climate change canary islands water reserves

Climate change could halve Canary Islands’ water reserves

Climate change to push Canary Islands’ water reserves to the limit

Climate change is set to place unprecedented strain on the Canary Islands’ water reserves, according to a new study from the University of La Laguna (ULL). The research warns that over the rest of this century, there will be a dramatic reduction in rainwater available across all the islands, with reserves potentially halved.

Drastic reductions forecast for western and eastern islands

For El Hierro, the worst-case scenario predicts a drop of between 50% and 70%, while Tenerife is expected to see losses of around 50%. The situation is even more critical in the eastern islands. In Gran Canaria, the study projects an almost complete depletion of reserves, which are currently limited to small mountainous areas in the north and centre of the island.

Study focuses on climatic water balance

The research, published in the journal Environmental Monitoring and Assessment and coordinated by Professor Juan Carlos Santamarta, a researcher in the Department of Agricultural Engineering and Natural Environment at ULL, focuses on what is known as the “climatic” or “potential” water balance. This indicator is calculated using two variables: precipitation, which adds water to the territory, and evapotranspiration, which removes it. It does not, therefore, include contributions from desalination, which is widely used in the Canaries and is one of the key resources for combating water scarcity. This approach was chosen because measuring only the water obtained from the climate allows the impact of climate change on the resource to be isolated.

Growing variability and more frequent droughts

In this context, a study by the Fundación Renovables shows that the impact of climate change on the islands is already evident. Indeed, 2024 was the driest year in the Canary Islands since 1961, with just 138.8 litres of rainfall per square metre recorded. By contrast, 2025 was the wettest year in the series. However, as Professor Santamarta explains, the trend “is not that less rain falls each year,” but rather that there is greater variability and more frequent droughts, which affects long-term recharge capacity.

This variability has already led to a decline in aquifer recharge, which in the western islands remains one of the main ways of obtaining water resources. In Tenerife, for example, effective aquifer recharge has fallen from 36% to 29% over four decades—a drop from 348 to 283 cubic hectometres per year.

High-resolution modelling for a complex terrain

To obtain this data, the research team adapted the Ficlima methodology for the Canary Islands to project how the climatic water balance will change. This technique translates global climate models to a highly detailed local scale, capturing the particularities of a territory with complex topography and numerous microclimates. The analysis offers a resolution of 100 metres—the first time such a level of detail has been available for the archipelago—and is based on the international climate models of the Sixth Assessment Report of the United Nations’ Intergovernmental Panel on Climate Change (IPCC).

Projections are made for three time horizons: the short term (2021-2050), medium term (2040-2070), and long term (2071-2100), under various greenhouse gas emission scenarios, ranging from the most optimistic to the most critical.

Human activity adds to the pressure

Alongside this climatic pressure, the study highlights the impact of human activity, particularly population growth and the heavy water demands of tourism—which in some cases is five times that of the local population—as well as agriculture. The general trend observed in the projections is a decline in the climatic water balance, which becomes more pronounced as the century progresses. The analysis also notes that these changes will be strongly influenced by altitude, pointing out that coastal areas of the archipelago already have a zero climatic water balance, which will lead to increased water stress across the territory as a whole.

Strategies to mitigate scarcity

The researchers stress that the study provides useful data for managing the resource more efficiently, especially given the growing competition for water between high-demand sectors such as tourism and agriculture. Among the strategies already helping to mitigate scarcity are seawater desalination, the reuse of wastewater, and improvements in water storage and distribution.

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