Future Projections in Agricultural Drought Characteristics for Greece Under Different Climate Change Scenarios †
Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
*
Author to whom correspondence should be addressed.
†
Presented at the 17th International Conference on Meteorology, Climatology, and Atmospheric Physics—COMECAP 2025, Nicosia, Cyprus, 29 September–1 October 2025.
Environ. Earth Sci. Proc. 2025, 35(1), 29; https://doi.org/10.3390/eesp2025035029
Published: 16 September 2025
Abstract
Changes in agricultural drought frequency (DF), duration (DD) and severity (DS) in Greece are investigated based on 11 high-resolution EURO-CORDEX regional climate model simulations covering the period 1971–2100 under three different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5) with the use of the SPI and SPEI. Increases in DF, DD and DS are more prominent in the 2071–2100 period under RCP8.5. Central and southern Greece, the Aegean islands and Crete experience the largest increases under RCP4.5 and RCP8.5. Under RCP2.6, changes in DD and DS are less pronounced, especially over northern Greece.
Keywords:
droughts; SPI; SPEI; EURO-CORDEX; Regional Climate Models; RCPs; future projections; climate change; agriculture; Greece1. Introduction
The Mediterranean region is considered a hot spot of climate change, with increasing trends in near-surface temperature and changes in precipitation over the last few decades [1], affecting the frequency and duration of drought events during the recent past and the future [2,3,4,5]. Greece, being in the heart of the Eastern Mediterranean, has experienced an increased number of extreme hot temperature events [6], which are projected to increase by the end of the 21st century [7]. Considering that future projections of precipitation point toward a decrease in the total amount of precipitation (despite the tendency of intensification for the strongest precipitation extremes) in association with the increasing heat stress [7,8,9,10], dry conditions will likely be enhanced, thus increasing drought risk and severity.
Given these reasons, a national project with the acronym CLIMPACT (National Network on Climate Change and its Impacts; https://climpact.gr/main/, accessed on 25 May 2025) was initiated in an effort to update our knowledge on the impacts of climate change in Greece and the surrounding regions. Currently in its second phase, CLIMPACT focuses on the impacts of climate change on specific sectors of the economy, health and the environment in Greece.
2. Materials and Methods
In this study, data from eleven sets of regional climate model (RCM) simulations implemented within the framework of the EURO-CORDEX initiative (https://www.euro-cordex.net/, accessed on 25 May 2025) at a horizontal resolution of 0.11° [11,12] were used (Table 1). Each set carried out four different simulations: one historical simulation covering the period 1950–2005 and three for the period 2006–2100, each under a different Representative Concentration Pathway (RCP) scenario, driven by a global climate model (GCM) simulation implemented within the framework of the Coupled Model Intercomparison Project Phase 5 (CMIP5) [13]. The three RCPs used here are RCP2.6 (strong mitigation scenario) [14], RCP4.5 (moderate mitigation scenario) [15] and RCP8.5 (no mitigation scenario) [16].
For each simulation, RCP scenario and gridpoint, time series of two drought indices were computed for the period 1971–2100: the standardized precipitation index (SPI, which accounts for anomalously low rainfall) [17] and the standardized precipitation evapotranspiration index (SPEI, which accounts for high temperatures and scarce precipitations) [18]. Both indices were computed at a 6-month scale (referring to agricultural droughts) and the entire 1971–2100 period was considered as a baseline to fit the underlying distribution of the drought indicators following Spinoni et al. [4,5]. The longer the baseline period, the more robust the calculation of the standardized drought [19].
Drought events were detected with the same methodology implemented in Spinoni et al. [4]: “a drought event starts when the drought indicator falls below one negative standard deviation for at least two consecutive months and ends when the indicator turns positive”. Drought frequency was then defined as the number of events in a given period. In this work, the three investigated 30-year periods are 1971–2000 (representing the reference period), 2021–2050 (representing the near future) and 2071–2100 (representing the end of the century). Drought duration was considered the sum of the number of months of an event. The severity of an event was calculated as the sum (in absolute values) of all the monthly indicator values between the start and the end of the event [4,5]. The robustness of the results was calculated using a comprehensive method. In cases where the results are statistically significant and at least 7 out of 11 RCMs agree on the sign of change, these results are considered robust. If the results are not statistically significant or models do not agree on the sign of change, then they are characterized as non-robust or conflicting, respectively.
3. Results
Changes in agricultural drought frequency (DF) for the near future (2021–2050) and the end of the century (2071–2100) relative to the reference period (1971–2000) under the three different RCP scenarios are presented in Figure 1. The central and southern parts of Greece show the largest changes in DF in all cases and especially under RCP8.5. In the case of SPEI-6, DF is projected to increase mainly over regions south of Thessaly in both future periods under RCP4.5 and RCP8.5, which is a robust feature among all climate models. One the other hand, SPI-6 shows a robust increase in DF over the same regions only by the end of the century under RCP4.5 and particularly RCP8.5. Results obtained using SPEI-6 are generally more robust, with the detected drought events increasing by more than 10 (up to 7) over Thessaly, the Peloponnese, Crete and the southern Aegean under RCP8.5 (RCP4.5). It is important to note that the SPEI incorporates both precipitation and potential evapotranspiration, making it more sensitive to the statistically robust temperature changes projected over Greece under all three RCP scenarios [7]. Through use of the SPI, robust changes are obtained under RCP4.5 and particularly RCP8.5, mostly for the end-of-century period.
In Figure 2, changes in drought duration (DD) are shown. In accordance with DF changes, DD shows the largest increases during 2071–2100 under RCP8.5, especially for the drought events detected using SPEI-6. Regions south of Central Greece experience the greatest changes under RCP8.5, with DD increasing by more than 10 (up to 7) months for droughts detected using SPEI-6 (SPI-6). Under RCP4.5, DD is projected to increase by up to 6 (4) months by the end of the century based on SPEI-6 (SPI-6). Under RCP2.6, DD shows little to no change, even though DF increases (at least in the case of SPEI-6).
Changes in drought severity (DS) are depicted in Figure 3. Drought duration and severity changes tend to show similar results, as they are intrinsically correlated [4]. Consequently, DS is projected to increase the most by the end of the century under RCP8.5, and more so for the droughts detected with SPEI-6. Robust increases in DS are projected across Thessaly, the Peloponnese, Central and South Aegean and Crete in the end-of-century period under RCP4.5 and RCP8.5 for SPI-6 and during both future periods under all three RCPs for SPEI-6.
4. Conclusions
In this work, changes in the frequency, duration and severity of agricultural droughts in Greece were assessed using an ensemble of 11 high-resolution EURO-CORDEX RCM simulations covering the period 1971–2100 under three different RCPs (RCP2.6, RCP4.5 and RCP8.5). Two drought indicators were employed: the SPI, which considers precipitation only, and the SPEI, which also considers temperature. Changes in drought frequency (DF), duration (DD) and severity (DS) for the near future (2021–2050) and the end of the century (2071–2100) were calculated relative to the reference period (1971–2000). Increases in DF, DD and DS are more prominent in 2071–2100 under RCP8.5, especially for the drought events that were detected using the SPEI. The central and southern parts of Greece experience the largest increases, along with the southern Aegean islands and Crete, under RCP4.5 and RCP8.5. The multi-model ensemble results are robust since most of the RCMs used in this work show statistically significant increases over the aforementioned regions. Under RCP2.6, changes in DD and DS are less pronounced with lower statistical significance, especially over Central and northern Greece.
Author Contributions
Conceptualization, A.K.G., D.A. and P.Z.; methodology, A.K., A.K.G., D.A. and P.Z.; software, A.K. and A.K.G.; validation, A.K. and A.K.G.; formal analysis, A.K., A.K.G. and D.A.; investigation, A.K., A.K.G., D.A. and P.Z.; data curation, A.K. and A.K.G.; writing—original draft preparation, A.K.; writing—review and editing, A.K., A.K.G., D.A. and P.Z.; visualization, A.K. and P.Z.; supervision, P.Z.; project administration, P.Z.; funding acquisition, P.Z. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the project “Support for Enhancing the Operation of the National Network for Climate Change (CLIMPACT)”, National Development Program, General Secretariat of Research and Innovation, Greece (2023ΝA11900001—Ν. 5201588).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
The EURO-CORDEX simulations used for the analysis are publicly available via https://esgf-data.dkrz.de/search/cordex-dkrz/ (last accessed on 1 April 2021).
Acknowledgments
We acknowledge the World Climate Research Program’s Working Group on Regional Climate, and the Working Group on Coupled Modelling, the former coordinating body of CORDEX and responsible panel for CMIP5. We also thank the climate modeling groups for producing and making their model output available. Finally, we acknowledge the Earth System Grid Federation infrastructure, an international effort led by the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison, the European Network for Earth System Modelling and other partners in the Global Organization for Earth System Science Portals (GO-ESSP). The results presented in this study have been produced using Aristotle University of Thessaloniki (AUTH) high-performance computing infrastructure and resources.
Conflicts of Interest
The authors declare no conflicts of interest.
References
- Gutiérrez, J.M.; Jones, R.G.; Narisma, G.T.; Muniz Alves, L.; Amjad, M.; Gorodetskaya, I.V.; Grose, M.; Klutse, N.A.B.; Krakovska, S.; Li, J.; et al. Atlas. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change; Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S.L., Péan, C., Berger, S., Caud, N., Chen, Y., Goldfarb, L., Gomis, M.I., et al., Eds.; Cambridge University Press: Cambridge, UK; New York, NY, USA, 2021; pp. 1927–2058. [Google Scholar]
- Spinoni, J.; Naumann, G.; Vogt, J.V.; Barbosa, P. The Biggest Drought Events in Europe from 1950 to 2012. J. Hydrol. Reg. Stud. 2015, 3, 509–524. [Google Scholar] [CrossRef]
- Gudmundsson, L.; Seneviratne, S.I. Anthropogenic Climate Change Affects Meteorological Drought Risk in Europe. Environ. Res. Lett. 2016, 11, 044005. [Google Scholar] [CrossRef]
- Spinoni, J.; Vogt, J.V.; Naumann, G.; Barbosa, P.; Dosio, A. Will Drought Events Become More Frequent and Severe in Europe? Int. J. Climatol. 2018, 38, 1718–1736. [Google Scholar] [CrossRef]
- Spinoni, J.; Barbosa, P.; Bucchignani, E.; Cassano, J.; Cavazos, T.; Christensen, J.H.; Christensen, O.B.; Coppola, E.; Evans, J.; Geyer, B.; et al. Future Global Meteorological Drought Hot Spots: A Study Based on CORDEX Data. J. Clim. 2020, 33, 3635–3661. [Google Scholar] [CrossRef]
- Founda, D.; Varotsos, K.V.; Pierros, F.; Giannakopoulos, C. Observed and Projected Shifts in Hot Extremes’ Season in the Eastern Mediterranean. Glob. Planet. Chang. 2019, 175, 190–200. [Google Scholar] [CrossRef]
- Georgoulias, A.K.; Akritidis, D.; Kalisoras, A.; Kapsomenakis, J.; Melas, D.; Zerefos, C.S.; Zanis, P. Climate Change Projections for Greece in the 21st Century from High-Resolution EURO-CORDEX RCM Simulations. Atmos. Res. 2022, 271, 106049. [Google Scholar] [CrossRef]
- Zittis, G.; Bruggeman, A.; Lelieveld, J. Revisiting Future Extreme Precipitation Trends in the Mediterranean. Weather Clim. Extrem. 2021, 34, 100380. [Google Scholar] [CrossRef]
- Zittis, G.; Almazroui, M.; Alpert, P.; Ciais, P.; Cramer, W.; Dahdal, Y.; Fnais, M.; Francis, D.; Hadjinicolaou, P.; Howari, F.; et al. Climate Change and Weather Extremes in the Eastern Mediterranean and Middle East. Rev. Geophys. 2022, 60, e2021RG000762. [Google Scholar] [CrossRef]
- Zanis, P.; Georgoulias, A.K.; Velikou, K.; Akritidis, D.; Kalisoras, A.; Melas, D. Future Projections of Precipitation Extremes for Greece Based on an Ensemble of High-Resolution Regional Climate Model Simulations. Atmosphere 2024, 15, 601. [Google Scholar] [CrossRef]
- Jacob, D.; Petersen, J.; Eggert, B.; Alias, A.; Christensen, O.B.; Bouwer, L.M.; Braun, A.; Colette, A.; Déqué, M.; Georgievski, G.; et al. EURO-CORDEX: New High-Resolution Climate Change Projections for European Impact Research. Reg. Environ. Chang. 2014, 14, 563–578. [Google Scholar] [CrossRef]
- Jacob, D.; Teichmann, C.; Sobolowski, S.; Katragkou, E.; Anders, I.; Belda, M.; Benestad, R.; Boberg, F.; Buonomo, E.; Cardoso, R.M.; et al. Regional Climate Downscaling over Europe: Perspectives from the EURO-CORDEX Community. Reg. Environ. Chang. 2020, 20, 51. [Google Scholar] [CrossRef]
- Taylor, K.E.; Stouffer, R.J.; Meehl, G.A. An Overview of CMIP5 and the Experiment Design. Bull. Amer. Meteo. Soc. 2012, 93, 485–498. [Google Scholar] [CrossRef]
- van Vuuren, D.P.; Stehfest, E.; den Elzen, M.G.J.; Kram, T.; van Vliet, J.; Deetman, S.; Isaac, M.; Klein Goldewijk, K.; Hof, A.; Mendoza Beltran, A.; et al. RCP2.6: Exploring the Possibility to Keep Global Mean Temperature Increase below 2°C. Clim. Chang. 2011, 109, 95. [Google Scholar] [CrossRef]
- Thomson, A.M.; Calvin, K.V.; Smith, S.J.; Kyle, G.P.; Volke, A.; Patel, P.; Delgado-Arias, S.; Bond-Lamberty, B.; Wise, M.A.; Clarke, L.E.; et al. RCP4.5: A Pathway for Stabilization of Radiative Forcing by 2100. Clim. Chang. 2011, 109, 77. [Google Scholar] [CrossRef]
- Riahi, K.; Rao, S.; Krey, V.; Cho, C.; Chirkov, V.; Fischer, G.; Kindermann, G.; Nakicenovic, N.; Rafaj, P. RCP 8.5—A Scenario of Comparatively High Greenhouse Gas Emissions. Clim. Chang. 2011, 109, 33. [Google Scholar] [CrossRef]
- McKee, T.B.; Doesken, N.J.; Kleist, J. The Relationship of Drought Frequency and Duration to Time Scales. In Proceedings of the 8th Conference on Applied Climatology, Anaheim, CA, USA, 17 January 1993; Volume 17, pp. 179–183. [Google Scholar]
- Vicente-Serrano, S.M.; Beguería, S.; López-Moreno, J.I. A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index. J. Clim. 2010, 23, 1696–1718. [Google Scholar] [CrossRef]
- Wu, H.; Hayes, M.J.; Wilhite, D.A.; Svoboda, M.D. The Effect of the Length of Record on the Standardized Precipitation Index Calculation. Int. J. Climatol. 2005, 25, 505–520. [Google Scholar] [CrossRef]
Figure 1.
Drought frequency changes for the periods 2021–2050 and 2071–2100 relative to 1971–2000 based on SPI-6 (1st and 2nd column) and SPEI-6 (3rd and 4th column) under RCP2.6 (top row), RCP4.5 (middle row) and RCP8.5 (bottom row). Areas without markings indicate robust changes, while hatched (/) and cross-hatched (X) areas indicate non-robust and conflicting signals, respectively.
Figure 1.
Drought frequency changes for the periods 2021–2050 and 2071–2100 relative to 1971–2000 based on SPI-6 (1st and 2nd column) and SPEI-6 (3rd and 4th column) under RCP2.6 (top row), RCP4.5 (middle row) and RCP8.5 (bottom row). Areas without markings indicate robust changes, while hatched (/) and cross-hatched (X) areas indicate non-robust and conflicting signals, respectively.
Figure 2.
As in Figure 1, but for drought duration.
Figure 2.
As in Figure 1, but for drought duration.
Figure 3.
As in Figure 1, but for drought severity.
Figure 3.
As in Figure 1, but for drought severity.
Table 1.
List of the eleven EURO-CORDEX sets of simulations used in this study.
| RCM. | Driving GCM | Realization |
|---|---|---|
| ALADIN63.v2 | CNRM.CNRM-CERFACS-CNRM-CM5 | r1i1p1 |
| CCLM4-8-17.v1 | CLMcom.ICHEC-EC-EARTH | r12i1p1 |
| HIRHAM5.v2 | DMI.ICHEC-EC-EARTH | r3i1p1 |
| RACMO22E.v1 | KNMI.ICHEC-EC-EARTH | r12i1p1 |
| RACMO22E.v2 | KNMI.CNRM-CERFACS-CNRM-CM5 | r1i1p1 |
| RACMO22E.v2 | KNMI.MOHC-HadGEM2-ES | r1i1p1 |
| RCA4.v1 | SMHI.ICHEC-EC-EARTH | r12i1p1 |
| RCA4.v1 | SMHI.MOHC-HadGEM2-ES | r1i1p1 |
| RCA4.v1 | SMHI.MPI-M-MPI-ESM-LR | r1i1p1 |
| REMO2009.v1 | MPI-CSC.MPI-M-MPI-ESM-LR | r1i1p1 |
| REMO2009.v1 | MPI-CSC.MPI-M-MPI-ESM-LR | r2i1p1 |
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MDPI and ACS Style
Kalisoras, A.; Georgoulias, A.K.; Akritidis, D.; Zanis, P. Future Projections in Agricultural Drought Characteristics for Greece Under Different Climate Change Scenarios. Environ. Earth Sci. Proc. 2025, 35, 29. https://doi.org/10.3390/eesp2025035029
AMA Style
Kalisoras A, Georgoulias AK, Akritidis D, Zanis P. Future Projections in Agricultural Drought Characteristics for Greece Under Different Climate Change Scenarios. Environmental and Earth Sciences Proceedings. 2025; 35(1):29. https://doi.org/10.3390/eesp2025035029
Chicago/Turabian StyleKalisoras, Alkiviadis, Aristeidis K. Georgoulias, Dimitris Akritidis, and Prodromos Zanis. 2025. "Future Projections in Agricultural Drought Characteristics for Greece Under Different Climate Change Scenarios" Environmental and Earth Sciences Proceedings 35, no. 1: 29. https://doi.org/10.3390/eesp2025035029
APA StyleKalisoras, A., Georgoulias, A. K., Akritidis, D., & Zanis, P. (2025). Future Projections in Agricultural Drought Characteristics for Greece Under Different Climate Change Scenarios. Environmental and Earth Sciences Proceedings, 35(1), 29. https://doi.org/10.3390/eesp2025035029
