Rapid Climate Changes in the Westernmost Mediterranean (Alboran Sea) Over the Last 35 kyr: New Insights From Four Lipid Paleothermometers (UK' 37, TEXH 86, RI-OH', and LDI)

This study was supported by Grant PID2019-104624RB-I00 funded by MCIN/AEI/ 10.13039/501100011033, Grants FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento P18-RT-3804 and P18-RT- 4074, and Research Group RNM-179 (Junta de Andalucia). The authors also thank the Unidad Cientifica de Excelencia UCE-PP2016-05 (University of Granada). This study also received funding from the Netherlands Earth System Science Center (NESSC) through a gravitation grant (024.002.001) to J. S. Sinninghe Damste and S. Schouten from the Dutch Ministry for Education, Culture and Science. M. Rodrigo-Gamiz acknowledges funding from the Andalucia Talent Hub Program co-funded by the European Union's Seventh Framework Program (COFUND-Grant Agreement No 291780) and the Junta de Andalucia and from the Juan de la Cierva-Incorporacion program in the University of Granada (IJCI-2017-33,755) from Secretaria de Estado de I + D + i, Spain. We thank the captain, crew, and participants of the Gasalb cruise onboard R/V Pelagia for assistance during sampling. We are also grateful to the Poznan Radiocarbon Laboratory (Poland), the Leibniz Laboratory for Radiometric Dating and Stable Isotope Research (Germany), and the Centre for Scientific Instrumentation (CIC, Spain) for analyses. The authors thank Jort Ossebaar, Anchelique Mets, Marianne Baas and Karsten Dekker (all at NIOZ) for laboratory assistance. Thanks to Prof. Giuseppe Siani (Universite Paris-Sud Orsay) and Jose Manuel Mesa Fernandez for their help and comments on the age model. We thank the Associate Editor, Dr. Yige Zhang, two anonymous reviewers, and Dr. Felix J. Elling for their helpful comments that improved the manuscript substantially. Funding for open access charge from Universidad de Granada/CBUA.The westernmost Mediterranean is one of the most sensitive areas to global climate change and high sedimentation rates allow recording high frequency variability. We present a high-resolution paleotemperature reconstruction over the last 35 kyr using, for the first time, four independent organic sea surface temperature (SST) proxies (UK' 37, TEXH 86, RI-OH' and LDI) based on alkenones, (hydroxy) isoprenoid GDGTs, and long-chain diols. We also generated a δ18O of planktonic foraminifera G. bulloides record together with records of bulk parameters (total organic carbon content, δ13Corg) and the accumulation rates of different biomarkers to provide insights into terrestrial input and primary producers. All derived-SST records showed similar trends over the last 35 kyr, revealing abrupt temperature variations during the last seven Dansgaard- Oeschger (D/O) cycles, the three Heinrich (H) events, the Last Glacial Maximum, and the Younger Dryas. H3 is recognized as the coldest event, while H1 was recorded by all SST proxies as the most abrupt one. In general, TEXH 86-, RI-OH'- and LDI-SST estimates were lower than those obtained from UK' 37. The LDI paleothermometer recorded the largest range of absolute SSTs over the whole period (ca. 20°C) followed by RI-OH' (ca. 16°C). TEXH 86, RI-OH' and LDI proxies reflected sudden SST changes during the D/O 6 and 5 particularly well. Low BIT values and the abundance of C32 1,15-diol in range with typical marine values indicated only minor input of continental organic matter. Accumulation rates of different lipid biomarkers were generally modulated by D/O cycles, suggesting enhanced productivity during D/O interstadials and the Bölling- Alleröd period.Grants FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento PID2019-104624RB-I00 MCIN/AEI/ 10.13039/501100011033 P18-RT-3804 P18-RT- 4074Research Group RNM-179Unidad Cientifica de Excelencia UCE-PP2016-05Netherlands Earth System Science Center (NESSC) through a gravitation grant 024.002.001Andalucia Talent Hub Program - European Union's Seventh Framework Program (COFUND-Grant) 291780 Junta de AndaluciaJuan de la Cierva-Incorporacion program in the University of Granada from Secretaria de Estado de I + D + i, Spain IJCI-2017-33,755Universidad de Granada/CBU

Constraints on the applicability of the organic temperature proxies UK'37, TEX86 and LDI in the subpolar region around Iceland

The Supplement related to this article is available online at doi:10.5194/bg-12-6573-2015-supplement.Subpolar regions are key areas for studying natural climate variability due to their high sensitivity to rapid environmental changes, particularly through sea surface temperature (SST) variations. Here, we have tested three independent organic temperature proxies (UK'37; TEX86; and the long-chain diol index, LDI) regarding their potential applicability for SST reconstruction in the subpolar region around Iceland. UK'37, TEX86 and TEXL86 temperature estimates from suspended particulate matter showed a substantial discrepancy with instrumental data, while long-chain alkyl diols were below the detection limit at most of the stations. In the northern Iceland Basin, sedimenting particles revealed a seasonality in lipid fluxes, i.e., high fluxes of alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) were measured during late spring and during summer and high fluxes of long-chain alkyl diols during late summer. The flux-weighted average temperature estimates had a significant negative (ca. 2.3 °C for UK'37) and positive (up to 5 °C for TEX86) offset with satellite-derived SSTs and temperature estimates derived from the underlying surface sediment. UK'37 temperature estimates from surface sediments around Iceland correlate well with summer mean sea surface temperatures, while TEX86-derived temperatures correspond with both annual and winter mean 0–200 m temperatures, suggesting a subsurface temperature signal. Anomalous LDI-SST values in surface sediments and low mass flux of 1,13- and 1,15-diols compared to 1,14-diols suggest that Proboscia diatoms are the major sources of long-chain alkyl diols in this area rather than eustigmatophyte algae, and therefore the LDI cannot be applied in this region.This work was supported by the Earth and Life Sciences Division of the Netherlands Organization for Scientific Research (NWO-ALW) by a grant (ALW 820.01.013) to J. S. Sinninghe Damsté. The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Seventh Framework Program (FP7/2007-2013) ERC grant agreement 226600

Algal lipids reveal unprecedented warming rates in alpine areas of SW Europe during the industrial period

Alpine ecosystems of the southern Iberian Peninsula are among the most vulnerable and the first to respond to modern climate change in southwestern Europe. While major environmental shifts have occurred over the last ~ 1500 years in these alpine ecosystems, only changes in the recent centuries have led to abrupt environmental responses, but factors imposing the strongest stress have been unclear until now. To understand these environmental responses, this study, for the first time, has calibrated an algal lipid-derived temperature proxy (based on long-chain alkyl diols) to instrumental historical data extending alpine temperature reconstructions to 1500 years before present. These novel results highlight the enhanced effect of greenhouse gases on alpine temperatures during the last ~ 200 years and the longterm modulating role of solar forcing. This study also shows that the warming rate during the 20th century (~ 0:18 ºC per decade) was double that of the last stages of the Little Ice Age (~ 0:09 ºC per decade), even exceeding temperature trends of the high-altitude Alps during the 20th century. As a consequence, temperature exceeded the preindustrial record in the 1950s, and it has been one of the major forcing processes of the recent enhanced change in these alpine ecosystems from southern Iberia since then. Nevertheless, other factors reducing the snow and ice albedo (e.g., atmospheric deposition) may have influenced local glacier loss, since almost steady climate conditions predominated from the middle 19th century to the first decades of the 20th century.This research has been supported by the Seventh Framework Programme (grant no. NAOSIPUK (623027)), the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación (grant no. CGL2017-85415- R), the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación (grant no. CGL2013- 47038-R), the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación (grant no. CGL2011-23483), and the Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía, Agencia de Innovación y Desarrollo de Andalucía (grant no. P11-RNM 7332). This research has also been supported by grant no. 87/2007 of the Organismo Autónomo Parques Nacionales (OAPN)-Ministerio de Medio Ambiente, the research group no. RNM-190 of the Plan Andaluz de Investigación, Desarrollo e Innovación (Junta de Andalucía), and the Ramón y Cajal Fellowship (fellowship no. RYC-2015-18966) of the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación

Evaluation of long chain 1,14-alkyl diols in marine sediments as indicators for upwelling and temperature

Long chain alkyl diols form a group of lipids occurring widely in marine environments. Recent studies have suggested several palaeoclimatological applications for proxies based on their distributions, but have also revealed uncertainty about their applicability. Here we evaluate the use of long chain 1,14-alkyl diol indices for reconstruction of temperature and upwelling conditions by comparing index values, obtained from a comprehensive set of marine surface sediments, with environmental factors such as sea surface temperature (SST), salinity and nutrient concentration. Previous studies of cultures indicated a strong effect of temperature on the degree of saturation and the chain length distribution of long chain 1,14-alkyl diols in Proboscia spp., quantified as the diol saturation index (DSI) and diol chain length index (DCI), respectively. However, values of these indices for surface sediments showed no relationship with annual mean SST of the overlying water. It remains unknown as to what determines the DSI, although our data suggest that it may be affected by diagenesis, while the relationship between temperature and DCI may be different for different Proboscia species. In addition, contributions from algae other than Proboscia diatoms may affect both indices, although our data provide no direct evidence for additional long chain 1,14-alkyl diol sources. Two other indices using the abundance of 1,14-diols vs. 1,13-diols and C30 1,15-diols have been applied previously as indicators for upwelling intensity at different locations. The geographical distribution of their values supports the use of 1,14 diols vs. 1,13 diols [C28 + C30 1,14-diols]/[(C28 + C30 1,13-diols) + (C28 + C30 1,14-diols)] as a general indicator for high nutrient or upwelling conditions

Summer temperatures during the Holocene inferred from a chironomid record from Sierra Nevada, southern Spain

XXI INQUA 2023. Rome. july 14-20 2023Accurate and continuous quantitative paleotemperature records from the past are rare in southern Iberia, mostly due to the scarcity of continuous sedimentary sequences in terrestrial environments from that area. In this study we show the first Holocene mean July air temperature reconstruction based on fossil chironomids from a sedimentary sequence obtained from Laguna de Río Seco, an alpine lake in Sierra Nevada, southern Spain. Reconstructed summer temperatures agree with changes in summer insolation and other palaeotemperature records from alpine environments from southern Europe and show the Holocene thermal maximum between 10 to 8.0 ka (1 ka = 1000 cal yr BP). Rapid cooling occurred after the warmest maximum and between ~8.0-7.0 ka and temperatures stabilized between ~6.5 and 3.0 ka. A further cooling trend started ~3.0 ka, and coldest summer conditions were reached at 1.4 ka (~550 CE) and ~0.2 ka (~1750 CE), coinciding with the Dark Ages and Little Ice Age, respectively. This record also shows relatively warmer summer temperature conditions during the Iberian-Roman Humid Period ~2.0 ka and during the Medieval Climate Anomaly at ~0.9 ka. Summer climate warming of more than two degree Celsius is observed in the last decades showing that recent warming is amplified in high alpine environments

Algal lipids reveal unprecedented warming rates in alpine areas of SW Europe during the industrial period

Alpine ecosystems of the southern Iberian Peninsula are among the most vulnerable and the first to respond to modern climate change in southwestern Europe. While major environmental shifts have occurred over the last similar to 1500 years in these alpine ecosystems, only changes in the recent centuries have led to abrupt environmental responses, but factors imposing the strongest stress have been unclear until now. To understand these environmental responses, this study, for the first time, has calibrated an algal lipid-derived temperature proxy (based on long-chain alkyl diols) to instrumental historical data extending alpine temperature reconstructions to 1500 years before present. These novel results highlight the enhanced effect of greenhouse gases on alpine temperatures during the last similar to 200 years and the long-term modulating role of solar forcing. This study also shows that the warming rate during the 20th century (similar to 0.18 degrees C per decade) was double that of the last stages of the Little Ice Age (similar to 0.09 degrees C per decade), even exceeding temperature trends of the high-altitude Alps during the 20th century. As a consequence, temperature exceeded the preindustrial record in the 1950s, and it has been one of the major forcing processes of the recent enhanced change in these alpine ecosystems from southern Iberia since then. Nevertheless, other factors reducing the snow and ice albedo (e.g., atmospheric deposition) may have influenced local glacier loss, since almost steady climate conditions predominated from the middle 19th century to the first decades of the 20th century.Peer reviewe

Paleoenvironmental evolution of Laguna Seca lake (Sierra Nevada, southern Iberia) since the Late Glacial

Comunicación oral en XXI INQUA Congress. Rome (Italy). 14-20th july 2023Laguna Seca lake at 2259 masl has provided the longest alpine sedimentary record in southern Iberia, registering the last ~18 kyr in a ~14-meter-long sediment core. The oldest part of the sedimentary record represents a phase of subaerial debris flows and a small glacier/nivation hollow. The sediment characteristics abruptly changed at ~15.7 cal kyr BP, when a lake environment was established. A multi-proxy approach (magnetic susceptibility, organic geochemical analyses in bulk sediment, XRF core scanner data, and algae identification) has allowed the characterization of three different environmental phases in this lake. Deep lake conditions are identified from ~15.7 to ~10.6 cal kyr BP, agreeing with overall increasing precipitation in southern Iberia coinciding with augmenting summer insolation. This part of the record is characterized by grey lutites with high total organic carbon (TOC) content, high algae productivity, high vascular plant inputs (high C/N ratio) from the catchment and low Fe/S ratio, suggesting low oxygen conditions in the water-sediment interphase. Between ~10.6 and 8.2-8.0 cal kyr BP higher TOC and low Fe/S ratio are also recorded as well as higher algae content and low C/N ratio suggesting high aquatic production and more algae contribution to the local organic matter pool. This period registered the highest lake levels agreeing with summer insolation maximum and highest precipitation in southern Iberia. An abrupt lowering of the lake level is recorded after 8.0 cal kyr BP in the area. This is deduced by the decrease in TOC and algae in the sediments and more siliciclastic contribution from the catchment basin, evidenced by a high increase in siliciclastic elements (Si, Al, K, Ti, among others), with increased oxic conditions in the water-sediment interphase pointed out by the high increase in Fe/S ratio. Additionally, a potential increase in north African aeolian inputs (rich in Fe cations and Fe compounds) can be interpreted for the Middle and Late Holocene, evidenced by high Fe/Al values. This environmental change agrees with an aridification trend previously observed in the southern Iberian Peninsula

Earliest Known Use of Marine Resources by Neanderthals

Numerous studies along the northern Mediterranean borderland have documented the use of shellfish by Neanderthals but none of these finds are prior to Marine Isotopic Stage 3 (MIS 3). In this paper we present evidence that gathering and consumption of mollusks can now be traced back to the lowest level of the archaeological sequence at Bajondillo Cave (Málaga, Spain), dated during the MIS 6. The paper describes the taxonomical and taphonomical features of the mollusk assemblages from this level Bj19 and briefly touches upon those retrieved in levels Bj18 (MIS 5) and Bj17 (MIS 4), evidencing a continuity of the shellfishing activity that reaches to MIS 3. This evidence is substantiated on 29 datings through radiocarbon, thermoluminescence and U series methods. Obtained dates and paleoenvironmental records from the cave include isotopic, pollen, lithostratigraphic and sedimentological analyses and they are fully coherent with paleoclimate conditions expected for the different stages. We conclude that described use of shellfish resources by Neanderthals (H. neanderthalensis) in Southern Spain started ∼150 ka and were almost contemporaneous to Pinnacle Point (South Africa), when shellfishing is first documented in archaic modern humans

Repli-Fósil-3D: Aplicación técnicas de replicación 3D para la mejora de las colecciones utilizadas en la docencia práctica del área de Paleontología

En este proyecto se ha pretendido perfeccionar la docencia práctica de las asignaturas del ámbito de la Paleontología y de las actividades divulgativas impartidas por el departamento de Estratigrafía y Paleontología, y por lo tanto mejorar el grado de aprendizaje del alumnado, mediante el uso de modelos y réplicas impresas en 3D de diferentes grupos fósiles que, por diversos motivos (escasez de muestras en nuestros laboratorios, tamaño o fragilidad), no pueden ser correctamente observados y/o manipulados por el alumnado. Esto ha permitido al profesorado del área de Paleontología adaptar las prácticas docentes y actividades divulgativas a los requerimientos de la sociedad y universidad actuales.The aim of this project has been to improve the practical teaching of subjects in the field of Paleontology and in other dissemination activities carried out by the Department of Stratigraphy and Paleontology, in order to enhance the student learning. To do so, this project printed 3D models and replicas of different fossil groups which, for various reasons (scarcity of samples in our laboratories, size or fragility), cannot be correctly observed and/or manipulated by students. This has allowed the teaching staff of the Paleontology area to adapt their teaching practices and dissemination activities to the requirements of today's society and university