Browsing by Subject "LAST GLACIAL MAXIMUM"

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  • Armstrong, Edward; Hopcroft, Peter O.; Valdes, Paul J. (2019)
    We present a continuous land-based climate reconstruction dataset extending back 60 kyr from 0 BP (1950) at 0.5 degrees resolution on a monthly timestep for 0 degrees N to 90 degrees N. It has been generated from 42 discrete snapshot simulations using the HadCM3B-M2.1 coupled general circulation model. We incorporate Dansgaard-Oeschger (DO) and Heinrich events to represent millennial scale variability, based on a temperature reconstruction from Greenland ice-cores, with a spatial fingerprint based on a freshwater hosing simulation with HadCM3B-M2.1. Interannual variability is also added and derived from the initial snapshot simulations. Model output has been downscaled to 0.5 degrees resolution (using simple bilinear interpolation) and bias corrected. Here we present surface air temperature, precipitation, incoming shortwave energy, minimum monthly temperature, snow depth, wind chill and number of rainy days per month. This is one of the first open access climate datasets of this kind and can be used to study the impact of millennial to orbital-scale climate change on terrestrial greenhouse gas cycling, northern extra-tropical vegetation, and megaflora and megafauna population dynamics.
  • Warmuth, Vera M.; Burgess, Malcolm D.; Laaksonen, Toni; Manica, Andrea; Magi, Marko; Nord, Andreas; Primmer, Craig R.; Saetre, Glenn-Peter; Winkel, Wolfgang; Ellegren, Hans (2021)
    Climate change influences population demography by altering patterns of gene flow and reproductive isolation. Direct mutation rates offer the possibility for accurate dating on the within-species level but are currently only available for a handful of vertebrate species. Here, we use the first directly estimated mutation rate in birds to study the evolutionary history of pied flycatchers (Ficedula hypoleuca). Using a combination of demographic inference and species distribution modelling, we show that all major population splits in this forest-dependent system occurred during periods of increased climate instability and rapid global temperature change. We show that the divergent Spanish subspecies originated during the Eemian-Weichselian transition 115-104 thousand years ago (kya), and not during the last glacial maximum (26.5-19 kya), as previously suggested. The magnitude and rates of climate change during the glacial-interglacial transitions that preceded population splits in pied flycatchers were similar to, or exceeded, those predicted to occur in the course of the current, human-induced climate crisis. As such, our results provide a timely reminder of the strong impact that episodes of climate instability and rapid temperature changes can have on species' evolutionary trajectories, with important implications for the natural world in the Anthropocene.
  • Qiu, Chunjing; Zhu, Dan; Ciais, Philippe; Guenet, Bertrand; Krinner, Gerhard; Peng, Shushi; Aurela, Mika; Bernhofer, Christian; Bruemmer, Christian; Bret-Harte, Syndonia; Chu, Housen; Chen, Jiquan; Desai, Ankur R.; Dusek, Jiri; Euskirchen, Eugenie S.; Fortuniak, Krzysztof; Flanagan, Lawrence B.; Friborg, Thomas; Grygoruk, Mateusz; Gogo, Sebastien; Gruenwald, Thomas; Hansen, Birger U.; Holl, David; Humphreys, Elyn; Hurkuck, Miriam; Kiely, Gerard; Klatt, Janina; Kutzbach, Lars; Largeron, Chloe; Laggoun-Defarge, Fatima; Lund, Magnus; Lafleur, Peter M.; Li, Xuefei; Mammarella, Ivan; Merbold, Lutz; Nilsson, Mats B.; Olejnik, Janusz; Ottosson-Lofvenius, Mikaell; Oechel, Walter; Parmentier, Frans-Jan W.; Peichl, Matthias; Pirk, Norbert; Peltola, Olli; Pawlak, Wlodzimierz; Rasse, Daniel; Rinne, Janne; Shaver, Gaius; Schmid, Hans Peter; Sottocornola, Matteo; Steinbrecher, Rainer; Sachs, Torsten; Urbaniak, Marek; Zona, Donatella; Ziemblinska, Klaudia (2018)
    Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5 degrees grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (V-cmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r(2) = 0.76; Nash-Sutcliffe modeling efficiency, MEF = 0.76) and ecosystem respiration (ER, r(2) = 0.78, MEF = 0.75), with lesser accuracy for latent heat fluxes (LE, r(2) = 0.42, MEF = 0.14) and and net ecosystem CO2 exchange (NEE, r(2) = 0.38, MEF = 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r(2) values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r(2) values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r(2) <0.1), likely due to the uncertain water input to the peat from surrounding areas. However, the poor performance of WT simulation did not greatly affect predictions of ER and NEE. We found a significant relationship between optimized V-cmax and latitude (temperature), which better reflects the spatial gradients of annual NEE than using an average V-cmax value.
  • Väliranta, Minna; Salonen, J. S.; Heikkilä, Maija; Amon, L.; Helmens, K.; Klimaschewski, A.; Kuhry, P.; Kultti, S.; Poska, A.; Shala, S.; Veski, S.; Birks, H. H. (2015)
    Holocene summer temperature reconstructions from northern Europe based on sedimentary pollen records suggest an onset of peak summer warmth around 9,000 years ago. However, pollen-based temperature reconstructions are largely driven by changes in the proportions of tree taxa, and thus the early-Holocene warming signal may be delayed due to the geographical disequilibrium between climate and tree populations. Here we show that quantitative summer-temperature estimates in northern Europe based on macrofossils of aquatic plants are in many cases ca. 2 degrees C warmer in the early Holocene (11,700-7,500 years ago) than reconstructions based on pollen data. When the lag in potential tree establishment becomes imperceptible in the mid-Holocene (7,500 years ago), the reconstructed temperatures converge at all study sites. We demonstrate that aquatic plant macrofossil records can provide additional and informative insights into early-Holocene temperature evolution in northernmost Europe and suggest further validation of early post-glacial climate development based on multi-proxy data syntheses.
  • Armstrong, Edward; Hopcroft, Peter O.; Valdes, Paul J. (2019)
    Regional climate models (RCMs) are often assumed to be more skillful compared to lower-resolution general circulation models (GCM). However, RCMs are driven by input from coarser resolution GCMs, which may introduce biases. This study employs versions of the HadAMB3 GCM at three resolutions (>50 km) to investigate the added value of higher resolution using identically configured simulations of the preindustrial (PI), mid-Holocene, and Last Glacial Maximum. The RCM shows improved PI climatology compared to the coarse-resolution GCM and enhanced paleoanomalies in the jet stream and storm tracks. However, there is no apparent improvement when compared to proxy reconstructions. In the high-resolution GCM, accuracy in PI climate and atmospheric anomalies are enhanced despite its intermediate resolution. This indicates that synoptic and mesoscale features in a RCM are influenced by its low-resolution input, which impacts the simulated climatology. This challenges the paradigm that RCMs improve the representation of climate conditions and change.
  • Strandberg, G.; Kjellstrom, E.; Poska, A.; Wagner, S.; Gaillard, M.-J.; Trondman, A.-K.; Mauri, A.; Davis, B. A. S.; Kaplan, J. O.; Birks, H. J. B.; Bjune, A. E.; Fyfe, R.; Giesecke, T.; Kalnina, L.; Kangur, M.; van der Knaap, W. O.; Kokfelt, U.; Kunes, P.; Latalowa, M.; Marquer, L.; Mazier, F.; Nielsen, A. B.; Smith, B.; Seppa, H.; Sugita, S. (2014)
  • Davis, Basil A. S.; Chevalier, Manuel; Sommer, Philipp; Carter, Vachel A.; Finsinger, Walter; Mauri, Achille; Phelps, Leanne N.; Zanon, Marco; Abegglen, Roman; Akesson, Christine M.; Alba-Sanchez, Francisca; Anderson, R. Scott; Antipina, Tatiana G.; Atanassova, Juliana R.; Beer, Ruth; Belyanina, Nina I.; Blyakharchuk, Tatiana A.; Borisova, Olga K.; Bozilova, Elissaveta; Bukreeva, Galina; Bunting, M. Jane; Clo, Eleonora; Colombaroli, Daniele; Combourieu-Nebout, Nathalie; Desprat, Stephanie; Di Rita, Federico; Djamali, Morteza; Edwards, Kevin J.; Fall, Patricia L.; Feurdean, Angelica; Fletcher, William; Florenzano, Assunta; Furlanetto, Giulia; Gaceur, Emna; Galimov, Arsenii T.; Galka, Mariusz; Garcia-Moreiras, Iria; Giesecke, Thomas; Grindean, Roxana; Guido, Maria A.; Gvozdeva, Irina G.; Herzschuh, Ulrike; Hjelle, Kari L.; Ivanov, Sergey; Jahns, Susanne; Jankovska, Vlasta; Jimenez-Moreno, Gonzalo; Karpinska-Kolaczek, Monika; Kitaba, Ikuko; Kolaczek, Piotr; Lapteva, Elena G.; Latalowa, Malgorzata; Lebreton, Vincent; Leroy, Suzanne; Leydet, Michelle; Lopatina, Darya A.; Antonio Lopez-Saez, Jose; Lotter, Andre F.; Magri, Donatella; Marinova, Elena; Matthias, Isabelle; Mavridou, Anastasia; Mercuri, Anna Maria; Manuel Mesa-Fernandez, Jose; Mikishin, Yuri A.; Milecka, Krystyna; Montanari, Carlo; Morales-Molino, Cesar; Mrotzek, Almut; Munoz Sobrino, Castor; Naidina, Olga D.; Nakagawa, Takeshi; Nielsen, Anne Birgitte; Novenko, Elena Y.; Panajiotidis, Sampson; Panova, Nata K.; Papadopoulou, Maria; Pardoe, Heather S.; Pedziszewska, Anna; Petrenko, Tatiana I.; Ramos-Roman, Maria J.; Ravazzi, Cesare; Rosch, Manfred; Ryabogina, Natalia; Sabariego Ruiz, Silvia; Salonen, J. Sakari; Sapelko, Tatyana V.; Schofield, James E.; Seppa, Heikki; Shumilovskikh, Lyudmila; Stivrins, Normunds; Stojakowits, Philipp; Svitavska, Helena Svobodova; Swieta-Musznicka, Joanna; Tantau, Ioan; Tinner, Willy; Tobolski, Kazimierz; Tonkov, Spassimir; Tsakiridou, Margarita; Valsecchi, Verushka; Zanina, Oksana G.; Zimny, Marcelina (2020)
    The Eurasian (nee European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60% from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019).
  • Wegner, Carolyn; Bennett, Katrina E.; de Vernal, Anne; Forwick, Matthias; Fritz, Michael; Heikkilä, Maija; Lacka, Magdalena; Lantuit, Hugues; Laska, Michal; Moskalik, Mateusz; O'Regan, Matt; Pawlowska, Joanna; Prominska, Agnieszka; Rachold, Volker; Vonk, Jorien E.; Werner, Kirstin (2015)
    Arctic coastal zones serve as a sensitive filter for terrigenous matter input onto the shelves via river discharge and coastal erosion. This material is further distributed across the Arctic by ocean currents and sea ice. The coastal regions are particularly vulnerable to changes related to recent climate change. We compiled a pan-Arctic review that looks into the changing Holocene sources, transport processes and sinks of terrigenous sediment in the Arctic Ocean. Existing palaeoceanographic studies demonstrate how climate warming and the disappearance of ice sheets during the early Holocene initiated eustatic sea-level rise that greatly modified the physiography of the Arctic Ocean. Sedimentation rates over the shelves and slopes were much greater during periods of rapid sea-level rise in the early and middle Holocene, as a result of the relative distance to the terrestrial sediment sources. However, estimates of suspended sediment delivery through major Arctic rivers do not indicate enhanced delivery during this time, which suggests enhanced rates of coastal erosion. The increased supply of terrigenous material to the outer shelves and deep Arctic Ocean in the early and middle Holocene might serve as analogous to forecast changes in the future Arctic.
  • Schenk, Frederik; Väliranta, Minna; Muschitiello, Francesco; Tarasov, Lev; Heikkilä, Maija; Björck, Svante; Brandefelt, Jenny; Johansson, Arne V.; Näslund, Jens-Ove; Wohlfarth, Barbara (2018)
    The Younger Dryas (YD) cold reversal interrupts the warming climate of the deglaciation with global climatic impacts. The sudden cooling is typically linked to an abrupt slowdown of the Atlantic Meridional Overturning Circulation (AMOC) in response to meltwater discharges from ice sheets. However, inconsistencies regarding the YD-response of European summer temperatures have cast doubt whether the concept provides a sufficient explanation. Here we present results from a high-resolution global climate simulation together with a new July temperature compilation based on plant indicator species and show that European summers remain warm during the YD. Our climate simulation provides robust physical evidence that atmospheric blocking of cold westerly winds over Fennoscandia is a key mechanism counteracting the cooling impact of an AMOC-slowdown during summer. Despite the persistence of short warm summers, the YD is dominated by a shift to a continental climate with extreme winter to spring cooling and short growing seasons.