Facing drought in the Mediterranean

Above-average temperatures and scarce precipitation: these are the two main ingredients of a drought that has been affecting the Mediterranean basin for years – specifically, for six years in Northern Africa, and for about two years in Europe. Particularly significant are the impacts on southern Italy, Spain, Portugal, and Morocco, to the extent that they have led, in some cases, to water use restrictions.

How does a drought play out in a region with such an imbalanced water supply between winter precipitation and summer water use? To answer this question, let’s have a look to the January 2024 report from the European Commission Joint Research Centre. CIMA Research Foundation contributed to the analysis, which investigates the various factors contributing to a drought in the Mediterranean region.

This study not only provides a deeper understanding of climate patterns and trends, but also underlines the urgent need for action to address this challenge.

The Report?

According to the report, the January situation was like this: “After an extremely hot 2023, dry conditions are again affecting most of the Mediterranean region and are already associated with severe impacts. In terms of availability of water resources, the evolution is uncertain and variable across the different sub-regions.”?

These first lines of the report remind us that droughts are a complex phenomenon that takes time to develop, and its consequences become evident over time. Water availability shortages are measured over a prolonged period, as slow, deep, non-independent processes. This is particularly true in the Med region, where most of the precipitation falls in winter and most of water uses are in summer!

Through the calculation of several indices and indicators, including the Combined Drought Indicator (CDI), the Standardized Precipitation Index (SPI) and the Heat and Cold Wave Index (HCWI), the report shows how the rising temperatures have exacerbated the effect of below-average rainfall over the course of the recent winters.? The direct impacts on agriculture, water supply and the natural ecosystems were already evident in many regions in January, especially in northern Africa, Spain and most of Mediterranean islands.?

Soil moisture, vegetation biomass and large-scale atmospheric conditions are then analysed, and finally the impacts that the combination of these factors were having on different crops is emphasised, as well as the consequent adoption of water management policies, which are essential to ensure long-term availability.

The contribution of CIMA Research Foundation

As we know, snow also plays an important role in water availability. In Italy, data up to January showed that snow has been scarce throughout 2023-24 winter. As a result of the dry conditions in the second half of January 2024, snow water resources throughout Italy were well below average conditions. As a result, the snow line was higher than usual, and the snowpack thinner.

The report states: “Considering the entire Alps in terms of snow-covered area, two extensive snowfall periods have been observed in early November 2023 and early December 2023, reaching an extent of snow-covered area even above the long-term average. However, the above average temperature caused a rapid and anticipated snowmelt and the depletion of the snowpack afterwards. After a less relevant and shorter snow event in mid-January 2024, the snow-covered area dropped to its minimum value by early February 2024 due to the warm temperature and the lack of precipitation”.?

The analysis over the Italian Alps is based on data and information provided by the operational snow monitoring system for Italy (S3M -Italy) developed and maintained by CIMA Research Foundation on behalf of the Italian Civil Protection Department (DPC). This system provides hourly snapshots of snow depth and mass content (SWE) at 200 metres resolution (Avanzi et al., 2023).?

As CIMA Research Foundation reported in its monthly updates, the situation improved throughout the following months, so that by April, for the first time in two years, the deficit in the Snow Water Equivalent (the water contained in the snow) is filled. Still, researchers draw attention to the fact that the deficit is still significant in the Apennines and at lower altitudes of the Alps. Moreover, high temperatures could cause early melts.?

But what more can we say today?

From seasonal forecasts to date

“Based on the Copernicus Climate Change Service (C3S) seasonal forecasts, warmer than usual conditions are likely to occur in Europe up to April 2024, with larger positive anomalies in the southern Mediterranean region. Precipitation forecasts are close to average or slightly wetter than average for the northern Mediterranean region, and mostly slightly drier than average in the southern Mediterranean region. Some variability between the models is present.”?

And so it was. According to the C3S climate bullettin, March 2024 was warmer globally than any previous March in data history, with an average surface air temperature ERA5 of 14.14°C. Furthermore, it was wetter than average in most of western Europe, with storms causing heavy rainfall over the Iberian Peninsula and southern France.??

As for the replenished snow deficit in Italy, these are good news, but they cannot make us forget the data - and the warning - from the IPCC: the climate crisis is already leading to more frequent and intense droughts in the Mediterranean basin. Even though the situation has currently improved, we know it will reoccur - perhaps soon.?