ALBERT

Description: Polar ice-core records suggest that an arctic or boreal source was responsible for more than 30% of the large increase in global atmospheric methane (CH4) concentration during deglacial climate warming; however, specific sources of that CH4 are still debated. Here we present an estimate of past CH4 flux during deglaciation from bubbling from thermokarst (thaw) lakes. Based on high rates of CH4 bubbling from contemporary arctic thermokarst lakes, high CH4 production potentials of organic matter from Pleistocene-aged frozen sediments, and estimates of the changing extent of these deposits as thermokarst lakes developed during deglaciation, we find that CH4 bubbling from newly forming thermokarst lakes comprised 33 to 87% of the high-latitude increase in atmospheric methane concentration and, in turn, contributed to the climate warming at the Pleistocene-Holocene transition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Walter, K M -- Edwards, M E -- Grosse, G -- Zimov, S A -- Chapin, F S 3rd -- New York, N.Y. -- Science. 2007 Oct 26;318(5850):633-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Water and Environmental Research Center, University of Alaska, Fairbanks, AK 99775, USA. ftkmw1@uaf.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17962561" target="_blank"〉PubMed〈/a〉

Description: It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west-an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trondelag in central Norway dating back ~10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andoya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Parducci, Laura -- Jorgensen, Tina -- Tollefsrud, Mari Mette -- Elverland, Ellen -- Alm, Torbjorn -- Fontana, Sonia L -- Bennett, K D -- Haile, James -- Matetovici, Irina -- Suyama, Yoshihisa -- Edwards, Mary E -- Andersen, Kenneth -- Rasmussen, Morten -- Boessenkool, Sanne -- Coissac, Eric -- Brochmann, Christian -- Taberlet, Pierre -- Houmark-Nielsen, Michael -- Larsen, Nicolaj Krog -- Orlando, Ludovic -- Gilbert, M Thomas P -- Kjaer, Kurt H -- Alsos, Inger Greve -- Willerslev, Eske -- New York, N.Y. -- Science. 2012 Mar 2;335(6072):1083-6. doi: 10.1126/science.1216043.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22383845" target="_blank"〉PubMed〈/a〉

Description: Although it is generally agreed that the Arctic flora is among the youngest and least diverse on Earth, the processes that shaped it are poorly understood. Here we present 50 thousand years (kyr) of Arctic vegetation history, derived from the first large-scale ancient DNA metabarcoding study of circumpolar plant diversity. For this interval we also explore nematode diversity as a proxy for modelling vegetation cover and soil quality, and diets of herbivorous megafaunal mammals, many of which became extinct around 10 kyr bp (before present). For much of the period investigated, Arctic vegetation consisted of dry steppe-tundra dominated by forbs (non-graminoid herbaceous vascular plants). During the Last Glacial Maximum (25-15 kyr bp), diversity declined markedly, although forbs remained dominant. Much changed after 10 kyr bp, with the appearance of moist tundra dominated by woody plants and graminoids. Our analyses indicate that both graminoids and forbs would have featured in megafaunal diets. As such, our findings question the predominance of a Late Quaternary graminoid-dominated Arctic mammoth steppe.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Willerslev, Eske -- Davison, John -- Moora, Mari -- Zobel, Martin -- Coissac, Eric -- Edwards, Mary E -- Lorenzen, Eline D -- Vestergard, Mette -- Gussarova, Galina -- Haile, James -- Craine, Joseph -- Gielly, Ludovic -- Boessenkool, Sanne -- Epp, Laura S -- Pearman, Peter B -- Cheddadi, Rachid -- Murray, David -- Brathen, Kari Anne -- Yoccoz, Nigel -- Binney, Heather -- Cruaud, Corinne -- Wincker, Patrick -- Goslar, Tomasz -- Alsos, Inger Greve -- Bellemain, Eva -- Brysting, Anne Krag -- Elven, Reidar -- Sonstebo, Jorn Henrik -- Murton, Julian -- Sher, Andrei -- Rasmussen, Morten -- Ronn, Regin -- Mourier, Tobias -- Cooper, Alan -- Austin, Jeremy -- Moller, Per -- Froese, Duane -- Zazula, Grant -- Pompanon, Francois -- Rioux, Delphine -- Niderkorn, Vincent -- Tikhonov, Alexei -- Savvinov, Grigoriy -- Roberts, Richard G -- MacPhee, Ross D E -- Gilbert, M Thomas P -- Kjaer, Kurt H -- Orlando, Ludovic -- Brochmann, Christian -- Taberlet, Pierre -- England -- Nature. 2014 Feb 6;506(7486):47-51. doi: 10.1038/nature12921.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark [2]. ; 1] Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, 40 Lai Street, 51005 Tartu, Estonia [2]. ; 1] Laboratoire d'Ecologie Alpine (LECA) CNRS UMR 5553, University Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France [2]. ; 1] Geography and Environment, University of Southampton, Southampton SO17 1BJ, UK [2]. ; 1] Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark [2] Department of Integrative Biology, University of California Berkeley, 1005 Valley Life Sciences Building, Berkeley, 94720 California, USA [3]. ; 1] National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, Blindern, NO-0318 Oslo, Norway [2] Department of Botany, Saint Petersburg State University, Universitetskaya nab. 7/9, 199034 Saint Petersburg, Russia [3]. ; 1] Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark [2] Ancient DNA Laboratory, Veterinary and Life Sciences School, Murdoch University, 90 South Street, Perth, 6150 Western Australia, Australia [3]. ; Division of Biology, Kansas State University, Manhattan, 66506-4901 Kansas, USA. ; Laboratoire d'Ecologie Alpine (LECA) CNRS UMR 5553, University Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France. ; 1] National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, Blindern, NO-0318 Oslo, Norway [2] Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, PO Box 1066, Blindern, NO-0318 Oslo, Norway (S.B.); Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A 43, 14473 Potsdam, Germany (L.S.E.); SpyGen, Savoie Technolac, 17 allee du lac Saint Andre, BP 274, 73375 Le Bourget-du-Lac Cedex, France (E.B.). ; Landscape Dynamics Unit, Swiss Federal Research Institute WSL, Zurcherstrasse 111, CH-8903 Birmensdorf, Switzerland. ; Institut des Sciences de l'Evolution de Montpellier, UMR 5554 Universite Montpellier 2, Bat.22, CC061, Place Eugene Bataillon, 34095 Montpellier Cedex 5, France. ; University of Alaska Museum of the North, Fairbanks, 99775-6960 Alaska, USA. ; Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, NO-9037 Tromso, Norway. ; Geography and Environment, University of Southampton, Southampton SO17 1BJ, UK. ; Genoscope, Institut de Genomique du Commissariat a l'Energie Atomique (CEA), 91000 Evry, France. ; 1] Adam Mickiewicz University, Faculty of Physics, Umultowska 85, 61-614 Poznan, Poland [2] Poznan Radiocarbon Laboratory, Poznan Science and Technology Park, Rubiez 46, 61-612 Poznan, Poland. ; Tromso University Museum, NO-9037 Tromso, Norway. ; Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066, Blindern, NO-0316 Oslo, Norway. ; National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, Blindern, NO-0318 Oslo, Norway. ; Permafrost Laboratory, Department of Geography, University of Sussex, Brighton BN1 9QJ, UK. ; 1] Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninsky Prospect, 119071 Moscow, Russia [2]. ; Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Oster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. ; Department of Biology, Terrestrial Ecology, Universitetsparken 15, DK- 2100 Copenhagen O, Denmark. ; Australian Centre for Ancient DNA, School of Earth & Environmental Sciences, University of Adelaide, Adelaide, 5005 South Australia, Australia. ; Department of Geology/Quaternary Sciences, Lund University Solvegatan 12, SE-223 62 Lund, Sweden. ; Department of Earth and Atmospheric Sciences, University of Alberta, T6G 2E3 Edmonton, Alberta, Canada. ; Government of Yukon, Department of Tourism and Culture, Yukon Palaeontology Program, PO Box 2703 L2A, Y1A 2C6 Whitehorse, Yukon Territory, Canada. ; INRA, UMR1213 Herbivores, F-63122 Saint-Genes-Champanelle, France. ; Zoological Institute of Russian Academy of Sciences, Universitetskaya nab. 1, 199034 Saint-Petersburg, Russia. ; Institute of Applied Ecology of the North of North-Eastern Federal University, Belinskogo Street 58, 677000 Yakutsk, Republic of Sakha (Yakutia), Russia. ; Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, 2522 New South Wales, Australia. ; Division of Vertebrate Zoology/Mammalogy, American Museum of Natural History, New York, 10024 New York, USA. ; 1] National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, Blindern, NO-0318 Oslo, Norway [2].〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24499916" target="_blank"〉PubMed〈/a〉

Description: The course of permafrost degradation depends on climate, vegetation, disturbance, and excess ground-ice content and distribution, which vary over time. Our understanding of possible future landscape trajectories under climate warming can be improved by observing past responses to changes in these critical drivers. Using a novel combination of lake-sediment records, field observations and LiDAR imagery, we reconstructed the late-Quaternary history of the marginal upland of the Yukon Flats, interior Alaska, a loess-mantled region with massive ground ice and numerous thermokarst lakes. Two lakes formed ~11,000-12,000 cal yr BP through inferred thermokarst processes. Charcoal in basal sediments indicates fire may have influenced lake initiation. In a third, older basin, major input of terrigenous silt occurred before or during this time. At all studied lakes, sedimentation has been stable through much of the Holocene. Meso-scale topographic features that are obscured by forest are revealed by LiDAR images to include widespread linear corrugations cutting across the uplands, deep gullies, and other features resembling lake drainage channels. These imply past dramatic surface-sediment mobilization. Lakes intersect the corrugations, indicating that the mobile phase occurred no later than the earliest Holocene. Several interacting factors may have been critical in first enhancing, then slowing, this activity. High summer insolation, increasing moisture, initially sparse vegetation, then development of woody cover and increase in fire disturbance likely combined to generate rapid and deep thaw of glacial-age permafrost. Initial lake lowering and generation of steep local topography favoring drying of uplands, a summer water deficit, and early-Holocene establishment of evergreen forest cover and consequent surface insulation likely combined to shift the system to a near-quiescent state (the system is not entirely inactive today: a partial lake drainage event was observed in 2103). The history and current state of this thermokarst-affected landscape differ from other regions. It has undergone non-linear shifts in process rates and developmental trajectory. Overall resilience to current and future environmental change here and in other regions may be equally individualistic.