Suchergebnisse

This research has been supported by the Leverhulme Trust (grant no. RC-2018-023), the European Research Council (grant no. 694481), the German Research Foundation (grant no. FE-1096/6-1), the Swiss Government Excellence Postdoctoral Scholarships (grant no. FIRECO 2016.0310), the National Science Centre of Poland (grant no. 2015/17/B/ST10/01656), the SCIEX Scholarship Fund (grant no. PSPB-013/2010), and the Estonian Research Council (grant no. MOBJD313). ; Sedimentary charcoal records are widely used to reconstruct regional changes in fire regimes through time in the geological past. Existing global compilations are not geographically comprehensive and do not provide consistent metadata for all sites. Furthermore, the age models provided for these records are not harmonised and many are based on older calibrations of the radiocarbon ages. These issues limit the use of existing compilations for research into past fire regimes. Here, we present an expanded database of charcoal records, accompanied by new age models based on recalibration of radiocarbon ages using IntCal20 and Bayesian age-modelling software. We document the structure and contents of the database, the construction of the age models, and the quality control measures applied. We also record the expansion of geographical coverage relative to previous charcoal compilations and the expansion of metadata that can be used to inform analyses. This first version of the Reading Palaeofire Database contains 1676 records (entities) from 1480 sites worldwide. The database (RPDv1b – Harrison et al., 2021) is available at https://doi.org/10.17864/1947.000345. ; Leverhulme Trust RC-2018-023 ; European Research Council (ERC) European Commission 694481 ; German Research Foundation (DFG) FE-1096/6-1 ; Swiss Government Excellence Postdoctoral Scholarships FIRECO 2016.0310 ; SCIEX Scholarship Fund PSPB-013/2010 ; Estonian Research Council MOBJD313

This research has been supported by the Directorate for Geosciences of the National Science Foundation (grant nos. AGS-1602105 and AGS-1903548). ; We thank the USGS John Wesley Powell Center for Analysis and Synthesis, which hosted a meeting that led to this synthesis effort. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US government. We thank the original data generators who made their data available for reuse, and we acknowledge the data repositories for safeguarding these assets. ; Holocene climate reconstructions are useful for understanding the diverse features and spatial heterogeneity of past and future climate change. Here we present a database of western North American Holocene paleoclimate records. The database gathers paleoclimate time series from 184 terrestrial and marine sites, including 381 individual proxy records. The records span at least 4000 of the last 12 000 years (median duration of 10 725 years) and have been screened for resolution, chronologic control, and climate sensitivity. Records were included that reflect temperature, hydroclimate, or circulation features. The database is shared in the machine readable Linked Paleo Data (LiPD) format and includes geochronologic data for generating site-level time-uncertain ensembles. This publicly accessible and curated collection of proxy paleoclimate records will have wide research applications, including, for example, investigations of the primary features of oceanatmospheric circulation along the eastern margin of the North Pacific and the latitudinal response of climate to orbital changes. The database is available for download at https://doi.org/10.6084/m9.figshare.12863843.v1 (Routson and McKay, 2020). ; National Science Foundation (NSF) AGS-1602105 AGS-1903548

The Iberian Peninsula is located at the intersection between the subtropical and temperate climate zones and the paleoclimate records from this region are key to elucidate the varying humidity and changing dominance of atmospheric circulation patterns in the Mediterranean-North African region in the past. Here we present a quantitative hydroclimate reconstruction for the last ca. 200 kyr from southern Iberian Peninsula based on pollen data from the Padul lake sediment record. We use the newly developed Scale-normalized Significant Zero crossing (SnSiZer) method to detect not only the statistically significant precipitation changes but also to estimate the relative magnitude of these oscillations in our reconstruction. We identify six statistically significant main humid phases, termed West Mediterranean Humid Periods (WMHP 1–6). These humid periods correlate with other West/ Central Mediterranean paleohydrological records, suggesting that similar climatic factors affected different areas of the Mediterranean. In addition, the WMPHs are roughly coeval with the African Humid Periods (AHPs) during high seasonality, suggesting the same North Atlantic ocean-atmospheric dynamics and orbital forcing as main drivers of both areas. In contrast, during low seasonality periods, the West Mediterranean still appears to be affected by the westerlies and the local Mediterranean rainfall systems with moderate-to-high precipitation, whereas West Africa was characterized by droughts. ; Academy of Finland (GRASS) 1316702 ; European Research Council (YMPACT) 788616 ; Spanish Government CGL2013-47038-R CGL2015-69160-R CGL2017-85415-R ; Junta de Andalucia European Commission P-20-00059 B-RNM-144-UGR18 ; Junta de Andalucia RNM-190 ; Gobierno de Aragon E02-20R ; German Research Foundation (DFG) FOR2358

This study was supported by the project B-RNM-144-UGR18 of the action "Proyectos I+D+i del Programa Operativo FEDER 2018 -Junta de Andalucia-UGR", the projects CGL2013-47038-R and CGL201785415-R, of the "Ministerio de Economia y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER", and the research group RNM-190 (Junta de Andalucia). 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 Ram ' on y Cajal Fellowship RYC-2015-18966 of the Spanish Government (Ministerio de Economia y Competividad). J.C. acknowledges the postdoctoral funding provided by the Academy of Finland (project number 316702). J.L.T. hosted the NAOSIPUK project (PIEFGA-2012-623027) at the University of Glasgow. A.L.-A PhD is funded by BES-2018-084293 (Ministerio de Economia y Competividad). M.J.R.R. acknowledges the postdoctoral funding by the European Research Council (ERC-2017-ADG-788616). This study was supported by an ERC Consolidator Grant (STEEPclim) to D.S. (Grant Agreement No. 647035). E.S. is supported by the DFG Cluster of Excellence 2077 >The Ocean Floor -Earth's Uncharted Interface The Ocean Floor -Earth's Uncharted Interface < at MARUM ; European Commission

This study was supported by the projects CGL2013-47038-R and CGL2017-85415-R funded by Ministerio de Economia y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER; Seneca Project 20788/PI/18; Junta de Andalucia FEDER Project B-RNM-144-UGR18, Proyectos I + D + i del Programa Operativo FEDER 2018 and the research group RNM-190 (Junta de Andalucia). Alejandro Lopez Aviles acknowledges the PhD funding, BES-2018-084293, provide by Ministerio de Economia y Competitividad of the Spanish Government. Antonio Garcia-Alix acknowledges the Ramon y Cajal fellowship, RYC-2015-18966, provided by the Ministerio de Economia y Competitividad of the Spanish Government. R. Scott Anderson acknowledges travel support from Northern Arizona University. ; Several organic and inorganic geochemical analyses have been carried out in the sedimentary record of the Borreguil de los Lavaderos de la Reina (BdlR-03), an alpine peat bog located on the north face of the Sierra Nevada (southern Iberian Peninsula). This study permitted a high-resolution reconstruction of paleoenvironmental evolution for the last similar to 2700 cal yr BP in the highest mountain range of southern Iberian Peninsula. An overall trend towards a climatic aridification and a reduction of aquatic environments is observed in this record. Insolation and long-term positive North Atlantic Oscillation trends were the most important factors controlling this aridification, forcing regional and local environmental changes. Four phases are differentiated within the paleoenvironmental evolution of BdlR-03: (1) a pre-bog environment from 2700 to 2600 cal yr BP with important siliciclastic sedimentation and low organic content; (2) a bog environment with important presence of terrestrial vascular plant, water availability and maximum humid conditions between similar to 2600 and similar to 1870 cal yr BP, coinciding with the Iberian-Roman Humid Period; (3) a subsequent drier bog environment, between similar to 1870 and similar to 300 cal yr BP during the Dark Ages, the Medieval Climate Anomaly and the first stages of the Little Ice Age, characterized by lower productivity that affected the development of terrestrial vascular plants and aquatic environments; and (4) a wetland environment with an increase of aquatic algae, development of ephemeral pools and unstable climate conditions between similar to 300 cal yr BP and the present, coinciding with the final stages of the Little Ice Age and the Modern Global Warming. This recent environmental pattern, which is opposite to the general aridification trend in the western Mediterranean, is likely explained by the gradual melting of the perennial ice and/or snow packs at higher elevations in the last centuries. Aeolian inputs would have continuously contributed nutrients to these nutrient-impoverished alpine environments. High dust inputs are especially noticed during the last similar to 200 years, which can be explained by human-induced enhanced aridification and the development of the commercial agriculture in some North African regions. In addition, the environmental signal in the last century seems to be significantly affected by human activities. ; Ministerio de Economia y Competitividad of Spain CGL2013-47038-R CGL2017-85415-R ; European Commission ; Junta de Andalucia FEDER Project B-RNM-144-UGR18 ; Ministerio de Economia y Competitividad of the Spanish Government BES-2018-084293 ; Ramon y Cajal fellowship by the Ministerio de Economia y Competitividad of the Spanish Government RYC-2015-18966 ; Fundacion Seneca 20788/PI/18 ; Junta de Andalucia ; Proyectos I + D + i del Programa Operativo FEDER 2018

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.

High-altitude peat bogs and lacustrine records are very sensitive to climate changes and atmospheric dust input. Recent studies have shown a close relationship between regional climate aridity and enhanced eolian input to lake sediments. However, changes in regional-scale dust fluxes due to climate variability at short scales and how alpine environments were impacted by climatic- and human-induced environmental changes are not completely understood. Here we present a multi-proxy (palynological, geochemical and magnetic susceptibility) lake sediment record of climate variability in the Sierra Nevada (southeastern Iberian Peninsula) over the Holocene. Magnetic susceptibility and geochemical proxies obtained from the high mountain lake record of Laguna Hondera evidence humid conditions during the early Holocene, while a trend towards more arid conditions is recognized since ĝ1/4 7000 cal yr BP, with enhanced Saharan eolian dust deposition until the present. This trend towards enhanced arid conditions was modulated by millennial-scale climate variability. Relative humid conditions occurred during the Iberian Roman Humid Period (2600-1450 cal yr BP) and predominantly arid conditions occurred during the Dark Ages and the Medieval Climate Anomaly (1450-650 cal yr BP). The Little Ice Age (650-150 cal yr BP) is characterized in the Laguna Hondera record by an increase in runoff and a minimum in eolian input. In addition, we further suggest that human impact in the area is noticed through the record of Olea cultivation, Pinus reforestation and Pb pollution during the Industrial Period (150 cal yr BP-present). Furthermore, we estimated that the correlation between Zr and Ca concentrations stands for Saharan dust input to the Sierra Nevada lake records. These assumptions support that present-day biochemical observations, pointing to eolian input as the main inorganic nutrient source for oligotrophic mountain lakes, are comparable to the past record of eolian supply to these high-altitude lakes. ; This study was supported by the project P11-RNM 7332 of the "Junta de Andalucía", the projects CGL2013-47038-R and CGL2015-66830-R of the "Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER", and the research groups RNM0190 and RNM179 (Junta de Andalucía). We also thank Unidad de Excelencia (UCE-PP2016-05). Jose Manuel Mesa-Fernández acknowledges the PhD funding provided by Ministerio de Economía y Competitividad (CGL2015-66830-R). Antonio García-Alix was also supported by a Marie Curie Intra-European Fellowship of the Seventh 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) and Marta Rodrigo-Gámiz from the Andalucía Talent Hub Program co-funded by the European Union's Seventh Framework Program (COFUND; grant agreement no. 291780) and the Junta de Andalucía. We thank Santiago Fernández, Maria Dolores Hernandez and Antonio Mudarra for their help recovering the core and Inés Morales for the initial core description and MS data. We thank Jaime Frigola (Universitat de Barcelona) for his help with XRF core scanning.

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 (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.