Author
Jeffrey P. Severinghaus
Other affiliations: University of Rhode Island, Scripps Institution of Oceanography, Scripps Health ...read more
Bio: Jeffrey P. Severinghaus is an academic researcher from University of California, San Diego. The author has contributed to research in topics: Ice core & Firn. The author has an hindex of 54, co-authored 158 publications receiving 10450 citations. Previous affiliations of Jeffrey P. Severinghaus include University of Rhode Island & Scripps Institution of Oceanography.
Topics: Ice core, Firn, Glacial period, Ice sheet, Deglaciation
Papers published on a yearly basis
Papers
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TL;DR: In this article, the isotopic abundances of atmospheric Ar were determined using a dynamically operated isotope ratio mass spectrometer with minor modifications and special gas handling techniques to avoid fractionation.
908 citations
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TL;DR: In this article, the authors demonstrate that rapid temperature change fractionates gas isotopes in unconsolidated snow, producing a signal that is preserved in trapped air bubbles as the snow forms ice.
Abstract: Rapid temperature change fractionates gas isotopes in unconsolidated snow, producing a signal that is preserved in trapped air bubbles as the snow forms ice The fractionation of nitrogen and argon isotopes at the end of the Younger Dryas cold interval, recorded in Greenland ice, demonstrates that warming at this time was abrupt This warming coincides with the onset of a prominent rise in atmospheric methane concentration, indicating that the climate change was synchronous (within a few decades) over a region of at least hemispheric extent, and providing constraints on previously proposed mechanisms of climate change at this time The depth of the nitrogen-isotope signal relative to the depth of the climate change recorded in the ice matrix indicates that, during the Younger Dryas, the summit of Greenland was 15 ± 3 °C colder than today
669 citations
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Dartmouth College1, Uppsala University2, Nagaoka University of Technology3, University of Copenhagen4, Heidelberg University5, Natural Resources Canada6, Oregon State University7, Centre national de la recherche scientifique8, Korean Ocean Research and Development Institute9, Swansea University10, University of Bern11, British Antarctic Survey12, University of Kansas13, National Institute of Polar Research14, University of Iceland15, Stockholm University16, Vrije Universiteit Brussel17, University of Colorado Boulder18, Alfred Wegener Institute for Polar and Marine Research19, University of Washington20, Arctic and Antarctic Research Institute21, Desert Research Institute22, Hokkaido University23, University of Grenoble24, University of California, San Diego25, Université libre de Bruxelles26, Utrecht University27, Oeschger Centre for Climate Change Research28, Max Planck Society29, Swiss Federal Institute for Forest, Snow and Landscape Research30, ETH Zurich31, United Arab Emirates University32, Paul Scherrer Institute33, École Polytechnique Fédérale de Lausanne34, University of East Anglia35, Geological Survey of Canada36
TL;DR: In this paper, the North Greenland Eemian Ice Drilling (NEEM) ice core was extracted from folded Greenland ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
546 citations
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TL;DR: Nitrogen and argon isotopes in trapped air in Greenland ice show that the Greenland Summit warmed 9 +/- 3 degrees C over a period of several decades, beginning 14,672 years ago, supporting a North Atlantic rather than a tropical trigger for the climate event.
Abstract: The last glacial period was terminated by an abrupt warming event in the North Atlantic ∼15,000 years before the present, and warming events of similar age have been reported from low latitudes. Understanding the mechanism of this termination requires that the precise relative timing of abrupt climate warming in the tropics versus the North Atlantic be known. Nitrogen and argon isotopes in trapped air in Greenland ice show that the Greenland Summit warmed 9 ± 3°C over a period of several decades, beginning 14,672 years ago. Atmospheric methane concentrations rose abruptly over a ∼50-year period and began their increase 20 to 30 years after the onset of the abrupt Greenland warming. These data suggest that tropical climate became warmer or wetter (or both) ∼20 to 80 years after the onset of Greenland warming, supporting a North Atlantic rather than a tropical trigger for the climate event.
532 citations
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TL;DR: The results indicate that orbital-scale Antarctic climate change lags Northern Hemisphere insolation by a few millennia, and that the increases in Antarctic temperature and atmospheric carbon dioxide concentration during the last four terminations occurred within the rising phase of Northern Hemisphere summer insolation.
Abstract: The Milankovitch theory of climate change proposes that glacial–interglacial cycles are driven by changes in summer insolation at high northern latitudes. The timing of climate change in the Southern Hemisphere at glacial–interglacial transitions (which are known as terminations) relative to variations in summer insolation in the Northern Hemisphere is an important test of this hypothesis. So far, it has only been possible to apply this test to the most recent termination because the dating uncertainty associated with older terminations is too large to allow phase relationships to be determined. Here we present a new chronology of Antarctic climate change over the past 360,000 years that is based on the ratio of oxygen to nitrogen molecules in air trapped in the Dome Fuji and Vostok ice cores. This ratio is a proxy for local summer insolation5, and thus allows the chronology to be constructed by orbital tuning without the need to assume a lag between a climate record and an orbital parameter. The accuracy of the chronology allows us to examine the phase relationships between climate records from the ice cores and changes in insolation. Our results indicate that orbital-scale Antarctic climate change lags Northern Hemisphere insolation by a few millennia, and that the increases in Antarctic temperature and atmospheric carbon dioxide concentration during the last four terminations occurred within the rising phase of Northern Hemisphere summer insolation. These results support the Milankovitch theory that Northern Hemisphere summer insolation triggered the last four deglaciations
466 citations
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01 Jan 2014
TL;DR: Myhre et al. as discussed by the authors presented the contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) 2013: Anthropogenic and Natural Radiative forcing.
Abstract: This chapter should be cited as: Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Coordinating Lead Authors: Gunnar Myhre (Norway), Drew Shindell (USA)
3,684 citations
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Potsdam Institute for Climate Impact Research1, University of Melbourne2, Pacific Northwest National Laboratory3, National Oceanic and Atmospheric Administration4, National Institute for Environmental Studies5, National Center for Atmospheric Research6, University of Shiga Prefecture7, Manchester Metropolitan University8, International Institute for Applied Systems Analysis9, Utrecht University10, Netherlands Environmental Assessment Agency11
TL;DR: In this article, the greenhouse gas concentrations for the Representative Concentration Pathways (RCPs) and their extensions beyond 2100, the Extended ConcentrationPathways (ECPs), are presented.
Abstract: We present the greenhouse gas concentrations for the Representative Concentration Pathways (RCPs) and their extensions beyond 2100, the Extended Concentration Pathways (ECPs). These projections include all major anthropogenic greenhouse gases and are a result of a multi-year effort to produce new scenarios for climate change research. We combine a suite of atmospheric concentration observations and emissions estimates for greenhouse gases (GHGs) through the historical period (1750-2005) with harmonized emissions projected by four different Integrated Assessment Models for 2005-2100. As concentrations are somewhat dependent on the future climate itself (due to climate feedbacks in the carbon and other gas cycles), we emulate median response characteristics of models assessed in the IPCC Fourth Assessment Report using the reduced-complexity carbon cycle climate model MAGICC6. Projected 'best-estimate' global-mean surface temperature increases (using inter alia a climate sensitivity of 3°C) range from 1.5°C by 2100 for the lowest of the four RCPs, called both RCP3-PD and RCP2.6, to 4.5°C for the highest one, RCP8.5, relative to pre-industrial levels. Beyond 2100, we present the ECPs that are simple extensions of the RCPs, based on the assumption of either smoothly stabilizing concentrations or constant emissions: For example,
3,144 citations
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Queen's University Belfast1, University of St Andrews2, Aix-Marseille University3, Historic England4, University of Sheffield5, University of Oxford6, Alfred Wegener Institute for Polar and Marine Research7, Xi'an Jiaotong University8, University of Minnesota9, Nanjing Normal University10, University of Hohenheim11, University of Kiel12, Lawrence Livermore National Laboratory13, University of California, Santa Cruz14, ETH Zurich15, University of Waikato16, Woods Hole Oceanographic Institution17, Heidelberg University18, Cornell University19, Lund University20, University of New South Wales21, University of Arizona22, University of Groningen23, University of Bristol24, University of Glasgow25, University of California, Irvine26, University of Bern27, Aarhus University28, Nagoya University29, Swiss Federal Institute for Forest, Snow and Landscape Research30, National Museum of Japanese History31, University of Bologna32
TL;DR: In this article, the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP.
Abstract: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.
2,800 citations
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TL;DR: The 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use is presented in this article.
Abstract: This paper gives the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into account the data considered in the 2006 adjustment as well as the data that became available from 1 January 2007, after the closing date of that adjustment, until 31 December 2010, the closing date of the new adjustment. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2010 set replaces the previously recommended 2006 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants.
2,770 citations
01 Jan 2007
TL;DR: The Third edition of the Kirk-Othmer encyclopedia of chemical technology as mentioned in this paper was published in 1989, with the title "Kirk's Encyclopedia of Chemical Technology: Chemical Technology".
Abstract: 介绍了Kirk—Othmer Encyclopedia of Chemical Technology(化工技术百科全书)(第五版)电子图书网络版数据库,并对该数据库使用方法和检索途径作出了说明,且结合实例简单地介绍了该数据库的检索方法。
2,666 citations