The impacts of future climate change on water security in the Mediterranean Basin

JPC Eekhout and J de Vente

April 23-28, 2023

EGU General Assembly, Vienna, Austria

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Abstract

The Mediterranean Basin is classified as one of the hot-spots for climate change, where a significant decrease of precipitation and an increase of temperature are expected. This will most likely lead to a redistribution of water within Mediterranean catchments. However, the scale and magnitude and spatial differences of the impact of climate change on water security across the Mediterranean is still uncertain. Here we present the preliminary results of a systematic review on the impact of climate change on water security in the Mediterranean Basin. In this systematic review we focused on studies performed in the Mediterranean Basin that apply a hydrological model forced by climate model output and report changes in blue and/or green water, i.e. water stored in rivers and reservoirs (e.g. runoff or reservoir storage) and water stored in soils (e.g. groundwater recharge). The variables obtained from the studies include variables related to study area, climate and hydrological models, and model output. Our preliminary results show that the general tendency is a decrease of precipitation and an increase of temperature, which will cause a decrease of projected blue and green water. This will have serious consequences for the potential of irrigated agriculture, industry and household water use in the Mediterranean Basin, which heavily rely on the availability of blue water. But also for rainfed agriculture, where a decrease of green water may force farmers to abandon their land or transform to irrigated agriculture.
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Slide 1 of The impacts of future climate change on water security in the Mediterranean Basin
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Welcome everybody, my name is Joris Eekhout and work at the Spanish National Research Council. On behalf of my co-author Joris de Vente I present our preliminary results on the impact of future climate change on water security in the Mediterranean Basin.
Slide 2 of The impacts of future climate change on water security in the Mediterranean Basin
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In the past several large-scale climate change impact assessments have been performed in the Mediterranean Basin, which showed a decrease in precipitation (southern part) and an increase in extreme precipitation (northern part), with implications for water resources.
Slide 3 of The impacts of future climate change on water security in the Mediterranean Basin
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These large-scale studies are very valuable, but we argue that catchment-scale studies can give a more detailed assessment of the impacts, due to the complex Mediterranean environments. So in this study, we aim to assess the impact of climate change on water security in the Mediterranean Basin, with a focus on the catchment-scale.
Slide 4 of The impacts of future climate change on water security in the Mediterranean Basin
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We focus on two types of water, where blue water, water stored as surface water, is mostly related to irrigated agriculture and industrial and household water use and green water, water stored in the soil, to rainfed agriculture and natural areas.
Slide 5 of The impacts of future climate change on water security in the Mediterranean Basin
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To achieve the objective, we are performing a systematic review that focuses on studies performed in the Mediterranean Basin that apply a hydrological model forced by climate model output and report changes in green and/or blue water.
Slide 6 of The impacts of future climate change on water security in the Mediterranean Basin
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The search strings consists of three parts, which are related the Mediterranean Basin (red), climate change (blue) and blue/green water (green). We use the Mediterranean Ecoregion as our study area.
Slide 7 of The impacts of future climate change on water security in the Mediterranean Basin
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The search string resulted in more than 3000 articles in the SCOPUS database. The next step is to screen the articles using some predefined inclusion and exclusion criteria.
Slide 8 of The impacts of future climate change on water security in the Mediterranean Basin
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Up to know we screened about a third of the database and included 80 studies. From these 80 studies we obtained 24 variables, which can be subdivided into study area, climate change, hydrological model, land use change and reference and future change variables.
Slide 9 of The impacts of future climate change on water security in the Mediterranean Basin
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This graph shows how many studies were performed in each year. The first study was performed in 1991 and currently we are in 2014.
Slide 10 of The impacts of future climate change on water security in the Mediterranean Basin
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In the next few slides I will show the climate change impacts. These graphs show the impacts considering all studies and show a decrease of blue and green water. They also show that more studies considered blue water than green water.
Slide 11 of The impacts of future climate change on water security in the Mediterranean Basin
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We subdivided the Mediterranean Basin into three regions, where most studies were performed in the northern region. However, the eastern region is projected to be most affected by climate change, especially related to blue water.
Slide 12 of The impacts of future climate change on water security in the Mediterranean Basin
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We also obtained data related to the future periods, which we categorized into three categories. The results show an increasing trend towards the end of the century.
Slide 13 of The impacts of future climate change on water security in the Mediterranean Basin
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These are our conclusions, that most studies in the northern part, that most studies consider blue water and that blue and green water are projected to decrease, with an increasing trend towards the end of the century.
Slide 14 of The impacts of future climate change on water security in the Mediterranean Basin
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Our future work consists of reviewing the remaining 2000 articles and quantifying the robustness of the methodologies and individual studies, with the aim to do a statistical treatment of the results.