CL4.9 | Mediterranean climate regions of the world: climate change, variability and extremes; impacts and adaptation
EDI
Mediterranean climate regions of the world: climate change, variability and extremes; impacts and adaptation
Convener: Andrea Toreti | Co-conveners: Annalisa Cherchi, Katrin Schroeder, Andreia RibeiroECSECS, Bikem EkberzadeECSECS, Ana BastosECSECS, Richard Seager
Orals
| Mon, 24 Apr, 14:00–15:45 (CEST)
 
Room 0.49/50
Posters on site
| Attendance Mon, 24 Apr, 10:45–12:30 (CEST)
 
Hall X5
Posters virtual
| Attendance Mon, 24 Apr, 10:45–12:30 (CEST)
 
vHall CL
Orals |
Mon, 14:00
Posters on site |
Mon, 10:45
Posters virtual
Mon, 10:45
Mediterranean climate regions of the world are located in transitional midlatitude zones like the Mediterranean basin area, western North America and small coastal areas of western South America, southern Africa and southern Australia. This transitional character makes them highly vulnerable to climate change. For all Mediterranean climate regions, the future holds high risks and uncertainty on biodiversity, aridity, ecosystems, and on the sustainability and the resilience of socio-economic systems. Innovative approaches to effective and sustainable climate adaptation and mitigation are, therefore, required. Understanding the past, characterizing the present and modeling the future become essential steps to estimate the risks, assess the impacts of climate change, and identify potential adaptation strategies.

This session intends to strengthen the exchanges among the communities studying the Mediterranean climate regions of the world and promote a multi-disciplinary approach in identifying and preparing shared solutions and practices. Studies focused on physical (including extremes, teleconnections, hydrological cycle) and biogeochemical (including biodiversity) aspects of Mediterranean climate regions, focusing on observed past changes and/or future climate projections, are welcome, as well as related social aspects including indigenous knowledge in mitigating climate risks. Analyses where multiple Mediterranean climate-type regions are considered and compared are highly welcome. Moreover, as a multidisciplinary MedCLIVAR session we encourage contributions from a broad range of disciplines and topics, e.g. dealing with: dynamics and processes of the climate system; sectoral impacts of climate change; climate change adaptation; innovative methods and approaches in climate science.

Orals: Mon, 24 Apr | Room 0.49/50

Chairpersons: Andrea Toreti, Annalisa Cherchi
14:00–14:05
5-minute convener introduction
14:05–14:15
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EGU23-9435
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solicited
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Highlight
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On-site presentation
The central Chile megadrought: World 's champion? 
Rene Garreaud

The last decade (2010–2021) was drier than average in all major Mediterranean Climate Regions (MCRs), except for the Mediterranean Basin, with mean rainfall deficits from -2% (Southwest Australia) to -33% (central Chile). In most cases, dry years have prevailed but intermingled with wet years except for central Chile, along the west coast of subtropical South America, where all years since 2010 were below average. This conforms the so-called central Chile mega drought, the driest decade in local history since at least the 14th century and, as we show in this work, for any of the MCRs since 1901. Within the megadrought, accumulation dropped to <70% of the mean during 2019 and 2021, causing an unprecedented decline in vegetation, shortage of potable water and other detrimental impacts in central Chile.

In addition to placing the central Chile megadrought in planetary context, we summarize the underlying mechanisms behind this climate extreme. While climatic anomalies during the last decade are broadly consistent with projections, natural variability originating in the subtropical southwest Pacific was conducive for dry conditions across the Pacific has been acting in concert with climate-change signal. As a result, the observed mean precipitation deficit was about three times larger than expected for the early decades of this century, more akin to those predicted for 2070-2090 under a heavy greenhouse gases emission scenario.

 

How to cite: Garreaud, R.: The central Chile megadrought: World 's champion?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9435, https://doi.org/10.5194/egusphere-egu23-9435, 2023.

14:15–14:25
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EGU23-12989
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ECS
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Virtual presentation
Assessment of the relationship of atmospheric blocking and heatwaves over the Mediterranean region 
Iliana Koutsoupi, Constantinos Cartalis, Kostas Philippopoulos, and Ilias Agathangelidis

The increasing trends of extreme heat and record-high temperatures in Europe are linked to large-scale circulation. The aim of this work is to investigate the role of atmospheric blocking on heatwaves over the Mediterranean region and to assess the drivers of such anomalies. The study is focused on the summer period and on the omega block upper-level weather pattern (i.e., a low-high-low pattern that remains stationary and distorts the progression of weather systems). The identification of the omega block patterns is based on the 500 hPa geopotential anomalies from 1981 to 2020 for the European region, using the state-of-the-art ERA5 reanalysis product at a 0.25° x 0.25° horizontal resolution. A duration threshold was employed (5 days) and 75 omega blocks are identified in total. Their persistence was typically between 5 and 10 days, and in a few cases, the pattern was observed for more than 20 days. An omega block classification was developed based on the blocking intensity using the 500 hPa geopotential gradient, and the events are characterized as weak, moderate, or strong. The majority of the events were classified as omega blocks with moderate intensity and only 3 cases as strong. In addition, the effect of the North Atlantic Oscillation (NAO)was examined, and a positive correlation between the omega events and the NAO negative phase was found and the majority of these events (approximately 70%) were located in the western European region. A significant finding based on the omega block characteristics is that during the last decade, an increase is found in their duration and intensity. The identification of the heatwave events over the Mediterranean region was based on the Excess Heat Factor (EHF) which is used to further categorize heatwaves by their severity. The effect of omega blocks on the EHF distribution is illustrated over the examined sector and specific case studies are also discussed. The results of the study illustrate the impact of atmospheric blocking on the predictability of extreme heat.

How to cite: Koutsoupi, I., Cartalis, C., Philippopoulos, K., and Agathangelidis, I.: Assessment of the relationship of atmospheric blocking and heatwaves over the Mediterranean region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12989, https://doi.org/10.5194/egusphere-egu23-12989, 2023.

14:25–14:35
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EGU23-12418
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ECS
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On-site presentation
Assessment of agronomic adaptation strategies to climate change in a Mediterranean watershed with SWAT+ 
Lorenzo Villani, Giulio Castelli, Estifanos Addisu Yimer, Albert Nkwasa, Daniele Penna, Ann van Griensven, and Elena Bresci

The Mediterranean region is considered a hotspot for climate change as it is expected to face more severe impacts compared to other regions of the world. To better understand these impacts and plan more effective adaptation strategies, integrated assessments should consider not only biophysical aspects, but also social, political, and economic ones. Plenty of models are available to simulate these various aspects, but certainly, the more models are included, the higher the complexity, which severely affects the reproducibility of the studies. Even when considering only biophysical aspects, related for example to water and food security, individual crop and/or hydrological models have intrinsic limitations. Integrated, distributed, agro-hydrological models such as the Soil and Water Assessment Tool (SWAT) might be the solution to overcome some of these drawbacks, including the point-scale nature of crop-growth models.

We applied the SWAT+ model in a medium-sized agricultural watershed in Central Italy, the Ombrone watershed, in order to comprehensively assess climate change impacts on crop production and water management and evaluate autonomous agronomic adaptation strategies. By forcing SWAT+ with five bias-corrected EURO-CORDEX climate models, we assessed future precipitation and temperature in the study area. Moreover, we simulated the fluxes of different water balance components and evaluated how they were affected by the increasing CO2 concentration. Then, we simulated future crop yield and water footprint of three representative crops - durum wheat, sunflower and irrigated maize - and evaluated the adaptive capacity of the agricultural systems by simulating simple adaptation strategies such as shifting sowing dates and applying supplemental irrigation. Finally, we estimated the effects of these adaptation strategies on water balance components.

While the temperature was predicted to increase, future precipitation showed much more uncertainty. Furthermore, considering the CO2 fertilization effect enhanced the uncertainty about future aridity conditions, with variables such as potential evapotranspiration that varied up to 50% when considering constant or increasing CO2 concentration. Crop yield was negatively affected mainly by the reduction of crop cycle length caused by increased temperatures, but with adaptation strategies it was possible to reduce losses or even obtain higher production. Finally, management changes such as the inclusion of cover crops in the crop rotation have a significant impact on some water balance components that cannot be neglected. The results of this study show the increasing need to adapt to climate change impacts in the Mediterranean cultivated catchments.

How to cite: Villani, L., Castelli, G., Addisu Yimer, E., Nkwasa, A., Penna, D., van Griensven, A., and Bresci, E.: Assessment of agronomic adaptation strategies to climate change in a Mediterranean watershed with SWAT+, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12418, https://doi.org/10.5194/egusphere-egu23-12418, 2023.

14:35–14:45
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EGU23-11311
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Highlight
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On-site presentation
Persistent anticyclonic conditions and climate change exacerbated the exceptional 2022 European-Mediterranean drought 
Davide Faranda, Salvatore Pascale, and Burak Bulut

A prolonged drought affected Western Europe and the Mediterranean region in the first nine months of 2022 producing large socio-ecological impacts. The role of anthropogenic climate change (ACC) in exacerbating this drought has been often invoked in the public debate, but the link between  atmospheric circulation and ACC has not received much attention so far. Here we address this question by applying the method of circulation analogs, which allows us to identify atmospheric patterns in the period 1836-2021 very similar to those occurred in 2022. By comparing the circulation analogs when global warming was absent (1836-1915) with those occurred recently (1942-2021), and by excluding interannual and interdecadal variability as possible drivers, we identify the contribution of ACC. The 2022 drought was associated with an anticyclonic anomaly over Western Europe persistent over December 2021-August 2022. Circulation analogs of this atmospheric pattern in 1941-2021 feature 500 hPa geopotential height anomalies larger in both extent and magnitude, and higher temperatures at the surface, relative to those in 1836-1915. Both factors exacerbated the drought, by increasing the area affected and enhancing soil drying through evapotranspiration. While the occurrence of the atmospheric circulation associated with the 2022 drought has not become more frequent in recent decades, there is an increase of its interdecadal variability for which the influence of the Atlantic Multidecadal oscillation cannot be ruled-out.

How to cite: Faranda, D., Pascale, S., and Bulut, B.: Persistent anticyclonic conditions and climate change exacerbated the exceptional 2022 European-Mediterranean drought, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11311, https://doi.org/10.5194/egusphere-egu23-11311, 2023.

14:45–14:55
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EGU23-10457
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On-site presentation
Climate change, landscapes and human impacts during the 4.2kyr event in Mesopotamia and beyond 
Daniel Hill, Michelle de Gruchy, Katleen Deckers, and Dan Lawrence

The 4.2kyr event saw major changes in civilizations across the world, often attributed to climate change and widespread drought. Indeed, there are high quality palaeohydrological proxies that seem to document a significant drying at this time in Egypt, the Indus Valley and in the Near East. In Mesopotamia, settlements were abandoned, agricultural practices shifted and the Akkadian Empire ended. Climate model simulations covering 5000-3000 years ago are able to reproduce much of the evidence for Holocene climate change and some of the key reductions in mid-late Holocene precipitation. However, unlike some other regions, the annual mean rainfall in Mesopotamia at 4.2kyr is similar to the adjoining millennia. The climate model simulates significant droughts during this time, but these are within the range seen both before and after.

The end of the middle Holocene saw rapid population growth in Mesopotamia, with significant urban centres putting pressure on local resources. Although the models suggest no significant change in climate, the archaeological evidence shows the exploitation of a dryer landscape, both in existing sites and new urban centres in dryer regions. This time also sees changing agricultural practices and the loss of available sources of wood. Vegetation models suggest little impact of climate change on the natural landscape, although drought years bring major losses in net primary productivity. However, human activities in Mesopotamia could have affected the landscape and exacerbated the impacts of existing drought cycles. We suggest that an unexceptional drought, combined with a large population and anthropogenic impacts on the landscape contributed to significant societal change in Mesopotamia at 4.2kyr.

How to cite: Hill, D., de Gruchy, M., Deckers, K., and Lawrence, D.: Climate change, landscapes and human impacts during the 4.2kyr event in Mesopotamia and beyond, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10457, https://doi.org/10.5194/egusphere-egu23-10457, 2023.

14:55–15:05
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EGU23-7894
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ECS
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On-site presentation
Improving the forecast quality of near-term climate projections in the Mediterranean region 
Josep Cos, Francisco Doblas-Reyes, Raül Marcos, and Markus G Donat

The Mediterranean region is often considered a climate change hotspot. State of the art climate projections display a large uncertainty due to factors such as the modeling approach or variability phasing, in particular for projections of the next few decades. With the great amount of climate information from the last Coupled Model Intercomparison Project (CMIP6), it is desirable to constrain the multi-model multi-member ensemble for the near-term future to obtain more robust and better performing projections. We explore different subsetting methods that select those members that better capture the variability at the starting date of the projection’s study period. To find the best information we explore variations of different parameters in the selection method based on relevant climate drivers in the Mediterranean region. Such parameters are the reference against which the best members are selected, and comprise: the time period used, the constraining regions considered and the variable or metric that drive the constraint. We find that these subsetting methods can improve the accuracy of near-term climate projections for the next 20 years compared to the unconstrained projections. This evaluation of the results allows us to make informed and robust decisions about the near-term future projections based on quality estimates borrowed from climate prediction practices.



How to cite: Cos, J., Doblas-Reyes, F., Marcos, R., and Donat, M. G.: Improving the forecast quality of near-term climate projections in the Mediterranean region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7894, https://doi.org/10.5194/egusphere-egu23-7894, 2023.

15:05–15:15
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EGU23-6043
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ECS
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Virtual presentation
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Projected changes in the distribution of global Mediterranean climate-type regions 
George Zittis, Diego Urdiales-Flores, Annalisa Cherchi, and Panos Hadjinicolaou

Mediterranean climate-type regions are characterized by warm-to-hot dry summers and mild, wet winters (Csa and Csb categories in Köppen classification). These regions are especially vulnerable to climate change since temperature and precipitation are expected to change in opposite directions. Impacts of extreme events (e.g., severe heat waves and prolonged droughts), challenges in water availability and food security, as well as other aspects of human livelihood, require a detailed global view of future changes in these unique mid-latitude zones.

Here, we explore the observed trends and future distribution of global Mediterranean climate-type regions (MCR). We analyze gridded observations and a bias-adjusted and statistically downscaled dataset of five global Earth System Models from Coupled Model Intercomparison Project phase 6 (CMIP6). For supporting decision-making and climate mitigation efforts, we focus on different global warming levels (e.g., 1.5, 2, 3, and 4°C) derived from the Shared Socioeconomic Pathway SSP5-8.5.

Our preliminary results show that for the rest of the 21st century, the CMIP6 models project that the total MCR area will not change significantly. However, our analysis highlights a robust poleward and eastward expansion of Csa zones at the expense of cooler climates (incl. Csb) over three regions, corresponding to a 21% increase in their area in the Mediterranean Basin, a 41% increase in North America-California, and 12.2% increase in South America-Central Chile. For every one additional degree of global warming, mean rainfall will likely decrease by about 4-5 % in most of the Mediterranean Basin, Southern Africa, and Southern Australia, while in South America-Central Chile, this decrease is more pronounced (near 10%). On the contrary, for every degree of global warming, mean rainfall will likely increase by about 5% in North America-California.

How to cite: Zittis, G., Urdiales-Flores, D., Cherchi, A., and Hadjinicolaou, P.: Projected changes in the distribution of global Mediterranean climate-type regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6043, https://doi.org/10.5194/egusphere-egu23-6043, 2023.

Discussion
15:15–15:25
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EGU23-15806
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ECS
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On-site presentation
Evolution of the Drivers of Stratification of the Gulf of Lion in a Changing Climate 
Douglas Keller, Yonatan Givon, Florence Sevault, Samuel Somot, Romain Pennel, Shira Raveh-Rubin, and Philippe Drobinski

Deep convection, or open-ocean convection, occurs in the higher latitude regions of the world and is an important ocean circulation process. It is formed when the stable density gradient along the ocean column is eroded by surface buoyancy loss, leading to an overturning that can span the entire depth of the column. In the western basin of the Mediterranean Sea (Med. Sea), this process can occur in the Gulf of Lion (GOL) and assists in the thermohaline circulation of the sea by forming the Western Mediterranean Deep Water (WMDW), which then laterally spreads throughout the western basin. Significant deep convection events occur every few years in the GOL, driven by the Mistral and Tramontane winds and the seasonal atmospheric change. However, in the future these events are expected to stop altogether due to increasing stratification. In this presentation, the changes in atmospheric forcing and stratification in the GOL are examined to determine the driving factor behind the collapse of the deep convection process in the region. This task is completed using NEMO simulations driven by the CMIP6 results of Météo France's RCSM6 regional model. The years from 2015 to 2100 are studied, under the SSP5 8.5 scenario (the worst case SSP scenario). Two sets of simulations are presented, a control and seasonal set. The seasonal set was forced with filtered atmospheric forcing to remove the effect of the Mistral and Tramontane. Comparing the two sets allows to determine the effects of the Mistral and atmospheric forcing separately. Results show an evolution in atmospheric forcing that effectively leads to no net change over time in the energy fluxes at the surface of the ocean. However, the stratification in the gulf increases, driven by advected stratification, with temperature as the primary advected quantity increasing stratification.

How to cite: Keller, D., Givon, Y., Sevault, F., Somot, S., Pennel, R., Raveh-Rubin, S., and Drobinski, P.: Evolution of the Drivers of Stratification of the Gulf of Lion in a Changing Climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15806, https://doi.org/10.5194/egusphere-egu23-15806, 2023.

15:25–15:35
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EGU23-3591
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Virtual presentation
The 4.2 ka BP event: global rearrangement of ocean-atmosphere interaction patterns forced Eastern Hemisphere societal collapses 
Harvey Weiss and Antoon Kuijpers

Consequent to excessive melt water discharge from Greenland forced by higher summer temperatures of the late Holocene Thermal Maximum, enhanced export of Labrador Current low-salinity waters into the Northwest Atlantic peaked ca. 4.2 ka BP, suppressing ocean deep convection and northward ocean heat transport, which implies changes in the Atlantic Meridional Overturning Circulation system.  At around 4.2 ka BP southward migration of the North Atlantic atmospheric Polar Front and the associated storm belt occurred in parallel with insolation-forced southward shift of the ITCZ and subsequent Southern Ocean warming. In the tropics, this rearrangement of global ocean-atmosphere interaction patterns led to temporarily reduced ENSO variability with a dominant La Nina regime. The marine and continental paleoclimate records are supported by present-day ENSO-La Nina climate features and teleconnections.

In the Eastern Hemisphere, the abrupt ~30% megadrought reductions of midlatitude westerlies’ precipitation coinciding with cooling and dust events, documented at decadal resolution, caused the cascading agro-production crises that led to adaptive societal collapses, regional abandonments, and refugia habitat tracking, from Chalcolithic Iberia to Early Bronze Greece and Levant, Akkadian Empire Mesopotamia, and Iran, beginning ~2250 - 2200 BCE. The synchronous four-phased Indian Summer Monsoon (ISM) megadroughts, known from congruent, sub-decadal/decadal precision East and West India lake sediment, marine and speleothem cores, forced adaptive abandonment of the five Harappan cities and habitat tracking eastward beginning ~2200 BCE. The abruptly reduced ISM Ethiopian precipitation, source of Nile River flow, and 4.2 ka BP megadroughts documented at tropical Lake Teli and Lake Turkana, caused abandonment of Old Kingdom Egypt delta settlement and seasonal riverine inundation lands, with violent collapse into First Intermediate Period polities ~2250 BCE. In the West Pacific, the Kuroshio Current was weakened by abrupt La Nina onset documented in Japan marine cores and in the Pacific Northwest, with sub-decadal resolution, in the Mt Logan ice core at 4.2 ka BP. Simultaneous reduction of the East Asian Summer Monsoon forced regional Longshan settlement collapses along the Yangtze River delta and in the East Haidai regions. Tropical Australia synchronously experienced megadrought documented at KNI-51 Cave and Black Springs, Kimberley.

Disruption of the North American Monsoon forced the 4.2 - 3.9 ka BP megadroughts observed in lake sediment cores from Idaho to Massachusetts and Maine.  The precipitation patterns of South America were disrupted from north to south at 4.2 ka BP, from tropical Andean Ecuador to Lake Titicaca and to southern Chile.  The disruptions included the Humboldt Current along the west coast, the continental monsoon along Brazil’s east coast, the ITCZ, and the South Atlantic Convergence Zone that crosses Brazil. The Patagonian series of abrupt 4.2 ka BP dry-cold events extended south to the Marguerite Bay, Antarctica, abrupt transition to colder, icier conditions. The cold snap at King George Island was followed by a 4.2 - 3.7 ka BP warm period. A wet west and dry east Andes are suggested by high resolution 4.2 ka BP event proxies and include the Patagonian 4.2 ka BP volcanic eruptions coeval with Hekla 4, Iceland, and Avellino, Italy.

How to cite: Weiss, H. and Kuijpers, A.: The 4.2 ka BP event: global rearrangement of ocean-atmosphere interaction patterns forced Eastern Hemisphere societal collapses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3591, https://doi.org/10.5194/egusphere-egu23-3591, 2023.

15:35–15:45
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EGU23-4158
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ECS
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On-site presentation
Precipitation response to climate change in the Mediterranean region – Forcings & Dynamics 
Benny Keller and Chaim Garfinkel

Which forcings and processes govern the projected future drying of the Mediterranean region as CO2 concentrations rise, and how do they interact? An intermediate-complexity moist general circulation model is used to investigate the precipitation response to climate change in the Mediterranean region. In particular, we examine stationary wave changes forced by land–sea contrast, zonal heat fluxes in the ocean, and topography, coupled with a quadrupling of initial CO2 concentrations. Eight different combinations are formed from the three forcings, and the linearity and additivity of the response are investigated. An expected decrease in precipitation over the Mediterranean region is found, accompanied by a strong anomalous ridge, with a significant difference in magnitude between the south-east and north-west of the region, as shown in previous studies. New results suggest that horizontal heat fluxes in the ocean may be a major forcing for future Mediterranean drying, especially over the eastern Mediterranean in winter. The influence of the land-sea contrast is found to be more complex than previously shown, varying from west to east and from north to south of the Mediterranean basin, suggesting further dynamics governing the response in each area. In an attempt to break down the influence of several components of the thermodynamic condition in the Mediterranean, we isolate geographical elements (the Mediterranean, continental Europe , etc.) and examine the precipitation and geopotential height field response, in hope to refine the future projection and better understand the dynamics governing it.

How to cite: Keller, B. and Garfinkel, C.: Precipitation response to climate change in the Mediterranean region – Forcings & Dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4158, https://doi.org/10.5194/egusphere-egu23-4158, 2023.

Posters on site: Mon, 24 Apr, 10:45–12:30 | Hall X5

Chairpersons: Andreia Ribeiro, Ana Bastos, Bikem Ekberzade
X5.202
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EGU23-1235
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Highlight
Impact of climate change on agro-climatic zones in Europe under different RCPs 
Aristeidis K. Georgoulias, Dimitris Akritidis, Roxanne S. Lorilla, Charalampos Kontoes, Andrej Ceglar, Andrea Toreti, and Prodromos Zanis

The rise of surface temperature due to climate change has a significant impact on the growth of different plant species, including aromatic plants, agricultural crops, fruit trees, and forests. Within the framework of the MICROSERVICES project, that aims on improving the capacity to predict the cascading effects of climate change on microbial diversity, crop-microbiome interactions and agricultural ecosystem functions, we studied the future projection of agro-climatic zones over Europe under two different IPCC Representative Concentration Pathways (RCP4.5 and RCP8.5). To this end, an ensemble of 11 bias-corrected EURO-CORDEX simulations covering the period 1981-2100 was used following the methodology of Ceglar et al. (2019)*. The agro-climatic zones were identified based on two temperature-related parameters, the Growing Season Length (GSL) and the Active Temperature Sum (ATS). The categorization into one of the 8 agro-climatic zones was implemented by applying the k-means clustering method for the reference period 1981-2010. Then, the agro-climatic zone patterns over Europe for the intermediate period 2031-2060 and the end-of-the-century period 2071-2100 were compared against that of the reference period. Our results point towards a strong northward shift of the agroclimatic zones, especially under the no-mitigation emission scenario (RCP8.5) at the end of the century. For the moderate mitigation scenario (RCP4.5), a significant shift of the agroclimatic zones is also observed for the intermediate and the end-of-the-century periods for extended areas in Europe. Our results are in line with that of Ceglar et al. (2019), who studied the migration of agro-climatic zones over Europe under the 2 oC warming level utilizing a subset of the simulations used in this study. *Ceglar et al., Earth's Future, 7, 1088-1101, https://doi.org/10.1029/2019EF001178, 2019.

This research was supported by the MICROSERVICES project funded by the General Secretariat for Research and Innovation (GSRI, Greece) under the Action ERANETs 2021A [Call ID: 037KE - A/A MIS 4888] (Project Number: T12ERA5-00075) and through the 2019-2020 BiodivERsA joint call for research proposals [BiodivClim ERA-Net COFUND programme].

How to cite: Georgoulias, A. K., Akritidis, D., Lorilla, R. S., Kontoes, C., Ceglar, A., Toreti, A., and Zanis, P.: Impact of climate change on agro-climatic zones in Europe under different RCPs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1235, https://doi.org/10.5194/egusphere-egu23-1235, 2023.

X5.203
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EGU23-4114
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ECS
Eddies characteristics and their relationship with cyclones in the Mediterranean Sea in the recent decades
(withdrawn)
Babita Jangir, Alok Kumar Mishra, and Ehud Strobach
X5.204
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EGU23-4396
Localisation of the ruins of ancient megalithic structures near water sources – a case study at Porto Santo Island, Portugal 
Agnese Kukela and Valdis Seglins

Porto Santo Island  is the northernmost and easternmost island of the archipelago of Madeira, located in the Atlantic Ocean west of Europe and Africa. The island is rare populated as result of historical terrace farming decline because of island slopes erosion and shortage of water resources. Modern days these areas are under afforestation activities.

Our research carried out in summer 2022 indicates that Porto Santo Island was inhabited before it was discovered by the Portuguese. The ruins of megalithic structures priory discovered on the island of Madeira, led to assumption that such ruins could also be found on Porto Santo. When the island, some stone blocks processed with stone tools were found. Additionally, the characteristic shapes given to the stones of ancient megalithic cultures have been determined, and the very simplified treatment of their surface with stone tools has been documented. Fragments of ancient marks and sings are still traceable on the surfaces of some stones, which are being studied. In some parts of the island the concentration of megaliths is higher, and the ruins of building structures can be mostly found in the eastern and northern parts of the island.

Typically, such ruins are not concentrated at the coastal area, but are located on an elevated relief surface at a height of about 130-150 meters. At this level, where the terrain is crossed by ravines with periodically flowing streams, there are places where the ruins of megalithic structures are most often found. In this area the ravine streams are still constant throughout the year, but towards the ocean they completely disappear and resume their flow only during the rainy season.

Most likely, the connection directly to water sources, which is a critical resource for life on the island, has determined the location of the monuments of the megalithic culture. Presumably, such a connection has also existed in the settlements of the inhabitants in unknown antiquity.

The limited number of monumental ruins on the island indicates the relative temporality of the existence of this ancient culture, as well as the small size of its population. When due to climatic changes, the rainy season is short and the amount of precipitation is insufficient for their infiltration, and such a phenomenon lasts for decades, the sources of drinking water dry up irretrievably and people must leave the island. In the case of Porto Santo, it is likely that the ancient inhabitants migrated to the nearby island of Madeira, which is richer in water resources.

Key words: ancient cultures, prehistory, stone processing, stone marks

The study has been founded by Iceland, Liechtenstein and Norway through the EEA and Norway Grants Fund for Regional Cooperation project No.2018-1-0137 “EU-WATERRES: EU-integrated management system of cross-border groundwater resources and anthropogenic hazards”.

How to cite: Kukela, A. and Seglins, V.: Localisation of the ruins of ancient megalithic structures near water sources – a case study at Porto Santo Island, Portugal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4396, https://doi.org/10.5194/egusphere-egu23-4396, 2023.

X5.205
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EGU23-4679
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ECS
Hysteresis of European Summer Mean and Extreme Precipitation in a CO2 Removal Experiment 
Nari Im, Daehyun Kim, Soon-Il An, and Jongsoo Shin

This study investigates the changes in the mean and extreme summer precipitation over Europe in a CO2-removal experiment, in which CO2 concentration is quadrupled and reduced back to the current climate level symmetrically over a 280-year period. Due to the pronounced summertime drying caused by greenhouse gas-induced warming, the mean and extreme precipitation decrease and bounce back during the CO2 ramp-up (RU) and ramp-down (RD) period, respectively. Interestingly, the degree of reduction in the mean precipitation is two times that of extreme precipitation. Also, the mean precipitation shows hysteresis with respect to CO2 forcing, which is absent in extreme precipitation. We show that the changes in the mean precipitation, in which convective precipitation is the dominant component, are tightly associated with those of the mean moist convective instability (MCI). Compared to the RU period, the mean MCI is lower during the RD period with a drier lower troposphere which is due to lower soil moisture and weaker surface evaporation. In contrast, the changes in extreme precipitation, whose major component is large-scale precipitation, closely follow those of the mean column relative humidity. Our results suggest that the partitioning of total precipitation into convective and large-scale components in models needs to be considered when analyzing model-simulated future projections of regional precipitation changes.

How to cite: Im, N., Kim, D., An, S.-I., and Shin, J.: Hysteresis of European Summer Mean and Extreme Precipitation in a CO2 Removal Experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4679, https://doi.org/10.5194/egusphere-egu23-4679, 2023.

X5.206
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EGU23-4991
Extreme Climate Changes in the MENA Region: Their Impacts and Effective Adaptation Strategies 
Manfred A. Lange

Countries of the Middle East and North Africa (MENA Region) are plagued by extremely hot, dry summers and extended warm spells, and are known as a “climate change hot spot”. Results of numerical climate models project heat waves lasting up to 90 days with temperatures of more than 50°C for the late 21st century. Since the region is heavily urbanized, enhanced warming in larger cities leads to outdoor conditions that become unbearable and pose extreme health risks to a large fraction of the human population. Decreases in precipitation are enhanced through heat-related processes and result in extreme water scarcity.

Such conditions need to be addressed by effective and well-founded adaptation strategies in the MENA region. With regard to the provision of potable water, desalination of sea- and brackish water becomes an almost unavoidable requirement for coastal cities. In order to maintain food security in water-scarce agricultural areas, innovative irrigation technologies in combination with smart agricultural practices need to be practiced. Extreme outdoor and indoor temperatures in urban settings require substantial space cooling through electrically driven air conditioners. In addition and preferentially, new buildings should be erected following strict rules for low to zero-energy houses. Existing buildings should undergo significant retrofitting efforts that reduce heat intake and minimize the use of air conditioning. In addition, and already practiced in some of the MENA countries, cities will have to provide “cooling spaces” for those inhabitants that live in poorly insulated buildings and cannot afford costly space cooling.

All of these measures require substantial amounts of electrical energy. This applies in particular to the desalination process, which consumes ca. 4 kWh/m3 of potable water. Assuming a need of ca. 100 lpd (lpd=liters per person per day; 100 lpd=0,1 m3). In a city of, e.g., 250 000 inhabitants, 25 000 m3 of potable water is needed, which requires 100 000 kWh (100 MWh) of electricity per day or 36 500 MWh (36,5 GWh) per year.

The electrical energy required for space cooling amounts to ca. 0,15 kW/m2 of indoor living space. Assuming a daily cooling load of 10 hours in a typical house/apartment will translate into 1,5 kWh/m2/d. Given a nominal requirement of indoor space of ca. 25 m2/person results in an energy need of 37,5 kWh/person/d. Assuming the above-described conditions of future extreme urban warming space cooling will be required for about 8 months (240 days) by 70% of a city’s population of 250 000 (175 000 persons), we derive at an annual electrical energy need of 1 575 GWh or ca. 1,6 TWh.

Given such numbers, it is not surprising that cities currently account for about 80% of energy globally and 75% of greenhouse gas emissions. Given the prospects of extreme climate change in the MENA region, this number is likely to rise. This underlines the urgent need to employ alternative renewable energy sources to satisfy demand. Moreover, it becomes increasingly apparent that effective adaptation strategies that reduce the risks to human communities and natural ecosystems rely on innovative and effective strategies in the framework of a Water-, Energy- and Food-Nexus.

How to cite: Lange, M. A.: Extreme Climate Changes in the MENA Region: Their Impacts and Effective Adaptation Strategies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4991, https://doi.org/10.5194/egusphere-egu23-4991, 2023.

X5.207
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EGU23-5334
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ECS
The distributions of precipitations have been changing across the Mediterranean region in the last 70 years… but not always as we expect ! 
Julie André

Climate change is known to have consequences on both mean and extreme precipitations, with potentially threatening impacts on societies. The Mediterranean region is particularly affected, being a hotspot of temperature and precipitation changes: this region is expected to get much drier, but with more extreme rainfalls. Though the two extremes of precipitations (absence of rain -drought, dry spells etc. - and very heavy rainfalls) are crucial and well-studied, the evolution of the rest of the rain distribution has been quite overlooked in the literature. Still its study might help to get a broader and more coherent picture of the evolution over the last decades. In the Mediterranean, we commonly expect a “water cycle paradox”, i.e. decreasing mean annual precipitation (“drying”) while very heavy rainfalls intensify.

In this presentation, we look at how the whole wet-days precipitation distribution changes, in the Mediterranean region over the recent past. We use reanalysis data (ERA5) covering the whole 1950-2021 period at daily timescale. We study the trends of the rain percentiles and their statistical significance over the last 70 years.

  • We see indeed sub-regions where the “water cycle paradox” is happening, such as the Iberia peninsula as a whole or more specifically Andalusia. For those, the quantile trend curve is in a “U-shape”, with decreasing rain quantiles up to a given threshold (“inversion quantile”) and then an increasing distribution tail. This “inversion quantile” can vary a lot from one place to another.

  • However we also find that the “U-shape” trend behavior is not the norm for the Mediterranean region: the situation is more complex. In fact, two additional behaviors are observed according to the location: some regions where the whole rain distribution decreases, and others where it all increases (which is a behavior more expected in Northern Europe or over the oceans). We give a map of the “U-shape” regions and of those two supplementary behaviors, and test its robustness.

  • By modeling the rainy days distribution with a simple Weibull law (2-parameters), we manage to get an analytical criterion for the type of rainfall percentiles trend behavior. This Weibull model also enables us, for regions having the “U-shape” behavior, to derive an analytical expression for the “inversion quantile”.

How to cite: André, J.: The distributions of precipitations have been changing across the Mediterranean region in the last 70 years… but not always as we expect !, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5334, https://doi.org/10.5194/egusphere-egu23-5334, 2023.

X5.208
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EGU23-7403
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ECS
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Analysis of the impact of climate change on grapevines in Turkey using heat unit accumulation–based indices 
Nazan An, M. Tufan Turp, Bora Orgen, Başak Bilgin, and M.Levent Kurnaz

Temperature is the most important factor influencing grapevine phenology and yield. Various indices have been developed that deal with the temperature sums that grapevines are exposed to during growth and maturation. With the help of these indices, predictions are made about whether the grapes will grow in a certain region and the quality of the grapevines. In this study, the future impacts of climate change on viticultural conditions in Turkey were projected by using Huglin index (HI), Winkler index (WI), and cool night index (CI). Under the RCP8.5 scenario, HI, WI, and CI indices for the future period of 2022–2050 were calculated for Turkey at 10 km spatial resolution with the RegCM4.4 model and compared with the 1972–2000 reference period. As a result of the study, a substantial increase in CI, HI, and WI and at least one level of categorical change were observed in the climatic conditions of the next 30 years in Turkey. These categorical shifts in CI, HI, and WI indicate that there may be changes in the geographical pattern of grapevine species grown in Turkey as well as the aroma and quality.

Acknowledgement: This research has been supported by Boğaziçi University Research Fund Grant Number 17601

 

How to cite: An, N., Turp, M. T., Orgen, B., Bilgin, B., and Kurnaz, M. L.: Analysis of the impact of climate change on grapevines in Turkey using heat unit accumulation–based indices, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7403, https://doi.org/10.5194/egusphere-egu23-7403, 2023.

X5.209
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EGU23-13767
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ECS
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Revisiting the Moisture Budget of the Mediterranean Region in the ERA5 Reanalysis 
Roshanak Tootoonchi, Simona Bordoni, and Roberta D'Agostino

The climate of the Mediterranean region (MedR) is characterized by mild-wet winters and dry-hot summers. The hydrological cycle is highly sensitive to the spatio-temporal characteristics of winter storms as they move into the region, which results in a distinctive and irregular rainfall pattern (D’Agostino and Lionello 2020).

Recent studies have identified the MedR as a climate change “hotspot” (Seager et al. 2014; D’Agostino and Lionello 2020), marked by intensifying temperature and precipitation (P) reduction. This P reduction cannot be simply attributed to the thermodynamic “wet-gets-wetter” response, pointing to the importance of circulation changes. However, exact dynamical mechanisms are yet to be understood. To this end, we revisit the moisture budget in the MedR using the 5th generation ECMWF reanalysis (ERA5) to: (1) explore how the different terms in the budget contribute to the observed climatological net P (precipitation minus evaporation (E)) patterns in the annual mean over land and sea, (2) assess the role of mean flow and transient eddies, and finally, (3) to expose any trends that might be present in the ERA5 dataset.

Moisture budget analyses reveal that most Mediterranean land areas (e.g., Europe and Turkey) have an excess of P over E. Annually averaged positive net P is particularly strong over high topographic regions (Alps and Balkans). Negative net P over the Mediterranean Sea confirms that, on average, the Mediterranean Sea is an evaporative waterbody.

Positive net P over the Mediterranean land regions is predominantly sustained by the sub-monthly transient eddies converging moisture that originate from the Mediterranean Sea. On the annual average, transient circulations (i.e., storm systems, extratropical cyclones) converge moisture over the Iberian Peninsula as well. In contrast, the annually averaged mean flow diverges moisture over most of the MedR (land and sea), except Adriatic Sea and north-western Africa (Tunisia, northern Algeria).

According to ERA5, net P in the MedR undergoes a significant decreasing trend owing to significant increase in E and a rather steady P in the 1979 – 2020 period. This is in line with previous work which show the projected drying in the MedR is already detectable (Seager et al. 2014). On a global scale, P and E within ERA5 show significant increasing trends during the analysis period. The increase in globally averaged E agrees well with the previous reanalysis product (i.e., ERA- Interim). However, the unrealistic increase in global P from ERA5 remains not well understood (Mayer et al. 2021).

 

References:

  • D’Agostino, R., & Lionello, P. (2020). The atmospheric moisture budget in the Mediterranean: Mechanisms for seasonal changes in the Last Glacial Maximum and future warming scenario. Quaternary Science Reviews, 241. https://doi.org/10.1016/j.quascirev.2020.106392
  • Mayer, J., Mayer, M., & Haimberger, L. (2021). Consistency and Homogeneity of Atmospheric Energy, Moisture, and Mass Budgets in ERA5. Journal of Climate, 34(10), 3955–3974. https://doi.org/10.1175/JCLI-D-20-0676.1
  • Seager, R., Liu, H., Henderson, N., Simpson, I., Kelley, C., Shaw, T., Kushnir, Y., & Ting, M. (2014). Causes of increasing aridification of the mediterranean region in response to rising greenhouse gases. Journal of Climate, 27(12), 4655–4676. https://doi.org/10.1175/JCLI-D-13-00446.1

How to cite: Tootoonchi, R., Bordoni, S., and D'Agostino, R.: Revisiting the Moisture Budget of the Mediterranean Region in the ERA5 Reanalysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13767, https://doi.org/10.5194/egusphere-egu23-13767, 2023.

X5.210
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EGU23-15233
The new reality of the Mediterranean: accelerating impacts of climate change 
Samira Khodayar Pardo, Paco Pastor, Jose Antonio Valiente, Laura Paredes-Fortuny, and Pau Benetó

The Mediterranean basin is a hot spot for climate change warming up to 1.5 times faster than the rest of the world with the Mediterranean Sea warming three times more than the oceans (MedECC 2020). A consensus exists about the magnification of extreme phenomena in the area under climate change (IPCC 2021). In fact, several types of risks currently affect and will continue affecting the region severely, from more frequent extreme weather events such as heat waves, droughts, or floods, to increasing sea surface temperature and coastal erosion due to rising sea levels. The impacts affect the region's ecosystems, economic activities, and, ultimately, human health. In addition, the effects also spread like “cascades” that generate multiple impacts in all socioeconomic sectors. Current change and future scenarios consistently point to significant and increasing risks during the coming decades in most impact domains such as water and energy resources, ecosystems, agriculture and food, fishery, health, and human security.

The impacts of climate change have accelerated on the Mediterranean coast of the Iberian Peninsula in the last decades. In this presentation, we will discuss this acceleration based on observations of the notorious and progressive rise in atmospheric and sea surface temperature and the generalized reduction of mean accumulated precipitation in the region. In this context, the magnification of extreme weather phenomena in the region will be described in detail focusing on the spatio-temporal evolution of terrestrial and marine heat waves, droughts as well as catastrophic extreme precipitation in the autumn period.

How to cite: Khodayar Pardo, S., Pastor, P., Valiente, J. A., Paredes-Fortuny, L., and Benetó, P.: The new reality of the Mediterranean: accelerating impacts of climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15233, https://doi.org/10.5194/egusphere-egu23-15233, 2023.

X5.211
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EGU23-17496
Map viewer of the CLICES project: information analysis tool and educational activity 
Dhais Peña Angulo, Victor Trullenque-Blanco, José Carlos González-Hidalgo, and Santiago Beguería

CLICES project (CLImate of the last Century in Spain) has been focused on temperature and precipitation analyses in mainland Spain during 1916-2015 period. To do that, information from National Meteorological Agency archives have been combined with data rescued from Annual Books (1916-2015) and high resolution grid (10x10 km) have been calculated. A web page has been created during the CLICES project with information on its main results, including a Map viewer section to allow view and consult the distribution of weather stations over time in the mainland Spain. The Map viewer includes information related to weather stations locations for the monthly temperature and precipitation for the 1915-2015 period. In addition, the Map viewer shows auxiliary information that includes elevation (shading), communication routes, and administrative bounderies. One of the great utilities that the Map viewer is to know the history of the spatial distribution of the meteorological stations, which have been linked to the socioeconomic history of mainland Spain itself. For example, the initial stations were mostly located in the main cities (capitals of province) before 1920, and then during 30´to 60´ data were recorded in a dense network stations. Maximum spatial density was achieved around 70´s and then a global decline in the network is observed. All these aforementioned facts must be considered when spatial and temporal analyses of the main elements of climate were performed. Then Map viewer can be used as a useful tool in educational activities from a geographical point of view which allows students to explain certain natural phenomena at different spatial scales, and their relationships with different elements of space. To access the Map viewer of the CLICES project, you must visit the website www.CLICES.unizar.es. Up to date to 2020 is being under current development.

How to cite: Peña Angulo, D., Trullenque-Blanco, V., González-Hidalgo, J. C., and Beguería, S.: Map viewer of the CLICES project: information analysis tool and educational activity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17496, https://doi.org/10.5194/egusphere-egu23-17496, 2023.

Posters virtual: Mon, 24 Apr, 10:45–12:30 | vHall CL

Chairpersons: Katrin Schroeder, Richard Seager
vCL.12
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EGU23-12819
Flow reversals and deep-water temperature and salinity trends in a Mediterranean Channel (2003-2019) 
Katrin Schroeder, Sana Ben Ismail, Mireno Borghini, Stefania Sparnocchia, and Jacopo Chiggiato

The Sardinia Channel (Mediterranean Sea) is a wide opening between Tunisia and Sardinia which has a sill at about 1900 m in a narrow deep trench that allows exchanges of the upper part of the deep waters to occur between the Algerian and the Tyrrhenian subbasins. The densest part of Western Mediterranean Deep Water (WMDW), which is trapped in the Algerian subbasin, is thus overflowing the sill when uplifted by recent and even denser WMDW. The less dense WMDW, circulating anticlockwise and alongslope may enter the Sardinia Channel directly following the Algerian slope. There is another water mass exchanged in this region, the Tyrrhenian Deep Water (TDW) which is a mixing product between the WMDW and waters coming from the Eastern Mediterranean.

The monitoring of thermohaline properties and currents has been operated at the sill between 2003 and 2019, to observe the variability of the deep water exchanged between the two adjacent subbasins. The θ time series collected at the sill since July 2003 shows an alternation of WMDW presence (lower θ and S, generally flowing eastward) and TDW presence (“pulses” of higher θ and S, generally flowing westward). Those TDW pulses are generally of short duration (between 1 day and 1 week) and are likely to be due to displacements of the interface between the two deep water masses. Thus, the mooring alternatively sampled WMDW (mainly) and TDW.

The Sardinia Channel trend component shows a continuous warming trend at a rate of 0.0067± 3.47*10-6 °C year-1, accounting for a total deep temperature increase of about 0.114 °C from 2003 to 2019. The salinity trend also shows a salinification at a rate of 0.0032 ±  2.02*10-6 year-1, with a total deep salinity increase of about 0.054 from 2003 to 2019. The density trend component shows a continuous densification at a rate of 0.0011± 9.60*10-7  kg m-3 year-1, with a total deep density increase of about 0.0187 kg m-3 from 2003 to 2019.

The ongoing climate change has amplified the scientific interest in time series and their importance is increasingly recognized even at the political level. Nonetheless, due to their high maintenance costs and the difficulty in maintaining them, they are still widely lacking. It is important to stress that an understanding of physical-chemical-biological processes in the oceans requires regular and long-term observations, that enable us to separate real long-term trends in environmental drivers from the natural variability of the system.

How to cite: Schroeder, K., Ben Ismail, S., Borghini, M., Sparnocchia, S., and Chiggiato, J.: Flow reversals and deep-water temperature and salinity trends in a Mediterranean Channel (2003-2019), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12819, https://doi.org/10.5194/egusphere-egu23-12819, 2023.

vCL.13
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EGU23-14381
Long-term climatic trends for the Mediterranean region and their association with atmospheric circulation 
Chris G. Tzanis, Aris Nasl Pak, and Kostas Philippopoulos

The Mediterranean region is characterized by high vulnerability and changes in the atmospheric circulation and water cycle with significant socio-economic implications. Many regions in the Mediterranean basin face extreme climate events, while others do not exhibit the same sensitivity to climate change. In this study, the spatial and temporal variability of climatic parameters such as precipitation, temperature, and dew point are investigated. Furthermore, their sensitivity to changes in atmospheric circulation is also examined in terms of the response of the surface climatic conditions for different atmospheric circulation types. Long-term data are extracted from the ERA 5 reanalysis dataset over the period of 1961-2020 (70 years) at a spatial resolution of 0.25° × 0.25°. The analysis procedure includes the identification of trends in the time series using the non-parametric Mann-Kendall and Sen's methods. Regions with statistically significant trends are identified and discussed. Discrepancies are also examined between the trends identified from the ERA 5 reanalysis datasets and from E-OBS and in-situ climate records. The atmospheric circulation framework is based on the following a) Definition of the spatial and temporal scales, b) Standardization of the spatial and temporal time series and data reduction using Principal Components Analysis c) Classification and assignment of cases into atmospheric circulation regimes using the k-means algorithm and d) Atmospheric circulation regimes assembly of the daily regimes (weather types) catalog. Trends and high-impact areas of global warming are identified and therefore the association between atmospheric circulation and climate change is highlighted.

How to cite: Tzanis, C. G., Nasl Pak, A., and Philippopoulos, K.: Long-term climatic trends for the Mediterranean region and their association with atmospheric circulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14381, https://doi.org/10.5194/egusphere-egu23-14381, 2023.

vCL.14
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EGU23-14875
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ECS
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Comparison of CMIP5 and CMIP6 mid- and end-century precipitation changes in California 
Desislava Petrova, Patricia Tarin-Carrasco, Aleksandar Sekulic, Jelena Lukovic, Maria Gali Reniu, Xavier Rodo, and Ivana Cvijanovic

Climate models have projected an overall drying in Mediterranean climate zones, with the exception of California, where the models have been split between predicting wetter or drier future conditions. This uncertainty is problematic for a major economy, where water scarcity, especially in southern California, has been an issue of concern during the last few decades. Here we compare the future projections of California’s winter (December, January, February) precipitation changes from the latest Coupled Model Intercomparison Project Phases 6 (CMIP6) and 5 (CMIP5). Over northern California the models from both ensembles agree on wetter future conditions. However, over southern California the models are almost equally divided between wetter or drier conditions, with projections ranging from -30% to +70% in CMIP5 and -20% to +80% in CMIP6 for the end of the century. The CMIP6 ensemble indicates wetter overall conditions, and features a larger model disagreement compared to CMIP5.

Interannual precipitation indicates more extremely wet or dry years over southern California in CMIP6 than in CMIP5. Some models even suggest that the five wettest years will account for as much as ~55% of the total 20-year rainfall considered, and the five driest for as little as ~5%. Dynamically, both ensembles project weakened subsidence over Baja California. This effect is stronger in CMIP6 than in CMIP5, consistent with the wetter mean conditions in CMIP6. In the western tropical Pacific our results point to strengthening of the Hadley circulation in CMIP6 that is not seen in CMIP5, and El Niño conditions prevailing over La Niña. CMIP6 models also project a stronger overall impact of ENSO on California’s precipitation than CMIP5 models.

How to cite: Petrova, D., Tarin-Carrasco, P., Sekulic, A., Lukovic, J., Gali Reniu, M., Rodo, X., and Cvijanovic, I.: Comparison of CMIP5 and CMIP6 mid- and end-century precipitation changes in California, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14875, https://doi.org/10.5194/egusphere-egu23-14875, 2023.

vCL.15
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EGU23-15428
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Highlight
Climate risk assessment for cereal and livestock sectors in Mediterranean areas 
Valentina Mereu, Josè Maria Costa-Saura, Antonio Trabucco, and Donatella Spano

Assessing climate-related risks on key economic sectors is of paramount relevance to inform policy makers and support the decision making process in designing adaptation plans and strategies to cope with climate change. Agriculture in the Mediterranean area is already experiencing negative impacts of climate changes and urgent adaptation actions are required to increase the resilience of agricultural systems. This study applied the impact chain approach to assess the expected climate risks for the cereal and livestock sectors to support the development of the Regional Adaptation Strategy to Climate Change (SRACC) of Sardinia (Italy) Region. Statistical socio-economic indicators were integrated with crop simulation models output and climate change scenarios to 2050, to investigate the exposure, vulnerability and hazard components according to the IPCC framework. The results were elaborated at the regional and municipal level to provided information for policy-makers at different administrative levels. This information allows the identification of the areas with greatest impact and the most critical aspects for which to focus adaptation efforts.

How to cite: Mereu, V., Costa-Saura, J. M., Trabucco, A., and Spano, D.: Climate risk assessment for cereal and livestock sectors in Mediterranean areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15428, https://doi.org/10.5194/egusphere-egu23-15428, 2023.

vCL.16
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EGU23-15435
Is climate the main driver of Mid-Holocene settlement dynamics on the Varamin plain? 
Fabian Kirsten, Anne Dallmeyer, Robert Busch, Thomas Böhmer, Reinhard Bernbeck, Susan Pollock, and Brigitta Schütt

For different areas throughout West Asia and the Middle East, settlement discontinuities and periods of cultural decline in the Mid-Holocene have been attested. Whether these phenomena were caused mainly by climatic factors, especially periods of drought, has been an ongoing scientific debate of the last decade(s).  One of these regions, the Varamin plain, is located few kilometers east of Teheran on an alluvial fan along the southern slopes of the Elburs-mountain-range (Northern Iranian Highlands). A recent archaeological survey on the Varamin plain revealed a striking absence of archaeological finds for the end of the Proto-Elamite period (Early Bronze Age) between approximately 5000 and 4100 BP that has been interpreted as a (temporal) abandonment of the plain. This crisis presumably lasted until the beginning of the Iron Age around 3500 BP.

Since paleoenvironmental and paleoclimatic information for this region are scarce, this study makes use of 3 different approaches to unravel the Holocene climate variability in West Asia in general and the Northern Iranian plateau specifically: a) analysis of climate reconstructions, b) a high-resolution snapshot simulation performed in ICON-NWP for the mid-Holocene time-slice (7000 BP) and c) a transient simulation performed with the Max Planck Institute Earth System Model (MPI-ESM) spanning the period from 8000 BP to pre-industrial (PI, 100 BP).

The comparison of the regional proxy-based climate reconstructions reveals a considerable degree of hetegorenity, impeding any straightforward inferences regarding possible paleoclimatic forcings for settlement dynamics. In particular, no specific drought period can be identified that coincides with the settlement crisis.

The model results show that there is a general aridification trend between 7000 BP and PI in West Asia. While absolute annual mean precipitation changes are small, the model data reveal a shift in seasonality of precipitation with drier autumns and winters but substantially wetter conditions during spring during mid-Holocene times. In combination with longer and colder winters during the Mid-Holocene, this may have enhanced water availability and therefore favored agricultural production.  Superimposed on this minor aridification trend, the model shows pronounced climatic variability with distinct multi-decadal wet and dry periods with variations of up to +/-12% in precipitation. Therefore, we cannot exclude that climatic events and variability including their geomorphological responses may have played a role in settlement discontinuties, but we can not clearly identify climate changes as the main driver.

How to cite: Kirsten, F., Dallmeyer, A., Busch, R., Böhmer, T., Bernbeck, R., Pollock, S., and Schütt, B.: Is climate the main driver of Mid-Holocene settlement dynamics on the Varamin plain?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15435, https://doi.org/10.5194/egusphere-egu23-15435, 2023.

vCL.17
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EGU23-16437
Potential effects of climatic trends on crop yield in the Mediterranean 
Emilio F. Santiago-Ventura and Andrea Román-Sánchez

Current climatic conditions tend to increase the frequency of droughts and may lead to increased aridity and evapotranspiration. This trend can cause adverse effects on agricultura due to water stress. Spain is the only country in Europe that is being affected by a characteristic aridity process according to USGS (2017). Andalusia, Southern Spain, is the most important agricultural region in Europe and one of the hardest affected by aridity. However we know little, if anything, about the relationship between aridity and crop yields in this region. Using data from ECAD and AEMET from more than 100 weather stations over the period 1959-2022, the temporal and spatial variability and trend of temperature and precipitation are analysed. Calculations are made for several indices of drought, aridity, continentality and oceanity to examine the relationship between them and the yield of a wide variety of crops. A high concentration and reduction of precipitation has been observed and the results obtained reflect a correlation between these indices of aridity, drought and continentality and the yield of selected crops. The trend of increasing aridity can be considered as a key factor in crop yields, especially in rainfed crops.

How to cite: Santiago-Ventura, E. F. and Román-Sánchez, A.: Potential effects of climatic trends on crop yield in the Mediterranean, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16437, https://doi.org/10.5194/egusphere-egu23-16437, 2023.