CL4.30

EDI
Climate change in the Mediterranean region: understanding the processes, assessing the impacts and designing adaptation

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.

Convener: Andrea Toreti | Co-conveners: Ana BastosECSECS, Piero Lionello, Andreia RibeiroECSECS
vPICO presentations
| Mon, 26 Apr, 15:30–17:00 (CEST)

vPICO presentations: Mon, 26 Apr

Chairpersons: Andrea Toreti, Ana Bastos, Andreia Ribeiro
15:30–15:35
15:35–15:45
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EGU21-6428
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ECS
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solicited
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Highlight
Tarek EI-Madany, Arnaud Carrara, Gerardo Moreno, M. Pilar Martin, Javier Pacheco-Labrador, Ulrich Weber, Sebastian Sippel, Miguel Mahecha, Markus Reichstein, and Mirco Migliavacca

Mediterranean ecosystems and their different vegetation types are adapted to the annual cycle between wet and cool winter periods and dry and hot summers. Within this cycle, productivity is strongly driven by water availability but also temperature. With climate change, the Mediterranean area, and especially the Iberian Peninsula is expected to receive less precipitation. Future projections of temperature distributions of the Iberian Peninsula predict shifts toward a higher mean (+2 °C) and maximum (+4 °C) temperature. As a result, an increase in drought frequency and duration can be assumed. The response of the vegetation, especially with respect to the different components of the carbon cycle [net ecosystem exchange (NEE) and its components gross primary productivity (GPP) and ecosystem respiration (Reco)] and plant stress are still not well understood for these ecosystems. One of the biggest unknowns is the impact of the timing of temperature and precipitation anomalies on the carbon balances of these ecosystems.

We present results from different studies focusing on the Iberian Peninsula showing the importance of the timing of temperature and water availability anomalies and how they influence the carbon balance of those ecosystems. While the impact of a strong compound heat and drought event during the summer period had only a very small impact on the carbon balance of the ecosystem a positive temperature anomaly during the winter period of 2015/16 caused a strong increase in ecosystem productivity. The differences in the ecosystem responses are a result of the different ecosystem conditions and limitations. During summer the analyzed ecosystems are already under conditions of strong water limitation and reduced ecosystem productivity (senesced grass layer and stressed trees) and thus the response to the compound event was low. While during winter, large parts of the Iberian Peninsula are temperature limited, and increased temperatures relieved this limitation and increased LAI i.e. fraction of absorbed photosynthetic active radiation. On the other hand, the timing of precipitation, that controls the water availability in the soil during the spring and autumn periods have a large impact on the annual carbon balance of these ecosystems as they can reduce or increase the growing season length, and thus the carbon sequestration of these ecosystems. A recent study indicates that the impact of warm winters is not only increasing GPP but also Reco with important memory effects (i.e. increase of Reco later in the season). As a result, winter warming might lead to increased carbon uptake during winter but leads to a reduction in net carbon uptake for the whole year. Given the predictions of warming winters in the Mediterranean areas, this might cause more implications for the carbon balance as compared to summer heatwaves and droughts.

How to cite: EI-Madany, T., Carrara, A., Moreno, G., Martin, M. P., Pacheco-Labrador, J., Weber, U., Sippel, S., Mahecha, M., Reichstein, M., and Migliavacca, M.: Timing matters – the importance of “when” droughts and temperature anomalies occur in the Iberian Peninsula, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6428, https://doi.org/10.5194/egusphere-egu21-6428, 2021.

15:45–15:47
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EGU21-725
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Highlight
Joel Guiot, Nicolas Bernigaud, Alberte Bondeau, and Laurent Bouby

Using a statistical emulator of a coupled climate-ecosystem model, this paper proposes a method to link the vine potential productivity and the viticulture extension in the Mediterranean area to global climate drivers, such as orbital parameters, solar and volcan activities and greenhouse gas concentrations. The emulator was calibrated on several tens of simulations of earth system models in various situations from the PMIP3 past (Last Glacial Maximum, Mid-Holocene, last millennium) and the CMIP5 future simulation up to 2100 under several RCP scenarios. The key climate variables produced by these simulations were introduced in an ecosystem model (BIOME4), so the ecosystem variables can be directly estimated from the global drivers. The large variation of situations used for calibration produces a robust emulator able to extrapolate to a large range of past and future climate states. Applied to the Mediterranean and European area, the emulator has been validated on several key periods of the past where the climate is known to have much changed. Finally, it was used to simulate the viticulture extension not only for these key past periods but also for different scenarios of the future, related to a global warming of 1.5°C, 2°C, 3°C and 5°C. Even if human groups are mainly responsible of viticulture extension, climate is a driver in the way that bad climate conditions may be a limit to extension or even a driver of regression.

The main findings are: (i) If the climate change projected for the future can be attributed to greenhouse gases increase as expected, the variations of the last millennia in the Mediterranean Basin can be attributed to the volcanic activity, the solar activity effect being negligeable; (ii) the effects of these volcanic forcing on the climate are not necessarily uniform across the basin and had a large impact on the viticulture as they were sufficiently important to be responsible of extension of viticulture on the whole Gaul during the Roman Climate Optimum; (iii) for the future, it is projected large difficulties for viticulture in Spain and North Africa. They will be particular important for a global warming of +3°C and more; (iv) there is little hope that an intense volcanic activity could slow down this regression.

How to cite: Guiot, J., Bernigaud, N., Bondeau, A., and Bouby, L.: The Mediterranean viticulture in response to global climate change drivers, the lesson of the past, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-725, https://doi.org/10.5194/egusphere-egu21-725, 2021.

15:47–15:49
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EGU21-1104
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ECS
Emilia Lamonaca and Fabio Gaetano Santeramo

Climate change has the potential to impact the agricultural sector. The impacts of climate change are likely to differ across producing regions of agricultural produce. Future climate scenarios may push some regions into climatic regimes favourable to agricultural production, with potential changes in areas planted with typical Mediterranean products. We examine which is the linkage between climate change and productivity levels in the selected agricultural sectors. Within the framework of agricultural supply response, we assume that acreage and yield are a function of climate change. We find that yield is affected by changes in temperatures and precipitations, with heterogeneous impacts. Acreage is also affected. The impacts vary across Mediterranean Regions, due to different specialisation and to the heterogeneity in climate between them.

How to cite: Lamonaca, E. and Santeramo, F. G.: Climate changes and Dynamics of the Agricultural Productions in the Mediterranean Region, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1104, https://doi.org/10.5194/egusphere-egu21-1104, 2021.

15:49–15:51
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EGU21-4763
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ECS
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Highlight
Virgílio A. Bento, Andreia F.S. Ribeiro, Ana Russo, Célia M. Gouveia, Rita M. Cardoso, and Pedro M.M. Soares

World food and drink production largely depends on wheat and barley crops, which are the basis of nutrition for both humans and animals. The Iberian Peninsula (IP), and particularly Spain, is responsible for a large percentage of farming areas dedicated to these two crops. Furthermore, the IP is known as a prominent climate change hot spot, with expected rising temperatures and a decrease in mean precipitation (with more extreme events). Thus, it is vital to understand the effects of climate change in wheat and barley yields in the IP.

Multiple linear regression (MLR) models were developed based on the relation between temperature and precipitation and both crop yields, with the aim of projecting these into the future. Three main objectives were pursued: (1) to establish the existence of a relationship between wheat and barley yields and temperature and precipitation, taking advantage of data from the EURO-CORDEX regional climate models (RCMs) forced with ERA-Interim; (2) to calibrate and validate MLR models using a selection of predictors from the same EURO-CORDEX RCMs; and (3) to apply these MLR models to EURO-CORDEX RCMs forced with global climate models (GCMs) for an historical period (1971-2000) and two future periods (2041-2070 and 2071-2100) according to two greenhouse gas emission scenarios (RCP4.5 and RCP8.5). Results show a dichotomic behaviour of wheat and barley future yields depending on the crop’s production region. Projections for the southern cluster of the IP show severe yield losses for both cereals, which may be a consequence of the increase in maximum temperatures in spring, particularly for RCP8.5 at the end of the 21st century. Conversely, projections for the northern cluster of the IP show an increase in yield output, which may be a result of the projected warming taking place within the early winter months.

This study reinforces the worth to implementing changes in the society to mitigate losses and to assess production gains/losses due to climate change. These may be implemented locally (different cultivar species), countrywide (implementing sustainable policies), or even globally (alleviate greenhouse gas emissions). This work was supported by project IMPECAF (PTDC/CTA-CLI/28902/2017), LEADING (PTDC/CTA-MET/28914/2017) and by IDL (UIDB/50019/2020).

How to cite: Bento, V. A., Ribeiro, A. F. S., Russo, A., Gouveia, C. M., Cardoso, R. M., and Soares, P. M. M.: The impact of climate change in wheat and barley yields in the Iberian Peninsula, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4763, https://doi.org/10.5194/egusphere-egu21-4763, 2021.

15:51–15:53
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EGU21-13120
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Highlight
Andrej Ceglar, Andrea Toreti, Matteo Zampieri, and Conxita Royo

Durum wheat (Triticum durum Desf.) is a minor cereal crop of key importance for making pasta, couscous, puddings, bread, and many other traditional foods, due to its physical and chemical characteristics. Durum wheat currently represents around 8% of the total wheat crop production, with the main cultivation region being concentrated in few suitable areas such as the Mediterranean Basin, the North American Great Plains, and the former USSR. The global demand for high-quality food made of durum wheat has been increasing, which poses a challenge in the face of climate change. The major share of durum wheat production is currently located in semi-arid climates, where the risk of climate extremes such as drought and heat stress will likely substantially increase in the future. 

We develop a global climate suitability model for durum wheat growth based on Support Vector Machines. We use CMIP6 data to assess the impact of climate change on future suitability for growing durum wheat globally. The total share of global arable land, climatically suitable for growing rainfed durum wheat, currently represents roughly 13% of the global arable land. However, climate change may decrease this suitable area of 19% by mid-century and of 48% by the end of the century, considering also the gain of suitable land areas, where durum wheat is not cultivated today. This net loss of suitable areas requires the development and the future adoption of effective and sustainable strategies to stabilize production and adapt the entire food supply chain.

How to cite: Ceglar, A., Toreti, A., Zampieri, M., and Royo, C.: Loss of climatic suitability for durum wheat production, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13120, https://doi.org/10.5194/egusphere-egu21-13120, 2021.

15:53–15:55
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EGU21-5579
Tim van der Schriek, Gianna Kitsara, Konstantinos V. Varotsos, and Christos Giannakopoulos

The Aegean region (Greece) preserves a wide genetic diversity amongst the honey bees (Apis mellifera L.) of its many islands and supports an important bee keeping industry. However, sector-specific regional impact studies, based on the latest high-resolution regional climate models (RCMs), are urgently required for developing successful local adaptation strategies for beekeeping and to preserve biodiversity under future climate change scenarios.

We evaluated direct climate change impacts on honey bees in the Aegean region through novel threshold temperature and precipitation indices, linked to critical bee behavior and colony mortality. There are strong relationships between ambient temperature and key bee colony behavior such as, for example, nest thermo-humidity regulation, annual population variability and foraging. Additionally, dry conditions and heatwaves have been empirically linked to declines in colony food stores and increased colony mortality rates. Impact projections used simulated temperature and precipitation data from an ensemble of seven RCMs under the medium (RCP4.5) and high (RCP8.5) emission scenarios for the control- (1971-2000), near future- (2031-2060) and distant future (2071-2100) periods. Simulated data were bias-adjusted using the long-term meteorological record of Naxos Island (central Aegean).

Overheating in summer constitutes a major challenge to nest temperature regulation. Thermal and humidity conditions are well-regulated in bee nests given their importance for colony health. Brood must remain at 33-36 oC and experience high relative humidity for proper development. Bees tend to start cooling nests when ambient temperatures are >25 oC. Evaporative cooling using water is of critical importance with temperatures above 35 oC and is remarkably effective in stabilising nest temperature at 36 oC, even as ambient temperatures are >60 oC. Thermoregulation is highly demanding, and brood is mainly reared during optimum periods with no/low need of regulation. Sustained high temperatures >40-45 oC cause significant colony losses. The highest foraging activity takes place in the temperature range from 12-25 oC, whereas there is no activity <7 oC and >43 oC. Winter colony mortality rates increase when the spring flowering period experiences very low rainfall and extreme temperatures.

Future climatic change projections show significant increases in seasonal temperatures and days without precipitation, which will negatively affect the region’s bees. More frequent and severe heat-extremes will characterize seasons from spring to autumn, forcing bee colonies to cool their nests more intensively. Meanwhile, the availability of water and nectar (used for evaporative cooling) will decrease during extreme warm-dry events. The increase in heat extremes will likely lead to increased colony losses. Temperatures within the range for optimal foraging activity are less likely to occur during the flowering period. Finally, years with spring seasons characterized by very low rainfall and extreme temperatures will become more frequent in the future which may result in increased winter mortality rates.

How to cite: van der Schriek, T., Kitsara, G., Varotsos, K. V., and Giannakopoulos, C.: The impact of temperature and precipitation changes on honey bees (Apis mellifera) in the Aegean region under future climate scenarios, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5579, https://doi.org/10.5194/egusphere-egu21-5579, 2021.

15:55–15:57
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EGU21-1709
Shlomit Paz

The Mediterranean Basin is undergoing a warming trend with longer and warmer summers, an increase in the frequency and the severity of heat waves, changes in precipitation patterns and a reduction in rainfall amounts. This populated region is characterized by significant gaps in the socio-economic levels, parallel with population growth and migration, increased water demand and forest fires risk. Consequently, the vulnerability of the Mediterranean population to human health risks increases significantly as a result of climate change.

Climatic changes impact the health of the Mediterranean population directly through extreme heat, drought or storms, or indirectly by changes in water availability, food provision and quality, air pollution and other stressors. The main health effects are related to extreme weather events, changes in the distribution of climate-sensitive diseases (such as West Nile virus, chikungunya and zika) and changes in environmental and social conditions. The poorer countries, particularly in North Africa and the Levant, are at highest risk. Climate change affects the vulnerable sectors of the region, including an increasingly older population, with a larger percentage of those with chronic diseases, as well as poor people and migrants, which are therefore more susceptible to the effects of extreme temperatures. For those populations, a better surveillance and control systems are especially needed parallel with adaptation plans that become ever more imperative. In order to achieve these goals, it is essential to define indicators of vulnerability and exposure based on health impact assessment, as well as indicators that will promote adaptation planning and resilience for health risk management. In view of the climatic projections and the vulnerability of Mediterranean countries, such indicators will contribute to correct preparedness at the regional and national levels.

How to cite: Paz, S.: Impacts of climatic changes on the Mediterranean population: public health aspects, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1709, https://doi.org/10.5194/egusphere-egu21-1709, 2021.

15:57–15:59
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EGU21-1946
George Katavoutas, Dimitra Founda, Gianna Kitsara, and Christos Giannakopoulos

To date, climate change has caused serious problems both in human societies and in various ecosystems. Worldwide, the observed climate change hazards include increased droughts and floods, extreme heat waves, sea-level rise, storms and changes in natural land cover. Tourism, as an important pillar of the economy, is expected to be further affected until the end of the century by climate change hazards. An important factor in the selection of a tourist destination is the climatic conditions of the location.

This research aims to investigate the observed and projected heat stress conditions in a top world tourist destination, the island of Santorini, in Greece. The Mediterranean has been identified as a vulnerable region regarding the heat related risk. Simulations by Regional Climate Models downscaled over the island of Santorini were performed for the 1982–2005 control period, the near future period 2035–2058 and the distant future period 2075–2098. The data for the future simulations are under the RCP4.5 and RCP8.5 future emissions scenarios. Thermal stress conditions were evaluated employing the Universal Thermal Climate Index (UTCI), which has a thermo-physiological basis and derived from the heat exchange theory between the thermal environment and the human body.

The analysis reveals that the thermal conditions in Santorini that cause moderate heat stress and strong heat stress are expected to increase in both RCPs scenarios in near and distant future. In particular, the exposure time under at least strong heat stress reaches 1.8% in the control period (1982–2005), increasing to 5.3% in the near future (2035–2058) and to 7.8% in the distant future (2075–2098) under the RCP4.5 scenario. In the distant future (2075–2098), under the RCP8.5 scenario, the exposure time under these conditions will exceed 12%.

The increasing heat related risk in one of the most popular tourist destinations in the world could be a wake-up call to the policy makers urging them to take prevention measures.

How to cite: Katavoutas, G., Founda, D., Kitsara, G., and Giannakopoulos, C.: Climate change impacts on thermal comfort in one of the most popular tourist destinations in the world, Santorini Island, Greece, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1946, https://doi.org/10.5194/egusphere-egu21-1946, 2021.

15:59–16:01
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EGU21-10195
Manfred A. Lange

The environmental conditions in urban settings are subject to processes and conditions within cities, on the one hand, and have a strong bearing on the overall conditions and the quality of life of the cities’ inhabitants, on the other. The built environment, in general, and buildings and infrastructure, in particular, play a major role in shaping the urban environment. At the same time, environmental conditions affect strongly the conditions within and outside of buildings.

The continued growth of cities in the Eastern Mediterranean and Middle Eastern (EMME) region, the demise of environmental quality adds to the challenges faced by their inhabitants. Of the many factors contributing to these threats, climate change and its amplification in urban structures, the increasing load of pollutants in air and water and the rising numbers of dust storms as well as the growing amount of solid and liquid waste stand out.

The significant increase in the number of cars and the rising quantity of energy production has contributed to ever-worsening air quality in EMME cities. More specifically, urban road transport represents one of the major sources of air-borne pollutants in many of these cities and causes substantial threats to the health of their inhabitants.

The Middle East and North Africa (MENA) and the EMME region are major sources of desert dust storms that travel north and east to Europe and Asia, thereby strongly affecting cities and their air quality in the EMME. Dust storms and suspended bacteria and viruses pose serious consequences to communities in the EMME region and are likely to worsen due to ongoing climate change.

Present and future changes in climate conditions will have numerous adverse effects on the EMME region, in general, and on EMME cities, in particular. This includes extended heat waves as well as enhanced water scarcity for inhabitants and green spaces. In combination with poor air quality, this will cause severe health risks for urban populations as well as the need for increased and extended periods of space cooling in private, commercial and municipal buildings. The greater needs for water and energy in urban structures are interrelated and have been described by the Water-Energy Nexus. The higher demand for water is increasingly satisfied through desalination, which is particularly energy-intensive. The need for additional space cooling during hot spells in cities will require more electricity.

The high rate of population growth, ever-increasing urbanization, changes in lifestyles and economic expansion in the EMME countries result in steadily increasing volumes of solid and liquid waste. The waste problems are exacerbated by the rising number of displaced persons and refugees in growing camps in some of the EMME countries, particularly, in Turkey, Jordan and Lebanon. The huge quantity of daily produced sewage sludge in Middle Eastern countries presents a serious challenge due to its high treatment costs and risks to the environment and human health.

This paper will address some of these challenges, which call for holistic and interdisciplinary efforts to design effective and sustainable adaptation strategies in EMME cities.

How to cite: Lange, M. A.: Current Threats to the Environmental Conditions in Cities of the Eastern Mediterranean, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10195, https://doi.org/10.5194/egusphere-egu21-10195, 2021.

16:01–16:03
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EGU21-3843
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ECS
burcu boza, yasemin ezber, and ömer l. şen

Turkey is a part of Eastern Mediterranean and located between 36-42° North latitudes and 26-45° East longitudes, where Europe meets Asia. The country, which mostly comprises the Anatolian Peninsula, is unique in terms of geographical position and topography and occupies a region which is highly sensitive to climate change. Considering that the region is prone to drying as a result of climate change, inferences about future precipitation patterns is of value.

Studies conducted by cosmogenic surface dating of boulder moraines revealed that, during Last Glacial Maximum (LGM; 21 Ka), the precipitation at the southwest of Anatolian Peninsula was higher than today, and at the northeast it was lower than today, which implies a regional heterogeneity. On the other hand, future projections of precipitation point out reverse conditions. That is, there will be lower (higher) than today precipitation at the southwest (northeast) of the country. Namely, a seesaw of precipitation variability prevails between cold climate of LGM and warm climate of future.

As a highland located at mid-latitudes, Anatolian Peninsula takes most of the precipitation during winter. What mainly drives the changes in winter precipitation is the changes in atmospheric circulation. Model simulations reveal a southward and northward displacement of polar jet stream and consistent shifts of storm tracks during LGM and in the future respectively. Knowing this fact, we investigated directions of winds which carry precipitation into Anatolian Peninsula, for the sake of explaining the dominant regional mechanism related to abovementioned seesaw pattern of precipitation.

We utilized monthly 850 hPa wind and precipitation data from the outputs of CCSM4.0 model of CMIP5 project and analyzed winds for past (LGM), present time and future conditions. Considering that it produces opposite conditions with comparable magnitudes with LGM, we used the RCP8.5 scenario. We found out that the 850 hPa winds entering from west into the peninsula are becoming more zonal (less tilted) as time passes from LGM to future. In other words, southwesterly winds evolve into westerly ones with a slight clockwise change of wind direction. This change considered together with orography of the peninsula explains the seesaw of precipitation variability over Anatolian Peninsula between cold and warm phases of global climate.

How to cite: boza, B., ezber, Y., and şen, Ö. l.: Seesaw of Precipitation Variability over Anatolian Peninsula between LGM and Future Projections: A Possible Role of Wind Direction Change, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3843, https://doi.org/10.5194/egusphere-egu21-3843, 2021.

16:03–16:05
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EGU21-6358
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ECS
Cristina Vegas Cañas, J. Fidel González Rouco, Jorge Navarro Montesinos, Elena García Bustamante, Etor E. Lucio Eceiza, Félix García Pereira, Ernesto Rodríguez Camino, Andrés Chazarra Bernabé, and Inés Álvarez Arévalo

This work provides a first assessment of temperature variability from interannual to multidecadal timescales in Sierra de Guadarrama, located in central Spain, from observations and regional climate model (RCM) simulations. Observational data are provided by the Guadarrama Monitoring Network (GuMNet; www.ucm.es/gumnet) at higher altitudes, up to 2225 masl, and by the Spanish Meteorological Agency (AEMet) at lower sites. An experiment at high horizontal resolution of 1 km using the Weather Research and Forecasting (WRF) RCM, feeding from ERA Interim inputs, is used. Through model-data comparison, it is shown that the simulations are annually and seasonally highly representative of the observations, although there is a tendency in the model to underestimate observational temperatures, mostly at high altitudes. Results show that WRF provides an added value in relation to the reanalysis, with improved correlation and error metrics relative to observations.

The analysis of temperature trends shows a warming in the area during the last 20 years, very significant in autumn. When spanning the analysis to the whole observational period, back to the beginning of the 20th century at some sites, significant annual and seasonal temperature increases of 1℃/decade develop, most of them happening during de 1970s, although not as intense as during the last 20 years.

The temporal variability of temperature anomalies in the Sierra de Guadarrama is highly correlated with the temperatures in the interior of the Iberian Peninsula. This relationship can be extended broadly over south-western Europe.

How to cite: Vegas Cañas, C., González Rouco, J. F., Navarro Montesinos, J., García Bustamante, E., Lucio Eceiza, E. E., García Pereira, F., Rodríguez Camino, E., Chazarra Bernabé, A., and Álvarez Arévalo, I.: An Assessment of Observed and Simulated Temperature Variability in Sierra de Guadarrama (Spain), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6358, https://doi.org/10.5194/egusphere-egu21-6358, 2021.

16:05–16:07
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EGU21-7020
Baruch Ziv, Ron Drori, Hadas Saaroni, Adi Etkin, and Efrat Sheffer

Previous observation analyses have shown a declining rainfall trend over Israel, mostly statistically insignificant. These findings support the projections of the climatic models for the 21th century. The current study, for the period 1975-2020, undermines these findings, and the alarming future projections, and elaborates changes in the distribution of the rain along the rainy season.

The annual rainfall has a negligible trend, of +0.002%/decade, the number of rainy days has declined by -1.9%/decade and the average daily rainfall has increased by +2.1%/decade, all statistically insignificant. In the mid-winter both rainfall and daily rain intensity increased, while these variables have declined in the autumn and spring. The implied contraction of the rainy season is estimated by 2 measures. The 'effective length', which is determined by the time between accumulation of 10% and 90% of the annual rainfall, lasting 112 days on the average. This has been shortened by seven days during the study period. The other is the Seasonality Index (SI), reflecting the temporal concentration of the rainy season around its center. The trend found indicates that the regional climate is shifting from being between 'Markedly seasonal with a long dry season' and 'Most rain in ≤3 months', further toward the latter.

The trend in Cyprus Low occurrence and in the Mediterranean Oscillation Index were found to explain the rainfall trends only partially. We suggest that the cause for the increase in the mid-winter rain intensity is the increase in sea-surface temperature, found over the east Mediterranean, and for the decline in the transition seasons, to the poleward expansion of the subtropical highs. The contraction of the rainy season on the one hand, and the increased daily rain intensity in the mid-winter on the other, have ecological and hydrological impacts in this vulnerable region. 

How to cite: Ziv, B., Drori, R., Saaroni, H., Etkin, A., and Sheffer, E.: Recent Changes in the Rain Regime in Israel 1975-2020, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7020, https://doi.org/10.5194/egusphere-egu21-7020, 2021.

16:07–16:09
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EGU21-8729
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ECS
Ferat Çağlar, Omer Yetemen, Kwok Pan Chun, and Omer Lutfi Sen

Climate variability related to trough locations in the Euro-Mediterranean region is determined by various semi-permanent pressure centers of teleconnections and synoptic features. These features are resulted from the interactions between mesoscale and global-scale patterns from sub-seasonal to decadal scales. The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) are the most common teleconnection patterns for depicting climate anomalies in this region. However, their skills for predicting climate anomalies gradually decays towards Eastern Europe and the Mediterranean.

The North Sea Caspian Pattern (NCP) is a middle troposphere teleconnection between the North Sea and the Caspian Sea. The skill of the suggested NCP index was tested for temperature and precipitation fields in the Eastern Mediterranean, and significant correlations were found particularly with temperature fields. The index had limited utilization because it was believed that the index could not represent precipitation anomalies well in the region.

We aimed to assess the competence of the NCP on indicating climate variability in a broader region. For this purpose, a high resolution, spatially continuous, and homogeneous data was needed. The European Center for Middle-Range Weather Forecasts (ECMWF) ERA5 reanalysis data was chosen for investigating monthly total precipitation, mean air temperature at 2-m height and 500 hPa mean geopotential fields for the period of 1950-2019. We produced correlation and composite maps of temperature, precipitation, and geopotential for the NCP and other common indices in the region. There were significant differences between the negative and positive phases of the NCP in Western Europe and the Caucasus regions. These areas coincided with the edges of the Mediterranean Trough. To understand the working mechanism of the index, cross-correlations between other indices were calculated. The Mediterranean Trough Displacement index showed significant positive correlations with the NCP, which indicates that the east-west migration of the through might have a significant effect on the strength of the NCP. Composite maps of mean geopotential height differences also provided support for this finding. Since the identified poles of the NCP are along both latitudinal and longitudinal directions, the NCP is sensitive to zonal and meridional circulation features.  For the areas with significant composite differences of temperature and precipitation, the skill of the NCP for predicting climate anomalies is comparable to the skills of the AO and the NAO.

We found strong evidence that the NCP is adequate for indicating not only monthly temperature but also precipitation anomalies particularly in Northwestern Europe and the Caucasus regions. 

This study is supported by the 2232 International Fellowship for Outstanding Researchers Program of the Scientific and Technological Research Council of Turkey (TUBITAK) under grant 118C329. The financial support from TUBITAK does not mean that the content of the publication reflects the approved scientific view of TUBITAK.

How to cite: Çağlar, F., Yetemen, O., Chun, K. P., and Sen, O. L.: Applicability of the North Sea Caspian Pattern as an indicator of the Euro-Mediterranean Climate Variability, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8729, https://doi.org/10.5194/egusphere-egu21-8729, 2021.

16:09–16:11
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EGU21-1599
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ECS
Clara E Estrela Segrelles, Miguel Ángel Pérez Martín, and Gabriel Gómez Martínez

Sea level rise produced by climate change severely affects coastal ecosystems. The increase in the area below sea level facilitates the penetration of the marine wedge and causes an increase in soil salinity. Coastal wetlands are areas of great ecological importance due to the richness of flora and fauna that inhabit them. A change in salinity conditions could lead to a reduction or loss of habitat for the wetland biota. Based on RCP4.5 and RCP8.5 CMIP5 multimodel scenarios, in the Western Mediterranean coast, the sea level will rise 0.16 m in the short term (2026 - 2045) and 0.79 m in 2100. Also, high-end scenarios indicate that sea level will rise between 1.35 m and 1.92 m in the long term.

A sea level rise analysis has been developed in the coastal wetlands of Júcar River Basin District (JRBD). The results show that coastal wetlands are the mainly area affected in the JRBD, so the 90% of the area under the sea level are wetlands. L’Albufera de Valencia is the main wetland in this basin and, also the main wetland affected. It is an anthropized humid zone, regulated by users through gates to preserve the adequate water level for agricultural and environmental purposes such as rice cultivation around the lake and bird habitats conservation, especially in winter. The outcome of the study shows a significative increase in the area below the sea from 507 ha and 4.2 hm3 of water volume at present to 3,244 ha that represents 42.6 hm3 of water volume in the short term. In the long term, the area below the sea is 7,253 ha which means 118.4 hm3 of water volume in the percentile 50 scenario and, in the worst extreme scenario, it is 13,896 ha that represents 289.7 hm3 of water volume. This leads to a redefinition of the lake management levels as a climate change adaptation measure to prevent the lake salinization and severe impacts in the lake ecosystem. L’Albufera lake levels need to be increased in the next years to avoid the sea water penetration, related to the sea level rise. Thus, in the short term the lake levels must be increased around 0.16 m and, in the long term, L’Albufera levels must be increased around 0.8 m.

How to cite: Estrela Segrelles, C. E., Pérez Martín, M. Á., and Gómez Martínez, G.: Climate Change Impacts on a Mediterranean Coastal Wetland due to Sea Level Rise (L’Albufera de Valencia, Spain), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1599, https://doi.org/10.5194/egusphere-egu21-1599, 2021.

16:11–16:13
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EGU21-9907
Elena Xoplaki, Elina Tragou, Alexandra Gogou, Vassilis Zervakis, Drosos Koutsoubas, Lorine Behr, Stamatis Petalas, and Maria Sini

Even before the introduction of the term “Marine Heat Wave” (MHW) and its statistical definition in global-scale studies, the scientific community had studied and recorded potentially harmful impacts of persistent conditions of warm surface layers and highly stratified water columns on the marine ecosystem. The main triggers for MHWs are yet not well understood and the current knowledge is mainly based on mass mortalities linked to temperature anomalies. EM-MHeatWaves is an interdisciplinary, collaborative, DAAD/IKYDA funded research project that investigates the atmospheric forcing, oceanic circulation and ecosystem response of MHWs in the Eastern Mediterranean Sea over the past 35 years. Two universities (Justus-Liebig-University Giessen, University of the Aegean) and one research center (Hellenic Centre for Marine Research) re-examine the definition of MHWs with emphasis on the Eastern Mediterranean by applying a holistic approach that includes reverse-engineering using model data and reanalysis covering the period 1985 to 2014. We focus on the Eastern Mediterranean because of the high sensitivity of the basin’s ecosystem to atmospheric and marine warming events, the invasion of tropical alien (Lessepsian) species, the characteristic oceanic circulation with the Eastern Mediterranean Transient events, the exchange with the Black Sea through the Turkish Strait System as well as the coastal upwelling areas. In order to study the spatiotemporal characteristics of Eastern Mediterranean MHWs we work towards a better understanding of the oceanographic processes as well as of the compounding character of the atmospheric contribution. Based on the response of marine biogeochemical cycles (depletion of subsurface oxygen levels, observed changes in the mixed layer and chlorophyll maxima depths, nutrient stoichiometries, carbon uptake and sequestration rates) and their impacts on ecosystems (i.e. shifts in planktonic and benthic community regimes, mass mortality events, disease outbreaks, etc.), triggered by the rise of ocean temperatures, we study the statistical characteristics of the oceanic temperatures and assess the corresponding ocean circulation, the synchronous and lagged contribution of the large scale atmospheric circulation. We further study the signature of these extreme Mediterranean MHW events in future projections from model runs with respect to duration, severity and spatial extent and compare them to reanalysis.   
EM-MHeatWaves aims at strengthening the partnership between the German and Greek institutions by conducting joint research at a high scientific level.

How to cite: Xoplaki, E., Tragou, E., Gogou, A., Zervakis, V., Koutsoubas, D., Behr, L., Petalas, S., and Sini, M.: EM-MHeatWaves: Eastern Mediterranean marine heatwaves - Ocean responses to atmospheric forcing and impacts on marine ecosystems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9907, https://doi.org/10.5194/egusphere-egu21-9907, 2021.

16:13–16:15
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EGU21-2240
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ECS
Ricardo D. Monedero-Contreras, Francisca Martinez-Ruiz, Francisco J. Rodríguez-Tovar, David Gallego-Torres, and Gert de Lange

The deposition of Organic-Rich Layers (ORLs) and sapropels in the Mediterranean Sea basins represents an exceptional record of severe changes in oxygenation over the recent geological past. Such changes are also associated to rapid productivity oscillations that involved a major increase in export fluxes of organic carbon. These episodes of enhanced production and preservation of organic matter can be used as a natural archive for studying oxygen fluctuations and deoxygenation events, and a better comprehension of the causes and consequences of past events will provide valuable information to further understand oxygen level variations in future scenarios. In general, sapropel deposition has been related to increased productivity and sluggish water circulation in response to African monsoon variability. To further understand how such conditions led to bottom water oxygen depletion, a multiproxy approach, including diverse geochemical and ichnological proxies, has been applied. Obtained results have provided new insights into the relationship between productivity and oxygen conditions in the water column and at the sediment-water interface. Sapropels intervals from cores recovered at four ODP Leg 160 sites were selected across an East-West transect of the Eastern Mediterranean basin entailing diverse depths and oceanographic regimes. At these sites, sapropel layers had been well characterized in terms of productivity (i.e. Ba/Al and TOC), and new analyses have been performed to provide additional redox proxies, i.e. degree of pyritization (DOP), trace elements ratios, and enrichment factors (EF) that have allowed a high-resolution reconstruction of bottom-water ventilation. Also, a preliminary ichnological approach is coupled with the geochemical information to assess the response of the macrobenthic trace maker community to the redox changes at the sediment-water interface. Trace metal proxies indicate a significant, though variable, decreasing oxygenation during sapropel deposition, also supported by important pyritization within sapropel layers.

How to cite: Monedero-Contreras, R. D., Martinez-Ruiz, F., Rodríguez-Tovar, F. J., Gallego-Torres, D., and de Lange, G.: Rapid changes in primary productivity and oxygen depletion during sapropel deposition: implications for reconstructing seawater oxygen levels, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2240, https://doi.org/10.5194/egusphere-egu21-2240, 2021.

16:15–16:17
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EGU21-8787
Florence Sevault, Robin Waldman, Samuel Somot, and Pierre Nabat

The Earth’s climate is regulated by the ocean, which absorbs, transports and releases heat through continuous exchanges with the atmosphere. In regional climate modelling, an increasing consensus has emerged on the added value of ocean-atmosphere coupled systems to allow for these exchanges, through interactive and realistic air-sea interactions. This coupling is controlled by the Sea Surface Temperature (SST), itself regulated by the capacity for the ocean component to store heat at depth.

We address here the question of heat storage and trend in the different depths of the Mediterranean Sea in a CMIP6 historical and SSP5-8.5 scenario with the Regional Climate System Model CNRM-RCSM6 driven by CNRM-ESM2-1 simulation. CNRM-RCSM6 is composed by ALADIN-Climate at a 12 km resolution for the atmosphere, with the interactive aerosol scheme TACTIC and the multi-surface model SURFEX v8, CTRIP at a 50 km resolution for the river routing with deep drainage, flood plains, and the lake parametrization FLAKE, NEMOMED12 at a 6 km resolution for the ocean, and OASIS3-MCT for a 1hr-coupling of the four models. The simulation begins in 1979 after 79 years of coupled spin-up, and a control simulation also exists.

We investigate the timing, location and magnitude of heat storage by the Mediterranean Sea. In particular, we assess the link between SST warming and vertical heat storage, and its possible seasonality. We illustrate the sensitivity of heat storage to salinity trends by comparing the western and eastern Mediterranean behaviours. Finally, we make use of an online heat trend diagnostic tool to characterize the dominant mechanisms of ocean heat storage in the Mediterranean Sea.

How to cite: Sevault, F., Waldman, R., Somot, S., and Nabat, P.: Mechanisms of heat storage and trend in the Mediterranean Sea in a high emission CMIP6 scenario with the regional climate system model CNRM-RCSM6., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8787, https://doi.org/10.5194/egusphere-egu21-8787, 2021.

16:17–16:19
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EGU21-12952
Eva Hartmann, Mingyue Zhang, Elena Xoplaki, and Sebastian Wagner

The Eastern Mediterranean and Middle East region is influenced by multiple large-scale atmospheric circulation patterns including the Indian Summer Monsoon the North Atlantic Oscillation (NAO), the East Atlantic / Western Russia and Scandinavian patterns. The area offers a broad spectrum, both in time and space, of long high-quality instrumental time series, documentary information and natural archives. Yet, recent reviews revealed that paleoclimate modelling with low horizontal resolution cannot fully help to understand the interactions of the multiple atmospheric patterns, the Mediterranean SSTs and connect potential climate impacts that may trigger or contribute to major social-historical events. Thus, there is a need to integrate high-resolution regional climate modelling into paleo applications. Furthermore, such integration will close the gap between the coarse resolution of climate models and the regional to local scale that is covered by the proxy and historical evidence and will enable a better data-model comparison. We use the regional climate model COSMO-CLM (CCLM) in an adjusted (orbital, solar and volcanic forcing, greenhouse gas concentrations and land-use changes) paleoclimate version. Simulations are performed with 0.44° and 0.11° spatial resolution on a domain including the Eastern Mediterranean and the Middle East in time slices of the past 2000 years. Simulations of the present (1979-2019) with this paleoclimate version of CCLM forced by ERA-Interim reanalysis data have shown promising results compared to observational and reanalysis data sets. The mean annual cycles of precipitation and temperature of the Mediterranean are correctly shown with high temperatures and low precipitation during the summer months and lower temperatures and higher precipitation during the winter months. Additionally, the effect of climate change is simulated with increasing temperatures during the last 40 years. Simulations of the present (1979-2019) and past periods (525-575 CE and 1220-1290 CE) forced by the MPI-ESM-LR ‘past2k’ simulations performed under the CMIP6 protocol will be performed at the next step and first results will be shown in the frame of this conference. The periods are chosen because of high volcanic activity and to study the volcanic influence on climate. Those results are going to be used to link historical events with the regional climate and contribute to a better understanding of the indirect and complex association between climate and society.

How to cite: Hartmann, E., Zhang, M., Xoplaki, E., and Wagner, S.: High Resolution Paleoclimate Simulations with the COSMO-CLM Model in the Eastern Mediterranean and Middle East, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12952, https://doi.org/10.5194/egusphere-egu21-12952, 2021.

16:19–17:00