Marín-Martín et al. (2025) A five-century tree-ring record from Spain reveals recent intensification of western Mediterranean precipitation extremes

Identification

• Journal: Climate of the past
• Year: 2025
• Date: 2025-11-13
• Authors: Marcos Marín-Martín, Ernesto Tejedor, Gerardo Benito, Miguel Ángel Saz, Mariano Barriendos, Edurne Martínez del Castillo, Jan Esper, Martín de Luis
• DOI: 10.5194/cp-21-2205-2025

Research Groups

• Department of Geology, National Museum of Natural Sciences-Spanish National Research Council (MNCN-CSIC), Madrid, Spain
• Departamento de Geografía y Ordenación del Territorio, Instituto Universitario de Investigación en Ciencias Ambientales de Aragón, Universidad de Zaragoza, Zaragoza, Spain
• Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA-CSIC), Barcelona, Spain
• Department of Geography, Johannes Gutemberg University, Mainz, Germany
• Global Change Research Institute, Czech Academy of Sciences, Brno, Czech Republic

Short Summary

This study reconstructs 520 years of quantitative precipitation in the Iberian Range, eastern Spain, using tree-ring data, revealing an unprecedented intensification in the frequency and intensity of hydroclimatic extremes during the late 20th and early 21st centuries compared to previous centuries.

Objective

• To reconstruct quantitative precipitation for the Iberian Range over the last five centuries using tree-ring data.
• To assess whether the frequency and intensity of hydroclimatic extremes (both wet and dry) have increased in the late 20th and early 21st centuries compared to a longer-term baseline.
• To improve the explained variance and temporal length of hydroclimate reconstructions, focusing on direct precipitation amounts rather than drought indices.

Study Configuration

• Spatial Scale: Iberian Range, eastern Spain (Teruel province, Aragón region), with five sampling locations within a 100 km radius. The reconstruction's spatial representativeness is centered over eastern and central Iberia, extending into southern France and northern Italy.
• Temporal Scale:
  • Tree-ring chronology and precipitation reconstruction: 1505–2024 CE (520 years).
  • Instrumental calibration and verification period: 1952–2022 CE.
  • Rogation ceremony records: 1650–1899 CE.
  • Target precipitation window: 320 days, spanning from 16 August of the previous year to 30 June of the current year.

Methodology and Data

• Models used:
  • Dendrochronological methods: Cross-dating (CDendro, COFECHA), standardization (dplR package, negative exponential curve or cubic smoothing spline, biweight robust mean, prewhitening for residual chronology).
  • Statistical analysis: Pearson correlation, Spearman correlation, Durbin-Watson statistic, mean sensitivity (MS), mean inter-series correlation (Rbar), signal-to-noise ratio (SNR), subsample signal strength (SSS).
  • Reconstruction model: Simple linear regression (transfer function).
  • Validation: Split-period calibration-verification (coefficient of determination (r²), reduction of error (RE) statistic), Bootstrapped Transfer Function Stability test (BTFS).
  • Extreme event identification: Percentile thresholds (1st, 5th, 95th, 99th percentiles).
• Data sources:
  • Tree-ring data: 173 increment cores from 103 living Pinus sylvestris L. and Pinus nigra Arn. trees collected from five sites in the Iberian Range, Spain.
  • Climate data (gridded precipitation datasets): SiCLIMA (0.005°, 1950–2020, daily), TerraClimate (0.042°, 1958–2023, daily), ROCIO (0.05°, 1951–2022, daily), SPREAD (0.05°, 1950–2012, daily), E-OBS (0.1° and 0.25°, 1920/1950–2023, daily), ERA5-Land (0.28°, 1950–2024, daily), CRU TS (0.5° and 1.0°, 1901–2023, monthly). The ROCIO dataset was selected for the final reconstruction due to its high resolution and strong correlation.
  • Historical data: Rogation ceremony records (rogativas pro pluvia and pro serenitate) from the "Ebro Valley" (DIEV) and "Mediterranean" (DIMED) clusters (1650–1899 CE), converted into a semi-quantitative drought index (DI). Qualitative historical documents were also used for context on wet extremes.

Main Results

• A 520-year (1505–2024 CE) quantitative precipitation reconstruction for the Iberian Range was successfully developed using Pinus sylvestris and Pinus nigra tree-ring widths.
• The reconstruction targets cumulative precipitation over a 320-day window (16 August of the previous year to 30 June of the current year).
• The linear regression model, calibrated with the high-resolution ROCIO dataset, demonstrated strong predictive skill (Pearson correlation coefficient r = 0.749 for the optimal window; coefficient of determination r² ranged from 0.47 to 0.63 in split-period validation, with positive RE values).
• The reconstruction revealed substantial multi-centennial variability in precipitation throughout the record.
• A significant and unprecedented intensification in the frequency and intensity of both wet and dry hydroclimatic extremes was observed during the late 20th and early 21st centuries within the 520-year context.
• The 21st century (2001–2024) exhibited an occurrence rate of 16.7% for exceptionally rare events (below the 1st percentile or above the 99th percentile), which is an order of magnitude higher than the 1.6% average rate for the preceding five centuries (1505–2000).
• A 51-year running standard deviation of precipitation showed a persistent rise in volatility after 1975, reaching values unprecedented in the 520-year record.
• Independent validation with rogation ceremony records showed statistically significant negative correlations (Spearman r ranging from -0.29 to -0.35) during the late 18th and early 19th centuries, indicating a convergence between tree-ring signals and societal perceptions of drought.

Contributions

• Provides an exceptionally long (over 500 years) quantitative precipitation reconstruction for the Iberian Range, a recognized climate change hotspot, offering crucial long-term context for interpreting recent and future hydroclimatic trends.
• Demonstrates the superior performance of high-resolution gridded precipitation datasets (e.g., ROCIO) for dendroclimatic calibration, significantly reducing uncertainty compared to coarser products.
• Focuses on reconstructing direct quantitative precipitation amounts, providing a more direct measure of past weather conditions compared to widely used drought indices.
• Employs a rigorous methodology, including detailed daily response function analysis, to precisely identify the optimal climate window influencing tree growth in this precipitation-limited environment.
• Offers robust empirical evidence of an unprecedented intensification of hydroclimatic extremes (both wet and dry) in the late 20th and early 21st centuries within the last five centuries, contributing to the debate on natural versus anthropogenic influences.
• Establishes a critical long-term baseline for evaluating ecosystem resilience and water resource vulnerability in the western Mediterranean.

Funding

• Comunidad de Madrid (Atracción Talento “César Nombela”, grant no. 2023-T1/ECO-29118)
• Fundación BBVA (“Beca Leonardo de Investigación Científica y Creación Cultural”, project MEDIRINGS)
• MEDYRISK project (grant no. PID2024-160542OB-I00) funded by MICIU/AEI/10.13039/501100011033 and ERDF/EU
• CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)

Citation

@article{MarínMartín2025fivecentury,
  author = {Marín-Martín, Marcos and Tejedor, Ernesto and Benito, Gerardo and Saz, Miguel Ángel and Barriendos, Mariano and Castillo, Edurne Martínez del and Esper, Jan and Luis, Martín de},
  title = {A five-century tree-ring record from Spain reveals recent intensification of western Mediterranean precipitation extremes},
  journal = {Climate of the past},
  year = {2025},
  doi = {10.5194/cp-21-2205-2025},
  url = {https://doi.org/10.5194/cp-21-2205-2025}
}

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