A review of 917 relative sea-level (RSL) data-points has resulted in the first quality-controlled database constraining the Holocene sea-level histories of the western Mediterranean Sea (Spain, ...France, Italy, Slovenia, Croatia, Malta and Tunisia). We reviewed and standardized the geological RSL data-points using a new multi-proxy methodology based on: (1) modern taxa assemblages in Mediterranean lagoons and marshes; (2) beachrock characteristics (cement fabric and chemistry, sedimentary structures); and (3) the modern distribution of Mediterranean fixed biological indicators. These RSL data-points were coupled with the large number of archaeological RSL indicators available for the western Mediterranean. We assessed the spatial variability of RSL histories for 22 regions and compared these with the ICE-5G (VM2) GIA model. In the western Mediterranean, RSL rose continuously for the whole Holocene with a sudden slowdown at ~7.5kaBP and a further deceleration during the last ~4.0kaBP, after which time observed RSL changes are mainly related to variability in isostatic adjustment. The sole exception is southern Tunisia, where data show evidence of a mid-Holocene high-stand compatible with the isostatic impacts of the melting history of the remote Antarctic ice sheet.
Our results indicate that late-Holocene sea-level rise was significantly slower than the current one. First estimates of GIA contribution indicate that, at least in the northwestern sector, it accounts at least for the 25–30% of the ongoing sea-level rise recorded by Mediterranean tidal gauges. Such contribution is less constrained at lower latitudes due to the lower quality of the late Holocene index points. Future applications of spatio-temporal statistical techniques are required to better quantify the gradient of the isostatic contribution and to provide improved context for the assessment of 20th century acceleration of Mediterranean sea-level rise.
Abstract
Future warming in the Mediterranean is expected to significantly exceed global values with unpredictable implications on the sea-level rise rates in the coming decades. Here, we apply an ...empirical-Bayesian spatio-temporal statistical model to a dataset of 401 sea-level index points from the central and western Mediterranean and reconstruct rates of sea-level change for the past 10,000 years. We demonstrate that the mean rates of Mediterranean industrial-era sea-level rise have been significantly faster than any other period since ~4000 years ago. We further highlight a previously unrecognized variability in Mediterranean sea-level change rates. In the Common Era, this variability correlates with the occurrence of major regional-scale cooling/warming episodes. Our data show a sea-level stabilization during the Late Antique Little Ice Age cold event, which interrupted a general rising trend of ~0.45 mm a
−1
that characterized the warming episodes of the Common Era. By contrast, the Little Ice Age cold event had only minor regional effects on Mediterranean sea-level change rates.
Abstract
One of the most devastating environmental consequences of war is the disruption of peacetime human–microbe relationships, leading to outbreaks of infectious diseases. Indirectly, conflicts ...also have severe health consequences due to population displacements, with a heightened risk of disease transmission. While previous research suggests that conflicts may have accentuated historical epidemics, this relationship has never been quantified. Here, we use annually resolved data to probe the link between climate, human behavior (i.e. conflicts), and the spread of plague epidemics in pre-industrial Europe (AD 1347–1840). We find that AD 1450–1670 was a particularly violent period of Europe’s history, characterized by a mean twofold increase in conflicts. This period was concurrent with steep upsurges in plague outbreaks. Cooler climate conditions during the Little Ice Age further weakened afflicted groups, making European populations less resistant to pathogens, through malnutrition and deteriorating living/sanitary conditions. Our analysis demonstrates that warfare provided a backdrop for significant microbial opportunity in pre-industrial Europe.
The 4.2 ka BP event in the Levant Kaniewski, David; Marriner, Nick; Cheddadi, Rachid ...
Climate of the past,
10/2018, Letnik:
14, Številka:
10
Journal Article
Recenzirano
Odprti dostop
The 4.2 ka BP event is defined as a phase of environmental stress
characterized by severe and prolonged drought of global extent. The event is
recorded from the North Atlantic through Europe to Asia ...and has led
scientists to evoke a 300-year global mega-drought. For the Mediterranean and
the Near East, this abrupt climate episode radically altered precipitation,
with an estimated 30 %–50 % drop in rainfall in the eastern basin. While many
studies have highlighted similar trends in the northern Mediterranean (from
Spain to Turkey and the northern Levant), data from northern Africa and
the central-southern Levant are more nuanced, suggesting a weaker imprint of this
climate shift on the environment and/or different climate patterns. Here, we
critically review environmental reconstructions for the Levant and show that,
while the 4.2 ka BP event also corresponds to a drier period, a different
climate pattern emerges in the central-southern Levant, with two arid phases
framing a wetter period, suggesting a W-shaped event. This is particularly
well expressed by records from the Dead Sea area.
In Northern Dobrogea, north of the Dunavăţ promontory, the Roman fortress of Halmyris was founded in the late 1st century AD on a Getic settlement dating to the middle of the 1st millennium BC, ...probably associated with a Greek emporium of the Classical and Hellenistic periods. At the time of the foundation of Halmyris, the Danube delta had already prograded several kilometres to the east leading to the progressive retreat of the sea and the formation of a deltaic plain characterised by numerous lakes and river channels. Here, we present the results of a multiproxy study combining sedimentology and palaeoecology to (1) understand the evolution of fluvial landscapes around Halmyris since ca. 8000 years BP and (2) identify the fluvial palaeoenvironments close to the city in Getic/Greek and Roman times, in order to locate and characterise the waterfront and the harbour. Our overriding objective was to improve understanding of human–environment relations in river delta settings. We demonstrate that Halmyris, protected by the Danubian floods due to its location on a palaeo-cliff top, had direct access to the river. A secondary channel of the Saint George, flowing north of the site, has been elucidated between the 7th century BC and the 7th century AD and could have been used as a natural harbour.
Plant species richness in mountainous regions generally follows a unimodal distribution with lower values at both low and high altitudes in relation to precipitation. In the Atlas mountains, Morocco, ...plant species richness is currently highest at 800–1200 m elevation, but the extent and altitudinal limits of this species-rich belt have shifted in the past with climate change.
Here, we trace the evolution of pollen taxonomic richness (PTR) as a proxy for plant species richness, with the aim of understanding the relationship with climatic changes over the past 19,000 years, and make some assumptions about future changes in species richness. Past PTR was inferred through an analogy with an extensive modern pollen dataset, and past climatic variables were reconstructed from a fossil record collected in the Middle Atlas, Morocco.
We found that the current PTR distribution in Morocco is more closely associated with precipitation than with temperature. During the last glacial period, both PTR and annual precipitation were low, and the analogs were located at lower altitudes than the altitude of the fossil record. During the early Holocene, the PTR increased by approximately 15%, and the modern analogs were found approximately 600–800 m higher than the analogs of the last glacial period. After 6000 years BP, we observe a steady decline in annual precipitation of approximately 30%, resulting in a species richness loss of approximately 18% and a retreat of the upper boundary of the species-rich belt.
Climate projections suggest that annual precipitation in Northwest Africa will decrease by 20–30% over the next 50 years, an annual amount comparable to that of the last glacial period, but under much warmer conditions and in a significantly shorter time. Such a decline in precipitation could result in an unprecedented loss of plant species richness of approximately 15% in just a few decades and put 35% of the protected areas at risk. The forested mountains above 1600 m could then resemble the treeless and less diverse steppes found at higher altitudes above today's tree line.
The SE coast of Iran is of great economic and environmental importance. Global climate change affects this coastline through sea level rise (SLR), compounded by a decrease in sediment budgets in ...coastal areas. This study developed a Coastal Vulnerability Index (CVI) for the SE coast of Iran using satellite, instrumental and field data. Eight risk variables were defined: coastal slope, regional coastal elevation, mean tidal range, mean significant wave height, rate of relative sea-level change, rate of shoreline change, environmental sensitivity and socio-economic sensitivity. The coast was divided into 27 segments based on geomorphic, environmental and socioeconomic traits. Coastal segments were categorized based on their vulnerability to each risk factor using a CVI. The resulting maps highlighted the vulnerability of each coastal segment to SLR. Approximately 50% of the coast is comprised of mostly rocky shores, which are less vulnerable to SLR. Approximately 33% of the coastal length, including sandy beaches, tidal flats and mangrove forests, were determined to be highly vulnerable to SLR. Approximately 12% of the coastline was determined to be moderately vulnerable. Population centers and infrastructure were ranked as highly-to-moderately vulnerable to SLR. This study highlighted the high vulnerability of low-lying areas, such as lagoons and mangroves, in the western part of the Iranian coast of Makran. Proper coastal management and mitigation plans are essential in the future to protect coastal societies and environments.
We combined biostratigraphical analyses, archaeological surveys, and Glacial Isostatic Adjustment (GIA) models to provide new insights into the relative sea-level evolution in the northeastern Aegean ...Sea (eastern Mediterranean). In this area, characterized by a very complex tectonic pattern, we produced a new typology of sea-level index point, based on the foraminiferal associations found in transgressive marine facies. Our results agree with the sea-level history previously produced in this region, therefore confirming the validity of this new type of index point. The expanded dataset presented in this paper further demonstrates a continuous Holocene RSL rise in this portion of the Aegean Sea. Comparing the new RSL record with the available geophysical predictions of sea-level evolution indicates that the crustal subsidence of the Samothraki Plateau and the North Aegean Trough played a major role in controlling millennial-scale sea-level evolution in the area. This major subsidence rate needs to be taken into account in the preparation of local future scenarios of sea-level rise in the coming decades.
Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future ...wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the 'monsoon pacemaker', attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile's deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan 'depeopling', reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world's deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The western Makran subduction zone is capable of producing considerable tsunami run-up heights that penetrate up to 5 km inland. In this study, we show how climate change has affected urbanization ...along the tsunami-prone Makran coastline during the past 35 years. To address this issue, we have employed climate data, satellite altimeter radar, geomorphology and historical shoreline changes in order to shed light on the factors leading to a decline in access to freshwater resources and also rapid urbanization. We furthermore consider the interactions between environmental changes and human-induced coastal and catchment modifications in increasing socioeconomic vulnerabilities of littoral areas. The results of this study show that agricultural and freshwater management methods along the Chabahar coastal plain date back to at least 1808 CE, when wetter climate conditions characterized the area. Severe climate changes have been pronounced since 2000. Within this context, the majority of agricultural lands have been abandoned due to increasing drought intensity and duration. Decreasing cultivation and limited access to freshwater resources have led to extensive urbanization particularly for the two cities of Konarak and Chabahar. Enhanced soil erosion, increasing summer monsoon wind speed, sea-level rise and the growing number of strong storm events are some of the climate change-related hazards for high to very high socially vulnerable zones. In addition to environmental risks, poor urban planning has increased damage to coastal infrastructures such as ports and desalination plants. Furthermore, industrial and urban growth in the northwest of the Makran could further enhance socioeconomic damage by earthquakes and tsunamis.
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