the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 16 Jun 2025
A five-century tree-ring record from Spain reveals recent intensification of western Mediterranean hydroclimatic extremes
Abstract. The Mediterranean basin, a recognized climate change hotspot, faces increasing hydroclimatic pressures, particularly from severe drought and precipitation events. To assess contemporary changes and potentially manage future impacts, it is crucial to understand the long-term context of this variability beyond the relatively short instrumental record. This study utilizes tree-ring records to reconstruct past hydroclimate in the Iberian Range of eastern Spain, a water-sensitive Mediterranean environment. We present a well-replicated tree-ring width chronology from Pinus sylvestris and Pinus nigra trees that calibrates and verifies significantly against cumulative instrumental precipitation over a 320-day period ending in June (r = 0.749; p < 0.01). The resulting 519-year reconstruction reveals substantial multi-centennial variability in precipitation and reveals an increase in the frequency and intensity of hydroclimatic extremes (both wet and dry) during the late 20th and early 21st centuries compared to the longer-term baseline. The reconstruction has a spatial representativeness centred over eastern and central Iberia and covaries with independent historical drought indices derived from rogation ceremony records during the late 18th and early 19th centuries. The documented intensification of hydroclimatic extremes is consistent with climate change projections and provides a baseline for evaluating ecosystem resilience and water resource vulnerability.
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Status: open (until 11 Aug 2025)
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RC1: 'Comment on egusphere-2025-2530', Anonymous Referee #1, 02 Jul 2025
reply
The authors developed a new precipitation reconstruction in western Mediterranean using tree-ring series from five sites and two pine tree species. This reconstruction extends the length of the hydroclimatic records for over 500 years, and focuses on quantitative precipitation rather than drought index. Multiple precipitation datasets and critical growth period beyond fixed monthly aggregations looks useful for identifying robust climate signals and improving the explained variance of reconstruction. This well-replicated tree-ring width based precipitation reconstruction indeed provides us a baseline for evaluating hydroclimatic extremes and related ecosystem and water resource variability. But there are still some problems should be resolved before it is considered for publication.
Main concerns:
- From the Title and Abstract, we expected to see sufficient evidences about “recent intensification of hydroclimatic extremes”, but there is few in Results and Discussion about it. Most of the results are about the reconstruction development and comparisons with rogation-derived drought indices.
- From Fig.7, we can see a little bit increase in frequency and intensity of wet and drought extremes after 2000 CE, but it is not proven. The variance of the reconstructed precipitation should be a good indicator to show it. Additionally, the running RABR should be shown in Fig. 6 to help evaluating the impacts of sample depth and inter-series correlations on variance of precipitation.
- Line 340-407, there are so many results (or discussion) about the comparisons between precipitation reconstruction and rogation-derived drought event, even including some correlations (Line 361, 366, 373,…), but no one figure and table to show these results. By using the method of giving the examples (a lot of “For instance”) to show the alignment of tree-ring based precipitation reconstruction with rogation ceremony records is not sufficient to support the precipitation influence on ecosystem and society, as maybe more disagree years happened.
- The organization of the manuscript is poor. (1) First, there are some repeat information in Discussion part. Such as, Line 416-419, “The resulting regional residual chronology demonstrates strong internal coherence (Rbar = 0.273), similar to those from other Mediterranean hydroclimatic reconstructions such as Esper et al. (2021); Klippel et al. (2018); Tejedor et al. (2016) (Rbar = 0.28; 0.31; 0.29). Our chronology retains a reliable common signal back to 1505 CE, as indicated by an SSS value consistently exceeding the 0.85 threshold (Buras, 2017; Cook and Kairiukstis, 1990; Wigley et al., 1984)”, which is repeat with Results. (2) Line 489-492, “Visual inspection of Fig. 7 highlights periods characterized by distinct wet or dry conditions, as well as shifts in variability. For instance, the reconstruction identifies notable drought periods, with years like 1526, 1527, 1879, 1931, 2005 and 2012 falling below the 5th percentile, and exceptionally wet periods, with years such as 1534, 1546, 1575, 1645, 1716, 1940, 2010 and 2013 exceeding the 95th percentile.” should be represented in Results part, as actually there is no discussion about it here. (3) The paragraph of Line 478-487 should be moved to the second paragraph from bottom as a summary to highlight the key aspects of this paper. Now, it is in the middle of discussion and disturbed the discussion about reconstructed precipitation.
Minor problems:
- About the Title, “precipitation extremes” is more exact than “hydroclimatic extremes” to highlight the study gap.
- Line 89, “June is the month with the highest pluviosity, followed by May” is inconsistent with Fig.1B, which shown precipitation in May is the highest, followed by April.
- Tree-ring series from five sites and two species were used for developing one chronology. How about the correlations between sites and species, and the uniformity of five chronologies at high frequency and low frequency variability? These informations could be plotted in Supplementary materials.
- Line 412-413, “capture the critical moisture accumulation phase influencing annual growth (late summer, autumn, winter and spring/early summer),” how to understand the autumn and winter precipitation influence on tree radial growth considering trees dormancy in winter.
- Line 445, “comparing our Fig. 6 extremes with their findings”, should be Fig. 7, right?
- Line 472-474, “The lack of strong correlation in earlier periods… influenced by biological memory, …” seems inconsistent with the feature of RES chronology with “pre-whitening to reduce autocorrelation”.
- 5 is not clear and takes up too much space.
Citation: https://doi.org/10.5194/egusphere-2025-2530-RC1 -
RC2: 'Comment on egusphere-2025-2530', Anonymous Referee #1, 02 Jul 2025
reply
The authors developed a new precipitation reconstruction in western Mediterranean using tree-ring series from five sites and two pine tree species. This reconstruction extends the length of the hydroclimatic records for over 500 years, and focuses on quantitative precipitation rather than drought index. Multiple precipitation datasets and critical growth period beyond fixed monthly aggregations looks useful for identifying robust climate signals and improving the explained variance of reconstruction. This well-replicated tree-ring width based precipitation reconstruction indeed provides us a baseline for evaluating hydroclimatic extremes and related ecosystem and water resource variability. But there are still some problems should be resolved before it is considered for publication.
Main concerns:
- From the Title and Abstract, we expected to see sufficient evidences about “recent intensification of hydroclimatic extremes”, but there is few in Results and Discussion about it. Most of the results are about the reconstruction development and comparisons with rogation-derived drought indices.
- From Fig.7, we can see a little bit increase in frequency and intensity of wet and drought extremes after 2000 CE, but it is not proven. The variance of the reconstructed precipitation should be a good indicator to show it. Additionally, the running RABR should be shown in Fig. 6 to help evaluating the impacts of sample depth and inter-series correlations on variance of precipitation.
- Line 340-407, there are so many results (or discussion) about the comparisons between precipitation reconstruction and rogation-derived drought event, even including some correlations (Line 361, 366, 373,…), but no one figure and table to show these results. By using the method of giving the examples (a lot of “For instance”) to show the alignment of tree-ring based precipitation reconstruction with rogation ceremony records is not sufficient to support the precipitation influence on ecosystem and society, as maybe more disagree years happened.
- The organization of the manuscript is poor. (1) First, there are some repeat information in Discussion part. Such as, Line 416-419, “The resulting regional residual chronology demonstrates strong internal coherence (Rbar = 0.273), similar to those from other Mediterranean hydroclimatic reconstructions such as Esper et al. (2021); Klippel et al. (2018); Tejedor et al. (2016) (Rbar = 0.28; 0.31; 0.29). Our chronology retains a reliable common signal back to 1505 CE, as indicated by an SSS value consistently exceeding the 0.85 threshold (Buras, 2017; Cook and Kairiukstis, 1990; Wigley et al., 1984)”, which is repeat with Results. (2) Line 489-492, “Visual inspection of Fig. 7 highlights periods characterized by distinct wet or dry conditions, as well as shifts in variability. For instance, the reconstruction identifies notable drought periods, with years like 1526, 1527, 1879, 1931, 2005 and 2012 falling below the 5th percentile, and exceptionally wet periods, with years such as 1534, 1546, 1575, 1645, 1716, 1940, 2010 and 2013 exceeding the 95th percentile.” should be represented in Results part, as actually there is no discussion about it here. (3) The paragraph of Line 478-487 should be moved to the second paragraph from bottom as a summary to highlight the key aspects of this paper. Now, it is in the middle of discussion and disturbed the discussion about reconstructed precipitation.
Minor problems:
- About the Title, “precipitation extremes” is more exact than “hydroclimatic extremes” to highlight the study gap.
- Line 89, “June is the month with the highest pluviosity, followed by May” is inconsistent with Fig.1B, which shown precipitation in May is the highest, followed by April.
- Tree-ring series from five sites and two species were used for developing one chronology. How about the correlations between sites and species, and the uniformity of five chronologies at high frequency and low frequency variability? These informations could be plotted in Supplementary materials.
- Line 412-413, “capture the critical moisture accumulation phase influencing annual growth (late summer, autumn, winter and spring/early summer),” how to understand the autumn and winter precipitation influence on tree radial growth considering trees dormancy in winter.
- Line 445, “comparing our Fig. 6 extremes with their findings”, should be Fig. 7, right?
- Line 472-474, “The lack of strong correlation in earlier periods… influenced by biological memory, …” seems inconsistent with the feature of RES chronology with “pre-whitening to reduce autocorrelation”.
- 5 is not clear and takes up too much space.
Citation: https://doi.org/10.5194/egusphere-2025-2530-RC2
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