Present-day Climate Change Research Articles

Tipping detection using climate networks

The development of robust Early Warning Signals (EWSs) is necessary to quantify the risk of crossing tipping points in the present-day climate change. Classically, EWSs are statistical measures based on time series of climate state variables, without exploiting their spatial distribution. However, spatial information is crucial to identify the starting location of a transition process and can be directly inferred by satellite observations. By using complex networks constructed from several climate variables on the numerical grid of climate simulations, we seek for network properties that can serve as EWSs when approaching a state transition. We show that network indicators such as the normalized degree, the average length distance, and the betweenness centrality are capable of detecting tipping points at the global scale, as obtained by the MIT general circulation model in a coupled-aquaplanet configuration for CO2 concentration-driven simulations. The applicability of such indicators as EWSs is assessed and compared to traditional methods. We also analyze the ability of climate networks to identify nonlinear dynamical patterns.

Long-term variation in thermal strain on the human body in the region of Siedlce

Aim of the studyAs a result of the increase in average air temperature associated with the present-day climate change, heatwaves are forecast to occur with increasing frequency. What is more, they will be longer, more intense, and potentially very dangerous for human health and life. The present work reports the day-to-day variation in air temperature and the variation of thermally characteristic days in Siedlce from 2001 to 2023.Material and methodsDay-to-day values of average and maximum air temperatures were obtained from the Siedlce Meteorological Station. The day-to-day variation in air temperature was determined across six ranges, and their frequencies in each month were calculated. Additionally, based on the maximum temperature, the number of thermally characteristic days (from cold to hot) was identified, and sequences of hot and very hot days were determined. The direction of trends in the number of hot and very hot days was also established.Results and conclusionsIn the Siedlce region, days marked by significant day-to-day temperature changes occurred on average 4.8 days per year, them being the most frequent in January (5.5 days/year) and least frequent in October (3.7 days/year). Comparing the number of hot and very hot days between the periods 2001-2012 and 2013-2023, an increase of about 6 hot days and 3 very hot days was observed. The trend coefficients for these changes were also positive, amounting to 0.43 and 0.24 days, respectively. The most frequent were sequences of hot days which were 4 to 6 days long.

On the influence of rock glacier dynamics on the runoff in basin of the Ulken Almaty (Bolshaya Almatinka) River, Northern Tien Shan

The purpose of the work was to study the dynamics of mountain stone glaciers and streams flowing down from them for an understanding their hydrological significance. Two glaciers: Morenny and Gorodetsky, were analyzed, both located in the river Ulken Almaty (Big Almatinka) basin, Northern Tien Shan. On the average, the rate of surface displacement of the Morennoye glacier is higher than that of the Gorodetsky, which is associated with increased ice content of the last one. The increase in rates of surface displacement of both stone glaciers revealed in 2021–2022 when compared to previous years turned out to be consistent with the widely discussed idea of intensification of such glaciers dynamics under the present-day climate changes and glacier retreats. It was found that the stone glaciers have a pronounced influence on the water regime, temperature and chemical composition of watercourses formed by water running out from them. They are distinguished by the almost complete absence of intraday fluctuations in the level, temperature, and specific electrical conductivity of water, which are more pronounced in rivers and streams with glacial alimentation during the summer time. Some waterflows from the Gorodetsky glacier do not freeze in winter, which is indicative of significant groundwater reserves in its body. The waters of each of the above stone glaciers differ in their characteristic mineralization, temperature, and the ratio of the major ions. The stable water flow from such glaciers can play an important role in maintaining a river runoff during periods of the low stream discharge.

Extreme Weather and Women: Exploring Impacts and Responses

Extreme weather caused by climate change is increasingly attracting public attention, and the shortage of food, water and many other resources caused by extreme weather has put women, as a vulnerable group, to an even more severe test, substantially affecting their everyday life, physical and mental health. In the context of the present-day climate change, issues affecting women demand an enormous amount of attention since, while being at an unfair disadvantage in the fight against climate change, they are a force to be reckoned with. This paper based on accumulating and assessing the existing literature and investigates the effects of climate change-induced extreme weather conditions on women and offers suggestions and tactics for minimizing the negative impact that weather extremes cause. The concept of "gender equality" should be considered in climate action and decision-making, it is argued, in order to support the equal and healthy development of society.

One catastrophic flood every millennium: Synchronicity of extreme floods and global warm periods in the multi-archive record of the Roman theatre of Guadix (Granada, SE Spain)

Past global changes are typically registered in both natural (e.g., geologic-geomorphological, atmospheric-climatic, hydrologic-glacial and biological) and cultural records (e.g., archaeological, historical and documentary sources). Nevertheless, there are few sites in the world where sedimentary and archaeological evidence combine to provide information about two or more past millennial climate changes. In this regard, the Roman city of Guadix (Granada, SE Spain) represents a singular location, whose Roman theatre (1st century CE), recently discovered in 2007, contains palaeo-flood evidences that can be related to the two latest global warm periods: the Roman and Medieval epochs.In this research, detailed geological analyses are carried out. These analyses consisted in careful descriptions of vertical stratigraphic sections (lithology, structures…) and lateral correlation panels; as well as fluvial facies models to interpret the sedimentary environments for each sequence. This sedimentological information was combined with the study of archaeological remains, radiocarbon dating and optically stimulated luminescence, and three major flood events have been identified: two of them dating back to the beginning of the 1st century CE (period of the Pax Romana Empire); and the other occurring at the end of the 12th century (Islamic Almohad period). Such extreme hydrological events were synchronous with two warm periods: the Roman Climatic Optimum and the Medieval Warm Period. This seems to suggest that the meteorological fluctuations associated to climate changes during warming periods (such as the current one associated with present-day climate change) very likely produce such extraordinary or extreme events, which can mobilise large amounts of solid load (sands, silts and clays) and trigger sudden changes in the configuration of the river system (channel avulsions, meander cut-offs and captures among tributaries) and alluvial fans (at tributary mouths).We believe that the documented observations provide an analogy for the current warming period. In this regard, flood risk management in the current city of Guadix, whose hazard and risk maps were drawn up according to the criteria of the European Flood Directive, should take into account: (i) the millennial recurrent character of catastrophic floods in Guadix, well above the 500-year return period officially considered; (ii) the importance of the mobilisation of solid load in flood hazard and risk, which can obstruct drains and reduce the capacity of channels and bridges; (iii) the geomorphological dynamics, capable of modifying the position of the channels and thus the delimitation of hazard and risk zones; (iv) the role of non-permanent tributaries of the Guadix River during storms and heavy rain, related to quasi-stationary convective cells. Only in this way, will flood hazard and risk maps be useful in territorial and urban planning, civil protection during emergencies and the reduction of damage from future catastrophic floods. The present study highlights how geoarchaeological and palaeo-environmental records can be a highly valuable source of data for the improvement of flood hazard assessments in the 21st Century.

Population status, habitat preferences and predictive current and future distributions of three endangered Silene species under changing climate.

One of the most crucial steps in the practical conservation of endangered endemic mountain plants is to address their population size status and habitat requirements concurrently with understanding their response to future global warming. Three endangered Silene species-Silene leucophylla Boiss., S. schimperiana Boiss., and S. oreosinaica Chowdhuri-in Egypt were the focus of the current study. These species were examined for population status change, habitat quality variables (topography, soil features, and threats), and predictive current and future distributions. To find population size changes, recent field surveys and historical records were compared. Using Random Forest (RF) and Canonical Correspondence Analysis (CCA), habitat preferences were assessed. To forecast present-day distribution and climate change response, an ensemble model was used. The results reported a continuous decline in the population size of the three species. Both RF and CCA addressed that elevation, soil texture (silt, sand, and clay fractions), soil moisture, habitat-type, chlorides, electric conductivity, and slope were among the important variables associated with habitat quality. The central northern sector of the Saint Catherine area is the hotspot location for the predictive current distribution of three species with suitable areas of 291.40, 293.10, and 58.29 km2 for S. leucophylla, S. schimperiana, and S. oreosinaica, respectively. Precipitation-related variables and elevation were the key predictors for the current distribution of three Silene species. In response to climate change scenarios, the three Silene species exhibited a gradual contraction in the predictive suitable areas with upward shifts by 2050 and 2070. The protection of these species and reintroduction to the predicted current and future climatically suitable areas are urgent priorities. Ex-situ conservation and raised surveillance, as well as fenced enclosures may catapult as promising and effective approaches to conserving such threatened species.

Nanoengineering of metal-based electrocatalysts for carbon dioxide (CO2) reduction: A critical review

Massive carbon dioxide (CO2) emissions from the extravagant use of traditional fossil fuels and heavy anthropogenic activities have been the predominant causes of present-day global warming and climate change. Electrocatalytic CO2 reduction reaction (eCO2RR), typically in the aqueous phase, is regarded as a sustainable strategy to transform CO2 into value-added chemical compounds (e.g., precious hydrocarbons and oxygenates), thus addressing the global concerns of non-renewable energy sources (e.g., fossil fuels) depletion and ever-increasing environmental pollution simultaneously. Nevertheless, due to the slack kinetics of eCO2RR and inevitable undesired side reactions (e.g., hydrogen evolution reaction; HER), highly active, selective, and stable electrocatalysts are crucially demanded to promote this thermodynamically uphill reaction. Metal-based nanomaterials have proven promising prospects among various electrocatalysts used for eCO2RR due to their ease of synthesis, high activity, and resource abundance. While copper (Cu)-based electrocatalysts are typical choices for the C–C coupling and thus generation of multicarbon (C2+) chemicals (e.g., ethylene (C2H4) and ethanol (CH3CH2OH)), other transition metal (TM)-based catalysts such as tin (Sn), zinc (Zn), silver (Ag), and their oxides are often utilized for producing light and monocarbon products (e.g., carbon monoxide (CO), formate (COOH−), methane (CH4), and methanol (CH3OH)). This review highlights the contemporary advancements in materials and nanoengineering strategies for exploring potential metal-based catalysts for efficient eCO2RR. In the meantime, challenges in obtaining a highly selective and stable electrocatalyst will be discussed. Recent efforts toward addressing the stability-and selectivity-related issues will also be presented in detail.

Ocean biogeochemistry in the coupled ocean–sea ice–biogeochemistry model FESOM2.1–REcoM3

Abstract. The cycling of carbon in the oceans is affected by feedbacks driven by changes in climate and atmospheric CO2. Understanding these feedbacks is therefore an important prerequisite for projecting future climate. Marine biogeochemistry models are a useful tool but, as with any model, are a simplification and need to be continually improved. In this study, we coupled the Finite-volumE Sea ice–Ocean Model (FESOM2.1) to the Regulated Ecosystem Model version 3 (REcoM3). FESOM2.1 is an update of the Finite-Element Sea ice–Ocean Model (FESOM1.4) and operates on unstructured meshes. Unlike standard structured-mesh ocean models, the mesh flexibility allows for a realistic representation of small-scale dynamics in key regions at an affordable computational cost. Compared to the previous coupled model version of FESOM1.4–REcoM2, the model FESOM2.1–REcoM3 utilizes a new dynamical core, based on a finite-volume discretization instead of finite elements, and retains central parts of the biogeochemistry model. As a new feature, carbonate chemistry, including water vapour correction, is computed by mocsy 2.0. Moreover, REcoM3 has an extended food web that includes macrozooplankton and fast-sinking detritus. Dissolved oxygen is also added as a new tracer. In this study, we assess the ocean and biogeochemical state simulated with FESOM2.1–REcoM3 in a global set-up at relatively low spatial resolution forced with JRA55-do (Tsujino et al., 2018) atmospheric reanalysis. The focus is on the recent period (1958–2021) to assess how well the model can be used for present-day and future climate change scenarios on decadal to centennial timescales. A bias in the global ocean–atmosphere preindustrial CO2 flux present in the previous model version (FESOM1.4–REcoM2) could be significantly reduced. In addition, the computational efficiency is 2–3 times higher than that of FESOM1.4–REcoM2. Overall, it is found that FESOM2.1–REcoM3 is a skilful tool for ocean biogeochemical modelling applications.

Stepwise deforestation during the Permian-Triassic boundary crisis linked to rising temperatures

Although the trajectory of the marine mass extinction at the ∼252-Ma Permian-Triassic (P-Tr) boundary has been well studied, details of the coeval collapse of terrestrial ecosystems remain murky. Here, we use hydrocarbon biomarker compositions and other geological records (i.e., organic carbon isotopes (δ13Corg), charcoal abundance, and Hg content) from a tropical peatland succession in southwestern China to reconstruct in detail the history of terrestrial ecosystem collapse during the P-Tr crisis. Our high-resolution hydrocarbon biomarker records reveal that this collapse proceeded in a stepwise manner with increasing intensity as the crisis unfolded. We recognize three discrete crisis stages: Stage I within the uppermost Xuanwei Formation and Stages II and III within the lowermost Kayitou Formation. Stage I, the early crisis stage, is marked by a significant decline in terrestrial biomass (continuing into the later stages), as recorded by reduced C29 steranes relative to total steranes and a concomitant reduction in the ratio of pristane to phytane (Pr/Ph). Stage II, the main crisis stage, records intensified soil erosion and sediment flux as revealed by rising dibenzofuran (DBF) content and high hopane/sterane ratios, the disappearance of coal seams, a sharp negative shift in δ13Corg, and peak concentrations of charcoal reflecting increased wildfire incidence. Stage III, the late crisis stage characterized by enhanced soil erosion, corresponds to peak values of Hg and Hg/TOC but no charcoal peak, suggesting intensified volcanism and a return to a humid climate. These stages closely follow temperature records, which show a stepwise rise during the crisis interval, implying that the deforestation process was strongly influenced by punctuated rises in temperature and/or its attendant effects (e.g., climate aridification). This P-Tr transition scenario suggests that global warming can trigger deforestation and reduce terrestrial carbon storage, thus serving as a positive climate feedback, with important implications for present-day climate change.

The complex interplay between plant-microbe and virus interactions in sustainable agriculture: Harnessing phytomicrobiomes for enhanced soil health, designer plants, resource use efficiency, and food security

The present-day climate change scenario represents a substantial peril to the global population concerning food security, given the potential impacts on agricultural productivity, food availability, and accessibility. The excessive use of agrochemicals, as fertilizers and pesticides, leads to the deterioration of soil health as well. Sustainable land-use practices without perturbing the soil ecosystem are achievable only with a comprehensive mechanism. The current need for sustainable agriculture is fulfilled by harnessing the noble services of plant-microbial association. Microhabitats around plant roots represent the region of maximum microbial activity. Microbiomes play a functional role in affecting plant growth, soil fertility and biogeochemical cycles. Plant-microbe interactions are highly specific to the host controlled by root exudates, metabolites, environmental factors and symbiotic associations e.g. legume-rhizobia and plant-fungi association. Proper strategies for the use of microbial inoculants will certainly facilitate the various crop improvement programs. The present review, therefore, exemplifies the various studies on the potential of plant microbiomes for sustainable agricultural ecosystems coupled with assuring food security. The review also summarizes recent trends in plant microbiome diversity, the relationship between host plant and microbe, transgenic plants, designer plants and their role in mitigating soil stress. Nevertheless, the future of the global population and food production rely on the prospects of plant microbiome ingenuity.

Carbonate-rock aquifers in arid environments (central Tunisia, Western Mediterranean province): gravity and time domain electromagnetic methods investigations

Gravity and time domain electromagnetic (TDEM) methods were used in this study to investigate the subsurface hydrogeology of the carbonate-rock aquifer in arid environments (central Tunisia, Western Mediterranean province). The El Houdh basin can be considered an appropriate case for evaluating the vulnerability of groundwater resources under present-day climate change. The identification of structural context and the discontinuities affecting the Eocene or Campanian to Maastrichtian carbonates is an important key to recognize water recharge and discharge pathways and to develop effective and long-term groundwater exploration strategies. First, we have produced an available residual gravity field using a specific Gaussian filter. Then, we generated derivative maps, Euler deconvolution solutions map and a 3D gravity model to delineate different anomalies and to estimate the depth-to-basement parameter and the subsurface density contrasts. Positive and negative anomalies mapping and 3D gravity modelling showed that the El Houdh basin is associated with an asymmetric ‘perched syncline’ with a segmentation into NE–SW sub-basins (local negative residual anomalies) separated by NW–SE lineaments. The TDEM survey was calibrated using boreholes to image the karst saturated and unsaturated zone and to deduce the epikarst and endokarst relationship. Finally, the proposed method provides a fast and valuable approach for better management of hydrogeological exploitation. Thematic collection: This article is part of the Climate change and resilience in Engineering Geology and Hydrogeology collection available at: https://www.lyellcollection.org/cc/climate-change-and-resilience-in-engineering-geology-and-hydrogeology

Physical climate change and the sovereign risk of emerging economies

AbstractI show that rising temperatures can detrimentally affect the sovereign creditworthiness of emerging economies. To this end, I collect long-term monthly temperature data of 54 emerging markets. I calculate a country’s temperature deviation from its historical average, which approximates present-day climate change trends. Running regressions from 1994m1 to 2018m12, I find that higher temperature anomalies lower sovereign bond performances (i.e., increase sovereign risk) significantly for countries that are warmer on average and have lower seasonality. The estimated magnitudes suggest that affected countries likely face significant increases in their sovereign borrowing costs if temperatures continue to rise due to climate change. However, results indicate that stronger institutions can make a country more resilient towards temperature shocks, which holds independent of a country’s climate.

Planetary bioengineering on Earth to return and maintain the atmospheric carbon dioxide to pre-industrial levels: Assessing potential mechanisms

We are all familiar with the episodes in the deep time history of Earth that enabled life to emerge in such abundance. Episodes like the formation of a Moon large enough and near enough to cause tides in the Earth’s waters and rocks, a core of sufficient iron with sufficient angular momentum to generate a protective magnetosphere around Earth, and assumption of a planetary axis angle that generates the ecological variation of our seasonal cycles. The living things that did arise on this planet have been modifying their habitats on Earth since they first appeared. Modifications that include the greening of Earth by photosynthetic organisms, which turned a predominantly reducing atmosphere into an oxidising one, the consequent precipitation of iron oxides into iron ore strata, and the formation of huge deposits of limestone by calcifying organisms. The episodes on which we wish to concentrate are 1) the frequent involvement of marine calcifiers (coccolithophores, foraminifera, molluscs, crustacea, corals, echinoderms), that have been described as ecosystem engineers modifying habitats in a generally positive way for other organisms, and 2) the frequent involvement of humans in changing the Earth’s biosphere in a generally negative way for other organisms. The fossil record shows that ancestral marine calcifiers had the physiology to cope with both acidified oceans and great excesses of atmospheric CO2 periodically throughout the past 500 million years, creating vast remains of shells as limestone strata in the process. So, our core belief is that humankind must look to the oceans for a solution to present-day climate change. The marine calcifiers of this planet have a track record of decisively modifying both oceans and atmospheres but take millions of years to do it. On the other hand, humanity works fast; in just a few thousand years we have driven scores of animals and plants to extinction, and in just a few hundred years we have so drastically modified our atmosphere that, arguably, we stand on the verge of extinction ourselves. Of all Earth’s ecosystems, those built around biological calcifiers, which all convert organic carbon into inorganic limestone, are the only ones that offer the prospect of permanent net removal of CO2 from our atmosphere. These are the carbon-removal biotechnologies we should be seeking to exploit.

Quantitative Kinetics of the Reaction between CH2OO and H2O2 in the Atmosphere.

Criegee intermediates (CIs) are generated from the ozonolysis of unsaturated hydrocarbons in the atmosphere. They have an important role in determining the implications of atmospheric bimolecular reactions with other atmospheric species. The reaction between CH2OO and H2O2 plays a crucial role in understanding how CIs impact the HOx budget in the atmosphere. The reaction mechanism and kinetics are critical to atmospheric modeling, which is a prominent challenge in present-day climate change modeling. This is particularly true for bimolecular reactions that involve complex reaction sequences. Here, we report the mechanism and quantitative kinetics of the CH2OO + H2O2 reaction by using a novel dual-level strategy that contains W3X-L//CCSD(T)-F12a/cc-pVTZ-F12 for the transition state theory and M11-L/MG3S functional method for direct dynamics calculations using canonical variational transition state theory with small-curvature tunneling to obtain both recrossing effects and tunneling. The present work shows that the CH2OO + H2O2 reaction has a negative temperature dependency with the decrease in the rate constant of CH2OO + H2O2 from 1.31 × 10-13 cm3 molecule-1 s-1 to 3.80 × 10-14 cm3 molecule-1 s-1 between 200 and 350 K. The calculated results also show that the CH2OO + H2O2 reaction can have an impact on the H2O2 profile under certain atmospheric conditions. The present findings should have implications for the quantitative kinetics of Criegee intermediates with other hydroperoxides.

Simulation and Projection of Climate Extremes in China by a Set of Statistical Downscaled Data.

This study assesses present-day extreme climate changes over China by using a set of phase 6 of the Coupled Model Intercomparison Project (CMIP6) statistical downscaled data and raw models outputs. The downscaled data is produced by the adapted spatial disaggregation and equal distance cumulative distribution function (EDCDF) method at the resolution of 0.25° × 0.25° for the present day (1961–2014) and the future period (2015–2100) under the Shared Socioeconomic Path-way (SSP) 2-4.5 than SSP5-8.5 emission scenario. The results show that the downscaling method improves the spatial distributions of extreme climate events in China with higher spatial pattern correlations, Taylor Skill Scores and closer magnitudes no matter single model or multi model ensemble (MME). In the future projections, large inter-model variability between the downscaled models still exists, particular for maximum consecutive 5-day precipitation (RX5). The downscaled MME projects that total precipitation (PTOT) and RX5, will increase with time, especially for the northwest China. The projected heavy precipitation days (R20) also increase in the future. The region of significant increase in R20 locates in the south of river Yangtze. Maxi-mum annual temperature (TXX) and percentage of warm days (TX90p) are projected to increase across the whole country with larger magnitude over the west China. Projected changes of minimum annual temperature (TNN) over the northeastern China is the most significant area. The higher of the emission scenario, the more significant of extreme climates. This reveals that the spatial distribution of extreme climate events will become more uneven in the future.

Global record of "ghost" nannofossils reveals plankton resilience to high CO2 and warming.

Predictions of how marine calcifying organisms will respond to climate change rely heavily on the fossil record of nannoplankton. Declines in calcium carbonate (CaCO3) and nannofossil abundance through several past global warming events have been interpreted as biocalcification crises caused by ocean acidification and related factors. We present a global record of imprint-or "ghost"-nannofossils that contradicts this view, revealing exquisitely preserved nannoplankton throughout an inferred Jurassic biocalcification crisis. Imprints from two further Cretaceous warming events confirm that the fossil records of these intervals have been strongly distorted by CaCO3 dissolution. Although the rapidity of present-day climate change exceeds the temporal resolution of most fossil records, complicating direct comparison with past warming events, our findings demonstrate that nannoplankton were more resilient to past events than traditional fossil evidence suggests.

On the Exploitation of Remote Sensing Technologies for the Monitoring of Coastal and River Delta Regions

Remote sensing technologies are extensively applied to prevent, monitor, and forecast hazardous risk conditions in the present-day global climate change era. This paper presents an overview of the current stage of remote sensing approaches employed to study coastal and delta river regions. The advantages and limitations of Earth Observation technology in characterizing the effects of climate variations on coastal environments are also presented. The role of the constellations of satellite sensors for Earth Observation, collecting helpful information on the Earth’s system and its temporal changes, is emphasized. For some key technologies, the principal characteristics of the processing chains adopted to obtain from the collected raw data added-value products are summarized. Emphasis is put on studying various disaster risks that affect coastal and megacity areas, where heterogeneous and interlinked hazard conditions can severely affect the population.

Urbane šume i klimatske promene

Spatial and urban plans have recently given an increased focus to the sensitive issue of planning the urban resilience of existing and establishing new urban forests. Urban forests are recognised as an extremely important factor of environmental quality, while scientific studies indicate that the health condition of urban forests is threatened by present-day climate change. There have been relatively few systematic assessments of the causes of tree die-back in urban areas in Serbia. Research, forest establishment planning and tree monitoring to estimate possible consequences to existing trees will enable city authorities and managing bodies to raise the issue of urban forest resilience to climate change to a higher level and incorporate it into urban planning. Future scenarios in which urban forests are resistant to potential adverse climate change will depend on the scope of activities of adaptive planning of urban forest establishment and adaptive management of existing ones. Therefore, it is necessary to conduct long-term studies of monitoring the condition of urban forests in the large cities of Serbia (Belgrade, Novi Sad, Niš, Subotica, etc.) in the coming period in order to identify specific problems and remediate the consequences such as deteriorated tree health condition and die-back.

Environmental evidence of Valencia lagoon coastal barrier stabilization from 8500 BP to Present. Climate and eustatic variations

The Albufera de Valencia is one of the largest lagoon in the Spanish Mediterranean. Two continuous borehole cores reaching depths of 8 and 14 m in the northern part of the lagoon underwent sedimentological, micropaleontological and biological study. The organic content was also analysed, and 14C radiometric dating and amino acid racemization were performed. Study of the content of benthic foraminifera and n-alkanes and alkanoic acids in the lagoon sedimentary record identified several periods.The core records showed seven different environments: alluvial; freshwater marsh; brackish marsh; brackish lagoon; brackish lagoon with marine connection, backbarrier flat, and backshore. These environments changed due to eight phases associated with the transgression and regression of the barrier system, which caused the shift from exposed environments as the backshore with washover, to the typical low-energy lagoon and marsh deposition.The paleoenvironmental evolution described above is interpreted as a response to global climate changes. The shift from an alluvial setting to a brackish lagoon is probably related to the late of Early Holocene sea level rise ending at the Holocene Climate Optimum, when the highest sea level was reached. The persistence of the brackish lagoon, with no marine connection, is probably synchronous with dry conditions in the area (Booth et al., 2005) at the time of Bond event 3 (i.e., 4.2 ka) in the North Atlantic region (Bond et al., 2001). Finally, the arrival of large amounts of sediment triggered the accretion of the barrier, also enhancing coastal progradation until the present day. These results allow an evaluation of the impact of anthropic action on the Valencia lagoon, especially since the eighteenth century, and a short- and medium-term projection of the consequences of present-day climate change.

Features of modern climate changes in the Arctic and their consequences

The paper is based on the results reported in an invited speaker presentation at the scientific conference dedicated to the 100th anniversary of AARI in March 2020. The features of present-day rapid climate changes in the Arctic and their consequences are assessed. The presented results include those obtained in the framework of the program of the Presidium of the Russian Academy of Sciences "Climate change: causes, risks, consequences, problems of adaptation and regulation" and the Russian-German project QUARCCS (QUAntifying Rapid Climate Change in the Arctic: regional feedbacks and large-scale impacts). An assessment is made of the relative contribution of natural and anthropogenic factors to the formation of temperature trends at different time horizons in the Arctic. In view of the rapid changes of the Arctic climate, the prospects of the Northern Sea route are examined. According to the estimates obtained, the dominant role of radiative forcing is manifested in the Arctic latitudes on time scales of about half a century or more. New climatic phenomena (in particular, the formation of craters in the Yamal Peninsula under the conditions of melting permafrost) and new effects (including the change in the trends of changes in sea waves in the waters of the Arctic basin) indicate the achievement of a certain critical level of regional and global warming, comparable to the warming of the Holocene Climate Optimum. At the same time, modern climate models can not only reproduce the key features of current climatic regimes and their variability, but also provide adequate predictive estimates even for complex processes in the Arctic.