Santamarta et al. (2026) Island water stress: analyzing the Canary Islands’ hydrological response to climate change

Identification

• Journal: Environmental Monitoring and Assessment
• Year: 2026
• Date: 2026-04-10
• Authors: Juan C. Santamarta, Alejandro García-Gil, Susana Clavijo-Núñez, Noelia Cruz-Pérez
• DOI: 10.1007/s10661-026-15219-y

Research Groups

• Departamento de Ingeniería Agraria y del Medio Natural, Universidad de La Laguna (ULL), Tenerife, Spain
• Geological and Mining Institute of Spain (IGME), Spanish National Research Council (CSIC), Madrid, Spain

Short Summary

This study projects the long-term evolution of the water balance in the Canary Islands under climate change, utilizing a high-resolution downscaling methodology. Results indicate a significant decrease in water availability across the archipelago by the end of the century, driven by increased evapotranspiration and stable or reduced precipitation, with some islands facing severe water depletion.

Objective

• To evaluate the potential impacts of human actions and climate change on hydrological processes and water balance in the Canary Islands.
• To specifically analyze how climate change alters long-term water balance dynamics and the spatiotemporal distribution of water resources in the region.

Study Configuration

• Spatial Scale: Canary Islands archipelago (seven main islands, approximately 7500 km² total area). High-resolution projections at 100 m × 100 m.
• Temporal Scale:
  • Historical baseline: 1985–2014 (30-year reference period).
  • Future projections: Near future (2021–2050), mid-future (2041–2070), and late future (2071–2100).

Methodology and Data

• Models used:
  • FICLIMA methodology (Fundación para la Investigación del Clima) for downscaling large-scale climate simulations to regional hydrology, employing analogue stratification and geographically weighted regression (GWR).
  • Ensemble of ten CMIP6 climate models (e.g., ACCESO-CM2, BCC-CSM2-MR, CanESM5, CMCC-ESM2, CNRM-ESM2-1, EC-EARTH3, MPI-ESM1-2-HR, MRI-ESM2-0, NorESM2-MM, UKESM1-0-LL) aligned with IPCC AR6 and Shared Socioeconomic Pathways (SSPs).
  • Simplified monthly water balance calculation: WBm = WBm−1 + Prm−ETom (Water Balance = previous month's Water Balance + Precipitation - Evapotranspiration).
• Data sources:
  • Historical climate records (1985–2014) from weather stations across the Canary Islands.
  • Geographic Information Systems (GIS) layers from CanaryClim database and SITCAN Canary Islands Atlas (including precipitation, temperature, cloud cover, land surface temperature (LST), Normalized Difference Vegetation Index (NDVI), aspect, northness, eastness, altitude, distance to seashore).
  • Reanalysis data: ERA5 (0.25° × 0.25° global coverage, hourly data for relative humidity and precipitation) and ERA5-Land (0.1° × 0.1° over continental areas).
  • IPCC AR6 Shared Socioeconomic Pathways (SSPs), including SSP2-4.5 (intermediate) and SSP5-8.5 (worst-case).

Main Results

• A general trend of progressively decreasing water balance is projected across the Canary Islands, worsening towards the end of the century.
• This decline is primarily driven by increasing evapotranspiration rates and stable or decreasing precipitation levels.
• Coastal areas across all seven islands currently exhibit an almost negligible water balance and are expected to face even greater water stress.
• Island-specific projections by the end of the century under worst-case scenarios (SSP5-8.5):
  • El Hierro: Expected reduction in water balance of 50% to 75%, with decreases of up to 150 mm in the central region.
  • Gran Canaria: Projected to experience an almost complete depletion of its water reserves.
  • La Palma: Slight short-to-medium-term increase in water availability in the northeast, but long-term decline due to increased evapotranspiration.
  • La Gomera: Anticipated partial to near-total reduction in water balance.
  • Tenerife: Estimated reductions of approximately 50% in water balance, translating to decreases of 50 mm to 100 mm.
  • Fuerteventura and Lanzarote: Annual water balance is effectively zero, and water stress will be exacerbated.

Contributions

• This study provides the first high-resolution (100 m × 100 m) climate change projections for the water balance in the Canary Islands, adapting the FICLIMA methodology to the archipelago's complex orography and microclimates.
• It offers critical insights into future water availability trends, enabling policymakers and water managers to develop adaptive and sustainable strategies for water security in a region heavily reliant on tourism and agriculture.
• The research contributes valuable data to the SICMA-Canarias public access platform, fostering further research and climate change adaptation efforts in the region.

Funding

• European Union’s Horizon 2023 green research and innovation programme under grant agreement No. 101157447 (project GENESIS: Geologically Enhanced NaturE-based Solutions for climate change resiliency of critical water InfraStructure).
• Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.
• FIClima (Climate Research Foundation) for developing the platform with local climate change scenarios.

Citation

@article{Santamarta2026Island,
  author = {Santamarta, Juan C. and García-Gil, Alejandro and Clavijo-Núñez, Susana and Cruz-Pérez, Noelia},
  title = {Island water stress: analyzing the Canary Islands’ hydrological response to climate change},
  journal = {Environmental Monitoring and Assessment},
  year = {2026},
  doi = {10.1007/s10661-026-15219-y},
  url = {https://doi.org/10.1007/s10661-026-15219-y}
}