make Italy the centre of genetic diversity of this taxon. There was no evidence of mitochondrial DNA structuring with geographic correlation. At the population genetic level, our multilocus approach based on nuclear markers returned a shallow genetic structure. Nonetheless, we disclosed the presence of at least four distinct genetic clusters (namely the Adriatic, two Tyrrhenian and the Calabrian clusters). Our findings do not support the two hypotheses proposed to explain the low level of mitochondrial polymorphism in this taxon, namely the genetic hitch‐hiking due to selective sweep and the historical human‐mediated colonization hypotheses. Based on the fossil record, the presence in Italy of this taxon since the Pleistocene Epoch is plausible. Given the discordance in genetic structure between mitochondrial and nuclear DNA, the exact role of the Italian Peninsula in shaping the observed patterns of genetic diversity during the Pleistocenic climatic oscillations needs further investigation.

Impact of climatic oscillations on marlin catch rates of Taiwanese long-line vessels in the Indian Ocean

This study explored the influence of climatic oscillations on the striped, blue, and silver marlin catch rates in the Indian Ocean by using logbook data from Taiwanese large-scale fishing vessels and climate records from 1994 to 2016. Only the Madden–Julian oscillation (MJO) and the subtropical Indian Ocean dipole (SIOD) had immediate effects on the striped and silver marlin catch rates. The positive and negative phases of the IOD at the lags of 7 and 3 years corresponded to increased and decreased catch rates, respectively, for both the striped and blue marlin, contrasting to the reverse pattern for the silver marlin. Similarly, all three marlin species experienced decreased and increased catch rates respectively during the positive and negative phases of the Pacific decadal oscillation. The striped and blue marlin catch rates decreased and increased during the positive and negative phases, respectively, of the SIOD and MJO with various lags. Our results suggest that the impacts of climatic oscillations on fish species are crucial for policymakers and coastal communities for managing marine resources, forecasting changes in marine ecosystems, and developing strategies to adapt to and mitigate the effects of climate variability.

Pleistocene climatic oscillations influenced the emergence of geographically widespread and restricted genetic lineages in an Andean grasshopper species group

Abstract The grasshopper Trimerotropis pallidipennis species complex is distributed across arid and semi-arid environments from North to South America, reaching high altitudes along the Andes Mountain range. Currently, there are four valid species of Trimerotropis in South America. However, some species were found to comprise several genetic lineages. Here, we describe the genetic structure, lineage diversification, and environmental requirements within the Trimerotropis species complex in South America based on sequences from the mitochondrial COI gene, 4048 single nucleotide polymorphisms, and ecological niche modelling. The analyses revealed the existence of at least five lineages: two with a restricted geographical distribution and three with a very wide one. The results provide evidence that glacial cycles promoted not only the presence of refuge areas but also the isolation of widely distributed lineages on the eastern and western sides of the southern Andes, potentially driving the emergence of the Trimerotropis sp. lineage, which can tolerate more temperate habitats. Our results provide evidence for the effects of Pleistocene climatic changes on the diversification history of a South American grasshopper species complex.

Rapid Climate Links Between High Northern Latitudes and Tropical Southeast Asia Over the Last 40 ka

AbstractThe climate response of tropical Southeast Asia to abrupt climate change originating from high northern latitudes remains poorly understood. Here, marine sediments recovered from the Northwest Borneo Trough are analyzed to trace variations in terrigenous material composition associated with sea level and palaeoflood activities over the past 40 ka. We describe for the first time the influence of sea level change on terrigenous deposition from a tropical island with small mountainous rivers surrounded by narrow continental shelves and the coupling between North Atlantic dynamics and climate feedbacks in tropical Southeast Asia during the Dansgaard‐Oeschger stadials. This study demonstrates that climate oscillations occurring at high northern latitudes can be transmitted to tropical Southeast Asia through the functions of sea level, the East Asian winter monsoon and the Intertropical Convergence Zone. Such information is fundamental to correctly assessing future sea level rise and flood risks in tropical Southeast Asia.

Towards an Integrated and Accurate Planktonic-Foraminiferal-Deduced Bio-Chrono-Stratigraphic Framework of Late Quaternary Mediterranean Marine Cores

The late Quaternary is a key stratigraphic interval as it encompasses the Late Glacial to Holocene transition, which is characterized by a series of pronounced centennial climate oscillations and subsequent short-term events of paleoceanographic variability. Across this stratigraphic interval, significant turnovers and faunal changes in the composition and abundance of planktonic foraminiferal assemblages are well-documented through their high-resolution quantitative analysis performed in the south Aegean core NS-18. The identification of 10 synchronous bioevents among the Mediterranean sub-basins allows accurate inter-basinal correlations over the study time interval, thus contributing to the development of a robust chronostratigraphic framework for this setting. Moreover, the identification and timing of additional 20 diachronous bioevents, in conjunction with the already established bio-ecozonation scheme of the Aegean Sea, provide a continuous record of faunal changes (in terms of species-specific distributional abundances) which can be used as an additional locally expressed biochronological tool for the eastern Mediterranean deep-sea cores. The present study certainly indicates that the cause-and-effect relationships between the paleoceanographic/paleoclimatic perturbations and biological response require a highly resolved regional chronostratigraphy.

Univariate and bivariate spatiotemporal characteristics of heat waves and relative influence of large-scale climate oscillations over India

Heat waves (HWs) have grown in frequency, duration, and intensity in last few decades globally and even the latest climate projections (CMIP6) reveal these to get worsen under enhanced global warming. HWs have adverse impacts over biophysical and human systems, therefore, to analyse the impacts of HWs accurately, it is required to understand the regional trend and variability associated with HWs. We carried out a bivariate copula-based joint exceedance probabilistic analysis of HW characteristics to better assess the vulnerability of Indian regions. The regions with comparatively higher HW frequency, higher intensity, longer duration, and lower joint return period of HW frequency and intensity were selected as vulnerable to HWs. Rajasthan, Madhya Pradesh, Uttar Pradesh, Punjab, Bihar, Chhattisgarh, Gujrat, Karnataka, Maharashtra, Telangana, Andhra Pradesh, and Odisha states of India have been found vulnerable and are projected to get even more vulnerable in the future as per the recent climate projections. To unveil the spatiotemporal variability in HW characteristics, we investigated the relative influence of crucial large-scale climate oscillations (LSCOs) i.e., ENSO, IOD, and AMO on HW by introducing these atmospheric variables as covariates in nonstationary extreme value theory (EVT)-based models. The statistical analysis from generalized extreme value distribution of temperature extreme with LSCOs reveals that ENSO and IOD simultaneously have been influencing the extreme in 21.2%, 25.9% and 23.1% of total region taken into consideration in April, May and June month respectively.