Atmospheric CO2 and Temperature. What is Normal?

–How much of a change in CO2 concentration and other GHGs is natural? –What is the normal range of CO2 and temperature variability? How is normal defined in this context? –What is the relationship between CO2 and global temperatures

Pliocene Marine Transgressions of Northern Alaska: Circumarctic Correlations and Paleoclimatic Interpretations

At least three marine transgressions of Piliocene age are recorded by littoral to inner-shelf sediments of the Gubik Formation, which mantles the Arctic Coastal Plain of northern Alaska. The three recognized transgressions were eustatic high sea levels that, from oldest to youngest, are informally named the Colvillian, Bigbendian, and Fishcreekian transgressions. The geochronology is based up amino acid geochemistry, paleomagnetic studies, vertebrate and invertebrate paleontology, and strontium isotope age estimates. Pollen, plant macrofossils, and marine vertebrate and inventebrate remains indicate that these transgressions occurred when the Arctic was at least intermittently much warmer than it is now. The Colvillian transgression took place at sometime between 2.48 and 2.7 Ma, when adjacent coastal areas supported an open boreal forest or spruce-birch-woodland with scattered pine and rare fir and hemlock. The Bigbendian transgression occurred about 2.48 Ma. Climate conditions were probably slightly cooler than during the Colvillian transgression, but probably too warm for permafrost and too warm for even seasonal sea ice in the region. Nearby vegetation was open spruce-birch woodland or parkland, possibly with rare scattered pine. The Fishcreekian transgression took place sometime between 2.14 and 2.48 Ma and was also characterized by warm marine conditions without sea ice. During the waning stages of this transgression, however, terrestrial conditions were relatively cool, and coastal vegetation was herbaceous tundra with scattered larch trees in the vicinity. Other marine units from this time period occur around the Arctic Basin. The three oldest transgressions recognized from the Seward Peninsula may be broadly correlated with the three Piliocene transgresions of the Arctic Coastal Plain. The Tusatuvayam beds in Kamchatka possibly correlate with one of the two younger transgressions of northern Alaska. The non-marine Worth Point Formation of Banks Island may be younger than all three of the transgressions of the Arctic Coastal Plain, and marine sediment of the Beaufort Formation on Meighen Island is slightly older than the Colvillian transgression. None of the Piliocene marine units on Baffin Island can be confidently correlated with the high sea level events of northern Alaska. The upper Kap Kobenhavn Formation and the upper Loden Elv Formation of Greenland most likely correlate with the Fishcreekian transgression.Key words: Arctic, amino acids, Pliocene, Pleistocene, paleoclimate, marine transgressions, sea level, Alaska, Gubik FormationRÉSUMÉ. Au moins trois transgressions marines datant du pliocène sont inscrites dans les sediments allant du littoral à l’interieur de la plateforme de la formation Gubik, qui recouvre la plaine côtière arctique de l’Alaska septentrional. Les trois transgressions reconnues correspondent à des fortes remontées du niveau de la mer et ont reçu, dans l’ordre chronologique, les noms informels de formations "colvillienne", "bigbendienne" et "fishcreekienne". La géochronologie s’appuie sur la géochimie des acides aminés, des études paléomagnétiques, la paléontologie de vertébrés et d’invertébrés ainsi que sur des estimations de datation à l’isotope du strontium. Les pollens, les macrofossiles végétaux ainsi que les restes de vertébrés et d’invertébrés marins indiquent que ces transgressions se sont produites alors que l’Arctique  était, pour le moins de façon intermittente, beaucoup plus chaud que maintenant. La transgression colvillienne a eu lieu à un moment donné entre 2,48 et 2,7 Ma, alors que les zones côtières adjacentes supportaient une forêt boréale ouverte ou des bois d’épinettes-bouleaux avec quelques pins éparpillés et de rares sapins et pruches. La transgression bigbendienne a eu lieu aux alentours de 2,48 Ma. Les conditions climatiques étaient probablement un peut plus froides que durant la transgression colvillienne, mais aussi probablement trop chaudes pour le pergélisol et en tout cas trop chaudes pour permettre la création d’une banquise - même saisonnière - dans la region. La végétation proche consistait en des bois ou des forêts-parcs d’épinettes-bouleaux avec peut-êtrequelques pins éparpillés. La transgression fishcreekienne a pris place à un moment donné entre 2,14 et 2,48 Ma et a aussi été caractérisée par des conditions marines chaudes sans banquise. Durant le declin de cette transgression cependant, les conditions climatiques terrestres étaient relativement froides et la végétation côtière se composait de toundra herbacée semée de mélèzes aux alentours. D’autres unites marines datant de cette période se trouvent autour du bassin de l’Arctique. Les trois plus anciennes transgressions établies dans la péninsule Seward peuvent être dans l’ensemble corrélées avec les trois transgressions du pliocène de la plaine côtière arctique. Les couches Tusatuvayam dans la Kamchatka sont peut-être corréler avec l’une des deux transgressions les plus jeunes de l’Alaska septentrional. La formation non marine Worth Point de l’île de Banks est peut-être plus jeune que les trois transgressions de la plaine côtière arctique et les sediments marins de la formation de Beaufort dans l’île Meighen sont légèrement plus anciens que la transgression colvillienne. On ne peut avec certitude corréler aucune des unités marines du pliocène sur l’île de Baffin avec les événements eustatiques qui ont amené une  élévation du niveau marin dans l’Alaska septentrional. La partie supérieure de la formation Kap Kobenhavn et celle de la formation Loden Elv du Groenland sont probablement à corréler avec latransgression fishcreekienne.Mots clés: Arctique, acides aminés, pliocène, pléistocène. paléoclimat, transgressions marines, niveau de la mer, Alaska, formation de Gubi

Complex Drilling Logistics for Lake El'gygytgyn, NE Russia

Lake El’gygytgyn was formed by astrophysical chance when a meteorite struck the Earth 100 km north of the Arctic Circle in Chukotka 3.6 Myrs ago (Layer, 2000) on the drainage divide between the Arctic Ocean and the Bering Sea. The crater measures ~18 km in diameter and lies nearly in the center of what was to become Beringia, the largestcontiguous landscape in the Arctic to have escaped continental scale glaciation. Within the crater rim today, Lake El’gygytgyn is 12 km in diameter and 170 m deep, enclosing 350–400 m of sediment deposited since the time of impact (Gebhardt et al., 2006). This setting makes the lake ideal for paleoclimate and impact research

David Moody Hopkins (1921-2001)

David M. Hopkins, a Quaternary geologist widely known for his broad-ranging studies of the Bering Land Bridge region ("Beringia"), passed away at his home in Menlo Park, California, on November 2, 2001. Dave was a longtime member of Alaskan units of the U.S. Geological Survey (USGS). In search of a deeper understanding of Beringia, he became a pioneer in interdisciplinary research and in collaborative research with Russian investigators. Following his retirement from the USGS in 1985, Dave became director of the Alaskan Quaternary Center and Professor of Quaternary Studies at the Fairbanks campus of the University of Alaska. During the 57 years of his professional career, he was a mentor, friend, and source of inspiration to several generations of Arctic scholars. ... After graduating from the University of New Hampshire with a bachelor's degree in Geology in 1942, he joined the USGS and began graduate studies at Harvard University. Dave spent his initial field seasons with the USGS in southern regions of Alaska, where he investigated strategic minerals, engineering geology, and other aspects of geology that were considered essential to the ongoing war effort. In 1944, he was inducted into the Army and assigned to carry out meteorological observations at Cold Bay, situated at the tip of the Alaska Peninsula. Following his discharge, Dave resumed graduate studies at Harvard and field work with the USGS. He obtained an M.S. degree in Geology (1948) and a Ph.D. in Quaternary Geology (1955) from Harvard University. In 1947, Dave began geological investigations on the Seward Peninsula under the permafrost program of the USGS Alaska Terrain and Permafrost Section (which later became the Branch of Alaskan Geology). ... In 1948, he initiated a productive collaboration with the botanist Robert Sigafoos. Their seminal publications on the interactions of permafrost, soil, and vegetation on the Seward Peninsula are considered classics today. Dave also began a long-term collaboration with the archeologist Louis Giddings on dating and reconstructing the paleoecology of prehistoric village sites and other early human habitations in northwestern Alaska. ... Dave's investigations of elevated and submerged gold-bearing beaches at Nome during the 1950s initiated his long-lasting interest in the sea-level history of Beringia and the paleoecology of parts of the Bering platform that are submerged today. ... Dave's broadening interests in the paleoecology of Beringia led to increasing contacts with Russian colleagues that developed into a fruitful, 40-year collaboration across the Bering Strait. ... After Dave's retirement from the USGS, he began a second career of teaching and research as Distinguished Professor of Quaternary Studies at the University of Alaska at Fairbanks (UAF). ... As a direct result of Dave's broad-ranging research on the northern Seward Peninsula, the U.S. National Park Service (NPS) set aside much of his former field area as the Bering Land Bridge National Preserve. ... Dave's scientific influence encompasses such diverse fields as bedrock geology, marine geology, paleontology, limnology, hydrology, ecology, archeology, and paleoclimatology - the topics of his more than 200 refereed papers and abstracts. Numerous awards and commendations from the USGS and other scientific organizations recognized his contributions. ... During his highly productive career, Dave always found time to advise and encourage younger colleagues and students. ... We shall all miss his warmth, his humor, and his infectious passion for Beringia, but his legacy of inspired research and interdisciplinary scholarship will be enduring. ..

The Age and Origin of the Little Diomede Island Upland Surface

Geomorphology and projected uplift rates indicate that the upland surface of Little Diomede Island may represent a high sea level stand that occurred 2.6 million years ago in the Bering Strait. The 350-363 m upland surface of the island could be correlative with the York terrace, an uplifted marine terrace previously recognized on the southern flanks of the York Mountains, Seward Peninsula. The modern surface of Little Diomede Island is composed of a cryoplanation terrace enclosing a central blockfield and rimmed with tors. Beryllium-l0 cosmogenic isotope analysis of two tors and three outcrops from the upper surface indicate the island has been under the influence of a subaerial periglacial environment at least for the last 36 000 years (MIS 3) and probably for 254 000 (MIS 7/8). Unequivocal evidence does not exist to support glaciation of Little Diomede Island. La géomorphologie et les taux d'exhaussement obtenus par extrapolation révèlent que la surface de haute terre de l'île de Petite Diomède pourrait représenter un relief ayant existé dans le contexte d'un niveau de mer élevé qui avait cours il y a 2,6 millions d'années dans le détroit de Béring. La surface de haute terre de l'île, atteignant de 350 à 363 m, pourrait être en corrélation avec la terrasse de York, terrasse marine surélevée, découverte antérieurement sur les flancs méridionaux des monts York situés dans la péninsule Seward. La surface actuelle de l'île de Petite Diomède se compose d'une terrasse de cryoplanation entourant un champ central de blocs rocheux et circonscrite par des tors. L'analyse isotopique cosmogonique au 10béryllium de deux tors et de trois affleurements de la surface la plus haute révèle que l'île a subi l'influence d'un environnement périglaciaire subaérien pendant au moins les 36 000 dernières années (3e étage isotopique marin) et probablement 254 000 ans (7e/8e étage isotopique marin). On ne possède pas de preuve non équivoque d'une glaciation de l'île de Petite Diomède

Circum-Arctic Late Tertiary/Early Pleistocene Stratigraphy And Environments - A Preface

...During the 1980s the Geological Survey of Canada (GSC) and the U.S. Geological Survey (USGS) initiated a program of joint workshops and cooperative field excursions. The first meeting took place in Calgary, Alberta, in 1984. It dealt with correlation of Quaternary deposits in northwestern North America, but touched on the Tertiary. A second GSC/USGS workshop in early 1987 concerned the Quaternary history of interior basins of Alaska and Canada, but once again the Tertiary became an item of discussion because some of the basins contain a thick sequence of Pliocene and Miocene sediments. It was apparent from the questions that arose at these meetings that there was a need for a dedicated forum on the late Tertiary. The authors organized and convened a workshop with that theme in Denver, Colorado, in October 1987. The papers in this special issue are based on presentations and discussions at that meeting. ..

Oceanographic and Climatic Change in the Bering Sea, Last Glacial Maximum to Holocene

Post‐glacial sea level rise led to a direct connection between the Arctic and Pacific Oceans via the Bering Strait. Consequently, the Bering Sea experienced changes in connectivity, size, and sediment sources that were among the most drastic of any ocean basin in the past 30,000 years. However, the sedimentary response to the interplay between climate change and sea level rise in high‐latitude settings such as Beringia remains poorly resolved. To ascertain changes in sediment delivery, productivity, and regional oceanography from the Last Glacial Maximum (LGM) to the Holocene, we analyzed sedimentological, geochemical, and isotopic characteristics of three sediment cores from the Bering Sea. Interpretations of productivity, terrestrial input, nutrient utilization, and circulation are based on organic carbon isotopes (δ13Corg), total organic carbon (TOC), bulk nitrogen isotopes, total organic nitrogen, carbon/nitrogen ratios, elemental X‐ray fluorescence data, grain size, and presence of laminated or dysoxic, green intervals. Principal component analysis of these data captures key climatic intervals. The LGM was characterized by low productivity across the region. In the Bering Sea, deglaciation began around 18–17 ka, with increasing terrestrial sediment and TOC input. Marine productivity increased during the Bølling‐Allerød when laminated sediments revealed dysoxic bottom waters where denitrification was extreme. The Younger Dryas manifested increased terrestrial input and decreased productivity, in contrast with the Pre‐Boreal, when productivity markedly rebounded. The Pre‐Boreal and Bølling‐Allerød were similarly productive, but changes in the source of TOC and a δ13Corg depletion suggest the influence of a gradually flooding Bering Shelf during the Pre‐Boreal and Holocene