Mediterranean Iberian Peninsula Research Articles

Trend Analysis and Spatial Behaviour of the Fire Weather Index in the Mediterranean Iberian Peninsula, 1971–2022

ABSTRACTThe Fire Weather Index (FWI) is a widely used metric to estimate the wildfire risk based on climatological variables. As anthropogenic climate change is expected to increase wildfire risk by affecting the climate of the Mediterranean Iberian Peninsula, we assess the expected increase in wildfire risk during the past decades. For this purpose, we employ a dataset containing daily FWI values in a 0.25° × 0.25° grid for each day of a 52‐year period, between 1971 and 2022, and perform a trend analysis at a statistically significant level. We evaluate the relation between FWI and spatial (altitude, latitude, and distance to the sea) variables to look for significant correlations. An analysis is performed at the geographic level by focusing on changes in concrete, relatively homogenous zones (subregions) to broadly study spatial patterns of change. The most relevant results are (1) the FWI shows an increasing trend across the study area (0.01 confidence level); (2) the FWI is determined by temperature variations on a multiyear scale, but annually by more volatile precipitation patterns; (3) the FWI does not uniformly behave across either space or time, and is subject to different variations in different zones; (4) summer and winter are the seasons with the most significant increase, and autumn is the only not significant season; (5) very high or extreme risks are increasingly prevalent across the territory, increasing wildfire risk and (6) the FWI more rapidly rises in areas further north, at a longer distance to the sea and at higher altitudes, with the Iberian System being the most affected region. The increase in wildfire risk requires putting in place more preventive measures. Our study results coincide with climatological trend studies on the region and bridge a knowledge gap as regards the historical climatology of the FWI.

Historical floods in the southeastern Iberian Peninsula since the 16th century: Trends and regional analysis of extreme flood events

Studies related to historical floods have generated much knowledge about flood patterns and frequencies in recent years. Extending the series of floods to a longer range of time allows society to clarify what has happened in the past, and thus know what may happen in the future. From the descriptions of primary and secondary sources, a classification of historical floods has been carried out following a method specifically adapted for the study area. The southeastern Iberian Peninsula is the last region to compile historical floods in the Mediterranean Iberian Peninsula. Therefore, the main objective of the present study is to extend the flood series of historical events for four river basins: the Almanzora, Antas, Aguas and Andarax. First, flood events are classified according to their descriptions, generating a dataset of all flood events from 1500 to the present day for each basin. Second, we analyze the trends in the historical series, identifying four trend periods linked with the availability of records: 1500–1850, 1850–1900, 1900–1955 and 1955–2000. Notably, the trend in recent decades has broken with normality because of the large number of lower magnitude events. Lastly, we compare our dataset with seven historical series from different rivers elsewhere in the Iberian Peninsula. The results show a high correlation with all southeastern basins and less with the northern and Atlantic basins. For the purposes of the analysis, we considered only the extraordinary and catastrophic floods in all basins, that is, the floods of magnitude 3 or 4 (M3 or M4), and we identified two flood gaps in 1500–1540 and 1660–1720; two flood-poor periods in 1790–1845 and 1955–1970; and five flood-rich periods in 1540–1560, 1610–1654, 1720–1745, 1860–1891 and 1970–1990 in relation to the four river basins in the study area and the other seven Iberian basins, the last century is highly biased by the construction of reservoirs in all basins. The analysis of historical floods shows a link between the flood-gap periods and negative phases of NAOi and TSI. From 1970, lower flood magnitudes occurred during periods of highest amounts of information, an increase in tourism areas. Consequently, the last flood-rich period clearly stands out because of the disparity of the data, and the consequences are biased, for example, by surface runoff in urban areas where non-irrigated agricultural areas were traditionally located, resulting in an increase in economic damage.

Seasonal behaviour and influence of altitude on fog‐water collection in the Eastern Iberian Peninsula (2003–2012)

AbstractA study on fog‐water collection potential at the Mediterranean Iberian Peninsula was carried out for the period 2003–2012. The area is denoted by a high population density, with fairly common water restrictions in certain periods during the year. Moreover, climate change projections point out a sharp drop in precipitation for this sector of the western Mediterranean Basin that would aggravate water problems. This work aims to look closely at knowledge of fog‐water collection and it presents results about: its behaviour during different seasons of the year; the fog‐water collection potential on dry days (precipitation <1 mm); the influence of site elevation on both collected volumes and the number of days with fog‐water collection. To do so, daily fog‐water collection data were analysed from 2003 to 2012 with a dense network of 23 fog‐water collectors, which run along the Mediterranean coast of the Iberian Peninsula. The most relevant results were: (a) the seasonal periods with the largest recorded fog‐water volumes were autumn and spring; the highest percentages of days with fog‐water collection were obtained in summer and autumn; (b) on days when precipitation was null or negligible (<1 mm), maximum daily fog‐water captures were considerable and exceeded 25 L m−2 at more than half the studied sites; (c) the greater the positive difference in elevation between nearby stations, the larger the positive difference in both fog collected volumes and fog days at equal exposition to prevailing winds, differences that increase in the summer period. Mount Muela (Murcia Region), combining a pair of stations only distanced by 600 m but at a 92‐m elevation difference, reported a contrast of two times the collected volume at the upper station compared to the lower and an increment of 61% more days with fog occurrence. Mount Montseny (Catalonia), with a pair of stations distanced by 1,600 m horizontally and 398 m in elevation difference, obtained a sixfold variation between stations for fog‐water collection and a 73% increment in foggy days.

Sign-switching ecological changes in the Mediterranean Basin at 4.2 ka BP

Around 4.2 ka BP, several ancient civilizations declined, during a climatic fluctuation documented by many archaeological and palaeoenvironmental studies of locations around the world. However, the nature, timing, and regional expressions of this climate event are still uncertain. Through a detailed survey of Mediterranean pollen records, we show clear spatiotemporal patterns in tree cover variations over the Mediterranean Basin, characterized by regions with increasing forest cover before 4.2 ka BP and decreasing afterwards (NW Iberian Peninsula, South-central Mediterranean), and regions with contemporary opposite dynamics (Mediterranean Iberian Peninsula, Morocco, S Balkan Peninsula, and the Levant). At the same time, in the geographical belt longitudinally stretching from southern France to the Caucasus, no significant changes in tree cover are recorded. This coherent system of ecological configurations, possibly determined by the reorganization of semi-permanent high/low pressure cells, brings order to the contradictory climate signals of the 4.2 ka BP event. The discovery of ecological processes of opposite polarity at a sub-continental scale sheds new light on geographical patterns of past and present environmental vulnerability to rapid climate change in the Mediterranean Basin.

Chemical characterization in coastal fog and rain at Mount Monduver fog-collection station, Mediterranean Iberian Peninsula

An experimental site was selected for fog- and rain-water quality analyses. The selected location corresponds to Mount Monduver of 843 m elevation, being geographically centered in the Mediterranean Iberian Peninsula. Single fog- and rain-water samples were taken manually with a dedicated fog and rain collectors, to prevent any contamination with dry-deposition. Besides, a permanently exposed fog collector and a rain gauge were also used for the collection of water samples affected by dry deposition. Results indicated that all chemical analyses complied with Spanish drinking water regulations, except for the particular case of the dry-deposition contaminated water samples. A further statistical data analysis, together with five-day air mass backward trajectories, was performed. Two sample clusters could be differentiated which were also discriminated against by the two principal components obtained. Cluster-1 members comprised higher levels of conductivity and ion concentration, while cluster-2 members corresponded to lower levels of solutes. The second principal component related to pH levels showed the majority of samples centered at neutral values. The backward trajectory analysis indicated that the origin and route followed by the air masses leading to sample members in cluster-1 were over the Mediterranean Sea and mainly obtained in summer and autumn; while trajectories associated to sample members in cluster-2 had their origin primarily over the Atlantic Sea occurring only in winter and spring. The larger ion loads presented in fogs developed from Mediterranean air masses may be explained through the role of sea breezes on the confinement of pollutants into the atmosphere.

High-resolution Neanderthal settlements in mediterranean Iberian Peninsula: A matter of altitude?

Neanderthals are widely known to be a resilient human species that successfully faced constant and strong environmental fluctuations modifying the landscapes they inhabited and the availability of their potential resources. It has been traditionally assumed that environmental features could strongly affect human behaviour due to the stretch relationship between their potential prey and the availability of habitats. Environmental changes would produce a high variability in the settlement patterns of the Neanderthal groups. However, the preponderant influence of environmental conditions on these human groups has recently been strongly questioned. This is especially true for the Iberian Peninsula, where latitudinal position and orographic features supported the persistence of environmental conditions that allowed the permanence of a wide range of biotopes and animal and vegetal resources. In the present study, we reconstruct the Neanderthal settlement patterns (i.e. duration and season) from four archaeological sites located in the Mediterranean area of the Iberian Peninsula: Arbreda Cave (Serinyà, Girona), Teixoneres Cave (Moià, Barcelona), Abric Romaní (Capellades, Barcelona), and El Salt (Alcoy, Alicante). We focus on identifying whether they show a high variability in settlement patterns and check for the existence of local influences, such as the altitude. To reach these objectives, we designed a multi-proxy approach combining tooth wear and dental cementum analysis of the main Neanderthal preys: Cervus elaphus, Equus ferus, Equus hydruntinus, Bos primigenius and Capra pyrenaica. Our results first suggest that local features (i.e. orography, altitude, and environment) appear to be predominant factors determining the main feeding behaviour of the ungulates hunted by Neanderthals. Additionally, seasonal environmental variations seem to have influenced horse migratory behaviour, involving altitudinal movements in search of high-nutritive pastures. Neanderthal survival strategies and settlement patterns seem to have been less affected by environmental particularities and more linked to selective prey procurement based on the seasonal resource availability. Therefore, the duration and seasonality of their settlement patterns and their mobility throughout the landscape indicate they had a high level of knowledge on the territory they inhabited, as well as on the behaviour and availability of their potential preys.

Fagus sylvatica L. Peripheral Populations in the Mediterranean Iberian Peninsula: Climatic or Anthropic Relicts?

European beech is a temperate species with peripheral populations in the Mediterranean mountains. These Mediterranean beech forests have often been interpreted as climatic relicts. However, the use of this term does not always seem appropriate because their recent post-glacial expansion in the Iberian Peninsula makes it difficult to disentangle the effects of climate from those associated with land use. Moreover, the observed recovery of Mediterranean beech forests after landuse abandonment is not what might be expected of a climatic relict. Our objective is to clarify this issue by studying one of these Mediterranean ‘‘relict’’ populations located at the south-western margin of this species (Iberian Central Range), discriminating between subpopulations with dissimilar land-use legacies. Differences between the climatic range of this population and the rest of the European beech forests were explored. Historic and recent shifts in the species distribution area were studied by reviewing paleorecords from the literature and contrasting historical and recent cartography. Field data on population structure and demography were also examined. The climatic analyses do not point to climatic marginality of the peripheral population studied. Furthermore, the results revealed no evidence of reduction in area or confinement over recent decades. Contrary to what is expected for climatic relict species under current climate, beech is expanding in the studied mountain following the abandonment of traditional land uses, particularly since the middle of the twentieth century CE. Our results do not support the concept of a climatic relict but rather, they point to the importance of anthropogenic legacies to explain the distribution area, population dynamics and current conservation status of Mediterranean beech forests.

Towards a new approach for dendroprovenancing pines in the Mediterranean Iberian Peninsula

Dendroprovenancing studies frequently use site chronologies to identify the origin of archaeological and historical timber. However, radial growth (tree-ring width, TRW) of tree species is influenced by both local and regional climate scales. Here we investigate how the use of annually-resolved Blue Intensity (BI) measurements can enhance dendroprovenancing precision of black pine (Pinus nigra Arn.) and Scots pine (P. sylvestris L.) on the Iberian Peninsula. Principal Component Gradient Analyses (PCGA) was used to assess geographical patterns of annual variation in different TRW and BI proxies of pine trees from two mountain ranges in the Central System and Andalusia in Spain. Local climate-growth relationships were quantified to identify underlying causes of identified groups with diverse growth patterns. Two distinct elevational groups were observed when performing PCGA on latewood BI time series with the response to summer drought as the main factor causing the differences. Both P. nigra and P. sylvestris BI time series were found to be more related to summer drought at low-elevation sites showing an increase in sensitivity at lower latitudes. PCGA of TRW time series allowed to discriminate between trees from Andalusia and Central System within the elevation groups. February and October temperatures were found to be the main climatic factors causing the differences in TRW time series among the high- elevation sites, whereas for low-elevation trees it was the average winter temperature influencing TRW. A subsequent leave-one-out analyses confirmed that including latewood BI time series improves the precision of dendroprovenancing of pine wood in the Iberian Peninsula.

Influences of synoptic situation and teleconnections on fog‐water collection in the Mediterranean Iberian Peninsula, 2003–2012

AbstractFog‐water collection has been widely analysed for its quantification and potential uses; however, there are few studies assessing the synoptic conditions and large‐scale teleconnection patterns that affect its occurrence. Focusing on the Mediterranean Iberian Peninsula, this work aims to analyse the synoptic patterns, both at surface level and 850 hPa geopotential height, that most likely to favour fog‐water collection, and to quantify the relationship between fog‐water collection and the NAOi (North Atlantic Oscillation index), MOi (Mediterranean Oscillation index) as well as WeMOi (Western Mediterranean Oscillation index) teleconnection patterns. For this purpose, daily fog‐water observations from a dense network of 23 fog‐water collectors located along the Mediterranean Iberian Peninsula for 2003–2012 were analysed in relation to synoptic patterns and the three‐teleconnection indices. The major findings are: (a) The most favourable synoptic patterns for fog‐water collection are maritime advections carrying humidity from the Mediterranean basin, and cyclonic circulations, whereas anti‐cyclonic situations generally led to large number of foggy days with low fog‐collection rates. (b) In terms of winds at 850 hPa, the most favourable low‐level flows for fog‐water collection are associated with strong winds (>5.1 m s−1) from the Mediterranean. Atlantic winds generally cause a greater number of fog days than Mediterranean winds, with less fog‐water collection rates. (c) WeMOi has the greatest influence on fog‐water collection, mainly during winter and spring months, with statistically significant negative relationships for most of the stations. MOi also shows a great influence, with a large number of statistically significant negative correlations, mainly during the same months as WeMOi. Lastly, NAOi presented the lowest and no significant negative correlations with fog‐water collection.

Spatio-temporal variability of fog-water collection in the eastern Iberian Peninsula: 2003–2012

Among the different inputs involved in the hydrological system, fog water measured by man-made passive devices is one of the most unknown components, although it could be an additional water resource for specific environmental applications (forest restoration, forest firefighting, etc.). Focusing on the Mediterranean Iberian Peninsula, the aim of this work is to quantify fog-water collected by a 24-fog-stations network spread across three latitudinal sectors with different locations (coastal, pre-littoral and inland), and to determine the most productive sites. Measurements from the network show that distance-to-sea, latitude or elevation differences between stations are factors affecting fog-water collection potential. The network, based on passive cylindrical omnidirectional fog-water collectors, was active during the period 2003–2012. In addition to fog collection, other environmental variables such as rainfall, wind speed and wind direction, air temperature and relative humidity were measured. These ancillary data were used in a specific data reduction technique to eliminate the simultaneous rainwater component from the fog water measurements, and in the retrieval of the optimum mean wind directions to harvest fog-water efficiently. It was concluded that (i) positive differences in elevation allow greater collection rates, even under 100 m differences; (ii) optimum harvesting wind directions for inland locations are in line with the orientation of the existent valley coupled with the shortest path to the coastline, their collected fog-water volumes being generally smaller than those near the coast; (iii) fog-water collection at coastal locations present more dispersed optimal wind directions, ranging from north to the direction of the most immediate coastline; and (iv) there is a practically null dependence of the optimum mean wind direction on seasonality, but a strong dependence of fog-water captured volumes, however.

Lateglacial to Early Holocene recursive aridity events in the SE Mediterranean Iberian Peninsula: The Salines playa lake case study

Twelve pollen-inferred aridity major and minor events (S1 to S12) have been identified at Salines playa lake (SE Iberian Peninsula, 475 m asl, 38° 30′ 02″ N 00° 53′ 18″ W) from the Lateglacial to the Early Holocene (Boreal). These dry events consist of an increase in the aridity quotient calculated as a function of selected pollen taxa at 13.4, 13, 12.55, 12.2, 11.9, 11.45, 11, 10.6, 10.3, 10, 9.5 and 8.3 ka cal BP. These dry events correspond to the previous identified cold spells such as the Younger Dryas, as well as the 8, 7, 6 and 5 Bond events, and 11.4 and 9.3 events. This climate record highlights the complex glacial-interglacial transition in extra-tropical latitudes, with centennial-scale abrupt climate fluctuations, a signature scarcely recorded in other palaeoecological records of the SE Iberian Peninsula. This work has major implications for the study of human socio-ecological systems and resilience in SE Iberia during the Epipaleolithic and Mesolithic periods.

Charcoal and pollen analysis: Examples of Holocene fire dynamics in Mediterranean Iberian Peninsula

The present study focuses on charcoal particles (a component of vegetal ashes, Bodí et al., 2014) counted during palynological analysis. The absolute frequencies of this microcharcoal have been correlated with pollen percentages of resprouts, mesic trees, Pinus or AP (arboreal pollen), in order to observe patterns in the spread of wildfires, dynamic changes in plant succession, and possible cyclicities in Holocene microclimatic changes. The sites selected for this work are located within the Mediterranean area of the Iberian Peninsula and in the Eivissa Balearic Islands, between 42°16′ N and 36°47′ N. Results show two brief changes in vegetation dynamics during the Holocene. The first coincides with the 8.2calkyr event and marks both the beginning of Holocene dynamic changes in plant succession and the Climatic Optimum. During this first phase, charcoal peaks coincide with minimum percentages of mesic taxa (low rainfall) and occur just before an increase of resprout taxa (taxa which grow after fires). The second change happens at the ~4.2calBPkyr event, when fires are most frequent and resprout taxa increase their values compared to mesic taxa and forest cover (AP). We have also observed some differences in vegetal dynamics studied at different latitudes, which appear to be punctuated by climate or insularity. In short, (i) actual succession of Mediterranean vegetation can be recognized in the past; (ii) resilience in vegetation is more common during the first half of the Holocene than in the recent Holocene: A trend to aridity, reduced biomass and anthropization has caused vegetation resilience to decline; (iii) synchronicity between fire peaks of different sequences studied is very rare; and (iv) coincidence of many peaks of charcoal with Bond events inclines us to think that fires are more conditioned by the climate than by anthropogenic impact.

The Medieval Climate Anomaly in the Iberian Peninsula reconstructed from marine and lake records

Selected multi-proxy and accurately dated marine and terrestrial records covering the past 2000 years in the Iberian Peninsula (IP) facilitated a comprehensive regional paleoclimate reconstruction for the Medieval Climate Anomaly (MCA: 900–1300 AD). The sequences enabled an integrated approach to land–sea comparisons and, despite local differences and some minor chronological inconsistencies, presented clear evidence that the MCA was a dry period in the Mediterranean IP. It was a period characterized by decreased lake levels, more xerophytic and heliophytic vegetation, a low frequency of floods, major Saharan eolian fluxes, and less fluvial input to marine basins. In contrast, reconstruction based on sequences from the Atlantic Ocean side of the peninsula indicated increased humidity. The data highlight the unique characteristics of the MCA relative to earlier (the Dark Ages, DA: ca 500–900 years AD) and subsequent (the Little Ice Age, LIA: 1300–1850 years AD) colder periods. The reconstruction supports the hypothesis of Trouet et al. (2009), that a persistent positive mode of the North Atlantic Oscillation (NAO) dominated the MCA.

The end of the Upper Palaeolithic in the Mediterranean Basin of the Iberian Peninsula

This paper presents a synthesis of the Magdalenian in the Mediterranean Basin of the Iberian Peninsula, with special attention to the lithic and bone/antler assemblages, rock art, economy and radiocarbon dates. The data obtained in Cendres cave, situated in the middle of the Mediterranean Iberian Peninsula, permit articulation of the discussion about the Lower, Middle and Upper Magdalenian in this region. Furthermore, the paper discusses the end of the Magdalenian sequence with the Epimagdalenian industries.

Is rainfall erosivity increasing in the Mediterranean Iberian Peninsula?

AbstractThe risk of erosion and desertification is one of the main environmental concerns in the Mediterranean Iberian Peninsula. Changes in precipitation are expected in Mediterranean areas because of climate change, but predictions are not certain. For this reason, dense precipitation databases are required to explore observed changes in the amount, concentration and variability of precipitation, to gain a clearer understanding of the dynamics involved in the main climatological agent of erosion. For this study, we took the recently developed MOPREDAMES dataset, which includes 1113 complete and homogeneous monthly rainfall series from the Mediterranean fringe of the Iberian Peninsula (IP) covering the period 1951–2000. These were used to calculate and analyse trends in Total Annual Precipitation (Pt), the Precipitation Concentration Index (PCI) and Modified Fourier Index (MFI). Our results show that, although there were decreases in annual rainfall, increases in the concentration of precipitation also predominated in the Mediterranean Iberian Peninsula during the period 1951–2000. However, spatial variability of these trends is high, and changes in rainfall erosivity exhibit a complex spatial pattern. Thus, decreases in rainfall erosivity are detected under semiarid conditions (Central Ebro basin and South East IP), while increases mainly occur in dry and sub‐humid areas. We present a detailed spatial description of the results and discuss their implication for the risk of erosion and desertification in different regions of the study area. Copyright © 2009 John Wiley & Sons, Ltd.

Seasonal precipitation trends in the Mediterranean Iberian Peninsula in second half of 20th century

AbstractThis is a study of the changes in annual and seasonal precipitation amounts and variability, during the period 1951–2000, using MOPREDAMES. This dataset includes 1113 complete and homogeneous monthly precipitation time series from the Mediterranean Iberian Peninsula (IP), and corresponds to the five official Spanish hydrological divisions which drain into the Mediterranean Sea. The time series of annual and seasonal precipitation were used to test for trends. The absolute value of the anomaly time series was also tested for trends to identify changes in interannual variability of precipitation. The significance of these changes was assessed using the non‐parametric Spearman rank test. The intensities of observed changes, both on mean values and variability, were estimated by using linear regression techniques. Finally, we analysed the area affected by different trends by using raster maps and spatial statistics, in addition to calculating the global balances for the five hydrological divisions. We detected high variability in precipitation regimes and conditions in the study area; nevertheless, a decrease in seasonal and annual precipitation has predominated in the east of the IP during the second half of the 20th century. On an annual scale, precipitation has diminished over 90.1% of the study area. Additionally, a high percentage of the territory was affected by diminishing precipitation at a seasonal level: 85% (of territory) in summer, 82% in spring, 64% during winter and 61% in autumn. Taking the study area as a whole, seasonal precipitation decreases are ranked as follows: summer (−22.5%), spring (−19.3%), winter (−7.3%), and autumn (−5.2%), with a decrease in the value of the global mean annual precipitation − 12.4%. We also detected an increase of precipitation variability in winter (+23.5%) and summer (+11.4%), and a decrease in autumn and spring (−14.9 and − 16.8%, respectively) with a global mean value of + 7.8%. Copyright © 2008 Royal Meteorological Society