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Adapting to climate change in the Mediterranean region represents a critical socio-economic and environmental challenge. Different levels of exposure and vulnerability as well as different projected changes characterize the Mediterranean region. Understanding the past, characterizing the present and modelling the future are therefore essential steps to estimate the risks, assess the impacts of climate change, and identify potential adaptation and mitigation strategies. This multidisciplinary MedCLIVAR session encourages contributions from a broad range of disciplines and topics, e.g. dealing with: dynamics and processes of the climate system; sectorial impacts of climate change; climate change adaptation and mitigation; innovative methods and approaches in climate science. The session focuses on all time scales from paleoclimate to future model projections as well as on all relevant socio-economic sectors.

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Convener: Andrea Toreti | Co-conveners: Ana BastosECSECS, Piero Lionello, Nathalie Combourieu Nebout, Marie-Alexandrine Sicre
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| Wed, 06 May, 08:30–12:30 (CEST)

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D3520 |
EGU2020-5687
| Highlight
Manfred A. Lange

The region of the Middle East and North Africa (MENA region) encompasses countries of the eastern Mediterranean, the Middle East, and North Africa, from Morocco in the West to the Islamic Republic of Iran in the East and from the Syrian Arab Republic in the North to the Republic of Yemen in the South. It is home to some 500 million inhabitants and is characterized by widely varied political and economic settings and a rich cultural heritage. Stark environmental gradients, as well as significant differences in the provision of ecosystem services, both East to West and South to North, are typical for the MENA Region.

Climate changes in the Mediterranean Basin, in general, and in the MENA countries, in particular, currently exceed global mean values significantly. Numerical model results indicate that this trend will continue in the near future and imply that the number of extreme summer temperatures and heatwaves may increase significantly over the coming decades. At the same time, a decrease in precipitation and a significantly longer dry season for most MENA countries than at present are anticipated. This leads to a significantly increased demand for water and energy. In addition, other factors further exacerbate these demands in the MENA, including the general economic development, extreme population growth and increasing urbanization, changes in lifestyle, shifting consumption patterns, inefficiencies in the use of resources that result from technical and managerial inadequacies and energy and water subsidies in several countries of the region to name but a few.

The impacts of climate change will be particularly severe in urban settings and large cities of the Mediterranean Basin and the MENA region. Cities will see an enhanced heat accumulation compared to the surrounding rural land due to heat-build-up in buildings, transportation infrastructure, and enhanced human activities. Reduced ventilation within cities exacerbates the warming, particularly during summer heatwaves. Consequently, additional, energy-intensive space cooling will be needed in order to maintain acceptable indoor conditions. With regard to water scarcity, the aforementioned decreases in precipitation will reduce available drinking water for city inhabitants and green spaces. This requires the provision of unconventional water sources, e.g., through desalination, which requires significant quantities of energy. Overall, climate change will exacerbate resource demand for water and energy, in general, and in urban settings, in particular.

However, the provision of water and energy are interrelated. In order to maintain water and energy security in the MENA region, these issues need therefore be considered holistically in the framework of the Water-Energy-Nexus (WEN).

The present paper aims to elucidate some of the interrelationships between water and energy resources and their provision and will briefly outline a few of the possible mitigation/adaptation options/strategies to reduce adverse impacts of climate change on the MENA region and its inhabitants.

How to cite: Lange, M. A.: The Water-Energy Nexus in the Middle East and North Africa under Climate Change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5687, https://doi.org/10.5194/egusphere-egu2020-5687, 2020

D3521 |
EGU2020-10605
Raquel Lorente-Plazas, Alexandre M. Ramos, Juan P. Montávez, Sonia Jerez, Ricardo M. Trigo, and Pedro Jimenez-Guerrero

Long filaments of high integrated water vapor transport (IVT) content, widely known as atmospheric rivers (ARs), play a relevant role in the water cycle being also associated with many extreme flooding events worldwide. In this work, we inspect whether similar structures can be found over the western Mediterranean. The methodology used here to detect these AR-like structures is based on standard ARs detection methods but imposing a strong IVT advection westward component. The ERA5 global reanalysis and Spain02 high resolution gridded observational dataset are used, covering the period 1979-2017, to analyze the composites of mesoscale features and associated impacts on rainfall.

Results show that AR-like structures over the Mediterranean (abbreviated here Med-ARs) have relatively low incidence with an approximately once-per-year frequency. Nevertheless, these rare events are usually associated with extreme precipitation, often amplified by orographic features, contributing to more than 40% to the annual precipitation in some cases (Lorente-Plazas et al., 2020). During a typical Med‐AR, the value of IVT increases significantly due to high horizontal winds and water vapor contents. Med-ARs are always associated to the placement of a cutoff cyclone with the cold core over northwestern Africa and warmer air mass over northern Europe. The vertical structure of Med-ARs suggests an occluded front with a low-level jet in the warmer front where Med‐ARs reside and, moisture penetrating into high atmospheric levels where cold and warm front intersect leading to severe convection. To sum up, long filaments of IVT can be found over the western Mediterranean Sea, traveling in an east-west direction, playing a relevant role in hydrometeorological impacts. Although these structures share some features with ARs over the Pacific/Atlantic Ocean they present so many specific characteristics that can be also considered to constitute a variant of this well-established meteorological phenomenon.

 

Acknowledgments

The author would like to acknowledge the financial support by Fundação para a Ciência e Tecnologia (FCT) through project UIDB/50019/2020 – IDL. A. M. Ramos was supported by the Scientific Employment Stimulus 2017 from FCT (CEECIND/00027/2017).

 

References

Lorente-Plazas, R., Montavez, J. P., Ramos, A. M., Jerez, S., Trigo, R. M., & Jimenez-Guerrero, P. (2019). Unusual Atmospheric-River-like structures coming from Africa induce extreme precipitation over western Mediterranean Sea. Journal of Geophysical Research: Atmospheres, 124. doi: 10.1029/2019JD031280

How to cite: Lorente-Plazas, R., Ramos, A. M., Montávez, J. P., Jerez, S., Trigo, R. M., and Jimenez-Guerrero, P.: Unusual Atmospheric-River-like structures coming from Africa induce extreme precipitation over western Mediterranean Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10605, https://doi.org/10.5194/egusphere-egu2020-10605, 2020

D3522 |
EGU2020-4499
Katrin Schroeder, Sana Ben Ismail, Jacopo Chiggiato, Mireno Borghini, and Stefania Sparnocchia

Climate change is one of the key topics of our century. The study of processes related to climate change in the atmosphere, the open ocean, the deep sea or even in shallow coastal waters require sustained long-term observations, often deploying sophisticated and expensive equipment. According to the Deep-Ocean Observing Strategy (DOOS, http://deepoceanobserving.org/), the deep ocean (below 200 m water depth) is the least observed, but largest habitat on our planet by volume and area. With more than 90% of anthropogenic heat imbalance absorbed by the oceans, monitoring long-term changes of its heat content, and over its full depth, is essential to quantify the planetary heat budget.

The Mediterranean Sea is a mid-latitude marginal sea, particularly responsive to climate change as reported by recent studies. Straits and channels divide it into several sub-basins and the continuous monitoring of these choke points allows to intercept different water masses, and thus to document how they changed over time. This monitoring, in many cases, is done under the umbrella of the CIESM Hydrochanges program (http://www.ciesm.org/marine/programs/hydrochanges.htm). Here we report the long-term time series of physical data collected in two of these choke points: the Sardinia Channel (1900 m) and the Sicily Channel (400 m).

The Sardinia Channel allows the Western Mediterranean Deep Water (WMDW) to enter the Tyrrhenian Sea (depths > 3000 m), connecting it with the Algerian Sea (depths > 2500 m). This water mass has experienced a significant increase of heat and salt content over the past decades, due both to a gradual process and to and abrupt event, called Western Mediterranean Transition (WMT). The monitoring at the sill (1900 m) of the Sardinia Channel since 2003 shows this very clearly, and the interannual trends are significantly stronger than the global average trends.

The Sicily Channel (sill at 400 m) separates the Mediterranean in two main basins, the Eastern Mediterranean Sea and the Western Mediterranean Sea. Here the thermohaline properties of the Intermediate Water (IW) are monitored since 1993, showing increasing temperature and salinity trends at least one order of magnitude stronger than those observed at intermediate depths in the global ocean.

We investigate the causes of the observed trends and in particular discuss the role of a changing climate over the Mediterranean, especially in the eastern basin, where the IW is formed. The long-term records in two Mediterranean channels reveal how fast the response to climate change can be in a marginal sea compared to the global ocean, and demonstrates the essential role of long time series in the ocean.

How to cite: Schroeder, K., Ben Ismail, S., Chiggiato, J., Borghini, M., and Sparnocchia, S.: Long term changes in the deep sea: examples from two Mediterranean Channels, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4499, https://doi.org/10.5194/egusphere-egu2020-4499, 2020

D3523 |
EGU2020-5037
| Highlight
Maria Francisca Cardell, Arnau Amengual, and Romualdo Romero

Europe and particularly, the Mediterranean countries, are among the most visited tourist destinations worldwide, while it is also recognized as one of the most sensitive regions to climate change. Climate is a key resource and even a limiting factor for many types of tourism. Owing to climate change, modified patterns of atmospheric variables such as temperature, rainfall, relative humidity, hours of sunshine and wind speed will likely affect the suitability of the European destinations for certain outdoor leisure activities.

Perspectives on the future of second-generation climate indices for tourism (CIT) that depend on thermal, aesthetic and physical facets are derived using model projected daily atmospheric data and present climate “observations”. Specifically, daily series of 2-m maximum temperature, accumulated precipitation, 2-m relative humidity, mean cloud cover and 10-m wind speed from ERA-5 reanalysis are used to derive the present climate potential. For projections, the same daily variables have been obtained from a set of regional climate models (RCMs) included in the European CORDEX project, considering the rcp8.5 future emissions scenario. The adoption of a multi-model ensemble strategy allows quantifying the uncertainties arising from the model errors and the GCM-derived boundary conditions. To properly derive CITs at local scale, a quantile–quantile adjustment has been applied to the simulated regional scenarios. The method detects changes in the continuous CIT cumulative distribution functions (CDFs) between the recent past and successive time slices of the simulated climate and applies these changes, once calibrated, to the observed CDFs. 

Assessments on the future climate potential for several types of tourist activities in Europe (i.e., sun, sea and sand (3S) tourism, cycling, cultural, football, golf, nautical and hiking) will be presented by applying suitable quantitative indicators of CIT evolutions adapted to regional contexts. It is expected that such kind of information will ultimately benefit the design of mitigation and adaptation strategies of the tourist sector.

How to cite: Cardell, M. F., Amengual, A., and Romero, R.: Assessment of the future climate potential for tourism over Europe using a combination of downscaling approaches and quantitative impact models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5037, https://doi.org/10.5194/egusphere-egu2020-5037, 2020

D3524 |
EGU2020-21775
William Rapuc, Pierre Sabatier, Julien Bouchez, Jérôme Gaillardet, Laurent Augustin, Andrea Piccin, Ulrich von Grafenstein, and Fabien Arnaud

Human activities and climate variability have direct impacts on the dynamic of the Critical Zone (CZ) both in quantitative (increase of the flux of organic and mineral matter) and qualitative way (modification of the biogeochemical cycles). Mountainous areas hold a strong CZ dynamic due to their inherent environmental conditions. Among them, European Alps are of prime interest because they have been impacted by human activities over the last millennia. To understand the CZ trajectories, we need to develop long term monitoring far beyond the current instrumental period. To reach this objective we adopt a source-to-sink approach based on geochemical analyses with i) Nd and Sr isotopic composition to trace sediment sources form the watershed and ii) major and traces elements compositions to reconstruct the evolution of  sources weathering states over this period. The watershed of Lake Iseo, located in the Val Camonica (NW Italy) was chosen for its substantial size (1.777km²), its various geological context, helping the identification of the different sources of sediment inputs, and a well-documented anthropization history. 25 samples of fine fluviatile sediments were sampled on the flood plain of the main tributaries of Lake Iseo and were linked to a 15.5m long lake sediment core, retrieved from the deep basin of the lake and covering the last 2,000 years. The fluctuations of the sediment inputs coming from the different sources is discussed from the  Roman period until the recent warming through Medieval Optimum and Little Ice Age period to disentangle the influence of both climate (precipitation, glacial dynamics) and human activity onto the dynamic of the CZ throughout the erosion and the chemical weathering of the soils in this Mediterranean Alpine region.

How to cite: Rapuc, W., Sabatier, P., Bouchez, J., Gaillardet, J., Augustin, L., Piccin, A., von Grafenstein, U., and Arnaud, F.: Critical zone dynamic over the past 2,000 years record in large Mediterranean Lake (Iseo, Italia): Climate versus human impacts, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21775, https://doi.org/10.5194/egusphere-egu2020-21775, 2020

D3525 |
EGU2020-14958
Gonzalo Jiménez-Moreno, R. Scott Anderson, María J. Ramos-Román, Jon Camuera, Jose Manuel Mesa-Fernández, Antonio García-Alix, Francisco J. Jiménez-Espejo, and José S. Carrión

In this study, we synthesized pollen data from seven sites from the Sierra Nevada in southern Spain to investigate the response of forests in the western Mediterranean area to centennial- and millennial-scale climate changes and to human impact during the Holocene. In particular, here we focused in Cedrus pollen abundances, which most-likely originated from Northern Africa and were carried to Sierra Nevada by wind. Although Cedrus abundances are generally lower than 1% in the studied pollen samples, a comparison with North African pollen records shows similar trends at long- and short-term time-scales. Therefore, this record could be used as a proxy for changes in this forest species in North Africa. A Middle and Late Holocene Cedrus pollen increasing trend has been observed in the Sierra Nevada synthetic record, which seems to be the result of decreasing summer insolation. This would have produced overall cooler annual temperatures in Northern Africa (Atlas and Rif Mountains), benefiting the growth of this cool-adapted montane tree species, and lower summer evaporation, increasing available moisture during the summer, which is critical for this water-demanding species. Millennial- and centennial-scale variability also characterize the Sierra Nevada Cedrus synthetic record. Cedrus abundance oscillations could have been produced by well-known millennial-scale climatic variability that controlled cedar abundance in montane areas of N Africa.  

How to cite: Jiménez-Moreno, G., Anderson, R. S., Ramos-Román, M. J., Camuera, J., Mesa-Fernández, J. M., García-Alix, A., Jiménez-Espejo, F. J., and Carrión, J. S.: The Holocene Cedrus pollen record from Sierra Nevada (S Spain), a proxy for climate change in N Africa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14958, https://doi.org/10.5194/egusphere-egu2020-14958, 2020

D3526 |
EGU2020-2864
Assaf Hochman, Pinhas Alpert, Hadas Saaroni, Tzvi Harpaz, Joaquim G. Pinto, and Gabriele Messori

Extreme weather events have long been considered challenging to predict. It is likely that global warming will trigger extreme weather in many regions of the globe and especially over the Mediterranean ´hot spot´. Therefore, extreme weather events have been selected as one of the grand challenges of the World Climate Research Program.

The intrinsic predictability of a weather system, or any dynamical system, depends on its persistence and its active number of degrees of freedom. Recent developments in dynamical systems theory allow to compute these metrics for atmospheric configurations (1). In most of the mid-latitudes, synoptic scale patterns exert a strong control on regional weather, thus, stimulating a broad interest, especially in weather forecasting. Recently, we have integrated the dynamical systems approach with a synoptic classification algorithm over the Eastern Mediterranean (2).  It was shown that the dynamical systems perspective provides an extremely informative tool for evaluating the predictability of synoptic patterns and especially of weather extremes.

The novel perspective, which leverages a dynamical systems approach to investigate the predictability of extreme weather events, outlines a new avenue of research that may be fruitfully applied at operational weather and climate forecasting services in the Mediterranean Region and around the globe.

References

  1. Faranda D, Messori G, Yiou P. 2017. Dynamical Proxies of North Atlantic Predictability and Extremes. Scientific Reports 7, 412782017b. DOI: 10.1038/srep4127
  2. Hochman A, Alpert P, Harpaz T, Saaroni H, Messori G. 2019. A New Dynamical Systems Perspective on Atmospheric Predictability; Eastern Mediterranean Weather Regimes as a Case Study. Science Advances 5. DOI: 10.1126/sciadv.aau0936

How to cite: Hochman, A., Alpert, P., Saaroni, H., Harpaz, T., Pinto, J. G., and Messori, G.: A New Avenue of Research for Improving the Predictability of Weather Extremes - The Eastern Mediterranen as a Case Study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2864, https://doi.org/10.5194/egusphere-egu2020-2864, 2020

D3527 |
EGU2020-16474
| Highlight
Lydia Bowler, Tamar Hodos, Matthew Bosomworth, Matthew Jacobson, Melanie Leng, Hai Cheng, and Dominik Fleitmann

During the 13th and 12th centuries BCE (3.25-3.05 kyrs BP), the prosperous and globalized Late Bronze Age (LBA) world system came to an abrupt end in the eastern Mediterranean (EM). During this time, the EM witnessed the demise of powerful and well-established empires and state systems, including the Hittite empire in Anatolia and the Mycenean palace system in the Aegean (Yakar, 2006; Deger-Jalkotzy, 2008). The end of the LBA also saw the destruction and abandonment of numerous urban centres such as Mycenae, Troy, Ugarit, across an area of approx. 6 million km2 (Knapp and Manning, 2016). The causes of this widespread and critical transition in the EM’s history, often referred to as the LBA “collapse”, have been debated for several decades and remain contentious. Notably, the idea of climate change in the form of widespread drought has been postulated, with the suggestion of a 3.2 kyrs BP ‘megadrought’ event presented in the last decade (Kaniewski et al. (2013; 2015; 2017; 2019a). This PhD project addresses the climate hypothesis, by examining whether climate may have acted as a contributing factor for the LBA collapse and subsequent transition into the Early Iron Age (EIA).

In order to provide a comprehensive assessment of palaeoclimatic conditions during the LBA/IA transition, a review of all existing palaeoenvironmental  records that cover the interval 3.5-2.5 kyrs BP across the EM has been undertaken. As part of this assessment, this study also presents new high-resolution multi-proxy stalagmite records covering this time interval from Kocain and Sofular Caves in Turkey. In total, 83 records were entered into a database for assessment in order to select the key hydroclimatic proxy records to be examined in this study. The resulting assessment of the remaining 14 highly resolved records from across the EM has not provided strong evidence of a major synchronous and widespread climatic event suggestive of the supposed ‘3.2 megadrought event’. Instead, the results of this study present a highly complex picture of palaeoclimatic conditions between 3.5-2.5 kyrs BP, which is partly related to site and sample-specific factors (e.g. chronological uncertainties, cave environment) and the high degree of regional climatic variability. However, a period of increasingly arid conditions from approx. 3.3-3.1 kyrs BP is apparent in several records including Anatolian records from Uzuntarla, Sofular and Kocain Caves. Future work by this team will specifically assess this aridity evidence in the Anatolian stalagmite records, with the aim to further improve the temporal resolution and chronologic control of these records. Additionally, future work will also integrate our palaeoclimatic findings with associated archaeological evidence. Engagement with the archaeological material is critical as integrated studies can provide us with more nuanced discussions, which are needed to capture the true complexity that surrounds both the archaeology and palaeoclimatic reconstruction for this period. Significantly, this archaeological engagement therefore allows us to more accurately assess the impact that increasing aridity and possible drought events may have had on the agriculturally dependent societies of the LBA in Anatolia. 

How to cite: Bowler, L., Hodos, T., Bosomworth, M., Jacobson, M., Leng, M., Cheng, H., and Fleitmann, D.: Evaluating the influence of climate on the Late Bronze Age collapse in the eastern Mediterranean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16474, https://doi.org/10.5194/egusphere-egu2020-16474, 2020

D3528 |
EGU2020-5676
| Highlight
David Santillan, Luis Garrote, Ana Iglesias, and Vicente Sotes

Traditional Mediterranean crops, such as grapevine, a permanent wood crop, are well adapted to the lack of water and recurrent drought in the Mediterranean region. This study uses grapevine production indicators that are widely used by practitioners, linking science to the tools used by practitioners and therefore encouraging action and innovation among all stakeholders. The study evaluates potential adaptation choices that may contribute to real-time policy analysis and development as national and international policies and agreements in the grapevine production sector. The climate changes scenarios are derived from global datasets. Adaptation efforts are estimated proportionally to the change of the climatic indices and are categorized into low, medium or high, as a function of the excepted changes in climatic indices. The study emphasizes that non-informed adaptation limits future choices in areas severely impacted. The content of the study is based on the results of the iSQAPER (http://www.isqaper-project.eu/) H2020 project and the UPM Adapt project.

How to cite: Santillan, D., Garrote, L., Iglesias, A., and Sotes, V.: Climate Change risks and adaptation for Mediterranean grapevine production , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5676, https://doi.org/10.5194/egusphere-egu2020-5676, 2020

D3529 |
EGU2020-7774
| Highlight
Jose A. Jiménez

The coast around Barcelona can be considered a good paradigm of the highly pressured Mediterranean coastal zone. The combination of decreasing river sediment discharges, increasing urbanization and infrastructure development makes this a very sensitive coastline. If we also consider potential effects of SLR, future conditions will significantly worsen and, for urban coastal environments, this will be a significant challenge since natural and anthropic conditions will largely constrain the development and implementation of adaptation measures.

The coastal zone around Barcelona comprises different typologies which are common along the Mediterranean: (i) city front formed by artificial beaches; (ii) longshore transport (Sl) dominated coastline with different barriers and without accommodation space due to intensive urbanization and existing infrastructures (coastal railway); (iii) Sl-dominated coastline with accommodation space; (iv) harbor. This variability determines that current processes and hazards largely vary along the coast, and that expected SLR-induced impacts will also significantly vary. This variability is also found from the socio-economic standpoint, with different stakeholders with different interests and needs. Some examples are: the Barcelona municipality requiring healthy beaches to provide recreation space for beach users, and protection against storm impacts. The railway operator that needs to maintain overtopping rates below a given threshold to maintain train operability. Campsite owners requiring a stable coastline to have enough recreation space for clients (beach users) and to avoid infrastructure damages. In overall, the combination of hazards and stakeholders provides a wide range of (Mediterranean) conditions to be found in urban and periurban coastal environments and, in consequence, it is a good test site to develop general adaptation strategies for this kind of coasts.

Previous works have identified suitable adaptation measures: (i) a sediment management strategy to maintain beaches within a given status; (ii) a new spatial planning to promote the adaptation of uses in areas with existing accommodation space; (iii) accept to “sacrifice” some beaches in highly eroding zones; (iv) structures redevelopment to maintain targeted functionality. In order to develop an efficient and integrated adaptation strategy for the entire coast, it is necessary to build up an adaptation pathway incorporating different measures and their corresponding tipping points (ATP). The goal is to assess adaptation needs with time (to answer stakeholders’ needs), to determine ATPs, and to properly define adaptation measures. For this purpose, it is necessary to have detailed information on expected conditions (forcing, processes and hazards) taking place during the adaptation period. Within this context, this work will present a suitable adaptation pathway to this coastal stretch to SLR to maintain functions currently provided by the coast and considering stakeholders preferences and needs. Presented solutions could be used as an example for other Med urban coastal environments.   

This work was carried out within the framework of the M-CostAdapt (CTM2017-83655-C2-1-R) research project, funded by the Spanish Ministry of Economy and Competitiveness (MINECO/AEI/FEDER, UE).

How to cite: Jiménez, J. A.: Multi-purpose adaptation to SLR in Mediterranean urban coastal environments: the Barcelona case, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7774, https://doi.org/10.5194/egusphere-egu2020-7774, 2020

D3530 |
EGU2020-6088
| Highlight
Joaquim Tomàs-Ferrer, Marina Sanz-Martín, Gabriel Jordà, M. Pilar Tugores, and Enric Massutí

Western Mediterranean Sea is immersed in a warming process, at least since the beginning of the XX century. Moreover, climate simulations project an accelerated warming at all depths for the next decades. The effects of sea warming on demersal species of high commercial interest is an open question of paramount relevance for the management of their fisheries. Unfortunately, the answer is not simple as it involves a complex chain of interactions between environmental conditions and the different trophic levels. A first limitation is that there is no clear knowledge of the thermal limits of these species, so the direct impact of warming on the individuals cannot be assessed.

 The aim of this study is to establish the thermal limits of 24 selected demersal or benthopelagic species of fishes, crustaceans and cephalopods of commercial interest and the effects of global warming on their distributions in the Western Mediterranean. In particular, we selected Merluccius merluccius, Arsteus antennatus, Parapenaeus longirostris, Octopus vulgaris, Nephrops norvegicus, Mullus barbatus, M. surmuletus, Pagellus erythrinus, P. bogaraveo, Sepia officinalis, Solea solea, Phycis blennoides, Lophius budegassa, L. piscatorius, Illex coindetti, Eledone cirrhosa, E. moschata, Lepidorhombus boscii, Helicolenus dactylopterus, Trachurus trachurus, T. mediterraneus, Aristaeomorpha foliacea, Todarodes sagittatus and Loligo vulgaris. First, we reviewed the literature regarding temperature range where each species has been found. We also used global databases of species distribution and cross them with temperature information to characterise a conservative range of optimal temperatures for each species. Once the thermal ranges were defined, we compared them with the current projections of temperature evolution of Mediterranean waters to describe the future changes in the suitable habitat of the studied species due to ocean warming.

Our results suggest that, under a business-as-usual scenario (RCP8.5), at the end of the century 8 of 19 species will see their potential habitat greatly reduced, 3 of 19 will find a moderate reduction and 8 of 19 will not be directly affected by the warming.

How to cite: Tomàs-Ferrer, J., Sanz-Martín, M., Jordà, G., Tugores, M. P., and Massutí, E.: Potential vulnerability of demersal fisheries to Western Mediterranean warming, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6088, https://doi.org/10.5194/egusphere-egu2020-6088, 2020

D3531 |
EGU2020-11884
Roberto Suarez-Moreno, Richard Seager, and Yochanan Kushnir

The Mediterranean region is a semi-arid climate zone, subject to droughts, where water resources are scarce and observational data and climate models suggest a tendency towards greater aridification. Moreover, the Mediterranean region is an area of social and political instability and, in the Middle East, open warfare, which might be further stressed by climate change. The North Atlantic Oscillation (NAO) is the dominant mode of winter climate variability in the North Atlantic sector, playing the leading role in driving Mediterranean hydroclimate variability from seasonal to multidecadal timescales, whereas the influence of sea surface temperatures (SSTs) remains unclear. Nevertheless, the mechanism underlying the NAO is still under debate, and the possibility for coupled ocean-atmosphere decadal interactions, for which several mechanisms have been proposed, would support the role of SST. Based on observations and reanalysis, we conduct a statistical-observational analysis to explore the decadal drivers of Mediterranean hydroclimate variability for the winter half-year (October-to-March) wet season. Our results put forward the uneven intraseasonal influence of the decadal NAO, being the leading driver during the winter peak season (December-to-March), while decadal Atlantic-Mediterranean SST variability exhibit a consistent link for the first months of the wet season (October-to-January). These results emphasize the need to further explore the ocean-atmosphere feedback mechanisms and their possible modulations under climate change. Understanding these mechanisms is essential to improve predictability of hydroclimate in the Mediterranean region, leading to adaptation strategies that mitigate the effect of climate change on the vulnerable population.

How to cite: Suarez-Moreno, R., Seager, R., and Kushnir, Y.: Observational analysis of Mediterranean decadal hydroclimate variability: role of Atlantic-Mediterranean sea surface temperatures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11884, https://doi.org/10.5194/egusphere-egu2020-11884, 2020

D3532 |
EGU2020-13478
Melika Baklouti, Rémi Pagès, Mohamed Ayache, Nicolas Barrier, Florence Sevault, Samuel Somot, and Thierry Moutin

In recent studies, the Mediterranean region is once again identified as a region particularily sensitive to climate change, with recorded temperature and sea level rises during the last decades exceeding the mean variations recorded at global scale. Moreover, according to climate scenarios, there seems to be some consensus regarding the impact on climate change on some hydrodynamical features, as for example on stratification which should become stronger and more persistant. However, nothing or very few is known about the expected changes nor in the structure and the functionning of the planktonic food web, neither in the main biogeochemical cycles. This study is intended to progress on this issue, using a coupled (one way) physical-biogeochemical model: CNRM-RCSM4/NEMO-MED12/Eco3M-Med. A 110-year simulation over the period 1990-2100 has been run and from 2006, the simulation is forced by a RCP 8.5 regional scenario of the Med Sea (a control simulation has also been run simultaneously). After having verified the model's ability to describe the main characteristics of the marine planktonic food web and biogeochemistry through several comparisons with available data during the historical period, the model outputs have been analyzed. Preliminary results indicate a significant decrease in the annual primary production and the export of organic carbon at 200 and 1000 m in both the eastern and the western basins, associated with changes in the structure of the planktonic community.

How to cite: Baklouti, M., Pagès, R., Ayache, M., Barrier, N., Sevault, F., Somot, S., and Moutin, T.: How will climate change affect the planktonic food web and the biogeochemistry of the Mediterranean Sea according to the RCP 8.5 scenario ?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13478, https://doi.org/10.5194/egusphere-egu2020-13478, 2020

D3533 |
EGU2020-17652
| Highlight
Nathalie Combourieu-Nebout, Vincent Coussin, Yannick Miras, Aurélie Penaud, Sandra Picard Casal, Odile Peyron, Bassem Jalali, Marie-Alexandrine Sicre, Nathalie Babonneau, and Antonio Cattaneo

The 4.2 ka event is considered a key-period of the Mediterranean climate because of its potential impact on human societies over the Holocene. Numerous records provide a detailed description on its expression in continental and marine archives (e.g. Bini et al, 2019). They generally indicate cold/dry conditions, although not uniformly expressed across the Mediterranean, and summer dryness reinforced by dry winters. Palynological data from the central Mediterranean basin show a complex response of the vegetation during this climatic event that seems to be more pronounced in the southern sites.

In this study, we developed a multidisciplinary approach on two sequences collected in the Western Mediterranean Sea to insight the response of the W-Mediterranean forest along a North-South transect. The two marine records, KSGC-31 (43°N - 3°17.9’E; 60 m water depth, Gulf of Lion margin at 20 km from the coast) and MD04-2801 (36°30.99’ N - 0°30.03’ W, 2067 m water depth, 12km from the Algerian coast) were used to document regional changes in the basin between 5 and 3 kyr BP at a multi-decadal to centennial scale temporal resolution.

Information derived from palynological (pollen, spores, dinocysts, microalgae and non-pollen palynomorphs) and marine proxy data (alkenone-derived SSTs, isotopes...) are combined to evaluate environmental and hydrological changes and how this relate to human activities. Our findings highlight coherent climatic patterns and time-lags along a South-North transect in the Western Mediterranean during the establishment of droughts. They also reveal the first indications of human impact in the two areas. Overall, our study shows the effectively of our approach based on cross-analysis of continental palynological and marine evidences to decipher the chronology of sequence of events embedded in multiproxy records.

Bini, M., Zanchetta, G., Perşoiu, A., et al. : The 4.2 ka BP Event in the Mediterranean region: an overview, Clim. Past, 15, 555–577, https://doi.org/10.5194/cp-15-555-2019, 2019.

How to cite: Combourieu-Nebout, N., Coussin, V., Miras, Y., Penaud, A., Picard Casal, S., Peyron, O., Jalali, B., Sicre, M.-A., Babonneau, N., and Cattaneo, A.: Paleoenvironmental changes, climate and human impact in the Western Mediterranean Sea during the 4.2 Kyr event along a North-South Transect , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17652, https://doi.org/10.5194/egusphere-egu2020-17652, 2020

D3534 |
EGU2020-751
Efstathia Tringa, Konstantia Tolika, and Efthimia Kostopoulou

Extreme temperature values are an issue that concerns every society around the world since their impact can cause serious problems even to public health. During the winter months, southeastern Europe and especially the Balkan Peninsula, is characterized by high temperature variability and is often affected by extreme weather events resulting in the creation of serious socio-economic problems. There is therefore a need to further study the causes that contribute to creation of such cold winter spells, so that in the future there will be the possibility of timely forecasting and therefore alerting in order to better prepare each society. The present work provides an extensive climatic analysis of the cold extreme sequences that occurred in the Balkan Peninsula. This climatology includes temporal variations and classification of extreme cold spells according to their source of creation and their characteristics. More specifically, the aim of this work is to study the temporal and spatial variability of the extreme cold spells and to determine the circulation conditions of the occurrences. Daily temperature data from 20 Balkan stations has been collected from the “European Climate Assessment and Datasets” (https://www.ecad.eu/) for the period 1958-2019 (62 years). A cold spell is defined as a sequence of at least 3 cold days, i.e. when the minimum air temperature is below than the 10th percentile of the probability density function from the observation (i.e. Tmin<P10).  After identifying the extreme cold spells, the above parameters are used to describe each event, namely frequency, duration, severity and intensity. The most intense cold spells of have been studied in a synoptic analysis to investigate their fundamental dynamic characteristics and to examine their association with anomalies in the upper layer of the atmosphere. All in all, the proposed study aims to understand the atmospheric circulation conditions that exist in advance and during the extreme cold spells. In addition, the final concept will investigate to identify possible common circulation types associated with their occurrence so that in the future the early indications of such patterns can contribute the early prediction of corresponding extreme cold spells.

How to cite: Tringa, E., Tolika, K., and Kostopoulou, E.: Statistical and Dynamical study of the cold winter spells over the Balkan Peninsula., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-751, https://doi.org/10.5194/egusphere-egu2020-751, 2019

D3535 |
EGU2020-1592
Ioannis Koutsogiannis, Chris G. Tzanis, Kostas Philippopoulos, and Anastasios Alimissis

Climate change is well-established as the major environmental issue of concern by the scientific community and the policy-makers around the globe. In order to examine climate variability both at a global and regional scale, key climatic variables such as temperature and humidity are examined in climate research. A significant temperature rise could lead to unsustainable conditions for the natural and human ecosystems. Additionally, water vapor is  recognized as the most important natural greenhouse gas, playing a principal role in the hydrological cycle. Specific and relative humidity are sensitive to temperature changes and therefore, examining temperature along with humidity variations is considered essential for the deeper understanding of the atmosphere’s thermodynamic and radiative processes. This study focuses on the analysis of future temperature, specific and relative humidity trends at different atmospheric pressure levels over the eastern Mediterranean region based on data from an ensemble of regional climate multi-model simulations for each of the Representative Concentration Pathways, namely RCP4.5, RCP8.5 and RCP2.6. The main purpose of this study is to examine whether statistically significant changes in the climate of the eastern Mediterranean are likely to occur in the future and investigate the relationship between temperature and humidity variations. The results of the monthly, seasonal and annual trend analysis are discussed.

How to cite: Koutsogiannis, I., Tzanis, C. G., Philippopoulos, K., and Alimissis, A.: Assessing future temperature and humidity trends using an ensemble of high-resolution simulations for the eastern Mediterranean region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1592, https://doi.org/10.5194/egusphere-egu2020-1592, 2019

D3536 |
EGU2020-2712
Dario Conte, Piero Lionello, and Silvio Gualdi

Dynamical downscaling through coupled regional climate model plays an important role to improve climate information at regional fine-scale, since it modulates information produced by GCM, combining planetary scale processes with regional scale processes.  This study describes the impact of climate change  on rainfall over the Mediterranean region, downscaling, at two different horizontal grid resolutions (0.44 and 0.11 degs), a Global Climate Model (GCM at 0.75 degs) by means of a coupled Regional Climate System Models (RCSM). We analyze the effect of adopting model version with different horizontal resolutions (0.11, 0.44 e 0.75 degs), considering  two climate representative concentration pathways (rcp4.5 and rcp8.5). The spatial pattern on different aspects of precipitation climatology are investigated such as increase/decrease in the intensity of precipitation events, extremes and annual amount of wet days. Moreover, since the grid models cover a wide and complex climate geographic area, the rainfall probability over six sub-regions are calculated: (1) Alps, (2) North-Western coast, (2) South Italy, (3) central part of the Mediterranean sea, (4) Greece Anatolia peninsula and Levantine basin. Although, the evaluation of RCSM downscaling is complex and depends on several factors such as: variables considered, geographic area, topography, model configuration and so on, the results show that it produces an significant improvement, adding information with regards to fine-scale spatial pattern, respect to that provided by GCM.

ACKNOWLEDGEMENT: This contribution is based on work conducted by the authors within the SOCLIMPACT project, that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776661. The fullname of the project is "DownScaling CLImate ImPACTs and decarbonisation pathways in EU islands, and enhancing socioeconomic and non-market evaluation of Climate Change for Europe, for 2050 and Beyond". The opinions expressed are those of the author(s) only and should not be considered as representative of the European Commission’s official position.

Keywords:  widespread heavy rainfall, coupled numerical models, daily rainfall, climate scenarios, climatology of heavy rainfall.

 

How to cite: Conte, D., Lionello, P., and Gualdi, S.: Impacts of model spatial resolution on intense and heavy precipitation events over the Mediterranean region., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2712, https://doi.org/10.5194/egusphere-egu2020-2712, 2020

D3537 |
EGU2020-4974
| Highlight
Hao Yu and Xuefeng Cui

Heat extremes have serious impact on human and agriculture over the world. As one of the prominent climate change “hot spots”, Mediterranean area, especially, its eastern area is expected to be more vulnerable to heat exposure, due to its population density and high rates of urbanization. The Paris Agreement aims to control global warming below +2℃ comparing to pre-industrial level. It is interesting to study how heat extremes would change in Mediterranean area in a +1.5 ℃ and +2 ℃ global warming world and how they impact on human and agriculture.

Based on the high resolution climate scenario data from CORDEX-MED, we calculate several heat waves indices e.g. HWN (the total number of events), HWD (the length of the longest event), HWF (the total number of heat waves days), HWA (the hottest day (amplitude) of the hottest event) and EDD (extreme degree days, 30℃ used to study impact on maize yield). We find that in most Mediterranean areas, both heat waves intensity and frequency have a robust increase in a +1.5 ℃ and +2 ℃ global warming world and cause more people exposure to heat waves in different shared socioeconomic pathways (SSPs). The most prominent areas are central Spain, Italy and Turkey. Also, more maize growing areas in Mediterranean will experience yield losses.

How to cite: Yu, H. and Cui, X.: Risks and impacts of Heat Extremes under 1.5 ℃ and 2 ℃ global warming Over Mediterranean areas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4974, https://doi.org/10.5194/egusphere-egu2020-4974, 2020

D3538 |
EGU2020-5212
Kazuyo Tachikawa, Laurence Vidal, José N. Pérez-Asensio, Marta Garcia, Adnya Pratiwi, and Hartmut Schulz

The Mediterranean thermohaline circulation is sensitive to ongoing climate change and generally stagnant circulation is expected by the end of the 21st century. In the past, the eastern Mediterranean Sea has experienced slower ventilation as demonstrated by rhythmic occurrence of organic-rich sediments “sapropels”. The two sapropels S1 (Holocene) and S5 (Last Interglacial) were formed under conditions of excess fresh water inputs via Nile river in relation to insolation-driven African monsoon intensification and deglacial meltwater inputs from the North Atlantic. In addition to the Nile river discharge, the paleodrainage toward Gulf of Sirte off Libya has been proposed although its contribution could be significantly different between S1 and S5 because of distinct monsoon intensification. Since the response of circulation to freshwater forcing could vary with the region of perturbation, comparison of S1 and S5 deposited in the Gulf of Sirte will provide key information on the Mediterranean ventilation sensitivity.

We applied a multi-proxy approach (bulk elemental composition by XRF scanning, redox sensitive elemental concentration, planktonic foraminiferal δ18O and benthic foraminiferal faunal assemblages) to core SL95 (32º46.46N, 19º11.46E; 1390 m water depth) from the eastern side of the Gulf of Sirte. Both S1 and S5 are marked by prominent peaks of Ba/Al and Ba/Ti with more pronounced Ba enrichment for S5. Redox sensitive elements such as U and Mo present enrichment prior to the Ba peaks that can be interpreted as reduced ventilation before sapropel deposition. However, expected reduced oxygenation is not synchronous with benthic foraminiferal faunal changes, suggesting possible remobilisation of the trace elements during sapropel interruption and/or post-sapropel oxygenation. Acquisition of high-temporal resolution data of Globigerinoides ruber δ18O and benthic foraminiferal assemblages is in progress. We will discuss potential influence of (partial) ventilation at intermediate water depths during sapropel interruption in association with 8.2 event and possible different freshwater inputs at S1 and S5 depositions.

How to cite: Tachikawa, K., Vidal, L., Pérez-Asensio, J. N., Garcia, M., Pratiwi, A., and Schulz, H.: Comparison of Holocene and Last Interglacial sapropels in the Gulf of Sirte (eastern Mediterranean), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5212, https://doi.org/10.5194/egusphere-egu2020-5212, 2020

D3539 |
EGU2020-5942
Ioanna Kaza, Dimitra Founda, Christos Giannakopoulos, and Dionysia Kolokotsa

Nowadays, the global climate change has important impacts on many aspects of human life such as agriculture, economy, health and energy consumption. The issue of climate change has concerned the scientific community as the solutions have to be direct and effective. Studies on energy demands under a climate change environment are particularly useful as they improve our understanding of the impacts of changing climate on energy sector. This research focuses on a very responsive to climate change area, the Mediterranean, and attempts to analyze the climate and energy demand trends, processing historical temperature records from weather stations at seven Mediterranean cities (Nicosia, Athens, Rome, Palma, Montpellier, Madrid and Seville) for the period of 1970 – 2018. Consecutively, cooling degree days (CDD) and heating degree days (HDD) have been estimated according to the given climatic data. These simple indicators are very useful as they point out the amount of energy demand, according to the deviation of a standard temperature value (threshold).

The research has shown a statistically significant increase in the ambient air temperature at all cities, ranging from 0.37 to 0.50 0C per decade on annual basis, but with notably higher increasing trends in summer compared to winter.  Consequently, the energy demand for cooling interior spaces has increased as well.  On the other hand, there is a significant decrease of heating demand. Annual CDDs have increased at rates reaching up to 65 degrees per decade over the study period (Nicosia), while the rate of decrease in HDDs ranges approximately between 55 and 110 degrees per decade at the selected cities. The analysis has been conducted on different timescales (monthly and annual) in order to approach the optimal accuracy. 

 

Further, our results will be used to validate simulations of CDD and HDD from Regional Climate Models downscaled over the areas of interest for a reference period, while future simulations will be realized to find projected trends in CDDs and HDDs at the Mediterranean cities by the end of the century.

How to cite: Kaza, I., Founda, D., Giannakopoulos, C., and Kolokotsa, D.: Long-term trends in heating and cooling degree days at Mediterranean cities, in the context of climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5942, https://doi.org/10.5194/egusphere-egu2020-5942, 2020

D3540 |
EGU2020-6715
Jose Carlos Gonzalez-Hidalgo, Leire Sandonís-Pozo, Dhais Peña-Angulo, Michele Brunetti, and Santiago Beguería

There exists a debate in the scientific research about the evolution of daily thermal amplitude (DTR) along the 20th century, Id est: if the trend in minimum temperatures (night time) has been more pronounced than that of maximum temperatures (daily time). General speaking it has been accepted that until the 1980´s the trend of the DTR has been negative and then changes to positive ones. Notwithstanding, regional and sub-regional dataset developed during the last decades has shown that DTR behaviour is high variable. It has been suggested that the Iberian Peninsula, because of its geographical location (latitude and position between two contrasted water masses), is one of the places in witch climate research could find results that anticipate future global climate conditions.

The new dataset MOTEDAS_Century (MOnthly TEmperature DAtaset of Spain) combines data from the Spanish national meteorological office (AEMET) archives with data rescued from annual books spanning the first decades of the 20th Century. This dataset allowed us to produce a high resolution (10x10 km) grid of minimum and maximum temperatures spanning over the last century (1916-2015). In the present research we will show a spatial analysis of the DTR (Tmax-Tmin) evolution by using moving windows from the total period (1916-2015) to a minimum time span of twenty years (1996-2015). Trends were calculated at monthly scale at each pixel series by means of a pre-whitened Mann-Kendall test in order to determine the sign and significance of trends.

The main results of the analysis are: i) trends were more pronounced for minimum temperature than maximum temperatures during warm months (July, August and September) in the southern and Mediterranean coastland; ii) the significant increasing trend of DTR disappears since the middle of the 1980´s; iii) at present, we only detect significant trends of DTR in December.

How to cite: Gonzalez-Hidalgo, J. C., Sandonís-Pozo, L., Peña-Angulo, D., Brunetti, M., and Beguería, S.: MOTEDAS Century Database. Thermal amplitude trends in Spanish mainland (1916-2015)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6715, https://doi.org/10.5194/egusphere-egu2020-6715, 2020

D3541 |
EGU2020-6831
| Highlight
Julia Moemken and Joaquim G. Pinto

Extreme climate events such as droughts can have very strong impacts both for society and the environment. In particular, the occurrence of severe droughts can endanger the balance of an ecosystem. While intact woodlands, e.g. the Iberian cork-oak ecosystem, are well adapted to withstand single severe drought events, both competition with invading species and recurrent droughts (i.e. droughts in consecutive years) may drive these systems towards critical limits. This is of crucial importance considering that the frequency, intensity and duration of extreme droughts are projected to increase in future decades in various regions all over the world, including the Mediterranean region.
We evaluate the occurrence and intensity of historical extreme drought events over the Iberian Peninsula for the past decades. Special focus is given to consecutive/recurrent drought events. Our study compares various indices for the identification of droughts, e.g. the SPEI (Standardized Precipitation Evapotranspiration Index), the SPI (Standardized Precipitation Index) or indices from the “Expert Team on Climate Change Detection and Indices” (ETCCDI). All indices are based on precipitation and/or temperature. We analyse different observational (E-OBS V17, V20, IBERIA01) and reanalysis datasets (ERA-Interim, ERA5) at several spatial resolutions, ranging roughly between 10 km and 25 km. The high resolution of the datasets enables the consideration of small-scale processes and local topographic effects which are relevant for extreme droughts, thus enabling a deeper insight on the physical mechanisms associated with droughts in the study area.

How to cite: Moemken, J. and Pinto, J. G.: Recurrence of historical drought events over the Iberian Peninsula in different observational datasets and reanalyses, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6831, https://doi.org/10.5194/egusphere-egu2020-6831, 2020

Chat time: Wednesday, 6 May 2020, 10:45–12:30

D3542 |
EGU2020-7212
George Kotsias, Christos Lolis, Nikolaos Hatzianastassiou, Piero Lionello, and Aristides Bartzokas

An objective definition of seasons for the Mediterranean region is performed based on the intra-annual variation of the frequencies of eight (8) objectively defined synoptic Weather Types (WTs). The data used for the determination of the 8 WTs are daily NCEP/NCAR Reanalysis grid point values of 2m air temperature, total cloud cover, 2m zonal and meridional wind components, 500hPa and 1000hPa geopotential height, 500hPa and 850hPa air temperature, 850hPa specific humidity and precipitable water over the Mediterranean region, for the period 1949-2018. Firstly, Principal Component Analysis (PCA) is applied to the inter-annual variations of the above parameters in order to reduce the dimensionality and then k-means Cluster Analysis (CA) is applied to the resultant Principal Components (PCs) in order to group dates with similar patterns of the above parameters, resulting in 8 synoptic WTs. Then, PCA and CA are applied again, now on the intra-annual variations of the frequencies of the resultant WTs and group dates of the year (seasons) with similar frequency distribution among the 8 WTs. According to the results, four (4) seasons are defined for the 70-year period 1949-2018. The same methodology is applied also for the five overlapping 30-year sub-periods 1949-1978, 1959-1988, 1969-1998, 1979-2008 and 1989-2018, leading to 4 seasons too. Although the characteristics of these seasons generally correspond to the ones of the four conventional seasons, there are differences regarding the onset and cessation dates and the duration. In general, it is found that winter and summer last about 4 months (115 and 114 days respectively), spring has a duration of about 2.5 months (72 days) and autumn lasts about 2 months (64 days). The most remarkable long-term changes of the seasons’ characteristics are: (i) the colder winters and warmer autumns during the last decades, (ii) the shortening of winter and spring due to later onset and earlier cessation dates, respectively, and (iii) the extension of autumn and summer due to later cessation and earlier onset dates, respectively.

How to cite: Kotsias, G., Lolis, C., Hatzianastassiou, N., Lionello, P., and Bartzokas, A.: An objective definition of seasons for the Mediterranean region based on synoptic weather types, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7212, https://doi.org/10.5194/egusphere-egu2020-7212, 2020

D3543 |
EGU2020-7889
Dimitra Founda, George Katavoutas, and Fragiskos Pierros

Today, there is a strong scientific consensus that severe weather phenomena and climatic extremes represent an increasing threat in the background of climate change, with profound and unpredictable impacts on the environment, economy and humans.  Heat waves (HWs) in particular, are among the most disastrous phenomena across the globe, imposing significant pressure on human health, with severe heat waves being associated with thousands of excess deaths in the past. Considerable recent research focuses on the study of the main characteristics of HWs (e.g. amplitude, duration or frequency) and their long-term trends, using different approaches and metrics. Such approaches differ with respect to the used climatic index (maximum, minimum, mean air temperature or combination), the use of fixed or dynamic temperature thresholds, the duration and others. The plethora of existing indices in literature and the lack of a universal metric to define HWs is underlined  in most studies.

  This research attempts to investigate how and to what extent are the long-term statistics and trends in HWs characteristics affected by the use of different definitions. The analysis was based on the centennial, uninterrupted records of air temperature of the National Observatory of Athens which constitute a unique material for the study of climatology of HWs in the long-term. Yet, capital cities of the eastern Mediterranean have been assigned as hot spots among other European cities, with respect to future heat-related risk.

The analysis revealed substantial deviations in HWs features among different definitions, as for instance changes in seasonal occurrence of HWs, or an eightfold increase in the number of HWs since the late 19th century, when the six-days minimum duration of HWs was replaced by three-days.

The better understanding of the impact of different HWs indices on their long-term statistics is crucial for better future projections, especially at a vulnerable to heat-related risk area, like the eastern Mediterranean.

 

How to cite: Founda, D., Katavoutas, G., and Pierros, F.: Climatology of heat waves characteristics based on different metrics- Application on a centennial air temperature record of the eastern Mediterranean , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7889, https://doi.org/10.5194/egusphere-egu2020-7889, 2020

D3544 |
EGU2020-8857
Eilat Elbaum, Chaim Garfinkel, Ori Adam, and Efrat Morin

Observations from the past century and projections for the end of this century exhibit a decrease in precipitation over the Eastern Mediterranean Sea and surrounding land areas, but the magnitude of the expected drying is unknown. Changes in precipitation are controlled by both thermodynamic (moist) and dynamic (dry) processes, but the relative contributions of these processes, in particular on regional scales, is not well understood. Previous studies have analyzed the ability of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) multi-model mean to represent the spatial and seasonal patterns of the Mediterranean hydroclimate. A wide spread exists among the individual models, which can be exploited to better understand the factors controlling future climate. Garfinkel et al. (2020)[i] found that large-scale mechanisms contribute about 50% of the model spread in Eastern Mediterranean drying. This study further explores the variance across models in projected changes of the moisture budget by decomposing them into mean dynamic, mean thermodynamic and transient components. These components are then related to the variance across models in projected large-scale processes. Through these analyses, uncertainties regarding future changes in precipitation can be reduced.

[i] Garfinkel, C. I. et al. (2020) ‘The role of zonally averaged climate change in contributing to inter-model spread in CMIP5 predicted local precipitation changes’, Journal of Climate, 33, pp. 1141–1154. doi: 10.1175/JCLI-D-19-0232.1.

How to cite: Elbaum, E., Garfinkel, C., Adam, O., and Morin, E.: Eastern Mediterranean Drying: Projected Changes in Dynamics and Thermodynamics and Their Relation to Large-Scale Processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8857, https://doi.org/10.5194/egusphere-egu2020-8857, 2020

D3545 |
EGU2020-11074
Mirna Matov and Elisaveta Peneva

The Black Sea is a large deep water basin on the border between European and Asian continents lying in the continental mid-latitude climate zone. Due to the prevailing westerlies during the year its climatic influence is better pronounced in the eastern border areas, however the sea is an important climatic factor for all borderline countries (Bulgaria, Romania, Ukraine, Russia, Georgia and Turkey). The open plane in north direction enables the propagation of the Siberian High influence in winter. From the other side, the Mediterranean Sea influence is significant through the Mediterranean cyclones passing frequently the area.

The impact of the Black Sea on the surrounding area is analyzed combining data from several different sources: atmospheric data from climate reanalysis and regular synoptic measurements in coastal meteorological stations, marine observations from in situ autonomous profilers and satellite data on ice coverage in winter time. The aim is to investigate the interannual-to-decadal variability of the thermal regime and the exchange of heat between atmosphere and sea. In addition, the relation to the intensity of the main climate centers of action (Siberian High and Mediterranean Low) is analyzed. The winter severity is defined in the different zones around the sea through the number of cold days and the connection with the sea temperature is studied.

How to cite: Matov, M. and Peneva, E.: Climate feedbacks in the Black Sea region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11074, https://doi.org/10.5194/egusphere-egu2020-11074, 2020

D3546 |
EGU2020-14062
| Highlight
Loredana Antronico, Roberto Coscarelli, Sebastiano D'Amico, Francesco De Pascale, Dante Di Matteo, and Anton Micallef

Coastal areas are particularly sensitive to climate change. Owing to a significant increase in human activities and pressures, these areas have become particularly susceptible to extreme physical phenomena that increase the exposure and vulnerability of population. The Authorities ought to make strong efforts to: i) take the necessary measures and actions to reduce the negative impacts of the natural phenomena on the coastal areas, which are also due to the climate change; ii) investigate the factors that influence the communities’ perception of natural hazards and the climate change. Indeed, in order to effectively manage the negative impacts of climate change both considerable scientific know-how and of people’s perception of the risk associated to them is paramount.

Within this framework, a Research Project funded under the Agreement on Scientific Cooperation between CNR and the University of Malta (UoM) was developed. The Project is organized in order to synergistically combine the various scientific researches of the two partners (CNR-IRPI and University of Malta) in the context of natural hazards, public knowledge and perception of geo-hydrological risk and climate change. Calabria (Southern Italy) and Malta, the two Mediterranean regions considered as target areas for the Project, show different geomorphological and climatic settings but, although with different exposure levels, they are both affected by extreme physical phenomena and climate change.

The goals of the Project are the following: i) identify the population’s awareness, perception and preparation concerning the effects that climate change has on coastal areas through online and face to face questionnaires; ii) assess the social vulnerability and develop a specific Index of Social Vulnerability in relation to natural hazards in the target areas (Calabria and Malta); iii) propose useful tools to local authorities and to responsible of territory planning and of risk prevision, prevention and management; iv) raise awareness among stakeholders and citizens around the issues linked to the effects of climate change on the increased frequency of extreme natural events. In the first half of the Project, a survey based on questionnaire for analysing population’s perception of geo-hydrological risks and climate change was carried out and the obtained results were analysed. At the end of the Project, the results will help to perform a wider and more thorough risk analysis that takes into account the potential increase in exposure and vulnerability of coastal areas population as a result of climate change in the two Mediterranean regions.

How to cite: Antronico, L., Coscarelli, R., D'Amico, S., De Pascale, F., Di Matteo, D., and Micallef, A.: Risk perception and social vulnerability of population in coastal areas subject to climate change in two Mediterranean regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14062, https://doi.org/10.5194/egusphere-egu2020-14062, 2020

D3547 |
EGU2020-15750
| Highlight
Marco Turco, Sonia Jerez, Markus Donat, Andrea Toreti, Sergio M. Vicente-Serrano, and Francisco J. Doblas-Reyes

Accurate and timely information of evolving drought conditions is crucial to take early actions and alleviate their impacts. A number of drought datasets is already available. They cover the last three decades and provide data in near-real time (using different sources), but they are all "deterministic" (i.e. single realisation), and data partly differ between them.  Here we first evaluate the quality of long-term and continuous climate data for timely meteorological drought monitoring considering the Standardized Precipitation Index. Then, by applying an ensemble approach, similarly to weather/climate prediction studies, we develop DROP (DROught Probabilistic; Turco et al. 2020), a new global land gridded dataset to monitor meteorological drought that gathers an ensemble of observation-based datasets providing near-real time estimates with associated uncertainty. This approach makes the most of the available information and brings it to the end-users. DROP, publicly available at https://drop.shinyapps.io/DROP/, is operationally updated every monthly and provides drought information in near-real time, i.e., up to the previous month. The high-quality and probabilistic information provided by DROP is useful for monitoring applications, and may help to develop global policy decisions on adaptation priorities in alleviating drought impacts, especially in countries where meteorological monitoring is still challenging.

 

References

Turco M, Jerez S, Donat M, Toreti M, Vicente-Serrano S M, Doblas-Reyes, F J. (2020). A global probabilistic dataset for monitoring meteorological droughts. Bulletin of the American Meteorological Society. Under review.

 

Acknowledgments

M.T. has received funding from the Spanish Ministry of Science, Innovation and Universities through the project PREDFIRE (RTI2018-099711-J-I00).

 

How to cite: Turco, M., Jerez, S., Donat, M., Toreti, A., Vicente-Serrano, S. M., and Doblas-Reyes, F. J.: DROP: a DROught Probabilistic near-real time monitoring tool , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15750, https://doi.org/10.5194/egusphere-egu2020-15750, 2020

D3548 |
EGU2020-17373
Convulsed western Mediterranean thermohaline circulation during the last glacial-interglacial transition from neodymium isotope ratios
not presented
Jaime Frigola, Leopoldo D. Pena, Albert Català, Jose Noel Pérez-Asensio, Ester Garcia-Solsona, Steve L. Goldstein, Fabrizio Lirer, and Isabel Cacho
D3549 |
EGU2020-17722
Jose Manuel Mesa-Fernández, Francisca Martínez-Ruiz, Marta Rodrigo-Gámiz, and Francisco J. Jiménez-Espejo

The westernmost Mediterranean basins is an exceptional and sensitive region for reconstructing past climate and oceanographic conditions. Geochemical signatures from diverse sediment records in the Alboran Sea and the Balearic basin, in particular, Ti/ca and Fe/Ca ratios, as proxies for the relative abundance of siliciclastic vs. carbonate fraction, have been investigated. These have also been compared with other previously studied records from the western Mediterranean and the Gulf of Cadiz to elucidate the mechanisms triggering the relative variations between the carbonate and siliciclastic fraction. The lithogenic fraction represents around 70% of the sediment in the Alboran basin, which mainly derived from riverine discharge and coastal erosion. Resuspension of fine sediment particles from the slope and the sea floor by bottom-water currents is a relevant process in these basin. The studied records are located between 850 m and 2400 m below the sea level, under the influence of the Western Mediterranean Deep Water (WMDW), which is restricted to a water depth below 500-600 m and to the Moroccan margin. This deep current is formed in the Gulf of Lion, when the superficial and intermediate waters sink by a density increase, and flow out the basin through the Gibraltar Strait, contributing to the Mediterranean Outflow Water (MOW) along with the Levantine Intermediate Water (LIW). The WMDW formation is enhanced during cold and arid periods. The comparison with other previously studied records, support important variations of the mechanisms triggering the relative contribution of carbonate and siliciclastic fractions during the last 20,000 yrs. The, Ti/Ca and Fe/Ca ratios increased during cold and arid periods, such as the Heinrich Event 1 (HE1) and the Younger Dryas (YD). These changes are more prominent in the Balearic basin and the eastern Alboran basin than in the western Alboran basin and the Gulf of Cadiz. Thus, we hypothesized that the increase in the Ti/Ca and Fe/Ca ratios is rather related to the enhanced WMDW production and more remobilization of fine siliciclastic sediments.

How to cite: Mesa-Fernández, J. M., Martínez-Ruiz, F., Rodrigo-Gámiz, M., and Jiménez-Espejo, F. J.: A geochemical approach to reconstructing sediment dynamic and thermohaline circulation in the western Mediterranean over the last deglaciation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17722, https://doi.org/10.5194/egusphere-egu2020-17722, 2020

D3550 |
EGU2020-19285
| Highlight
Serena Marras, Valentina Bacciu, Valentina Mereu, Antonio Trabucco, Sara Masia, Simone Mereu, Josè Maria Costa Saura, Paola Mercogliano, Giuliana Barbato, Veronica Villani, Gianluca Cocco, Giovanni Satta, and Donatella Spano

Mediterranean region is recognized as an hot spot for negative effects due to climate change. The region is already experiencing an increase in frequency and intensity of extreme weather events (i.e. drought conditions, fire, floods, and heat waves) and climate projections indicate a general exacerbation of such phenomena.

This work, performed in the framework of the Sardinia Region Adaptation Strategy to Climate Change and in collaboration with the LIFE Project Master-ADAPT, analyzed the impacts and the vulnerability to climate change in the Sardinia region (Italy) for three sectors: agricultural-forestry sector, the inland water systems, and the hydrogeological component.

The analysis used the innovative approach of developing "Impact Chains” per each sector and analyzed risk. A selection of indicators has been used (at municipality level) as proxy to assess climate hazard (for past and future conditions) and the exposure, sensitivity and adaptation capacity of the Region. This analysis represents the knowledge base required by local administrations for developing adaptation policies to climate change.

Results allowed to better understand climate vulnerability for the territory, and to guide the process of identifying adaptation objectives and options to face climate risk for each sector. Adaptation to climate change is a priority and local administrations need to work towards climate adaptation objectives and policies in order to strengthen climate resilience, reduce negative impacts due to climate change, and enable more effective management opportunities.

How to cite: Marras, S., Bacciu, V., Mereu, V., Trabucco, A., Masia, S., Mereu, S., Costa Saura, J. M., Mercogliano, P., Barbato, G., Villani, V., Cocco, G., Satta, G., and Spano, D.: Climate change vulnerability and impacts assessment in a Mediterranean region for adaptation purposes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19285, https://doi.org/10.5194/egusphere-egu2020-19285, 2020

D3551 |
EGU2020-20044
Alejandro J. López-Avilés, Antonio García-Alix, Gonzalo Jiménez-Moreno, Jaime L. Toney, and R. Scott Anderson

Remote small alpine lakes and wetlands from the Sierra Nevada mountain range (southern Spain) are exceptional ecological sensors of global change and preserve a complete post-glacial Holocene sedimentary record. Several organic and inorganic geochemical analyses carried out in the sedimentary record of the Borreguil de los Lavaderos de la Reina, a small bog located in the north face of the Sierra Nevada at 2421 m, have allowed us to reconstruct climate, vegetation and human interaction in the highest mountain range in southern Iberia in the last 3000 years. This study shows that during the Late Holocene there is a progressive climatic aridification, which produced a reduction in the aquatic environments in Sierra Nevada. The studied peat bog geomorphology and surrounding areas also conditioned the evolution of the local vegetation. An increasing trend in the detrital eolian input from northern Africa, as well as an important anthropic impact in the ecosystems (artificial drainage system among other activities) are observed in the studied record in the last century.

How to cite: López-Avilés, A. J., García-Alix, A., Jiménez-Moreno, G., Toney, J. L., and Anderson, R. S.: A reconstruction of paleoenvironments and climate change during the Late Holocene in Sierra Nevada: the organic and inorganic geochemistry record from the Borreguil de los Lavaderos de la Reina record (southern Iberian Peninsula), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20044, https://doi.org/10.5194/egusphere-egu2020-20044, 2020

D3552 |
EGU2020-20562
| Highlight
Andrea Toreti, Andrej Ceglar, Frank Dentener, Davide Fumagalli, Simona Bassu, Iacopo Cerrani, Stefan Niemeyer, Marian Bratu, and Lorenzo Panarello

Crop yields are influenced and affected by climate conditions and the occurrence of extreme events in critical phenological phases during the growing season. As projected climate change for Europe points to an increase of climate extremes as well as a significant warming together with changes in precipitation regimes, it is essential to assess impacts on key socio-economic sectors such as agriculture. Here, we analyse European wheat and maize yields as projected by a crop model driven by bias-adjusted Euro-CORDEX regional climate model simulations under the RCP4.5 and RCP8.5 scenarios. The main findings highlight as maize will be the most affected crop with limited effects of simple adaptation strategies; while a north-south dipole in the projected changes characterizes wheat yields. In the wheat regions negatively affected by climate change, adaptation strategies will play a key role in counterbalancing the impacts of the projected changes. 

How to cite: Toreti, A., Ceglar, A., Dentener, F., Fumagalli, D., Bassu, S., Cerrani, I., Niemeyer, S., Bratu, M., and Panarello, L.: Climate change impacts on European wheat and maize yields, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20562, https://doi.org/10.5194/egusphere-egu2020-20562, 2020

D3553 |
EGU2020-20609
Simona Bassu, Davide Fumagalli, Andrea Toreti, Andrej Ceglar, Francesco Giunta, Rosella Motzo, and Stefan Niemeyer

Understanding the effects of different combinations of sowing dates and choice of cultivars on maize yield is essential to develop appropriate climate change adaptation strategies. In this study, we explore the maize yield response of two models to changes in sowing dates and cultivars. In particular, we assess whether crop conditions around flowering can explain the variability of irrigated, potential crop yields across sowing dates and cultivars in Mediterranean climatic conditions where high temperatures may change the length of the grain filling period. Then, we investigate these responses under future climate projected conditions till 2060 by using Euro-CORDEX regional climate model simulations.

Main findings show that the approach based on anthesis conditions outperforms the model based on partitioning. This holds both under current and future climate conditions. Finally, both approaches agree on a warmer climate translating into lower yields (13-18%, average reduction with respect to the current climate conditions) than can only be partially offset by changes in phenology and sowing dates.

How to cite: Bassu, S., Fumagalli, D., Toreti, A., Ceglar, A., Giunta, F., Motzo, R., and Niemeyer, S.: Modelling the response of Mediterranean maize yields to projected climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20609, https://doi.org/10.5194/egusphere-egu2020-20609, 2020

D3554 |
EGU2020-366
Clara E Estrela Segrelles and Miguel Ángel Pérez Martín

According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, warming of the climate system is unequivocal and in recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Surface temperature is projected to rise, and rainfall patterns to change. Freshwater resources could be compromised due to climate change, especially in the Mediterranean region. Moreover, extreme events as droughts or floods are expected to occur more frequently.

For all these reasons, we propose the evaluation and implementation of a climate change adaptation river basin plan with the aim of reducing risks and improve resilience. Indeed, one of the goal 13 targets of the Sustainable Development Goals is strengthening resilience and adaptive capacity to climate-related hazards and natural disasters in all countries. The EU Strategy on adaptation to climate change encourage all members to implement adaptation strategies. For instance, climate change adaptation river basin plans are a reality in France, where basin adaptation plans have been published since 2014.

Evaluating risks and propose measures in order to reduce water vulnerability is needed in Jucar river basin (Eastern Spain) where water system is currently stressed. Jucar climate change adaptation basin plan should evaluate the specific qualities the basin has and the risks and vulnerabilities in order to strength water management. For this evaluation, we propose to assess the impact of the spatial distribution of precipitation and temperature within the case study for identifying the most vulnerability areas. Furthermore, the sea level rise will cause affection in groundwater aquifers that should be included on the proposed analysis.

How to cite: Estrela Segrelles, C. E. and Pérez Martín, M. Á.: Proposing an implementation of a climate change adaptation strategy at river basin scale. Application to the Jucar river basin., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-366, https://doi.org/10.5194/egusphere-egu2020-366, 2019

D3555 |
EGU2020-408
Iason Markantonis, Nadia Politi, Diamando Vlachogiannis, Nikolaos Gounaris, Karozis Stylianos, and Sfetsos Athanasios

Renewable energy (RE) is considered as the most attractive and climate friendly source of energy to mitigate GHG effects. Due to the inherent, “non stationary” nature of climate, it is of paramount importance to be able make risk-informed decisions considering also the future conditions when installing / operating RES in Greece. As the amount of solar energy falling on the earth’s surface is highly influenced by local and large scale atmospheric movement conditions, high resolution simulations should be used to calculate it.

The aim of this research is to generate a climatology atlas of mean yearly and seasonal values for the GHI for the “historic time period” 1980-2009 and compare it against future values in 2020-2050. The current study employs high resolution downscaled climate model data to generate future solar radiation atlases for Greece based on RCP4.5 and RCP8.5 scenarios. Greece is a country with high potential in renewable solar energy. Several studies have mentioned the high amount of sunshine hours in most parts of the country, (e.g. Matzarakis & Katsoulis, 20061, HNMS2).

The data for both historic and future period analyses are produced from WRF 5km downscaled model output with temporal resolution of 6 hours, using as input ERA-INTERIM and EC-EARTH input data, respectively. The study that has produced the atmospheric model dataset is described in Politi, et al. (2018)3. We explore spatio-temporal changes of the GHI climatology and identify those areas which will exhibit considerable changes in the future.

References:

  1. (Matzarakis & Katsoulis, 2006), ‘Sunshine duration hours over the Greek region’. Theoritical and Applied Climatology.
  2. HNMS, ‘Greece Climate Atlas’. http://climatlas.hnms.gr/sdi/
  3. (Politi, N. et al. 2018) ‘Evaluation of the AWR-WRF model configuration at high resolution over the domain of Greece’. Atmospheric Research Volume 208, 1 August 2018, Pages 229-245.

Acknowledgments
This work was supported by computational time granted from the Greek Research & Technology Network (GRNET) in the National HPC facility – ARIS - under project ID HRCOG (pr004020).

How to cite: Markantonis, I., Politi, N., Vlachogiannis, D., Gounaris, N., Stylianos, K., and Athanasios, S.: High resolution solar atlas for Greece under climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-408, https://doi.org/10.5194/egusphere-egu2020-408, 2019

D3556 |
EGU2020-13837
George Zittis, Adriana Bruggeman, Panos Hadjinicolaou, and Jos Lelieveld

The broader region of the eastern Mediterranean is a well-known climate change hot-spot. The combined warming and drying of the region’s mean climatic conditions have already been identified by a number of observation and modeled-based studies. Nevertheless, the future evolution of rainfall extremes has not been extensively assessed. Such events can cause severe flooding, damages to infrastructure and human casualties. In the present contribution, we use the output of a regional climate simulation in order to explore changes in the magnitude of such events. The WRF limited area model is used to dynamically downscale the bias-adjusted output of the global CESM1 model in a horizontal resolution of 12-km for the 1981-2100 period. In terms of greenhouse gas emissions and concentrations, a “business-as-usual” scenario (RCP8.5) was considered. Trends of the annual values of maximum daily rainfall are explored by using the non-parametric Sen’s Slope Estimator while the significance of these trends is assessed by applying the Mann-Kendall trend test. Preliminary analysis indicates negative trends for most of the region, with the exception of northern Turkey and parts of the Balkans. Despite these negative trends, the absolute magnitude of the most extreme events is projected to increase in the majority of the grid cells. Results are compared with gridded observations and model output from the EURO-CORDEX database.    

How to cite: Zittis, G., Bruggeman, A., Hadjinicolaou, P., and Lelieveld, J.: Future trends of precipitation extremes in the eastern Mediterranean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13837, https://doi.org/10.5194/egusphere-egu2020-13837, 2020

D3557 |
EGU2020-15769
Athanasios Ntoumos, Panos Hadjinicolaou, Georgios Zittis, and Jos Lelieveld

We assess observed and modeled temperature extremes over the MENA region during the last four decades. The purpose of our analysis is two-fold: I) provide an up-to-date, observationally based estimation of recent past evolution and ii) evaluate the performance of global climate model simulations. A list of indices of temperature extremes, based on threshold, percentile, heatwave and coldwave characteristics is used, as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). We derive the indices. We use daily near-surface air (2-metre) temperature (Tmax and Tmin) to derive the extremes indices for the period 1980-2018 from: 1) re-analyses (ERA-Interim, MERRA2) and gridded observational data (Berkeley) and ii) 18 CMIP5 model runs combining historical (1950-2005) and scenario runs (2006-2018 under RCP 2.6, RCP4.5 and RCP8.5). Using these reanalyses, observational and CMIP5 multimodel ensemble data-sets we derived their statistics (climatological average, trends) and produced maps for the MENA region. In addition, the CMPI5 indices were compared with the indices derived from the observational and reanalyses and their biases were revealed through spatial (maps) and temporal (time-series) comparison. It is found, as expected, that the choice of the RCP does not make any difference in the calculations up to 2018 but nevertheless the use of the three “scenarios” provides a better model sample for the evaluation against observations. Finally, the best performing global model realizations for the temperature extremes are revealed by the comparison of individual models with the re-analyses and observational data.

How to cite: Ntoumos, A., Hadjinicolaou, P., Zittis, G., and Lelieveld, J.: An up-to-date assessment of temperature extremes over the MENA region from observational and CIMP5 data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15769, https://doi.org/10.5194/egusphere-egu2020-15769, 2020

D3558 |
EGU2020-17688
Vincent Coussin, Aurelie Penaud, Nathalie Combourieu-Nebout, Odile Peyron, Yannick Miras, Marie-Alexandrine Sicre, Nathalie Babonneau, and Antonio Cattaneo

Past and present oceanographic and climatic conditions along the Algerian coast involve complex mechanisms. Atlantic Ocean surface waters enter the Mediterranean Sea by the Gibraltar strait and become the Algerian current flowing along the North African coast forming a succession of eddies. Deep-water upwelling plumes is another recurrent feature of the ocean circulation along the Algerian margin. Past vegetation changes and the role of paleohydrological changes have been poorly described in this region. This work combines palynological (pollen and dinoflagellate cysts) and biomarker data to assess changing environmental and climatic conditions over the past 14 ka BP (late glacial and Holocene) acquired from the marine core MD04-2801 (Algerian coast, 2067 m water depth, Prisma cruise).

A total of 79 samples have been analyzed over the last 14 000 years BP. Palynological and organic biomarker proxy data were used to investigate the links between past sea surface temperature (SSTs) and hydrological changes on the observed regional environmental changes documented at centennial timescale resolution. Our data indicate (i) recurrent upwelling cells during relatively dry climatic conditions of the Younger Dryas (12.7 to 11.7 ka BP), the Early Holocene (11.7 to 8.2 ka BP) and from 6 ka BP onwards, (ii) an increase of fluvial discharges between 8.2 and 6 ka BP during the African Humid Period, and the concomitant colonization of coastlands by the Mediterranean forest. The comparison between our results and other western Mediterranean palynological records underlines the singularity of our results along the Algerian margin in terms of dinocyst assemblages and notably the over-representation of heterotrophic taxa. Palynological data shows direct links between continental dryness and marine hydrological conditions. Finally, we applied the Modern Analogue Technique to our pollen assemblages along the core in order to reconstruct seasonal and annual precipitations and temperatures and compare our local climatic patterns to regional climate signals at basin scale for the Holocene period.

How to cite: Coussin, V., Penaud, A., Combourieu-Nebout, N., Peyron, O., Miras, Y., Sicre, M.-A., Babonneau, N., and Cattaneo, A.: Holocene Paleoenvironments in the Western Mediterranean Sea: palynological evidences on the Algerian coast and climatic reconstructions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17688, https://doi.org/10.5194/egusphere-egu2020-17688, 2020

D3559 |
EGU2020-20182
Bassam Ghaleb, Claude Hillaire-Marcel, Mehmet Ozkul, and Feride Kulali

The dating of travertine deposition and groundwater / hydrothermal seepages in relation to late Holocene climatic changes can be achieved using short-lived isotopes of the 238U decay series, as illustrated by the present study of the Pamukkale travertine system, at the northern edge of the Denizli and Baklan graben merging area (see Özkul et al., 2013; https://doi.org/10.1016/j.sedgeo.2013.05.018. The strongly lithified self-built channels and modern pools where analysed for their 238U, 234U, 230Th, 226Ra, 210Pb and 210Po contents, whereas 238U, 234U and 226Ra were measured in modern hydrothermal waters. When corrected for detrital contamination, 230Th-ages of travertine samples range from 1215±80 years, in the oldest self-built hydrothermal channels, to the Present (modern pool carbonate deposits) thus pointing to the inception of the existing huge travertine depositional systems during the very late Holocene, probably following the major Laodikeia earthquate of the early 7th century (cf. Kumsar et al., 2016; DOI 10.1007/s10064-015-0791-0). So far, the available data suggest three major growth phases of the travertine system: an early phase (7th to 8th centuries CE), an intermediate phase (~ 14th century CE) and a modern one, less than one century old. A more detailed survey of the travertine system would be needed to strengthen these age clusters, however, worth of mention is the fact they they broadly fit with the timing of humid episodes as reconstructed from a southern Turkey paleolake study (Jones et al., 2006; doi: 10.1130/G22407.1). Despite nearly identical 234U/238U activities in modern waters and travertines (1.132±0.006), the latter show decreasing 226Ra concentrations through time, from ~ 0.2 dpm/g in the oldest shelf-built channels to ~ 0.07 dpm/g in present day pool carbonates, thus pointing to a significant decrease in the hydrothermal activity since the inception of the travertine complex, and raising concerns about the response of the Pamukkale hydrothermal system to the present climatic trend. Indeed, the predicted decrease in precipitation of up to 30% in the forthcoming decades (Lelieveld et al., 2012; DOI 10.1007/s10584-012-0418-4) is likely to result in a lesser meteoritic water recharge of the aquifer system feeding the springs (Dilsiz, 2006; DOI 10.1007/s10040-005-0001-4).

How to cite: Ghaleb, B., Hillaire-Marcel, C., Ozkul, M., and Kulali, F.: Decreasing hydrothermalism at Pamukkale- Hierapolis (Anatolia) since the 7th century, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20182, https://doi.org/10.5194/egusphere-egu2020-20182, 2020

D3560 |
EGU2020-21402
Mary Robles, Odile Peyron, Guillemette Ménot, Elisabetta Brugiapaglia, Vincent Ollivier, Petros Tozalakyan, Khachatur Meliksetian, Lilit Sahakyan, and Sébastien Joannin

Armenia is located in the Caucasus Mountains and today, its vegetation is largely dominated by steppes closely linked with human practices. Armenian human history roots back to the Neolithic period, which questions long human influences on steppe and therefore climate reconstructions from vegetation data. Moreover, vegetation records from this region are often low resolution and do not cover the entire Holocene. Pollen-based climate reconstruction coupled to independent climate reconstructions appear necessary to fully understand climate forcing in the region during the Holocene. In this study, we introduce high-resolution pollen, geochemical analyses and temperature reconstruction based on pollen and branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Vanevan peat in Armenia. The wetland studied show major ecological changes observed through aquatic vegetation and sediment composition (XRF data). At the beginning of the Holocene, the study site is expected to be integrated in a larger Lake Sevan, then it became an independent lake and finally a peatland at 5700 cal BP. A drying phase is also attested around 4.2 kyrs, probably corresponding to the 4.2 ka climate event. Along the sequence, the vegetation is characterized by steppes dominated by Poaceae, Artemisia and Chenopodiaceae. However, forests composed of Quercus, Betula, Carpinus betulus and Ulmus, are more developed on slopes between 7600 cal BP and 5500 cal BP. Agriculture is observed since 5700 cal BP and correlates with occupation periods reported in archeological studies. Over this 10000 yrs-long record, we suppose that differences in response of wetland and vegetation to climate might be linked to ecological processes and human influence. The comparison between pollen-based climate reconstruction and temperature obtained with brGDGT calibrations promisingly illustrate these differences. Finally, we contextualize these results with other regional records to understand the impact of climate change on steppe vegetation in the Caucasus at a larger scale.

How to cite: Robles, M., Peyron, O., Ménot, G., Brugiapaglia, E., Ollivier, V., Tozalakyan, P., Meliksetian, K., Sahakyan, L., and Joannin, S.: Impact of climate change on steppe environments around Lake Sevan in Armenia during the Holocene, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21402, https://doi.org/10.5194/egusphere-egu2020-21402, 2020

D3561 |
EGU2020-22217
Investigation of the Climate Change Effects on the Mediterranean Region with the Hypothetical inclusion of the Istanbul Isthmus
(withdrawn)
Elcin Tan
D3562 |
EGU2020-22359
Mehdi Saqalli, Marianne Cahierre, Odile Peyron, Julien Azuara, Nathalie Combourieu-Nebout, Marie-Alexandrine Sicre, and Laurent Lespez

Formalizing the connections existing between socio-ecosystem components implies establishing the dynamical links between both societies and vegetation cover types along time and space. In order to synthesize knowledge of Mediterranean paleo-environments and populations, the MISTRALS PaleoMex program aims at developing a step by step multidisciplinary and spatialized model of the climate, vegetation and human implantations in the Mediterranean seashores of Occitania Province (France) during the Neolithic Eras. The first step is to reconstruct the vegetation covers in the absence of humans. For this, 95 tree and bush species known to have grown in the region in Neolithic times are considered, which combining present-time species, historical data and pollen sequences. These species are then grouped in Plant Functional Types (PFTs) according to their tolerance to three factors: the mean annual temperature, the pH and the soil water balance. Two clustering methods were first tested: HCA (Hierarchical Clustering Analysis) and k-means based on the species’ tolerance interval for each factors. The resulting PFTs were well-defined enough to statistically explain the total ecological variance but were misleading botanically speaking, by failing in identifying clearly well-known PFTs such as the pioneer groups. A third method was thus assessed based on group species’ overlap of their tolerance intervals. Only 80% of the total variance was explained but the resulting 8 PFTs are more representative of natural species associations including a well-identified pioneer species PFT. Further investigations may be pursued to reach a total of 11 PFT groups in order to explain 95% of the total local variance. This PFT stock will be assessed using a virtual spatialized cellular automaton model with a 1ha spatial resolution and seasonal timescale. Elevation, pedology and dynamic climatology for each season and hectare will allow deciphering the spatial and dynamic evolution of the vegetation cover as a localized repartition of these PFTs.

How to cite: Saqalli, M., Cahierre, M., Peyron, O., Azuara, J., Combourieu-Nebout, N., Sicre, M.-A., and Lespez, L.: Classification of ligneous vegetation into Plant Functional Types for a dynamic reconstitution of Neolithic vegetation cover in Occitania Mediterranean seashores, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22359, https://doi.org/10.5194/egusphere-egu2020-22359, 2020