Suchergebnisse

The Last Glacial Termination is marked by changing environmental conditions affected by abrupt and rapid climate oscillations, such as Heinrich Stadial 1 (HS1), which is characterized by extremely low sea surface temperatures (SST) and significant changes in northern hemisphere terrestrial landscape (e.g., vegetation) and human dispersion. Previous studies show that overall cold/dry conditions occurred during HS1, but the lack of high-resolution records precludes whether climate was stable or instead characterized by instability. A high-resolution paleoclimatic record from the Padul wetland (southern Iberian Peninsula), supported by a high-resolution chronology and contrasted with other records from southern Europe and the Mediterranean region, shows 1) that the age boundaries of HS1 in this area occurred at ∼18.0 kyr BP (median age = 17,970 cal yr BP; mean age = 18,030 ± 330 cal yr BP) and ∼15.2 kyr BP (median age = 15,210 cal yr BP; mean age = 15,200 ± 420 cal yr BP) and 2) that climate during HS1 was non-stationary and centennial-scale variability in moisture is superimposed on this overall cold climatic period. In this study, we improve the pollen sampling resolution with respect to previous studies on the same Padul-15-05 sedimentary core and suggest a novel subdivision of HS1 in 7 sub-phases, including: i) 3 sub-phases (a.1-a.3) during an arid early phase (HS1a; ∼18.4–17.2 kyr BP), ii) a relatively humid middle phase (HS1b; ∼17.2–16.9 kyr BP), and iii) 3 sub-phases (c.1-c.3) during an arid late phase (HS1c; ∼16.9–15.7 kyr BP). This climatic subdivision is regionally supported by SST oscillations from the Mediterranean Sea, suggesting a strong land-sea coupling. A cyclostratigraphic analysis of pollen data between 20 and 11 kyr BP indicates that the climate variability and the proposed subdivisions characterized by ∼2000 and ∼800-yr periodicities could be related to solar forcing controlling climate in this area. ; This research is supported by the projects CGL 2013-47038-R and CGL-2017-85415-R, B-RNM-144-UGR18, PhD funding BES-2014-069117 (J.C.) and Ramón y Cajal fellowship RYC-2015-18966 (A.G.-A.) provided by the Ministerio de Economía y Competitividad of the Spanish Government. Additional funding was provided by the project number 316702 from the Academy of Finland for a postdoctoral research contract (J.C.) and the research group RNM0190 and the project P11-RNM-7332 with a postdoctoral fellowship (M.J.R.-R.) from the Junta de Andalucía. M.J.R.-R. acknowledges the postdoctoral funding provided by the European Commission /H2020 (ERC-2017-ADG, project number 788616 ). Finally, we acknowledge two anonymous reviewers and the editor (Donatella Magri) for their very useful corrections and suggestions.

Recent studies have proved that high elevation environments, especially remote wetlands, are exceptional ecological sensors of global change. For example, European glaciers have retreated during the 20th century while the Sierra Nevada National Park in southern Spain witnessed the first complete disappearance of modern glaciers in Europe. Given that the effects of climatic fluctuations on local ecosystems are complex in these sensitive alpine areas, it is crucial to identify their long-term natural trends, ecological thresholds, and responses to human impact. In this study, the geochemical records from two adjacent alpine bogs in the protected Sierra Nevada National Park reveal different sensitivities and long-term environmental responses, despite similar natural forcings, such as solar radiation and the North Atlantic Oscillation, during the late Holocene. After the Industrial Revolution both bogs registered an independent, abrupt and enhanced response to the anthropogenic forcing, at the same time that the last glaciers disappeared. The different response recorded at each site suggests that the National Park and land managers of similar regions need to consider landscape and environmental evolution in addition to changing climate to fully understand implications of climate and human influence. © 2017 The Author(s). ; This study was supported by the project P11-RNM 7332 of the "Junta de Andalucía", the projects CGL2013-47038-R and CGL2015-67130-C2-1-R of the "Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER" and the research group RNM0190 and RNM309 (Junta de Andalucía). A.G.-A. was also supported by a Marie Curie Intra-European Fellowship of the 7th Framework Programme for Research, Technological Development and Demonstration of the European Commission (NAOSIPUK. Grant Number: PIEF-GA-2012-623027) and by a Ramón y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economía y Competividad). J.L.T. was also supported by a Small Research Grant by the Carnegie Trust for the Universities of Scotland and hosted the NAOSIPUK project (PIEF-GA-2012-623027). M. J. R-R acknowledges the PhD funding provided by Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía (P11-RNM 7332). We would like to thank to Dr. I.M. Sánchez Almazo (CIC- University of Granada), A. Cochrane, J. McGourlay, S. Pauchet (University of Glasgow), and Dr. S. Diez (IDAEA-CSIC) for their help preparing and analysing the organic and inorganic samples, as well as to Dr. I. Reche (University of Granada) for the aerosol samples from Sierra Nevada. Authors would also like to thank the journal editor K.H. Knorr and two anonymous reviewers for their comments improving the manuscript. ; Peer reviewed

Here we provide the geochemical dataset that our research group has collected after 10 years of investigation in the Sierra Nevada National Park in southern Spain. These data come from Holocene sedimentary records from four alpine sites (ranging from ∼2500 to ∼3000 masl): two peatlands and two shallow lakes. Different kinds of organic and inorganic analyses have been conducted. The organic matter in the bulk sediment was characterised using elemental measurements and isotope-ratio mass spectrometry (EA-IRMS). Leaf waxes in the sediment were investigated by means of chromatography with flame-ionization detection and mass spectrometry (GC-FID, GC-MS). Major, minor and trace elements of the sediments were analysed with atomic absorption (AAS), inductively coupled plasma mass spectrometry (ICP-MS), as well as X-ray scanning fluorescence. These data can be reused by environmental researchers and soil and land managers of the Sierra Nevada National Park and similar regions to identify the effect of natural climate change, overprinted by human impact, as well as to project new management policies in similar protected areas. © The Author(s) 2018. ; This study was supported by the project P11-RNM-7332 of the "Junta de Andalucía", the projects CGL2013-47038- R of the "Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER" and the research group RNM0190 and RNM309 (Junta de Andalucía). A.G.-A. was also supported by a Marie Curie Intra-European Fellowship of the 7th Framework Programme for Research, Technological Development and Demonstration of the European Commission (NAOSIPUK. Grant Number: PIEF-GA-2012-623027) and by a Ramón y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economía y Competividad). J.L.T. was also supported by a Small Research Grant by the Carnegie Trust for the Universities of Scotland and hosted the NAOSIPUK project (PIEF-GA-2012-623027). M.J.R-R acknowledges the PhD funding provided by Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía (P11-RNM 7332). J.C. acknowledges the PhD funding provided by "Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER". ; Peer reviewed

Recent studies have proved that high elevation environments, especially remote wetlands, are exceptional ecological sensors of global change. For example, European glaciers have retreated during the 20th century while the Sierra Nevada National Park in southern Spain witnessed the first complete disappearance of modern glaciers in Europe. Given that the effects of climatic fluctuations on local ecosystems are complex in these sensitive alpine areas, it is crucial to identify their long-term natural trends, ecological thresholds, and responses to human impact. In this study, the geochemical records from two adjacent alpine bogs in the protected Sierra Nevada National Park reveal different sensitivities and long-term environmental responses, despite similar natural forcings, such as solar radiation and the North Atlantic Oscillation, during the late Holocene. After the Industrial Revolution both bogs registered an independent, abrupt and enhanced response to the anthropogenic forcing, at the same time that the last glaciers disappeared. The different response recorded at each site suggests that the National Park and land managers of similar regions need to consider landscape and environmental evolution in addition to changing climate to fully understand implications of climate and human influence. ; This study was supported by the project P11-RNM 7332 of the "Junta de Andalucía", the projects CGL2013-47038-R and CGL2015-67130-C2-1-R of the "Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER" and the research group RNM0190 and RNM309 (Junta de Andalucía). A.G.-A. was also supported by a Marie Curie Intra-European Fellowship of the 7th Framework Programme for Research, Technological Development and Demonstration of the European Commission (NAOSIPUK. Grant Number: PIEF-GA-2012-623027) and by a Ramón y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economía y Competividad). J.L.T. was also supported by a Small Research Grant by the Carnegie Trust for the Universities of Scotland and hosted the NAOSIPUK project (PIEF-GA-2012-623027). M. J. R-R acknowledges the PhD funding provided by Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía (P11-RNM 7332).

Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (C-14, U-234/Th-230, optically stimulated luminescence (OSL), Ar-40/Ar-39-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft Access (TM) at https://doi. org/10.1594/PANGAEA. 870867. ; Basque Government postdoctoral fellowship [POS_2015_1_0006]; ERC; QUEST-DESIRE (UK and France); INQUA International Focus Group ACER; INTIMATE-COST ; info:eu-repo/semantics/publishedVersion

Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard–Oeschger (D–O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D–O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73–15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U∕230Th, optically stimulated luminescence (OSL), 40Ar∕39Ar-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft AccessTM at https://doi.org/10.1594/PANGAEA.870867. ; Basque Government postdoctoral fellowship [POS_2015_1_0006]; ERC; QUEST-DESIRE (UK and France); INQUA International Focus Group ACER; INTIMATE-COST ; Open Access Journal. ; This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.