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Natural hazards and disasters around the Caspian Sea

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Natural Hazards
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Suzanne Leroy at Maison Mediterranenne des Sciences de l'Homme, Lampea, Quaternary Ecosystems, Aix-en-Provence, France
Suzanne Leroy
  • Maison Mediterranenne des Sciences de l'Homme, Lampea, Quaternary Ecosystems, Aix-en-Provence, France
Raisa Gracheva at Institute of Geography, Russian Academy of Sciences
Raisa Gracheva
Andrei Medvedev
Andrei Medvedev
Andrei Medvedev
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Abstract and Figures

At a time, when the five riparian countries have renewed consultation with each other about the future of the Caspian Sea, it is appropriate to propose a state of the art of the potential natural threats to the regional environment. We present a critical review of geological, meteorological–climatological and hydrological hazards and disasters illustrated by many examples from within the Caspian drainage basin. Our work is set in the frame of an analysis of the factors contributing to the scale of the disasters. A brief overview of the mitigation measures in place and their future development is also included underlining the current limited warning systems (especially transboundary) despite improvements. While analysing past disasters is an essential source of information on which to base new mitigation, current and future conditions have poor or even no analogue in the past. Even though it clearly turns out that earthquakes are certainly the most deadly hazard, Caspian Sea level changes are by far causing the largest economical impact and affect the largest area and thus population. This review has also highlighted the need to create a Caspian database of natural hazards and disasters.
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Vol.:(0123456789)
Natural Hazards (2022) 114:2435–2478
https://doi.org/10.1007/s11069-022-05522-5
1 3
REVIEW ARTICLE
Natural hazards anddisasters aroundtheCaspian Sea
SuzanneA.G.Leroy1,2 · RaisaGracheva3,4 · AndreiMedvedev3
Received: 7 December 2021 / Accepted: 20 July 2022 / Published online: 9 August 2022
© The Author(s), under exclusive licence to Springer Nature B.V. 2022
Abstract
At a time, when the five riparian countries have renewed consultation with each other
about the future of the Caspian Sea, it is appropriate to propose a state of the art of the
potential natural threats to the regional environment. We present a critical review of geo‑
logical, meteorological–climatological and hydrological hazards and disasters illustrated
by many examples from within the Caspian drainage basin. Our work is set in the frame of
an analysis of the factors contributing to the scale of the disasters. A brief overview of the
mitigation measures in place and their future development is also included underlining the
current limited warning systems (especially transboundary) despite improvements. While
analysing past disasters is an essential source of information on which to base new mitiga‑
tion, current and future conditions have poor or even no analogue in the past. Even though
it clearly turns out that earthquakes are certainly the most deadly hazard, Caspian Sea level
changes are by far causing the largest economical impact and affect the largest area and
thus population. This review has also highlighted the need to create a Caspian database of
natural hazards and disasters.
Keywords Geologicalhazards· Meteorological–Climatologicalhazards· Hydrological
hazards· Disasters· Caspian Sea drainage basin
1 Introduction
The Caspian Sea region with its great diversity of environments and human occupations is
a natural domain where it has become essential to tackle hazard and disaster issues due to
an increase in population density and infrastructures. It is thus urgent to plan for adequate
mitigation plans. Beforehand, it is timely to compile and discuss disasters in the region
as new challenges, such as Climatic Change, appear. Moreover, “the Convention of the
Legal Status of the Caspian Sea” in 2018 has been signed (Convention 2018). The latter is
* Suzanne A. G. Leroy
suzleroy@hotmail.com
1 Mediterranean Laboratory ofPrehistory Europa‑Africa, Aix Marseille Univ, CNRS, Minist
Culture, LAMPEA, UMR 7269, 5 rue du Château de l’Horloge, 13094Aix‑en‑Provence, France
2 School ofEnvironmental Sciences, University ofLiverpool, LiverpoolL693GP, UK
3 Institute ofGeography, Russian Academy ofSciences, Moscow, Russia
4 National Research University Higher School ofEconomics, Moscow, Russia
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... However, the coastal shrinkage has led to wetland loss and ecosystem service reductions [6]. Moreover, despite the significant ecological and economic importance of this region, it faces substantial risks from ongoing shoreline changes [17,25,26]. Achieving a thorough understanding of the effects of fluctuating water levels on coastal morphology is essential for informing conservation efforts, enhancing coastal management strategies, and guiding regional development plans. ...
... The CS represents the largest enclosed inland water body on Earth, with an average depth of 211 m. The northern region features a flat, lowlying area with depths ranging between 5 m and 10 m [26], and it contributes to the unique sensitivity of the CS to water level fluctuations. This area is ecologically significant and hosts critical habitats for species such as Caspian seals and various migratory birds [30]. ...
... Additionally, the decline in shallow water areas may reduce benthic productivity and negatively affect fisheries. Furthermore, the large-scale exposure of the seabed, which is subject to wind erosion, may contribute to a higher frequency of dust storms, exacerbating eco-environmental degradation in the northern CS [26]. ...
Spatiotemporal dynamics of northern Caspian shorelines (1985–2023) and implications for coastal management: Lessons from the Aral Sea
Article
Full-text available
Dynamic changes to the northern Caspian Sea shoreline have significant ecological implications, including impacts to biodiversity and the surrounding environment. This study employs Landsat datasets, historical records, and geographic information systems (GIS) to quantitatively analyze spatiotemporal variations along the northern Caspian Sea coastline from 1985 to 2023. The findings demonstrate pronounced cyclic variations in the Caspian Sea’s water level. Compared to 1930, the water level decreased by 2.6 m by 2023, with 1935 marking the onset of a significant downward trend. From 1995 to 2023, a pronounced decline in the water level at a rate of 6.1 cm/year was observed. Multiscale temporal oscillations in water levels revealed periodic rises and falls with cycles ranging from 6–8 years to 10–16 years. Due to the broad and shallow morphology of the northern Caspian Sea, fluctuations in water level have resulted in significant displacements of the northern coastline. Between 1985 and 2023, the shoreline length decreased by 262 km, which is equivalent to a 17% reduction. The intensity of the coastline length index reached a critical point during from 2010 to 2015, after which it declined sharply by 3.67. By 2023, the coastline had shifted seaward by 1.33 × 10⁴ km² relative to that in 1985. This continuous retreat of the shoreline poses a severe threat to the ecological stability of the northern Caspian Sea. If the trend persists, then the disappearance of the eastern basin of the South Aral Sea may be replicated in the northern Caspian Sea by 2100. These findings provide critical insights for formulating effective coastal management strategies and conservation initiatives.
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... Long-term oscillations are more complex, with fluctuations ranging from −80 to þ50 m since the late Pleistocene (Svitoch 2009). During the Holocene, sea levels fluctuated between −80 and −15 m relative to present ocean levels (Leroy, Gracheva, and Medvedev 2022;Rychagov 1997). By 2200 years ago, the sea experienced significant regressions, including the Sassanian regression dating between 2200 and 750 years ago, and transgressions during the Little Ice Age (LIA), ranging between −35 and −15 m (Beni et al. 2013;Leroy, Gracheva, and Medvedev 2022). ...
... During the Holocene, sea levels fluctuated between −80 and −15 m relative to present ocean levels (Leroy, Gracheva, and Medvedev 2022;Rychagov 1997). By 2200 years ago, the sea experienced significant regressions, including the Sassanian regression dating between 2200 and 750 years ago, and transgressions during the Little Ice Age (LIA), ranging between −35 and −15 m (Beni et al. 2013;Leroy, Gracheva, and Medvedev 2022). Records show water level increases in the fifth, ninth, fourteenth, fifteenth, and nineteenth centuries, while lower levels happened in the fifth, sixth, ninth, and thirteenth centuries (Beni et al. 2013;Leroy, Gracheva, and Medvedev 2022). ...
... By 2200 years ago, the sea experienced significant regressions, including the Sassanian regression dating between 2200 and 750 years ago, and transgressions during the Little Ice Age (LIA), ranging between −35 and −15 m (Beni et al. 2013;Leroy, Gracheva, and Medvedev 2022). Records show water level increases in the fifth, ninth, fourteenth, fifteenth, and nineteenth centuries, while lower levels happened in the fifth, sixth, ninth, and thirteenth centuries (Beni et al. 2013;Leroy, Gracheva, and Medvedev 2022). The twentieth century witnessed a full sea-level cycle, with a decrease of 3 m from 1921 to 1978 and a subsequent rise of 2.7 m from 1978 to 1995 (Kroonenberg et al. 2007). ...
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... In addition to the aforementioned studies, it is clear that the CS basin, which holds the title of being the largest lake globally, is undergoing a decline in water levels as a result of its enclosed nature, and given the influence of global warming, evaporation contributes significantly to this decline in water level (Chen et al., 2017;Lahijani et al., 2023b;Samant and Prange, 2023). The decline of the Caspian Sea water level (CSL) poses a significant threat to its coastal zones, leading to notable environmental and socio-economic challenges (Leroy et al., 2022). This phenomenon has resulted in shoreline retreat, intensified coastal accretion, and the degradation of coastal habitats. ...
Analyzing Ogurja Island’s shoreline changes in response to the Caspian Sea water level decline
Article
Full-text available
  • Jan 2025
  • OCEANOLOGIA
Shorelines are vital and dynamic components of the coastal zone, constantly changing due to various environmental factors. These areas hold significant recreational, economic, and ecological importance, making the understanding of shoreline alterations critical. Unlike open oceans, the Caspian Sea (CS) has experienced a noticeable decline in water level since the late 1990s due to a combination of climatic variability, reduced riverine inflow, increased evaporation, and anthropogenic factors. This decline in water level is expected to drive morphological changes in the shorelines, with an overall trend of shorelines retreating seaward. In this study, the shoreline changes of Ogurja Island, the largest island in the CS, were analyzed using Sentinel-2 satellite imagery from 2015 to 2023, covering a total of 9 images, and the Digital Shoreline Analysis System tool. The study aimed to establish a relationship between these shoreline changes and the decline in the Caspian Sea water level (CSL). The results reveal a strong correlation, with shoreline movements reaching up to 80 m/year in some areas, and significant changes are expected with the projected CSL decline. This research offers an initial attempt to connect shoreline dynamics with water level fluctuations, highlighting the importance of considering shoreline changes in future water level predictions. The study recommends that future research focus on integrating advanced models, such as hydrodynamic simulations and machine learning techniques, to refine shoreline predictions and enhance understanding of the CS’s dynamic coastal environment.
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... Globally, uncontrolled urbanization, unorganized land use changes, deforestation, and fluctuating global climatic conditions create an unstable situation that results in various sorts of environmental issues, such as landslides, earthquakes, storm surges, drought, and flood, in different countries at the global scale [24,26,31]. Landslides are major natural geological hazards that cause damage to both property and lives. ...
Landslide vulnerability mapping using GIS-based statistical model for sustainable ecosystem management in the Himalayan region of Teesta River basin, India
Article
Full-text available
  • Apr 2025
Landslides are recognized as major natural geological hazards in the mountainous region, and they are accountable for enormous human causalities, damage to properties, and environmental issues in the Teesta River basin, Sikkim, India. GIS approaches are widely used in landslide susceptibility mapping (LSM) that can help relevant authorities to mitigate landslide risk. The binary logistic regression is applied to estimate the landslide susceptibility zonation (LSZ) in the upper Teesta River basin areas. The landslide inventory data are subdivided into training data sets (70%) for applying algorithms in models and testing data sets (30%) for testing model accuracy. The LSZ mapping is designed after analyzing multicollinearity test of 14 landslide CFs and the result shows that the VIF value is less than 10, and TOL is greater than 0.1, respectively. There is no multicollinearity for the 14 conditioning landslides factors. The upper Teesta River basin is categorized into five groups: very low-to-very high landslide susceptibility zones. The results highlighted that most of the middle and southern parts of the study region are highly prone to landslides compared to the other parts. The susceptibility of landslide in the upper Teesta River basin areas validated by performing the Receiver Operating Characteristics (ROC) curve, which showed an 83% confidence level. The present research demonstrated landslide vulnerability circumstances for the Teesta River basin, Sikkim, an area prone to landslides, emphasizing the need for an effective mitigation and management roadmap.
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... Therefore, evaluating the biodiversity and ecological status of Caspian Sea ecosystems is critical for developing conservation, restoration, enhancement, and sustainable development strategies. (Bagheri et al., 2012;Leroy et al., 2022) . ...
Assessment the ecological status of aquatic ecosystems using AMBI and BENTIX ecological indicators in the southern part of the Caspian Sea: along the Tamishan and Glandroud rivers (Noor County)
Article
Full-text available
  • Feb 2025
  • AQUAT ECOL
The primary objective of this study was to assess the ecological status of the southern Caspian Sea coast (Noor city) using the AMBI and BENTIX indices. Invertebrate sampling was conducted at six stations situated at the mouths of the Glandroud and Tamishan rivers. These stations included near-shore, mid-shore, and offshore locations at distances of 500 m, 1000 m, and 1500 m from the coastline, respectively. Sampling was carried out using a Van Veen grab with three replicate collections at each station. The results showed that the phylum Mollusca, class Bivalvia, order Cardiida, and family Cardiidae were the most abundant, comprising 82%, 65%, 44%, and 41% of the sampled communities, respectively. Additionally, bivalves dominated in terms of both diversity and density, occurring in the majority of stations. Ecological assessments based on the AMBI index revealed that the Glandroud River was categorized as slightly disturbed, while the Tamishan River ranged from slightly disturbed to moderately disturbed. According to the BENTIX index, the Glandroud River was classified as moderately to slightly disturbed, while the Tamishan River was classified as disturbed. A comparative analysis using the AMBI index indicated that the Tamishan River exhibited higher pollution levels, leading to a higher prevalence of resistant and opportunistic species at those stations.
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... Landslides could be one of the effects of climate change, increasing their frequency and posing increasing risk to human society (Lin et al., 2020;Zhang et al., 2021;WHO, 2023). This is especially true in places with a high population density and expanding land use development (Fuchs et al., 2017) where landslides not only damaged infrastructure and settlements but also resulted in fatalities and serious injuries (Leroy et al., 2022). The status and impact of landslides are anticipated to worsen in Turkey as a result of climate change with a rise in total precipitation and increase in the prevalence and intensity of rainfall events. ...
Examining the Impact of Landslide Hazards in the PeriUrban Areas by Global and Local Modelling Techniques
Chapter
  • Jun 2024
Landslides can be considered one of the most severe natural hazards globally, and their management has a key role to inman safety. Landslide susceptibility maps can help the sustainable management of peri-urban areas such as determining the target areas of projects to develop landslide resistant areas, forest planning, infrastructure planning, and land use zoning. This study aims to analyse the relationship between landslide occurrence and its determinants in a peri-urban region, namely Taşlıdere Basin located in Güneysu District of Rize, Turkey, through providing both global and local regression models. To consider spatial non-stationarity, geographically weighted regression was used as a local model. It was found that the local model outperformed the global model in the estimation of landslide susceptibility determinants. The spatial analysis results indicated that almost all variables had heterogeneous variation over the study area. Therefore, this study provides a methodology for understanding the local dynamics of landslide occurrence.
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... Methane, in fact, is a much more powerful greenhouse gas than CO 2 (Howarth, 2014). Furthermore, NGS, where associated with fire at the surface, is important to many cultures that revere these phenomena in the context of the Zoroasther cult (Amrikazemi and Mehrpooya, 2005;Kuhn, 2000;Leroy et al., 2022). Finally, but not least, the economic exploitation of mud seeps for geotourism has become an important business for the recreational and medical properties of mud baths (Herrera-Franco et al., 2020;Madeja and Mrowczyk, 2010). ...
View
Biochemical analysis of the Caspian Sea sediments: Implications for environmental pollution and bioremediation
Article
Full-text available
  • Dec 2024
The Caspian Sea, Earth's largest enclosed inland water body, faces significant environmental challenges due to anthropogenic pollution. This study aimed to assess pollution levels in the Caspian Sea sediments and evaluate the potential for microbial bioremediation. Sediment samples were collected from 15 sites along the Caspian coastline. Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (lead and cadmium) were quantified using GC-MS and AAS, respectively. Microbial community analysis was performed through 16S rRNA gene sequencing. Native bacterial strains were isolated, characterized for their pollutant degradation capabilities, and tested in laboratory-scale bioremediation experiments. Total PAH concentrations ranged from 119.5 to 2032.7 μg kg-1 dry weight, while mean concentrations of lead and cadmium were 67.9 and 2.15 mg kg-1 , respectively. Microbial analysis revealed diverse communities dominated by Proteobacteria, with genera known for hydrocarbon degradation (e.g., Pseudomonas and Alcanivorax) showing strong positive correlations with contaminant levels. Isolated bacterial strains demonstrated remarkable PAH degradation (up to 87% for naphthalene) and heavy metal removal capabilities. In microcosm experiments, bacterial consortia achieved up to 89.7% PAH removal and 61.4% lead removal after 30 days. This study provides comprehensive insights into the Caspian Sea sediments' pollution status and microbial ecology, revealing significant contamination and remarkable potential for intrinsic bioremediation. The identified native bacterial strains and consortia offer promising avenues for developing tailored bioremediation strategies, although further field-scale trials are necessary to validate their effectiveness under real-world conditions.
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On the Chronology and Development of Europe's Highest Aeolian Landform: The Sarykum Dune Complex in the North Caspian Region
Preprint
Full-text available
  • Jan 2025
The highest aeolian landform in Europe, the Sarykum dune complex, is located in the southwestern Caspian Depression near the Caucasus Mountains. Despite its prominence and accessibility, its morphology and evolution have been previously poorly understood. In this study we investigate the dune complex through a synthesis of geomorphological, geological, and geochronological methods. Our findings link its development to climatic aridification driven major regression phases of the Caspian Sea during the Late Pleistocene–Holocene. Optical stimulated luminescence dating indicates that dune formation began at least 70 ka during the Atelian regression, with reactivation around 12–8 ka during the Mangyshlak regression. By the early Holocene, the complex had nearly reached its modern height. The Shura-Ozen’ River, which divides the dune complex in two major segments, played a significant role in the complex’s evolution, influencing aeolian sediment transport and trapping material on its banks, particularly on the left bank, where the highest Central Massif is located. Extensive vegetation now stabilizes most of the complex, except for active ridges in the Central Massif. A numerical analysis of wind potential for dune migration, based on meteorological data spanning the past 55 years, shows that sand movement is primarily driven by self-sustaining NW–SE wind fluctuations. Paleowind analysis suggests that similar long-term wind patterns have persisted since the onset of aeolian deposition during the Atelian phase. Our multidisciplinary study sheds new light on the Sarykum dune complex's history and highlights its significance as a dynamic archive of climatic and geomorphic processes in the Caspian region.
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Nanoparticles in Air and Their Impact on Air Quality
Chapter
Full-text available
  • Mar 2024
The chances of nanoparticles (NPs) being discharged into the environment have escalated due to their extensive application in diverse fields and their approximate annual global production range of 550–33,400 metric tons. These nanoparticles, which are well known as biosafe materials, have gained an abundant attention due to their versatility and ease of usage in a number of industries, such as cosmetics, drugs, and agriculture. An ever-growing class of airborne pollutants are metal-containing nanoparticles derived from both natural and man-made sources. The increasing use of these particles has resulted in growing number of complex deposits in the air we breathe. The more of these particles we use, the more complicated the structures of the air we breathe become. The atmosphere contains nanoparticles from a variety of sources. Designed nanoparticles can leak into the atmosphere during manufacture and application. Most of the time, combustion processes related to energy generation, transportation by vehicles powered by gasoline or diesel, and other industrial activities result in the production of nanoparticles in urban settlements. Conversely, however, the nucleation and development of new particles, or new particle production, is a significant source of nanoparticles in rural areas. These compounds are released into the environment due to the growing use of engineered nanoparticles in residential and commercial settings. Awareness of these NPs’ mobility, reactivity, ecotoxicity, and persistence is necessary to evaluate the harm they pose to the environment.
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Storm surges and storm wind waves in the Caspian Sea in the present and future climate
Preprint
Full-text available
  • Sep 2021
This study is devoted to the analysis of the storm surges and wind waves in the Caspian Sea for the period from 1979 to 2017–2020. The models used are the circulation model ADCIRC and the wave model WAVEWATCH III with wind and pressure forcing from the NCEP/CFSR reanalysis. The modeling is performed on the unstructured grid with spacing to 300–700 m in the coastal zone. Mean and extreme values of surges, wave parameters, and storm activity are provided. The maximum significant wave height for the whole period amounts to 8.2 m. The average long-term SWH does not exceed 1.1 m. No significant trend in the storm activity was found. The maximum surges height amounts to 2.7 m. Analysis of the interannual variability of the surges occurrence showed that 7–10 surges with a height of more than 1 meter were obtained per year and the total duration of all these surges was 20–30 days per year. Assessment of the risk of coastal flooding was carried out by calculating the extreme values of the Sea for different return periods 5, 10, 25, 50, and 100 years. The extreme sea level values in the northern part of the Caspian Sea for the return period 100 years is close to 3 m and the areas with big surges are located along the eastern and western coasts. Based on climatic scenarios of CMIP5, a forecast is made for the recurrence of storm wind waves in the 21st century. A statistically significant increase of storm waves recurrence in the future was found, but it is not dramatically growing.
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Dynamics of a Giant Slow Landslide Along the Coast of the Aral Sea (Central Asia)
Conference Paper
Full-text available
  • Jul 2021
This paper presents the dynamics of the world's largest lateral mega-spreading landslide cluster along the western shoreline of the Aral Sea in Uzbekistan (Central Asia) using Interferometric Synthetic Aperture Radar (InSAR) time series analysis of three Sentinel-1 IW datasets over the period 2015–2020. It extends >50km wide and corresponds to a gravity-induced lateral spreading movement of relatively intact Sarmatian limestone blocks that are sliding over a highly plastic clay layer at rates up to 40 mm/yr with a clear dominance of horizontal motion at a nearly constant velocity. Slow vertical motions (up to 5 mm/yr) are localized along narrow strips of terraces where rock spread is attributed to rotational subsidence.
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Impacts of Variations in Caspian Sea Surface Area on Catchment‐Scale and Large‐Scale Climate
Article
Full-text available
  • Sep 2021
The Caspian Sea (CS) is the largest inland lake in the world. Large variations in sea level and surface area occurred in the past and are projected for the future. The potential impacts on regional and large‐scale hydroclimate are not well understood. Here, we examine the impact of CS area on climate within its catchment and across the northern hemisphere, for the first time with a fully coupled climate model. The Community Earth System Model (CESM1.2.2) is used to simulate the climate of four scenarios: (a) larger than present CS area, (b) current area, (c) smaller than present area, and (d) no‐CS scenario. The results reveal large changes in the regional atmospheric water budget. Evaporation (e) over the sea increases with increasing area, while precipitation (P) increases over the south‐west CS with increasing area. P‐E over the CS catchment decreases as CS surface area increases, indicating a dominant negative lake‐evaporation feedback. A larger CS reduces summer surface air temperatures and increases winter temperatures. The impacts extend eastwards, where summer precipitation is enhanced over central Asia and the north‐western Pacific experiences warming with reduced winter sea ice. Our results also indicate weakening of the 500‐hPa troughs over the northern Pacific with larger CS area. We find a thermal response triggers a southward shift of the upper troposphere jet stream during summer. Our findings establish that changing CS area results in climate impacts of such scope that CS area variations should be incorporated into climate model simulations, including palaeo and future scenarios.
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The fate of the Caspian Sea under projected climate change and water extraction during the 21 st century
Article
Full-text available
The Caspian Sea (CS) delivers considerable ecosystem services to millions of people. It experienced water level variations of 3 m during the 20th century alone. Robust scenarios of future CS level are vital to inform environmental risk management and water-use planning. In this study we investigated the water budget variation in the CS drainage basin and its potential impact on CS level during the 21st century using projected climate from selected climate change scenarios of shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs), and explored the impact of human extractions. We show that the size of the CS prescribed in climate models determines the modelled water budgets for both historical and future projections. Most future projections show drying over the 21st century. The moisture deficits are more pronounced for extreme radiative forcing scenarios (RCP8.5/SSP585) and for models where a larger CS is prescribed. By 2100, up to 8 (10) m decrease in CS level is found using RCP4.5 (RCP8.5) models, and up to 20 (30) m for SSP245 (SSP585) scenario models. Water extraction rates are as important as climate in controlling future CS level, with potentially up to 7 m further decline, leading to desiccation of the shallow northern CS. This will have wide-ranging implications for the livelihoods of the surrounding communities; increasing vulnerability to freshwater scarcity, transforming ecosystems, as well as impacting the climate system. Caution should be exercised when using individual models to inform policy as projected CS level is so variable between models. We identify that many climate models either ignore, or do not properly prescribe, CS area. No future climate projections include any changes in CS surface area, even when the catchment is projected to be considerably drier. Coupling between atmosphere and lakes within climate models would be a significant advance to capture crucial two-way feedbacks.
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Changes in spectral reflectance characteristics of the Northern Caspian zonal landscapes under pyrogenic influence
Article
Full-text available
  • Jan 2021
The article studies the regularities of pyrogenic changes in the spectral-reflective properties of semi-desert and desert landscapes in the year of fire. Changes in albedo and surface temperature affect atmospheric processes and lead to climatic changes. For this reason, it is necessary to study the features of seasonal and years long dynamics of the spectral-reflective characteristics of burned-out areas. The research is based on the long-term archive of data on the detection of active combustion, NDVI vegetation index, temperature and surface albedo over the period 2001-2019. The article presents field spectrometry data showing the differences in burned areas, open soils, green and dry vegetation. We have revealed a decrease in albedo and NDVI after fires in semi-desert landscapes by 10-20 %, which levels off at the end of the growing season. In desert landscapes, there is practically no decrease in albedo after fires, but an increase of 15-20 % follows, which can be traced for several years after burnout. For both types of landscapes, an excess of NDVI values in subsequently burnt-out territories is typical as compared to unburned ones. This is due to the fact that a certain supply of dry plant matter is required for the spread of fire. As a result, areas with a larger mortmass are burned out. The change in the surface albedo in the visible and infrared ranges can serve as a predictor for the algorithms used for recognizing burned-out areas in the studied types of landscapes. The fire regime of the territory should be taken into account when studying atmospheric processes and climatic changes. © 2021 Space Research Institute of the Russian Academy of Sciences. All rights reserved.
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A Comprehensive Assessment and Modeling of Land Use Changes in a Flood-Prone Watershed, Northeast of Iran
Article
  • Feb 2022
The Gorgan-rud river basin in the northeast of Iran has undergone extensive land use changes causing floods during the past decades. This study aims to investigate land use change and its correspondence to flood events during 1987–2017 in the study area. Six pixel- and object-based classifications algorithms were used for land use change modeling. The objected-oriented support vector machine with a scale length of 50 m was selected as the superior algorithm. The results indicated that croplands and residential/industrial areas have continuously expanded during 1987–2017. However, the area of forests, rangelands, and barren lands has decreased. It is predicted that by 2035, the area of croplands will expand by another 20,397 ha, and the forest area will shrink by about 16,966 ha. The spatiotemporal pattern of flood occurrences and damages correspond well with the pattern of land use changes in the study area.
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Caspian Sea levels over the last 2200 years, with new data from the S-E corner
Article
  • Feb 2022
  • GEOMORPHOLOGY
A revision of the data used to build the Caspian Sea level curve over the last 2200 years BP has been made based on a combination of geological and archaeo-historical data, using only those for which sufficient metadata were available. This compilation is completed by new sedimentological and palynological data from the south-east corner of the Caspian Sea, especially close to the known termini of the Sasanian Gorgan and Tammisheh Walls. A new calibration of the radiocarbon dates was used, i.e. with a freshwater offset reservoir of 351 ± 33 years. A literature survey of the Derbent lowstand indicated that this term has different definitions, depending on authors; it is thus to be used with caution. Here we therefore prefer to distinguish the mid-Sasanian lowstand and the later Medieval moderate lowstand. The “2600 years BP highstand” has not been found, mostly due to the calibration or recalibration of the datapoints used; data are indeed lacking at that time. Instead, a younger Parthian highstand (around 50 BCE–50 CE) is clearly defined. The maximal amplitude and speed of change of the Caspian Sea level were respectively of >15 m and 14 cm per year. Compared to last century, the latter rate is 25% higher, but the amplitude is more than five times larger. The climatic causes of the Caspian Sea level changes are discussed. It is far from a simple case of temperature forcing; temperature forcing may result in several effects, that may impact the Caspian Sea level variations in opposite ways. Moreover, human intervention on river diversion and natural hazards were likely, for several time periods.
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Climate-induced managed retreat in the U.S.: A review of current research
Article
  • Jun 2021
Human responses to climate change are continuing to evolve. At one time, mitigation (reduction) of human emissions of greenhouse gases appeared to offer the best response to prevent the worst impacts of a changing climate. It soon became clear, however, that the world would not be able to reduce emissions quickly enough or to a level sufficient to prevent, in the words of the United Nations Framework Convention on Climate Change, “dangerous anthropogenic interference with the climate system”. Climate change is already altering the frequency and severity of extreme weather events worldwide, and these trends are expected to increase in the foreseeable future. Accordingly, it is well recognized that adapting in place to the changing climate is necessary. Yet, that may not be enough. An additional step in responding to climate risks is emerging, one that requires fundamentally and permanently changing the human interactions with nature in parts of the world. This strategy is often referred to as “managed retreat,” but that term has become controversial, and other terms are needed that express inclusion of the positive societal benefits that can emerge from proactive action. This paper provides a review of the emerging themes within the literature of managed retreat as a climate risk management approach, uses examples from the transportation and infrastructure sector, collects and identifies important nomenclature and definitions, key decision-making considerations, and research gaps that warrant immediate attention. The results of this review are intended to be useful to academic climate change adaptation researchers and infrastructure practitioners alike.
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