CL3.1.4

Mediterranean-type climate regions are heavily dependent on cool season precipitation for water resources and agriculture.  Declines in cool season precipitation have been noted in the Mediterranean, Chile, southwest South Africa and southern Australia while California has also been experiencing recent droughts.  These changes have been attributed with some confidence to rising greenhouse gases, a poleward shift of storm tracks and Hadley Cell expansion.  However, from the perspectives of climate hazards such as fire and heat and ecosystem impacts, spring and summer climate change are also important.  For example, recent work shows that summer burned area in California’s Mediterranean-type climate depends on winter precipitation but also on precipitation, temperature and vapor pressure deficit in spring and early summer.   Here we consider trends over past decades in the impacts-relevant quantities of precipitation, surface temperature, humidity and vapor pressure deficit throughout the seasons for all the world’s five Mediterranean-type climate regions.  Trends from reanalyses are compared to those from CMIP6 models to attribute changes to radiative forcing and natural variability and the connections between change in thermodynamic quantities and the atmospheric circulation are explored.  We show that across the Mediterranean-type climate regions human-driven climate change throughout the year is generating changes in impacts-relevant climate quantities that will create substantial challenges to societies and ecosystems.

How to cite: Seager, R., Liu, H., Jacobson, T., Kushnir, Y., Simpson, I. R., Osborn, T. J., and Nakamura, J.: Recent trends in impacts-relevant climate in the world’s Mediterranean-type climate regions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13114, https://doi.org/10.5194/egusphere-egu22-13114, 2022.

The Mediterranean Basin (which includes the Mediterranean Sea and the countries bordering it) is often referred to as a hotspot for climate change and biodiversity. This image is used to illustrate the multiple risks for the region, its people and its ecosystems. These risks have been assessed by a new analysis of the scientific literature (MedECC 2020), concluding that it is the sum of climate change, pollution, unsustainable use of land and sea and the invasion of non-native species that induces these multiple risks, which are often underestimated. The Mediterranean territory is also a biodiversity hotspot with 25,000 plant species, 60% of which are endemic. It provided a “service” to plant and animal species as refuges during the last ice age (when the climate was much colder and the sea level was 120 m lower). These ecosystems are now under the triple threat of drought, rising sea level and intensified land use. Forest fires due to heat waves and droughts will be increasingly dramatic despite prevention efforts and fire response forces. Climate change, pollution and over-fishing are having a heavy impact on marine ecosystems, which contain 18% of known species and cover 0.82% of the global ocean. This talk will depict a picture of these present and future risks. A focus will be done on the viticulture which is iconic of the Mediterranean agricultural production and which is very vulnerable to climate change especially on its southern fringe where more intense and frequent droughts are projected. The methodology involves the use of a vegetation model offline coupled to earth system models. A shift of several degrees toward the north is projected for the vine area in case of a global warming larger than +2°C according to the pre-industrial period.

MedECC (2020) Climate and Environmental Change in the Mediterranean Basin – Current situation and Risks for the Future. First Mediterranean Assessment Report [Cramer, W., Guiot, J., Marini, K. (eds.)], Union for the Mediterranean, Plan Bleu, UNEP/MAP, Marseille, France, 632pp.

How to cite: Guiot, J.: Risks of environmental and climate change for the Mediterranean ecosystems, with a focus on mediterranean vines, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-773, https://doi.org/10.5194/egusphere-egu22-773, 2022.

Coastal ecosystems are hotspots of marine biodiversity, marine pollution, and multiple human interests. A large share of responsibilities of managing and protecting the coastal ecosystems - often rich in diversity and amenity values - is typically mandated to municipalities, communities and institutions sharing the coastline and catchment area. On the other hand, the quality of water – and hence the state of the coastal ecosystems – is also dependent on the level of water pollution in the neighboring regions.  The objective of this paper is to assess the leverage and effectiveness of local pollution mitigation efforts in improving the water quality of nearby coastal waters. For this end, we employ a systems approach and develop a modelling framework to describe human-nature-human interactions to conduct what-if analyses for alternative societal developments and levels of policy effort in nutrient abatement. Our case study area is Archipelago Sea in the Baltic Sea. We demonstrate that there is room and opportunity for clear improvement towards the Good Environmental State (GES) in most parts of the Archipelago Sea. However, GES is far from reachable in any Archipelago Sea area, coastal region or inner bay through unilateral local action conducted in the catchment draining to the Archipelago Sea only. Local water protection efforts are necessary but not adequate measure to render the Archipelago Sea to a good environmental state. GES can be achieved for most areas within Archipelago Sea through well-coordinated and carefully adjusted load reductions and joint action between regions and countries that share the Baltic Sea catchment, except for inner archipelago, river mouths and the inner bays. In these areas – which also occur to be amongst the hotspot areas for various human interests – GES could be achieved only through extremely expensive local mitigation effort in the catchment area. To reach GES also on inner archipelago would require major transitions, investment in R&D and subsequent technological advancements in the energy sector, wastewater treatment, agriculture, and control of nutrients stored in the sediments of coastal seas.  Moreover, this result calls for consideration on the relevance of current threshold values and targets for GES in different coastal zones.  There is need for either more detailed classification that better accounts for geomorphological qualities of the coastal zone, or a new set of indicators that reflect the provision of ecosystem services rather than biological production. Our simulations also imply that the phenology of phytoplankton biomass occurrence is altered by increased nutrient loads. The shifts in the timing and relative abundance of spring and summer blooms are worth considering when planning the mitigation measures and the optimal timing/targeting of them.

How to cite: Hyytiäinen, K., Huttunen, I., Kotamäki, N., Kuosa, H., and Ropponen, J.: To what degree can coastal waters be protected by local efforts?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1723, https://doi.org/10.5194/egusphere-egu22-1723, 2022.

How to cite: De Falco, C., Mooney, P., and Tjiputra, J.: Developing a high resolution coupled ocean-atmospheric model to understand reef fish distribution in the Eastern Tropical Pacific in the present and future climate, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9095, https://doi.org/10.5194/egusphere-egu22-9095, 2022.

Research that twins data from human (written) archives with data from natural environmental archives represents a rapidly advancing frontier in understanding the ecosystem and linked societal impacts of climatic change. The study of explosive volcanic eruptions, capable of inducing severe short-term climatic anomalies, provides a proving ground in which to develop the methodologies required to combine these disparate sources of evidence, and for showcasing the insights that can be achieved. Volcanic influences on the oceans are becoming increasingly understood, through advances in marine palaeoenvironmental proxies and more sophisticated Earth system modelling. At the same time, growing concern exists over the impacts of present and projected climatic changes on marine ecosystems and important higher trophic level species (Cod, Herring) exploited by commercial fisheries. Here we examine the impact of major explosive volcanism on North Atlantic sea-surface-temperatures (SSTs) using the Norwegian Earth System Model, and on North Sea Herring (1600-1860 CE) and Grand Banks Cod (1675-1827 CE) populations, using rigorously reconstructed catch volumes from contemporary documentation. We show that volcanic eruptions, identifiable through elevated sulfate levels in polar ice cores, impacted ocean temperatures and triggered population booms in both species during the first post-eruption decade. We also show this response to be consistent with expected increases in plankton productivity (a key food source for Cod and Herring) under lower SSTs in the North Sea and higher SSTs in the Grand Banks, respectively. We complement our historical analyses with Cod and Herring population modelling, similarly predicting a population boom in the first decade following a positive ecosystem disturbance (e.g., increased food availability for Cod and Herring, promoting increased survivorship). Lastly, we employ historical Herring price data to examine market responses post-eruption, observing an increase in prices in the first two post-eruption years, thus indicating an increased demand for Herring as a substitute for terrestrial agriculture likely to have been impacted by volcanic climatic anomalies. Our results will help improve fish population projections for the North Atlantic after the next big eruption. This work has been funded by the ERC NorFish (ID 669461) and 4-OCEANS (ID 951649) projects.

How to cite: Ludlow, F., Matthews, J., and Pausata, F.: Explosive Volcanism Drives Bumper North Sea and Grand Banks Fish Catch, 1600-1850 CE, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12080, https://doi.org/10.5194/egusphere-egu22-12080, 2022.

Environmental conditions along the Algerian margin (AM) involve complex atmosphere-hydrosphere-biosphere interactions with superimposed anthropogenic activities on adjacent watersheds across the Holocene. Surface waters of the Atlantic Ocean entering the western Mediterranean Sea become the Algerian Current (AC) flowing along the North African coast and generating anticyclonic eddies. Upwelled waters are other recurring hydrological feature reflecting the instability of the AC. In this area, Holocene vegetation and paleohydrological dynamics have not yet been described. The marine core MD04-2801 (2,067 m water depth) has been analyzed to assess environmental and climatic conditions over the last 14 kyrs BP at a secular-scale resolution to fill this gap. A multi-proxy approach including terrestrial (pollen grains and continental non-pollen palynomorphs such as Glomus spores and freshwater microalgae) and marine (dinoflagellate cysts or dinocysts) palynological data as well as sedimentological data (grain-size analysis and clay mineral assemblages) and biomarkers (alkenones and n-alkanes) have been used to investigate the links between past sea surface hydrological conditions characterized by the over-representation of heterotrophic dinocyst taxa (especially Brigantedinium spp.) and regional environmental changes on nearby watersheds. Quantifications of hydrological and climate parameters are also estimated using the Modern Analogue Technique applied to dinocyst and pollen assemblages. Our data evidence linkages between continental dryness or moisture and surface ocean conditions. High productivity is recorded during the cold and arid climate conditions of the Younger Dryas (12.7 to 11.7 ka BP). During the Early-Middle Holocene (11.7 to 8.2 and 8.2 to 4.2 ka BP), fluvial discharges increase concomitantly with the colonization of coastlands by the Mediterranean forest and oligotrophic conditions in the AM. In contrast, aridification characterizes the Late Holocene with the notable 4.2 ka BP megadrought  between 4.3 and 3.9 ka BP. Comparison between with other paleoenvironmental records from the Gulf of Cadiz to the Siculo-Tunisian strait underlines a west to east climatic gradient at orbital and infra-orbital timescales, with marked cold-dry events at 9, 8.1, 7.3 and 6.5 ka BP. This zonal gradient is discussed to explain contradictory results from the Alboran Sea to Tunisia. Finally, the last 3 kyrs BP highlight the establishment of modern ocean production conditions reflecting both vertical mixing in the AM (wind-driven eddies of the AC) and nutrient-enriched fluvial discharges intensified by human land-use.

How to cite: Coussin, V., Penaud, A., Combourieu-Nebout, N., Peyron, O., Sicre, M. A., Tisnerat-Laborde, N., Babonneau, N., and Cattaneo, A.: Holocene Paleoenvironments in the Western Mediterranean Sea: palynological evidences on the Algerian coast and climatic reconstructions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4655, https://doi.org/10.5194/egusphere-egu22-4655, 2022.

The human-nature interactions driving water quality deterioration in linked land-coast-sea systems are complex, including numerous components across different water environments. This complexity has led to many unsuccessful or insufficient efforts for water quality improvement, as seen, for example, in the Baltic Sea and its coasts that suffer from severe eutrophication long after several policies and measures have been repeatedly taken for mitigating excess nutrient loads. Considering the Swedish water management district of Northern Baltic Proper and its surrounding coastal areas and associated marine waters of the Baltic Sea, this study has used a system dynamics (SD) modelling approach to investigate possible future shifts in regional water availability and quality under different regional change scenarios. The SD model is developed based on a stakeholder-identified problem-oriented system network diagram that includes key land-coast-sea system interactions. The scenarios are developed based on scenarios of Representative Concentration Pathways (RCPs) and Shared Socio-economic Pathways (SSPs), complemented with insights from the IPCC report ‘Global warming of 1.5°C’ to reflect possible future changes in human pressures and hydro-climatic conditions. Relevant RCPs and SSPs are downscaled to region-specific change scenarios for associated model input variables, and their combined impacts on system behavior are evaluated using various key performance indicators defined for socioeconomic sectors, natural water systems, and policy and management aspects. Results show that further investment and development are needed for urban storm water handling and wastewater treatment from both water quantity and quality perspectives. Water quality management strategies also need to account for and target long-lived nutrient legacy sources to mitigate their further contribution to water quality problems in the study region. Furthermore, policy targets defined for water quality improvement, for example, in the Baltic Sea Action Plan, need to be updated based on regional water-related impacts of projected hydro-climatic changes and expected future socioeconomic conditions. The updated targets, however, can only be achieved if synergistic management measures are taken across the land-coast-sea continuum. SD modelling and scenario analysis, as established, applied and will be further developed in this study, can support identification of efficient policy and management strategies for water quality improvement by assessing their performance and exploring possible sustainable solutions under different future development scenarios.

How to cite: Seifollahi-Aghmiuni, S., Kalantari, Z., and Destouni, G.: System dynamics modelling of linked land-coast-sea systems for water quality management under different RCP-SSP scenarios, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7079, https://doi.org/10.5194/egusphere-egu22-7079, 2022.

A competence center of the water sector for boreal and subarctic catchment, river and lake environments was highly needed, as impacts of climate change on river basins, adaptation, and resilience request detailed analysis of the behavior of river basins under extreme conditions. This further demands detailed measurements in time and space of morphological, hydrological, and biological variables. A consortium of private and public institutions in Finland have been formed to establish a Sustainable Freshwater Competence Centre to support detailed monitoring, research, development of new techniques and equipment innovation.

The complete venture structure includes a network of public and private institutions that supports measurement the development of instruments; a research infrastructure, composed of eight sites (three supersites), and the development of digital solutions, such as digital twins and data transfer, to generate cost-effective monitoring and model river connectivity, hydrological processes, as well as nutrient and carbon loads from different land use in multi scale river basins.

Hydro-RDI-Network was inaugurated in 2021 to serve as the first Finnish competence center of the water sector. It aims to improve and implement river and catchment measurement, mapping, modelling approaches, and innovation. The Hydro-RI-Platform research infrastructure (2022 onwards) will facilitate solving environmental issues (e.g. erosion, flooding, water quality) of these fragile boreal and subarctic freshwater environments. A pool of unique instruments for bathymetric, hydrological, hydraulic, morphodynamic and water quality measurements, with a variety of autonomous under- and above-water sensor platforms, a mobile field laboratory facility, and a data sharing platform are developed to study essential scientific questions in present and future hydrology.

Green-Digi-Basin (2022 onwards) aims to develop state-of-the-art understanding on green and digital transform in river basin and provide new tools and integrated modelling approaches for sustainable water resource management to assess impacts of nature-based solutions (e.g. peatland restoration, wetland and gypsum treatment) and land use changes through boreal-subarctic river basins. These will be done by utilizing remote sensing technologies, laser scanning high-resolution water quality and flow sensors, river basin 3D-mapping and geospatial analyses. Online data transfer systems, automatic data analysis will serve processed data to modelling software such as national wide river basin model WSFS-VEMALA to develop digital twins for river basin management.

The holistic concept of the Sustainable Freshwater Competence Centre in Finland will create a broad and reliable source of hydrologic monitoring, research, development, and innovation to support the adaptation of the hydrology of the Baltic Region to climate change.

How to cite: B Uvo, C., Alho, P., Heiskanen, A.-S., Kaartinen, H., Kämäri, M., Lotsari, E., Marttila, H., Ronkanen, A.-K., and Silander, J.: A Sustainable Freshwater Competence Centre in Finland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6928, https://doi.org/10.5194/egusphere-egu22-6928, 2022.

Mediterranean climate types (MC) are characterized by temperate, wet winters, and hot or warm dry summers and are mostly found at the western edges of all inhabited continents in locations determined by the geography of winter storm tracks and summer subtropical anticyclones. According to the Köppen-Geiger classification, this climate type is classified as Csa and Csb. Although such regions are limited in terms of area, their current population exceeds 700 million inhabitants globally. According to the scientific literature, most MC regions, became hotter and drier during the last century, while future climate projections suggest that these observed trends will continue for the upcoming decades. This combined effect of warming and drying will likely augment the climate change impacts in the MC societies and ecosystems. In this study we investigate how these regions will be impacted by global warming compared to the rest of the world and other regions in the same latitudinal zone. For defining the Csa and Csb regions of the Köppen-Geiger classification, we used the gridded CRU monthly precipitation and temperature observations. Then we analyzed temperature anomalies (area-weighted means) in different MC sub-regions, including North America (NA), South America (SA), Mediterranean Basin (MB), and the southwest of southern Africa (SAF) and southwest Australia (SAU). Our analysis shows that Csa and Csb regions worldwide have not undergone significant spatio-temporal changes during the last 120 years. Nevertheless, we found differences in the observed temperature trends, particularly in the last four decades (1981-2020). In more detail, the Mediterranean Basin with an observed trend of about 0.4 °C/decade has warmed faster than the global mean (0.28 °C/decade) and other MC regions (0.15-0.28 °C/decade). Finally, we will explore the future climate evolution of MC regions and if the observed trends will continue in the 21st century by analyzing a bias-adjusted and statistically downscaled dataset of CMIP6 climate projections. For supporting decision-making and climate mitigations efforts we focus on different global warming levels (e.g., 1.5, 2, and 4°C).

Keywords: Köppen-Geiger, Climate Change; Mean temperature anomalies; World’s Mediterranean climates

How to cite: Urdiales, D., Zittis, G., and Hadjinicolaou, P.: Climate Change in Mediterranean climate-type regions: A global approach based on the Köppen-Geiger classification, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2802, https://doi.org/10.5194/egusphere-egu22-2802, 2022.

Ocean eddies, which present different properties to their surroundings, play pivotal roles in transporting heat, salt, organic carbon, and nutrients around the ocean, ending up controlling regional and global climate. Eddy kinetic energy (EKE), defined as the kinetic energy of the time-varying component, is one of the most crucial indicators for observing the upwelling and downwelling induced by ocean eddies. We aim to understand the future changes in ocean eddy activities and find the possible cause of them using an ultra-high-resolution climate simulation of CESM 1.2.2, with about 25 km horizontal resolution and 30 vertical levels in the atmosphere, and about 10 km horizontal resolution and 62 levels in the ocean, under different levels of greenhouse gas conditions: Present-day run (PD, fixed CO2 concentration of 367 ppm), Doubling CO2 run (2xCO2, 734 ppm), Quadrupling CO2 run (4xCO2, 1468 ppm). Model simulation shows that compared to PD, the global EKE will increase about 6.7 % and 14.7 % in 2xCO2 and 4xCO2, respectively, but with the nonuniformed spatial distributions. The results show that the EKE  increases about 12.5 % in 2xCO2 and decreases about 0.5 % in 4xCO2 in the Kuroshio Current region. In contrast, it decreases about 4.8 % (22.5 %) in 2xCO2 (4xCO2) in the Gulf Stream region. To find the underlying processes for the EKE change, we focus on identifying future changes in the energetics of eddy-mean flow interactions. Based on the energetics of eddy-mean flow interaction, the strengthened barotropic conversion will enhance the EKE in 2xCO2 over the Kuroshio Current region. Otherwise, the suppression of buoyancy flux will weaken the EKE in 2xCO2 and 4xCO2 over the Gulf Stream region.

How to cite: Yun, J., Ha, K.-J., and Lee, S.-S.: Understanding future changes in ocean eddy kinetic energy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10899, https://doi.org/10.5194/egusphere-egu22-10899, 2022.

In this work we present the principal results of analysis of spatio-temporal variations of extreme storm features over the Gulf of Gdańsk located in the southern Baltic Sea. By extreme storms we mean storms that induce highest waves in various regions of Gulf of Gdańsk. The analysis of meteorological conditions over the Baltic Sea and wind wave fields in the Gulf of Gdańsk was carried out using 44-year long time series of gridded hindcast REMO meteorological data (Jacob and Podzun, 1997; Feser et al., 2001) and HIPOCAS wind wave data (Cieślikiewicz et al., 2005). 

An important aim of this study is to obtain the most characteristic features of extreme storms that had created extreme risks and hazards in the Gulf of Gdańsk during the investigated period 1958–2001. The Gulf of Gdańsk is a very important sea basin for Poland. Two of three largest ports in Poland are in the Gulf of Gdańsk: the Port of Gdańsk and the Port of Gdynia.

In this study an objective measure of spatial variability of characteristic storm patterns linked with extreme local wave conditions is proposed. That variability measure is constructed based on special selection procedure of extreme storms using long-term significant wave height time series. We define a general spatial storm variability coefficient that may be estimated for various sea basins. In the present work this storm variability coefficient is determined for the Gulf of Gdańsk and its estimation procedure is described in detail.
 
In our study the long-term change in basic statistics of wind wave field over Gulf of Gdańsk is also analysed. This may be referred to as wind wave climate change analysis. It is done by determination of trends in statistical properties of basic wind wave parameters such as significant wave height, mean wave period and wave direction. An attempt is made to relate the trends found in extreme wind wave statistical characteristics to change in associated extreme storm patterns.

In this study probability distributions of significant wave height and mean wave period are determined. The presentation of spatial and temporal variations of the parameters of those probability distributions is yet another way of examining and presenting the spatio-temporal changes of wind wave climate in the Gulf of Gdańsk. Again, an attempt is made to relate those changes to change in characteristic features of meteorological conditions over the Baltic Sea, including storm patterns causing extreme local wave in various regions of the Gulf.

Acknowledgements

Computations performed within this study were conducted in the TASK Computer Centre, Gdańsk with partial funding from eCUDO.pl project No. POPC.02.03.01-00-0062/18-00.

References

Jacob, D., Podzun, R., 1997. Sensitivity studies with the regional climate model REMO. Meteorol. Atmospheric Phys. 119–129. https://doi.org/10.1007/BF01025368

Feser, F., Weisse, R., von Storch, H., 2001. Multi-decadal atmospheric modelling for Europe yields multi-purpose data. Eos 82. https://doi.org/10.1029/01EO00176

Cieślikiewicz, W., Paplińska-Swerpel, B., Soares, C.G., 2005. Multi-decadal wind wave modelling over the Baltic Sea, in: Coastal Engineering 2004. Presented at the Proceedings of the 29th International Conference, World Scientific Publishing Company, National Civil Engineering Laboratory, Lisbon, Portugal, pp. 778–790. https://doi.org/10.1142/9789812701916_0062

How to cite: Cieślikiewicz, W. and Cupiał, A.: Spatial variation of extreme storm characteristics over Gulf of Gdańsk and their long-term temporal changes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11404, https://doi.org/10.5194/egusphere-egu22-11404, 2022.

Understanding the physical development of the Gulf of Bothnia is vital in estimating the future of the area, both for humans and nature alike. 

In the SmartSea project we have made simulations of future scenarios for the Gulf of Bothnia. We have simulated a historical control period of 1976-2006 with three different downscaled global circulation model forcings, and use these as comparisons for runs made with corresponding model forcings for the years 2006-2100 with RCP 4.5 and RCP 8.5 scenarios. 

In this presentation we analyze the changes in salinity and overturning circulation development within the simulation runs. The overturning circulation is characterized by being divided into the two basins Bothnian Sea and Bothnian Bay divided by the Quarken. The circulation in each of the basins is composed of one estuarine circulation with a cyclonic one superimposed. 

Local changes in salinity within the Gulf of Bothnia are affected by the stratification, changes of current patterns and river inflows, although its general salinity development is largely determined by the changes in the Baltic Proper.

The comparison between our simulation runs demonstrate that small changes in conditions can produce very different salinity trends, as either weaken, or strengthen the general circulation of the GoB. While the general salinity trend over the 2006-2100 period is slightly decreasing, the trend can be on the rise for decades within the simulation.

How to cite: Siiriä, S.-M., Fredriksson, S., Haapala, J., and Arneborg, L.: The future of Gulf of Bothnia, possible changes on salinity and currents, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8533, https://doi.org/10.5194/egusphere-egu22-8533, 2022.

Iran is a country with large climate contrast and thus highly vulnerable to climate change. The two major mountain ranges, Alborz in the north and Zagros in the west, impede the penetration of Mediterranean and Caspian winds to the central plateau, leading to precipitation on the topographical highs as well as deserts in the center of the country. Semi-arid southern Iran has struggled with severe droughts for several decades, and destructive floods in recent years underscore the vulnerability to ongoing climate change.

Records of paleoclimate in the Middle East, useful for improving our knowledge about the natural variability of atmospheric circulation patterns in this region, are sparse in comparison to other regions. In particular, there are currently no paleoclimate studies based on speleothem archives in Iran which span the transition from the Last Glacial Maximum (LGM) to the Holocene. 

Here we report a well-dated, high-resolution stalagmite proxy record from the foothills of the Zagros Mountains, SIB-4, which for the first time covers the LGM as well as parts of the deglaciation and reaches into the early Holocene. SIB-4 oxygen isotope (δ¹⁸O) values are ~4‰ higher in the LGM relative to the early Holocene. Other stalagmite records in the Middle East also show higher δ¹⁸O values in the LGM relative to the Holocene, such as from Soreq cave in Israel[1] (Δδ¹⁸O = +3‰), Jeita cave in Lebanon[2] (Δδ¹⁸O = +2.5‰), Dim cave in Turkey[3]  (Δδ¹⁸O = +6‰), and Moomi cave in Oman[4] (Δδ¹⁸O = +2‰). A large portion of the Δδ¹⁸O of SIB-4 was likely caused by colder and drier conditions in the LGM. This interpretation is supported by the SIB-4 carbon isotope (δ¹³C) values, which are ~7‰ higher in the LGM relative to the early Holocene. These high δ¹³C values, which approach the values of the marine host rock, are attributed to sparse vegetation (steppe type) and related reduced soil bioproductivity. 

SIB-4 contains three growth hiatuses during the deglaciation, 17.8-17.2 ka, 15.1-14.7 ka, and 13.4-11.7 ka, all coincident with millennial- to centennial-scale dry periods previously identified by a dust record from a peat bog in Southeast Iran[1]. Dry conditions during the youngest SIB-4 hiatus are also supported by the δ¹⁸O and δ¹³C values which increase sharply immediately before the hiatus. SIB-4 δ¹⁸O and δ¹³C values decrease sharply at 14.7 ka, marking more humid conditions coincident with the onset of the last interstadial known from many records across the Northern Hemisphere.

How to cite: Soleimani, M., Carolin, S., Nadimi, A., and Spötl, C.: Stalagmite record of Last Glacial Maximum to early Holocene climate change in southwest Iran, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2885, https://doi.org/10.5194/egusphere-egu22-2885, 2022.