Many of the sandy beaches of Ibiza and Formentera could lose more than half of their width by the end of the century as sea levels rise, according to a doctoral thesis from the University of the Balearic Islands (UIB).
The projections
Using climate scenarios, the research estimates that:
- sea levels around the islands could rise by up to 103 cm by 2100 in an extreme scenario;
- around 36.5 km² of coastal land could be permanently flooded;
- the area affected by flooding during storms could increase by 41%;
- about 60% of beaches could lose more than half their current width.
The economic cost
Because the islands’ economy depends so heavily on tourism, and tourism depends on beaches, the study estimates the losses could be equivalent to around 7.2% of the islands’ GDP, taking 2019 as a reference.
How the study was done
The researcher combined computer models with field measurements:
- numerical simulations of coastal flooding and shoreline erosion;
- models of shoreline retreat that take account of waves, tides and how much sand is available;
- a comparison with traditional forecasting methods, showing that the improved approach better predicts how narrow beaches respond.
The work also developed a radar system (frequency-modulated continuous wave, or FMCW) that can measure waves and map the depth of the seabed up to 500 metres offshore, operating continuously without external calibration. It provides precise, real-time data for tracking changes on a beach.
Why narrow beaches are vulnerable
Many beaches in the Balearics are naturally narrow, often backed by cliffs, roads or buildings. With little sand and no room to move inland, they have a much smaller buffer against waves and storms. As the sea rises, they can disappear much faster than wide beaches backed by dunes.
What can be done
The study argues that the islands need to plan now, combining scientific forecasts with real-world monitoring. Options range from protecting dunes and seagrass meadows — which help hold sand in place — to managing development on the coast and, in some cases, accepting that the shoreline will move.
