Advanced climate models project a substantial decrease in future precipitation for the Mediterranean, consistent with recent observational studies suggesting declining rainfall levels often attributed to human-driven climate change. However, other researchers highlight significant variability in Mediterranean precipitation due to atmospheric circulation patterns, with overall stability over the long term. Given these conflicting findings, a detailed evaluation of precipitation trends is essential, relying on high-quality, densely distributed observational data and comparing climate model simulations with historical observations. Using a dataset from over 23,000 stations across 27 countries, we have demonstrated that Mediterranean precipitation has remained largely stable, exhibiting variability over multi-decadal and annual scales. While earlier studies have frequently linked the relatively small number of significant precipitation trends identified to anthropogenic influences, it seems more plausible that such trends are driven through variability in atmospheric circulation driven by the internal variability. Notably, this study found limited evidence of human activity directly affecting the atmospheric circulation mechanisms, whether on a large or regional scale. Moreover, our findings align with CMIP6 model simulations, both of which suggest the absence of a consistent long-term trend in precipitation.
How to cite: Vicente Serrano, S. M. and the Mediterranean Precipitation Analysis Team: Mediterranean precipitation remains stationary and is primarily driven by the natural dynamics of atmospheric circulation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7479, https://doi.org/10.5194/egusphere-egu25-7479, 2025.
The Middle East is a "hot spot" for climate change. Global climate models (GCM) have low spatial resolution and cannot capture the spatial variability of the region's climate. We developed a statistical downscaling (SD) method to assess expected temperature changes in diverse climate zones of the Eastern Mediterranean. The SD algorithm is based on finding past synoptic conditions ("analogues"), also known as the K-nearest neighbors (KNN) method. This method links coarse spatial resolution GCMs with past local measurements of temperature to provide the local future estimates.
The SD was trained on ERA5.1 reanalysis to characterize past synoptic conditions and 30 homogenized past local observations of surface temperature for the period 1979-2014. The algorithm optimization and validation were achieved through cross-validation against the historical observations. The process showed that gridded surface temperatures from global models are enough for optimal accuracy. The algorithm has been applied on 10 CMIP6 models for the historical period, the SSP245 [greenhouse gases (GHG) emissions rate decreases till the end of the 21st century] and the SSP585 (GHG emissions significantly increase till the end of the 21st century) scenarios.
Cross-validation of ERA5.1 and CMIP6-models downscaled results for the historical period show that the minimum and maximum temperature distributions generated by the SD algorithm closely fit those at the 30 measurement stations. Moreover, they are significantly more accurate than those derived from the coarse-resolution CMIP6 models, which show cold-biased thinner distributions.
After validation of the algorithm, we apply it to downscale CMIP6 models for the 2080-2100 period. The downscaled SSP245 scenario shows that minimum and maximum temperatures increase by up to 5o C and 4o C with respect to the reference historical period, respectively. For the downscaled SSP585 scenario maximum changes are as large 7o C and 5o C for minimum and maximum temperatures, respectively. More significant warming is observed during the cold season, in agreement with previously reported studies for the Northern hemisphere extra-tropics. The downscaled temperature estimations show their usefulness in projecting future temperatures at fine spatial resolution (well below the GCMs spatial resolution) that capture different climate characteristics (e.g., urban versus rural locations, low elevation versus mountain terrain), not possible to appropriately estimate from coarse GCMs.
On-going work focuses on additional future time periods and scenarios, further improvement of the algorithm in dealing with out-of-sample data, geographic transferability and use of the projected downscaled temperatures in human health studies.
How to cite: Garfinkel, C., Rostkier-Edelstein, D., Gelman, A., Morin, E., and Schendrik, L.: Projected temperature changes in the Eastern Mediterranean for the 21st century from downscaled GCMs , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9271, https://doi.org/10.5194/egusphere-egu25-9271, 2025.
The increasing duration and intensity of heatwaves have become a growing concern due to their implications for health, economy and agronomy. The data from the reference period 1950-2017 from different studies around the globe indicates an average increase of 1 day per decade in heatwave duration and between 2 and 6 °C per decade in intensity. This phenomenon is particularly evident in cities such as Valencia and other locations in the Mediterranean region, where extreme temperatures have reached record levels. In Valencia, for example, the highest temperature in its history was recorded in 2023, at 46.8 °C.
The objective of this contribution is to project trends for heatwaves by estimating various features, such as their duration, intensity, and cumulative impact, using heat index (HI) as a key metric to evaluate the risk and the degree of exposure associated with these extreme events in the Mediterranean city of Valencia. The analysis applies daily maximum temperature and relative humidity data for the period 1979 to 2100 from five global climate models of the CMIP6 (GFDL-ESM4, IPSL-CM6A-LR, MPI-ESM1.2-HR, MRI-ESM2-0, UKESM1-0-LL) and historical observations (1979-2014), processed with ERA5-Land grids (~9 km) and classified by climate change scenarios defined in the IPCC Sixth Assessment Report. Heatwave intensity was assessed using the HI, which combines temperature and humidity to estimate thermal sensation and its effects on health.
Since 2010, heatwaves have shown a significant increase in duration and intensity in Valencia. Between 2011 and 2013, the total number of heatwave days exceeded 25 days per year, with intensity peaks above 50 °C. Climate models reflect similar trends to historical trends, with MPI-ESM1-2-HR showing the closest alignment to the historical trend.
In the climate change analysis period from 2014 to 2100, the SSP370 and SSP585 scenarios show a more accelerated increase in exposed days and extreme heat values, with the most pronounced trends occurring after 2055. In contrast, the SSP126 scenario suggests stagnation in the duration and intensity of heatwaves at 2014 levels in some models. However, projections from models such as IPSL-CM6A-LR and MRI-ESM2-0 indicate persistently high values throughout the period, highlighting variations in model responses even under the same scenario.
The results highlight the rising trends in the intensity and duration of heatwaves in Valencia, clearly illustrating their progression over time in the context of climate change and the increasing frequency of extreme events. The use of the HI as a metric underscores its implications for human health and well-being. These findings emphasize the need for adaptive and preventive measures to address the growing impacts of heatwaves on the most vulnerable populations, especially in the Mediterranean cities.
Acknowledgements:
This study has received funding from the: “THE HUT project” (The Human-Tech Nexus – Building a Safe Haven to cope with Climate Extremes), under the European Union’s horizon research and innovation programme (GA No. 101073957).
How to cite: Fernandez-Garza, A., Gielen, E., Pulido-Velazquez, M., Rubio-Martin, A., Macian-Sorribes, H., and Avila-Velasquez, D.: Climate change projections of heatwaves in Valencia (Spain) using a heat index analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16524, https://doi.org/10.5194/egusphere-egu25-16524, 2025.
In recent years, an increase in the frequency and intensity of cyclones with tropical characteristics has been observed in areas of the Mediterranean Sea (De la Vara et al., 2021). The rise in this type of cyclones has triggered extreme weather conditions in many Mediterranean coastal regions (Romero & Emanuel, 2013). With the increasing focus on the study and characterisation of these types of cyclones (Gutiérrez-Fernández et al., 2024), numerous research efforts have employed different methodologies to investigate the favourable conditions for the development of cyclones with tropical characteristics in the Mediterranean (Romero & Emanuel, 2017). Among the methods used to study the favourable conditions for the development of tropical cyclones, one of the most widely applied is the Potential Intensity (PI; Holland, 1997). This index measures the theoretical maximum intensity a cyclone with tropical characteristics can achieve under specific atmospheric conditions. This method has been investigated in numerous studies on tropical cyclones and demonstrates that high values of this index are associated with a higher likelihood of intense tropical cyclone development (Emanuel, 2005; Wing & Camargo, 2007).
Therefore, the main motivation for this study is to analyse the evolution of the Potential Intensity (PI) over the past 70 years in the Mediterranean region. For this purpose, ERA5 reanalysis data (Hersbach et al., 2023) covering the period from 1950 to 2023 over the Mediterranean basin were used. The results indicate an increase in the values of this index, particularly during the autumn months, when most cyclones with stronger tropical characteristics occur. Finally, an individual analysis of this index was conducted under pre-development conditions for recent cyclones with tropical characteristics in the Mediterranean.
de la Vara, A., Gutiérrez‐Fernández, J., González‐Alemán, J. J., & Gaertner, M. A. (2021). Characterization of medicanes with a minimal number of geopotential levels. International Journal of Climatology, 41(5), 3300-3316.
Emanuel, K. (2005). Genesis and maintenance of" Mediterranean hurricanes". Advances in Geosciences, 2, 217-220.
Gutiérrez‐Fernández, J., Miglietta, M. M., González‐Alemán, J. J., & Gaertner, M. A. (2024). A new refinement of Mediterranean tropical‐like cyclones characteristics. Geophysical Research Letters, 51(8), e2023GL106429.
Hersbach, H., Bell, B., Berrisford, P., Biavati, G., Horányi, A., Muñoz Sabater, J., Nicolas, J., Peubey, C., Radu, R., Rozum, I., Schepers, D., Simmons, A., Soci, C., Dee, D., Thépaut, J-N. (2023): ERA5 hourly data on pressure levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS), DOI: 10.24381/cds.bd0915c6 (Accessed on 29/10/2024)
Holland, G. J. (1997). The maximum potential intensity of tropical cyclones. Journal of the atmospheric sciences, 54(21), 2519-2541.
Romero, R., & Emanuel, K. (2013). Medicane risk in a changing climate. Journal of Geophysical Research: Atmospheres, 118(12), 5992-6001.
Romero, R., & Emanuel, K. (2017). Climate change and hurricane-like extratropical cyclones: Projections for North Atlantic polar lows and medicanes based on CMIP5 models. Journal of Climate, 30(1), 279-299
Wing, A. A., Sobel, A. H., & Camargo, S. J. (2007). Relationship between the potential and actual intensities of tropical cyclones on interannual time scales. Geophysical research letters, 34(8).
How to cite: Gutiérrez-Fernández, J., Alvarez Castro, C., and Rodriguez-Guisando, E.: Is there an increase in favourable conditions for the development of cyclones with tropical characteristics in the Mediterranean basin? A study of Potential Intensity in the Mediterranean Region over the last 70 Years, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16866, https://doi.org/10.5194/egusphere-egu25-16866, 2025.
This study focused on four Mediterranean Sea (MS) cyclones classified as medicanes: Zorbas, Ianos, Apollo, and Daniel. Each of these cyclones traversed warm-core eddies (WCEs) during their propagation. We explored the influence of these eddies on the cyclones' development and examined how the eddies, including their biogeochemical properties, responded to the passage of the cyclones. Cyclones Zorbas and Apollo intensified considerably in close proximity to the WCEs. The intensification was accompanied by moisture convergence, yielding substantial precipitation. Additionally, chlorophyll-a concentrations and Phytoplankton increased after the cyclone passed over a WCE. Cyclone Ianos, the strongest recorded cyclone in the MS, underwent only marginal intensification above the WCE. However, in this case, a strong marine heatwave (MHW) was present later during the intensification, releasing more latent and sensible heat fluxes due to the high ocean heat content (OHC). Medicane Daniel has stood out as the deadliest recorded storm in Mediterranean history. Our analysis identified the presence of a WCE (OHC) and a moderate MHW at the location where the medicane intensified. These conditions led to high moisture convergence, increased total column water, and significant precipitation. Since the WCE and MHW features were situated near the coastal region, the medicane reached its maximum intensity just before landfall, potentially contributing to the reported severe damage in Libya. In the case of Ianos and Daniel, chlorophyll-a concentrations and Phytoplankton increased at the MHW location. All four cyclones responded similarly to elevated temperatures at the mesoscale (i.e., WCE) and regional scale (i.e., MHW). Our results stress the importance of mesoscale and regional SST variability and how they may regulate extreme storms like medicanes.
How to cite: Jangir, B. and Strobach, E.: Interaction between Medicanes and the Mediterranean Sea: Investigating Sea Surface Temperature Anomalies in the path of medicanes and the Case study of Medicane Daniel, the Deadliest Mediterranean Cyclone, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-934, https://doi.org/10.5194/egusphere-egu25-934, 2025.
The Mediterranean Sea undergoes a long-term salinification and warming with strong implications for its overturning circulation and subsequently for its regional climate. In this study ERA5 atmospheric reanalysis and En4 hydrographic monthly datasets were used to investigate the impacts of changing air-sea fluxes and stratification on deep water formation of the Mediterranean Sea over 1979-2023. Results indicate non-significant long-term changes in winter net heat flux controlling deep water formation at the major formation sites of the two sub-basins. However, winter sensible and latent heat fluxes show a pronounced decreasing trend resulting in a strong reduction of winter ocean heat loss in the Gulf of Lions over the last two decades. This is contrasted by increased turbulent air-sea heat fluxes driving enhanced winter ocean heat loss in the Aegean Sea during the same period. Large salinity increases are obtained across the basin mainly induced by warming-driven evaporation increases over 1979-2023. This excessive salinification may have strongly enhanced salt preconditioning in all major dense water formation sites, sustaining deep water formation despite of the increasingly warming climate. Results reveal that temperature and salinity increases largely counteract each other resulting in relatively small changes in density in most parts of the basin. However, the density contrast is significantly increasing between the upper layer which becomes lighter due to excessive surface warming and the deeper layers affected by large amounts of saltier/denser water masses mainly formed during strong climatic transient events in both sub-basins under anomalous winter surface cooling over one or two severe winters, particularly during the East Mediterranean Transient (EMT) in the early 1990’s and the Western Mediterranean Transition (WMT) in the mid-2000s. The combined effects of increased water-column stratification and decreasing winter ocean heat loss can have dramatic impacts on deep water formation as evidenced in the Gulf of Lions over the last decade.
How to cite: Skliris, N., Marsh, R., Breedon, M., and Josey, S.: Recent salinification, warming and stratification changes impacting deep water formation in the Mediterranean Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16860, https://doi.org/10.5194/egusphere-egu25-16860, 2025.
Due to the Adriatic basin unique orography-driven dynamics, the atmosphere-ocean interactions within this region are poorly represented in currently available regional climate models. To address this gap, the Adriatic Sea and Coast (AdriSC) kilometer-scale atmosphere-ocean model was developed to provide a more accurate assessment of climate hazards in the Adriatic under historical (1987–2017) and far-future (2070–2100) conditions. Our analysis of AdriSC model projections for the far-future climate reveals significant and alarming changes. These include pronounced land-sea atmospheric contrasts, intensified heatwaves, extreme rainfall, and droughts. Additionally, we observe enhanced surface saline lake effects during summer, a contracting yet intensified southern Adriatic cyclonic gyre, and strengthened vertical stratification over the South Adriatic Pit. Several of these changes, such as more frequent and prolonged heatwaves, are already observable and causing widespread socio-environmental impacts. Shifts in precipitation patterns, with altered timing and intensity, are increasing the risk of both droughts and floods, while rising ocean temperatures, salinities, and marine heatwaves are threatening marine ecosystems, fisheries, and aquaculture. These findings highlight the critical importance of robust kilometer-scale atmosphere-ocean modeling for accurately projecting and addressing extreme climate events. Expanding the AdriSC experiment with ensemble simulations under multiple climate scenarios would further enhance the reliability of these projections, providing invaluable insights for policymakers and local communities. Such work is essential for the development of effective adaptation and mitigation strategies to address the evolving climate challenges in the Adriatic region.
How to cite: Vrdoljak, I., Denamiel, C., and Vilibić, I.: Kilometer-scale trends, variability, and extremes of the Adriatic far-future climate (RCP 8.5, 2070−2100), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-407, https://doi.org/10.5194/egusphere-egu25-407, 2025.
As warming and drying future conditions may significantly affect the human and natural environment in the Mediterranean, the climate risks and vulnerabilities assessments are key to support adaptation strategies. In this context, the Portuguese National Roadmap for Adaptation 2100 (RNA2100) aimed at providing scientific support to adaptation policy exercises by (1) identifying and characterising climate change impacts on the most vulnerable domains in Portugal Mainland; (2) characterising socioeconomic impacts on different territorial scales and assess financial needs; and (3) contributing to the implementation of a National Spatial Planning Policy Programme. The most vulnerable domains focused by the RNA2100 include the coastal regions, water resources/agroforestry and wildfires. The RNA2100 followed three stages: regional climate scenarization, biophysical impacts for a number of sectors and hazards, and the economic analysis of selected impacts. The future projected climate for Portugal was characterized using a weighted multi-model multi-variable ensemble based on the EURO-CORDEX Phase I simulations, produced at 12 km resolution. One historical present climate period (1971-2000) and three future periods (2011-2040, 2041-2070, 2071-2100), under three different scenarios (RCP2.6, RCP4.5 and RCP8.5), were considered. The biophysical impact modelling was performed for four climate impact sectors: coastal erosion and flooding, forest fires, water and agroforestry systems.
Climate change poses a significant threat to water resources and agroforestry in mainland Portugal. Southern regions, particularly beyond the Tagus River, will face more significant impacts, with the Water Exploitation Index plus (WEI+) potentially increasing by up to +99 percentage points under RCP8.5 or around +22 points under RCP4.5. Without adaptation, economic losses in crop yields could reach €426 million annually under the moderate mitigation scenario and approach €670 million under the high emissions scenario. Even meeting Paris Agreement targets could still result in yearly losses of €172 million by 2100. The discourse on climate adaptation and wildfire management in the five NUTS II regions emphasizes the importance of multifaceted strategies in confronting the escalating threat of wildfires exacerbated by climate change. The results emphasize the pivotal role of awareness initiatives with coercive measures to effectively reduce ignitions and mitigate projected losses (saving from 290,000 euros/year in A.M.L. to 88 million euros/year in Centro). Portuguese coastal areas are extensively vulnerable to climate change impacts, with projections showing up to 587 km2 (RCP4.5) and 604 km2 (RCP8.5) of vulnerable coastlines by the end of the 21st century. Adaptation is overall recommended at national scale, despite the different results yielded by the cost-benefit analysis, depending on the region. Total inaction costs (without adaptation) are projected to surpass 12000 million € (RCP4.5) and 14000 million € (RCP8.5) until 2100, in contrast with approximately 5000 million € (for both scenarios) of expected adaptation costs.
Acknowledgements
This work is supported by the Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES through national funds (PIDDAC): UID/50019/2025 and LA/P/0068/2020 https://doi.org/10.54499/LA/P/0068/2020).
How to cite: Soares, P. M. M. and Team, F. O. S. O. T. U. O. L.: The Portuguese National Roadmap for Adaptation 2100: from regional climate simulations to economic costs and adaptation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13271, https://doi.org/10.5194/egusphere-egu25-13271, 2025.
Farmers confront a range of climate change-induced stressors, such as increasing temperatures, variations in rainfall, and the heightened frequency and intensity of extreme weather events, underscoring the varying risks in challenging decision-making processes. Increasing the success in adapting to climate extremes largely depends on a thorough understanding of farmers’ perspectives and abilities to face both immediate and prolonged climate disturbances. Strategies can differ based on intention (independent or self-directed), duration (short- or long-term), type and level of engagement (individual or community, local or global), and nature (technical, financial, institutional), whether they are applied before or after severe weather events and concurrent extremes. Furthermore, internal drivers (e.g., farmers’ characteristics, experiences, attitudes) and external predictors (e.g., innovation and technology, costs, incentives, support) tend to influence farmer risk perception, preparation intention, and adaptive capacity. Hence, it is imperative to conduct a conscientious assessment of how farmers face climate change to gain a deeper understanding of their vulnerability or resilience, and effectively move to increasing their adaptive capacity.
Following a bottom-up approach, this contribution delves into farmers’ behaviour regarding climate change by considering climate change awareness, perception, and adaptation. We conducted 921 surveys randomly among farmers in California, known as the California’s agricultural hub, concentrating about five million hectares growing more than 250 crops and producing ¼ of the nation’s food production. As one of the most climatically vulnerable regions globally, it is essential to examine how farmers experience, perceive, and respond to more frequent and intense extremes events (e.g., heatwave, drought, wildfire, erratic rainfall) together with evaluating the nature and nuance of (anthropogenic) climate change scepticism. Three main questions are addressed through descriptive and inferential statistics: 1) Do farmers recognize climate change as a major issue and identify who is responsible for? 2) What are the most perceived impacts and which effects are more evident among the farming community? and 3) How significantly do farmers promote adaptation strategies and what barriers reduce their resilience?
Preliminary results highlighted that 1) Farmers believe their farm is exposed to extreme events (75%), particularly challenging for irrigated crops (80%), 2) Warmer temperatures, heatwaves and droughts together with decreased rainfall and snowpack are reported by at least half of farmers, increasing changes in plant growth (59%), and 3) 2 out of 3 farmers introduce soil conservation techniques and switching to more efficient irrigation methods. However, some barriers are hindering adaptation, such as the high cost of investment (72%), the increasing environmental regulatory requirements (68%) or the lack of funding to support climate adaptation (e.g., water trading programs), which was pinpointed by half of the respondents. Additionally, we have explored the potential heterogeneity among farmers’ preferences and the influence and predictability between being aware and perceive climate change impacts, and perceive impacts and apply for adaptation measures. A better comprehension of the farmers’ behavior in terms of risk assessment and adaptive capacity can facilitate the transferability of bottom-up findings into behavior modelling as well as the customization of more targeted and flexible adaptation instruments and strategies.
How to cite: Ricart, S., Escriva-Bou, A., and Castelletti, A.: How Californian farmers perceive and react to climate change? A triple-loop approach to strengthening climate risk assessment from social learning, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4548, https://doi.org/10.5194/egusphere-egu25-4548, 2025.
San Bernardino Valley Municipal Water District (San Bernardino Valley) is a regional water management and resource agency in southern California, United States of America. San Bernardino Valley prioritizes collaborative approaches to climate adaptation and working with partner agencies and land managers within the watershed to develop innovative strategies to provide sustainable water supply and support the changing needs of our region’s people and environment. Climate change continues to alter climate conditions in southern California, a Mediterranean climate region. Changes in temperature, aridity, rainfall, and storm patterns present highly variable challenges to San Bernardino Valley’s planning and operations. Water supply reliability will continue to be impacted by changes in availability of local water and water imported into the San Bernardino area from northern California. Extreme weather events such as heat waves, more intense rainfall, and extended droughts are likely to increase in frequency or severity. Climate change also increases our exposure to extreme wildfire and impacts from sea level rise that affects water imported from northern California. These conditions may threaten the durability of taxpayer investments in water projects and the habitat conservation efforts associated with those projects.
Over the last three years, San Bernardino Valley staff and Board of Directors worked with partner agencies and a consulting team to evaluate regional climate vulnerabilities and develop a Climate Adaptation and Resilience Plan (CARP). The CARP is an adaptive guide designed to strengthen the District’s water reliability and proactively address existing and future climate change impacts. The CARP provides a collaborative adaptive management process that promotes flexibility in the Agency's responses to changes in climate projections and adjustments based on real-world conditions, potentially decades into the future. The CARP outlines an ongoing phased implementation of actions over 20 years that will reduce or minimize risks to San Bernardino Valley's infrastructure, operations, and investments.
Development of the CARP included conducting a greenhouse gas emissions inventory, assessing climate risks and vulnerabilities, identifying proposed actions to increase our ability to adapt and be resilient in the face of climate change, and develop a phasing and implementation plan. The CARP is organized around four Guiding Principles: (1) Maintain a diverse water portfolio, (2) Protect the Water Portfolio, (3) Improve operational and infrastructure resilience, and (4) Connect people to water and climate. Measures and actions are organized in the CARP through the Guiding Principles, providing a holistic approach to increasing our region’s resilience across its water sources, the ecosystems that its water resources rely on, its infrastructure and operations, and water uses in the communities it serves.
San Bernardino Valley is committed to developing new data-driven measures and strategies, leveraging emerging technologies and products, and updating the CARP on an ongoing basis to meaningfully adapt to emerging climate threats and maintain progress towards achieving resilience. Much like the natural systems within the region, the agencies and communities of our watershed are integrally connected, each contributing unique pieces of the innovative solutions that will support a sustainable and resilient future for our people and our shared environment.
How to cite: Woodside, G., Ojo, A., Palenscar, K., and Feldman, E.: Climate Adaptation and Resilience Plan for San Bernardino Valley, California, USA, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14474, https://doi.org/10.5194/egusphere-egu25-14474, 2025.
The Mediterranean Sea, a semi-enclosed basin, has experienced periodic anoxic events that resulted in sapropels—organic-rich sediment layers formed during deep-water oxygen depletion. While the main processes driving sapropel formation are understood, the ecological and morphological responses of planktonic species to these extreme conditions remain largely unexplored. This study aims to fill this gap by examining the composition, tolerance, and ecological responses of calcareous planktonic species, with a focus on planktonic foraminifera Globigerinoides ruber morphotypes and pteropod populations across sapropel formation events. To investigate these responses, we analyzed one sediment core retrieved from the Gulf of Sirte, covering the last 130 k years with a focus on sapropels S1 and S5. Microfossil samples were investigated using a microfossil sorter (MiSo) Robot at CEREGE, which automatically images and measures microfossils from the coarse sediment fraction, unlike conventional approaches, which focus on species abundance and identification solely. This approach allowed us to determine both abundance and size of the different specimens, at the species level, through the training of a Convolutional Neural Network (CNN) which was applied to label a large dataset (160,000 images). Our results reveal significant shifts in planktonic community composition and diversity throughout the sapropels S1 and S5. Planktonic foraminifera diversity decreased during sapropels, notably with a reduction in species like Globigerinoides ruber and Globigerinoides elongatus. In contrast, pteropod abundance increased, suggesting they may be more resilient to environmental changes due to their higher motility compared to foraminifera and lower species competition during these anoxic periods. Size variations in dominant species were also observed, with distinct changes linked to environmental stressors such as lower salinity. This study provides valuable insights into the resilience and adaptability of planktonic species environmental changes, offering a more refined understanding of sapropel-related ecological impacts on marine communities.
How to cite: Chaabane, S., de Garidel-Thoron, T., Schultz, H., Conrod, S., and Tachikawa, K.: Ecological responses of planktonic foraminifera and pteropods to sapropel formation in the eastern Mediterranean Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15986, https://doi.org/10.5194/egusphere-egu25-15986, 2025.
Models robustly project decreases in net precipitation (precipitation minus evaporation, P–E) due to human-induced warming over the Mediterranean region, in qualitative agreement with the simple thermodynamic "dry-get-drier" scaling of the atmospheric moisture convergence (Held and Soden, 2006). This thermodynamic scaling, however, neglects changes in relative humidity and horizontal temperature gradients, which might be important in a region of large land–ocean contrasts, such as the Mediterranean. Here we explore if and to what extent the extended scaling of Byrne and O'Gorman (2015), which incorporates these gradients and is based on climatological moisture fluxes and changes in surface properties only, might better capture the thermodynamic response of the Mediterranean hydroclimate projected by the end of the 21st century by ten models in the phase 6 of the Coupled Model Intercomparison Project (CMIP6) archive.
According to the CMIP6 multi-model mean, the simple scaling for the mean thermodynamic component, in the absence of changes in atmospheric circulation and advection, causes a negative P–E tendency over the Mediterranean Sea and the surrounding land areas and a weak positive P–E tendency over northwestern Africa. This is indeed an amplified pattern of the time mean flow: there is increased moistening (drying) where the time mean flow is convergent (divergent) in the base climate.
The extended scaling, unlike the simple scaling, predicts a wettening over the ocean, in the annual mean and through the seasonal cycle. While not fully accounting for the magnitude nor the extent of the wettening due to the “full” thermodynamic adjustment of the Mediterranean hydroclimate, inclusive of thermodynamic contributions from both moisture convergence and advection, the extended scaling outperforms the simple scaling by partially capturing the overall signal. Throughout the region, differences between the simple and the extended scaling primarily arise from the contribution of the terms involving the gradients of fractional changes in near-surface relative humidity and changes in the near-surface temperature, with the term involving changes in relative humidity being negligible. Even if largely cancelling, the two gradient terms give rise to a pattern grossly characterized by moistening over the ocean and drying over neighboring land regions.
The results of this work highlight how thermodynamical changes in the Mediterranean hydrological cycle result from an interplay between different mechanisms, arising from the thermodynamical contributions from both moisture convergence and horizontal advection. While the extended scaling has been shown to be an effective approach in explaining the deviation of the global annual-mean P–E response over land from the "wet-get-wetter" paradigm, it has not been evaluated for regional studies or different seasons. Our study shows that regional studies, such as those focusing on the Mediterranean, could also benefit from the extended scaling, enhancing our understanding of future hydroclimate changes in this vulnerable region.
References:
- Byrne, M. P., & O’Gorman, P. A. (2015). The response of precipitation minus evapotranspiration to climate warming: Why the “Wet-get-wetter, dry-get-drier” scaling does not hold over land. Journal of Climate, 28(20), 8078–8092. https://doi.org/10.1175/JCLI-D-15-0369.1
- Held, I. M., & Soden, B. J. (2006). Robust Responses of the Hydrological Cycle to Global Warming. Journal of Climate, 19(21), 5686–5699. https://doi.org/10.1175/JCLI3990.1
How to cite: Tootoonchi, R. and Bordoni, S.: Is the Projected Aridification in the Mediterranean Region a Simple "Dry-Get-Drier" Response?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2949, https://doi.org/10.5194/egusphere-egu25-2949, 2025.
The Mediterranean region is particularly sensitive to climate change as it is located at the crossroads of atmospheric processes. In the Mediterranean, and particularly in it’s eastern parts, the rate of warming is more pronounced than the global mean rate of warming, with projected increase up to 2.5-3.0 °C and simultaneous decrease in precipitation of 15 % by the end of the century.
Here, we investigate the contribution of different climate drivers to regional warming trends, focusing in the summer season. We are analyzing surface and atmospheric temperature trends in simulations from nine climate models participating in the Precipitation Driver and Response Model intercomparison project (PDRMIP). The model simulations have assumed idealized and abrupt forcing applied in global scale, specifically: doubling the CO2 concentrations, 10 times the present-day black carbon concentrations, 5 times the SO4 concentration, 3 times the CH4 concentration and 2% increase in total solar irradiance (TSI). Model results are compared with trends in reanalysis datasets and long-term radiosonde soundings in selected locations in the eastern Mediterranean.
Increases in CO2, CH4 and TSI cause a very similar seasonal variation of the temperature amplification, with a stronger magnitude simulated at the upper troposphere. Consistent to the surface amplification, the strongest warming in the upper troposphere is found in the June-July-August (JJA) season. SO4 causes a stronger upper tropospheric temperature amplification, particularly in July and August. BC aerosols, on the other hand cause a considerably stronger amplification in the JJA season which spreads to the upper troposphere the following months.
Our analysis highlights the important role of aerosols in the observed summer-time temperature trends in the Mediterranean and mechanisms are discussed.
How to cite: Misios, S., Douvis, K., Stavraka, T., Kapsomenakis, J., Solomos, S., Gkikas, A., Spyrou, C., Fountoulakis, I., Poupkou, A., Kalabokas, P., and Zerefos, C.: Summer-time Mediterranean amplification to different climate drivers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8848, https://doi.org/10.5194/egusphere-egu25-8848, 2025.
Seagrass meadows are pivotal marine ecosystems supporting biodiversity, stabilizing coastlines, and acting as major carbon sinks worldwide. Yet, these habitats are increasingly threatened by climate change. This global pattern is especially evident in the Mediterranean Sea, where rising temperatures and ocean acidification surpass global trends. This study presents a comprehensive vulnerability assessment for key Mediterranean seagrass families (Cymodoceaceae and Posidoniaceae) under different climate scenarios, using the latest Shared Socio-economic Pathways (SSPs) from the IPCC’s 6th Assessment Report. We integrated species distribution models (SDMs) and climate-niche factor analysis (CNFA) to capture sensitivity (encompassing ecological marginality and niche specialization) and exposure (quantifying climate departure from baseline conditions). Our ensemble SDMs, trained on an extensive dataset of seagrass occurrences and multi-decadal environmental data, revealed high predictive performance for both Cymodoceaceae and Posidoniaceae. Results indicate that Posidoniaceae generally exhibit higher risk owing to slower growth rates and reduced adaptive capacity. Under moderate to high emission scenarios (SSP2-4.5 and SSP5-8.5), hotspots of heightened seagrass vulnerability emerge in the northern and eastern Adriatic Sea, the northeastern Aegean-Levantine Seas, and parts of the Western Mediterranean. A marked “tipping point” in exposure-vulnerability relationships suggests that even incremental increases in climate stressors can trigger disproportionate ecological responses. Further, while warming also poses a significant threat, our findings identify ocean acidification as a dominant driver of future seagrass declines in the Mediterranean, with vulnerability trends persisting beyond 2070 under high-emission pathways. These insights emphasize the urgent need for integrated climate mitigation and targeted regional management strategies, including robust greenhouse gas emission reductions and local conservation measures. By elucidating the spatial heterogeneity of seagrass responses, this study offers a critical framework to prioritize interventions, protect essential ecosystem services, and guide policy-making for sustaining Mediterranean marine biodiversity and coastal resilience in an era of rapid environmental change.
How to cite: He, B., Li, Q., Li, Z., Zhao, J., and Mari, L.: Advancing climate change vulnerability assessment of Mediterranean seagrass meadows, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11424, https://doi.org/10.5194/egusphere-egu25-11424, 2025.
This study investigates climate change patterns in the western region of Türkiye using high-resolution bioclimatic variables to capture the detailed spatial and temporal changes. It is funded by the project titled Predicting the Distribution of Future Basic Forest Tree Species Using Different Climate Projections and Developing Adaptation Strategies for Turkey' which is implemented under the “Climate Change Adaptation Grant Program (CCAGP)”.
The western part of Türkiye is characterized by vast agricultural areas and majority of the nation’s forest stock both of which play critical roles in the country's economy and ecology. The region's agricultural lands serve as one of the primary suppliers of food and resources to urban centers, ensuring food security and economic stability. Additionally, the forests in this area are ecological hotspots, hosting approximately 300 endemic plant species and contributing to biodiversity conservation. The importance of agriculture and forestry in the region emphasize the need for a thorough understanding of climate impacts, facilitating the development of sustainable agricultural and forestry management practices and policies to protect these vital resources.
To explore these dynamics in depth, we conducted the regional climate model simulations using COSMO-CLM at a convective permitting resolution 2.5 km x 2.5 km, driven by the EC-EARTH3-Veg from the CMIP6. These simulations were carried out for both historical (1995-2014) and future periods, including the mid-century (2050-2059) and the end of the century (2090-2099) under SSP3-7.0 scenario. To assess the reliability of the regional climate model, we compared its output with observational data from the region for the reference period. Key variables such as temperature and precipitation were analyzed, and their values were contrasted against the on-site measurements. Subsequently, we calculated bioclimatic variables for the reference period, as well as for the mid-century and end-of-century projections, to assess how these climatic changes might affect the region over time.
This high-resolution analysis enables a detailed assessment of 19 bioclimatic variables and their trends throughout the century how the agricultural and forest areas respond to climate change. Acquiring knowledge of the projected increase in temperature and the decline in precipitation by the end of the century is crucial for understanding the impacts on these vital areas, which are essential for ecosystem health and biodiversity. Under the SSP3-7.0 scenario, our findings indicate that annual mean temperatures increase around 4.5°C when comparing the period of 1995-2014 with that of 2090-2099. Also, we found that annual precipitation amount over the region decreases around 170 mm/year, which indicates a nearly 25% reduction in the freshwater availability by the end of the century. Especially, the precipitation of the wettest month shows a comparable decrease across these periods. Understanding these shifting in bioclimatic variables is crucial to preserve the agricultural and forest areas with their biodiversity.
How to cite: Şahin, O., Moral, A. C., Yürük Sonuç, C., Salkım, E., and Ünal, Y.: Exploring Future Bioclimatic Changes In Western Türkiye Under SSP3 Projections, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10431, https://doi.org/10.5194/egusphere-egu25-10431, 2025.
Climate change is posing significant challenges in the agricultural sector. While olive trees are well adopted to the mediterranean environment, olive oil production is being especially vulnerable due to its reliance on stable climatic conditions [1]. A recent example of drought and heatwaves in the previous two years slashed Spanish production and contributed to the doubling of olive oil prices [2]. Changes in temperature and precipitation are affecting olive tree cultivation by posing challenges in the flowering and growing season [3], as well as the soil moisture and the available water resources for irrigation.
This study investigates the impacts of climate change on olive cultivation in Greece, by analyzing key climatic indicators relevant to olive cultivation, focusing on their historical trends and projected changes under mid-range (RCP4.5) and high-concentration (RCP8.5) scenarios. The analysis considers key indicators such as changes in the length of the dry season, the frequency of heat stress events, consecutive dry years, and shifts in critical flowering conditions (temperature, wind, and chilling accumulation). This research further explores soil management related sustainable agricultural practices to enhance crop resilience.
This research develops representative climatic indicators and examines their evolution across multiple scenarios and time horizons to provide a comprehensive overview of the climate change challenges faced by Greek olive producers. The findings are aiming to inform the development of strategies for implementing sustainable agricultural practices that enhance resilience, ensuring the long-term viability of olive oil production in the context of climate change.
[1] Kaniewski, D., Marriner, N., Morhange, C., Khater, C., Terral, J.F., Besnard, G., Otto, T., Luce, F., Couillebault, Q., Tsitsou, L. and Pourkerman, M., 2023. Climate change threatens olive oil production in the Levant. Nature Plants, 9(2), pp.219-227.
[2] Reiley, L., 2023. Olive oil prices reach record highs as Spain's harvest is halved. The Washington Post, Oct. 6, 2023, pp.NA-NA.
[3] Grillakis, M.G., Kapetanakis, E.G. and Goumenaki, E., 2022. Climate change implications for olive flowering in Crete, Greece: Projections based on historical data. Climatic Change, 175(1), p.7.
This work is supported by MINERVA Ltd. under the research project “Assessment of climate change impacts on olive oil production and implementation of sustainable agricultural adaptation practices in Greece”.
How to cite: Koutroulis, A., Daliakopoulos, I., and Grillakis, M.: Climate Change Impacts on Olive Oil Production in Greece: Challenges and Pathways to Resilience, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12096, https://doi.org/10.5194/egusphere-egu25-12096, 2025.
Climate change and variability are expected to intensify the hydrological cycle, altering precipitation patterns, especially in climate hot spots like the Mediterranean region. Despite extensive research, comprehensive studies using high-resolution datasets to assess spatial and temporal variability across the entire Mediterranean are limited. Here, we analyze trends in total precipitation, wet days, daily intensity, and quantile-based precipitation intensities using ten datasets from 2001 to 2019: E-OBS, EM-EARTH, ERA5-Land, GPM-IMERG, GSMaP, GPCP, GPCC, MERRA2-Land, MSWEP, and MSWX. Results indicate an increase in total precipitation driven by more wet days and intensified precipitation. Spatial analysis shows rising annual precipitation trends in the eastern and northern Mediterranean, while the western region, especially the Iberian Peninsula, exhibits declines. Annual precipitation and wet day frequency display mirrored patterns, with both metrics gradually increasing until 2012, followed by higher variability. Quantile analysis reveals rising precipitation trends across all, with medium-range quantiles (30th to 60th quantiles) showing the highest increases. These findings enhance our understanding of recent precipitation changes in the Mediterranean, crucial for water resource management, agriculture, and climate resilience.
How to cite: Rahmati Ziveh, A., Markonis, Y., Hanel, M., J. Lolis, C., and AghaKouchak, A.: Multi-source assessment of current precipitation dynamics over the Mediterranean region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-531, https://doi.org/10.5194/egusphere-egu25-531, 2025.
Wildfires are a natural feature of Mediterranean ecosystems. However, research efforts are unevenly distributed, with fire ecology of the Eastern Mediterranean remaining understudied compared to other parts of the biome. Furthermore, direct and indirect links between armed conflict and wildfires have been suggested for this region, interacting with climatological and ecological factors to create complex fire dynamics that are not yet well understood.
Mediterranean ecosystems are adapted to fire and in general exhibit strong regeneration capabilities. Nevertheless, with a drier and hotter climate anticipated in the future due to climate change, there is concern of overstretching the ecosystem’s regenerative ability. In the Eastern Mediterranean, while more research regarding fire regimes and fire risk has emerged in recent years, vegetation recovery after fire has rarely been investigated.
Using Lebanon as a case study, we aim to disentangle the roles of climate, armed conflict, and other human impacts in post-fire recovery patterns in Eastern Mediterranean ecosystems. Using a recently compiled, national fire occurrence dataset and publicly available vegetation indices data, we will first create a statistical model to identify areas where fire activity is primarily driven by climate vs. conflict. We will then study recovery trajectories of vegetation after wildfire to address the following questions: (1) Does vegetation recover after wildfire, and if so, on what timescales? (2) Which environmental factors control recovery dynamics? (3) Do climate- vs. conflict driven fires differ in their properties, e.g. size? and (4) Are there differences in recovery patterns between climate- and conflict-associated fires?
How to cite: Layritz, L. S., Majdalani, G., Zomer, M. A., Ermitão, T., Bastos, A., and Boettiger, C.: Post-fire recovery and the role of armed conflict in the Eastern Mediterranean - A case study in Lebanon, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12231, https://doi.org/10.5194/egusphere-egu25-12231, 2025.
