Four Decades of Surface Temperature, Precipitation, and Wind Speed Trends over Lakes of Greece

Increasing water temperature of the largest freshwater lake on the Mediterranean islands as an indicator of global warming

Global warming has been monitored for many years. The increase in air temperature and changes in the distribution and frequency of high temperatures are recorded continually. Lakes are one of the important water resources for aquatic ecosystems and water supply, which are significantly affected by global warming. The increase in lake water temperature increases the evaporation from the free lake surface, lowering the lake level, and changes the water quality. In the last few decades, analysis of changes in lake water temperature has been increasing. In situ measurements of water temperature in Vrana Lake on Cres island (Croatia), the largest freshwater lake on the Mediterranean islands, were analysed over 43 years. The results showed that the mean annual lake surface water temperature (LSWT) increased by 0.47 °C decade-1 (p < 0.0001). The increase in the mean annual lake summer surface water temperature (July-September) was 0.44 °C decade-1 (p < 0.0001), and the maximum annual LSWT was 0.56 °C decade-1 (p < 0.0001). All these amounts are in accordance with the published data on the increase in water temperature in the investigated European lakes. The number of days with LSWT higher than 25 °C increased by almost 9 d decade-1. An increase in the minimum LSWT (0.17 °C decade-1) corresponding to isothermal conditions was also determined but was not statistically significant. The minimum mean monthly LSWT increased by 0.36 °C decade-1 (p < 0.0001). Because the increase in water temperature can negatively affect the lake's ecosystem, and become a threat to safe water supply; LSWT, thermal stratification and evaporation should be continuously monitored. The impacts of climate warming on the lake stratification and aquatic ecosystems need to be further investigated.

Assessing temporal variability of lake turbidity and trophic state of European lakes using open data repositories

Water turbidity is one of the more important water quality parameters that is strictly linked with the productivity of the lake and is commonly used as an indicator of the trophic state. However, limited field data availability across wide geographic gradients may hinder the conduction of large scale longitudinal studies. In this study, time series of lake turbidity and trophic state index (TSI) between 2002 and 2012 were obtained from the Copernicus Lake Water products to create a large longitudinal dataset of lake variables for 22 European lakes. The dataset was combined with estimates of nutrient concentrations and surface water temperature obtained from the Hydrological Predictions for the Environment (HYPE) and ERA5-Land data repositories, that were used as environmental predictors. Hence, the validity of the lake water quality parameters was tested by a) exploring their spatial and temporal variability and b) identifying associations with the environmental predictors. For this purpose, seasonal Mann-Kendall tests were applied to find significant inter-annual trends of turbidity and TSI for each lake, and generalized additive models (GAMs) were employed to identify the main parameters that shape their temporal dynamics. Although we did not find significant inter-annual changes, our findings highlighted the strong influence of seasonality and surface water temperature in defining the temporal variability patterns in most of the lakes. In addition, the importance of nutrients varied among lakes as several lakes exhibited narrow nutrient gradients reflecting relatively stable nutrient conditions during the examined period. Other lake intrinsic factors, such as local climate and biotic interactions, are important drivers of shaping turbidity and nutrient dynamics. This study highlighted the usefulness of combining lake data from large repositories in conducting large scale spatial studies as a valuable asset for future lake research and management purposes.

Assessing Lake Response to Extreme Climate Change Using the Coupled MIKE SHE/MIKE 11 Model: Case Study of Lake Zazari in Greece

Lakes, either artificial or natural, are greatly important as a component in their catchments’ hydrology, but also as ecosystem service providers. However, due to climate change, they have begun to face numerous problems with their water quality and quantity. Furthermore, general circulation models (GCMs) show future climate change with a reduction in rainfall and increase in temperature. The aim of the current study is to present an application where GCMs and state-of-the-art hydrological modelling system MIKE SHE/MIKE 11 are combined for assessing the response of a Greek lake in terms of its water balance and water level under climate change. Four general circulation models (GCMs; GFDL-CM3, MIROC-ESM-CHEM, MIROC-ESM, IPSL-CM5A-LR) for the extreme climate change scenario of RCP8.5 were used in the basin of Lake Zazari in Greece as a case study. Results showed that, by keeping the irrigated demands (the main water user) unchanged in the future, the lake exhibited a lower water level for all GCMs, fluctuating from −0.70 to −1.8 m for the mean (min) water level and from −0.30 to −1.20 m for the mean (max) water level. Instead of the above and by preserving the amount of withdraw water n from the lake at a certain percentage of inflows, the irrigated area should be reduced from 54.1% to 64.05% depending on the circulation model.

Addressing sustainability gaps

Widespread industrialization, rapid urbanization, and massive transport through land, waters, and air have led to catastrophes such as climate change, water pollution, resource limitation, and pandemics causing severe economic consequences, massive influences on the natural environment and pose a great threat to the life sustainability. Sustainability topic has a long history, and many policies and initiatives are in effect for a sustainable planet Earth, still gaps of varying degrees exist in almost all sectors. This article addresses the essentiality of minimising the sustainability gaps exist in diverse realms of life and citing few examples. Creating a cyclic path for production-consumption process in the economic sector through promoting circular economy, learning from the natural processes through appropriate biomimicking, and knowledge-integration from diverse disciplines and emphasizing sustainability in the educational sector are shown to lower the sustainability gaps.

Long-Term Climatic Changes in Small Ruminant Farms in Greece and Potential Associations with Animal Health

The objectives of this work were (a) to present the changes in climatic parameters from 1989 to 2019, in 444 locations throughout Greece, where small ruminant farms have been based and (b) to present associations of the changes in the climatic parameters with clinical data related to small ruminant health. Climatic variables (1989–2019) were obtained for 444 locations with small ruminant farms throughout Greece. During this period, significant increases were noted in temperature-related parameters (annually 0.05 °C for average temperature and 0.14 °C for temperature range) and precipitation (annually 0.03 mm). There were significant differences in climatic conditions between locations of farms in accord with the management system applied therein, as well as in accord with the breed of animals on the farms (e.g., higher average temperature in locations with Greek breeds, higher temperature range in locations with imported breeds). There were significant associations of temperature-related parameters with the annual frequency of cases of neonatal hypothermia seen at a veterinary teaching hospital, as well as with the average proportion of Haemonchus contortus larvae in faecal samples and the frequency of cases of H. contortus resistance reported by a veterinary parasitology laboratory.

Unravelling Precipitation Trends in Greece since 1950s Using ERA5 Climate Reanalysis Data

Precipitation is one of the most variable climatic parameters, as it is determined by many physical processes. The spatiotemporal characteristics of precipitation have been significantly affected by climate change during the past decades. Analysis of precipitation trends is challenging, especially in regions such as Greece, which is characterized by complex topography and includes several ungauged areas. With this study, we aim to shed new light on the climatic characteristics and inter-annual trends of precipitation over Greece. For this purpose, we used ERA5 monthly precipitation data from 1950 to 2020 to estimate annual Theil–Sen trends and Mann–Kendall significance over Greece and surrounding areas. Additionally, in order to analyze and model the nonlinear relationships of monthly precipitation time series, we used generalized additive models (GAMs). The results indicated significant declining inter-annual trends of areal precipitation over the study area. Declining trends were more pronounced in winter over western and eastern Greece, but trends in spring, summer and autumn were mostly not significant. GAMs showcased that the trends were generally characterized by nonlinearity and precipitation over the study area presented high inter-decadal variability. Combining the results, we concluded that precipitation did not linearly change during the past 7 decades, but it first increased from the 1950s to the late 1960s, consequently decreased until the early 1990s and, afterwards, presented an increase until 2020 with a smaller rate than the 1950–1960s.