Drought Properties in Mediterranean Under Climate Change Scenarios

Drought is a complex phenomenon related to climate conditions. It can negatively affect vital sectors, threaten water and food security, and impact countries' environmental, social, and economic levels. The Mediterranean is one of the global areas where climate change impacts the most. This work aims to address the physical properties of different drought types under near-future climate in the Mediterranean.

To do so, we use a multi-model mean of the bias-adjusted and downscaled product of five Earth System Models participating in the Coupled Model Intercomparison Project - phase6 (CMIP6), provided by Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), under four shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) for the period 2021-2060, to estimate the Standardized Precipitation Evapotranspiration Index (SPEI) at 1-, 6-, and 12-month time scales, and address the meteorological, agricultural, and hydrological drought, respectively. Additionally, SPEI is calculated from the bias-adjusted CMIP6 historical simulations and the reanalysis ‘WFDE5’ for 1980-2014 as a historical and reference period.

The comparison of the CMIP6 with WFDE5, reveals a consistently increasing tendency for drought occurrences in the Mediterranean, particularly for agricultural and hydrological drought time scales. Nonetheless, an overestimation in historical trend magnitude is shown by the CMIP6 with respect to WFDE5. The projection results depict drought frequencies ranging between 12 - 25 % of the studied period 2021-2060, varying with regions and climate change scenarios. The tendency to increase the drought frequency is more pronounced in the southern than northern Mediterranean countries. On shorter time scales, the projected changes in the shape of the distribution are more evident than shifts in its mean, particularly for SSP1-2.6 and SSP2-4.5. Drought severity is remarkable in the aggregated time scales; consequently, more pressure is foreseen in the food and water sectors. Drought seasonality reveals a higher tendency for drought occurrences in summer (autumn) months for the meteorological (agricultural) droughts. The driving factor(s) for drought occurrence strongly depends on regional climate characteristics.

Finally, we discussed the methodological limitations, challenges, and potential future work. The addressed uncertainties, difficulties and complexity of quantifying drought, particularly for future scenarios, should not be an argument for inaction in investigating the potential impacts and the local response for the far years. It remains the key road for supporting countries to call for the integration of urgent adaptation and mitigation approaches to adverse climate impacts on socio-economic and vital sectors, and devote efforts to reducing the uncertainties sources.