Resolving Milankovitch: Consideration of Signal and Noise Stephen R
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Conversion of GISP2-Based Sediment Core Age Models to the GICC05 Extended Chronology
Quaternary Geochronology 20 (2014) 1e7 Contents lists available at ScienceDirect Quaternary Geochronology journal homepage: www.elsevier.com/locate/quageo Short communication Conversion of GISP2-based sediment core age models to the GICC05 extended chronology Stephen P. Obrochta a, *, Yusuke Yokoyama a, Jan Morén b, Thomas J. Crowley c a University of Tokyo Atmosphere and Ocean Research Institute, 227-8564, Japan b Neural Computation Unit, Okinawa Institute of Science and Technology, 904-0495, Japan c Braeheads Institute, Maryfield, Braeheads, East Linton, East Lothian, Scotland EH40 3DH, UK article info abstract Article history: Marine and lacustrine sediment-based paleoclimate records are often not comparable within the early to Received 14 March 2013 middle portion of the last glacial cycle. This is due in part to significant revisions over the past 15 years to Received in revised form the Greenland ice core chronologies commonly used to assign ages outside of the range of radiocarbon 29 August 2013 dating. Therefore, creation of a compatible chronology is required prior to analysis of the spatial and Accepted 1 September 2013 temporal nature of climate variability at multiple locations. Here we present an automated mathematical Available online 19 September 2013 function that updates GISP2-based chronologies to the newer, NGRIP GICC05 age scale between 8.24 and 103.74 ka b2k. The script uses, to the extent currently available, climate-independent volcanic syn- Keywords: Chronology chronization of these two ice cores, supplemented by oxygen isotope alignment. The modular design of Ice core the script allows substitution for a more comprehensive volcanic matching, once it becomes available. Sediment core Usage of this function highlights on the GICC05 chronology, for the first time for the entire last glaciation, GICC05 the proposed global climate relationships during the series of large and rapid millennial stadial- interstadial events. -
To What Extent Can Orbital Forcing Still Be Seen As the “Pacemaker Of
Sophie Webb To what extent can orbital forcing still be seen as the main driver of global climate change? Introduction The Quaternary refers to the last 2.6 million years of geological time. During this period, there have been many oscillations in global climate resulting in episodes of glaciation and fluctuations in sea level. By examining evidence from a range of sources, palaeoclimatic data across different timescales can be considered. The recovery of longer, better preserved sediment and ice cores in addition to improved dating techniques have shown that climate has changed, not only on orbital timescales, but also on shorter scales of centuries and decades. Such discoveries have lead to the most widely accepted hypothesis of climate change, the Milankovitch hypothesis, being challenged and the emergence of new explanations. Causes of Climate Change Milankovitch Theory Orbital mechanisms have little effect on the amount of solar radiation (insolation) received by Earth. However, they do affect the distribution of this energy around the globe and produce seasonal variations which promote the growth or retreat of glaciers and ice sheets. Eccentricity is an approximate 100 kyr cycle and refers to the shape of the Earth’s orbit around the Sun. The orbit can be more elliptical or circular, altering the time Earth spends close to or far from the Sun. This in turn affects the seasons which can initiate small climatic changes. Seasonal changes are also caused by the Earth’s precession which runs on a cycle of around 23 kyr. The effect of precession is influenced by the eccentricity cycle: when the orbit is round, Earth’s distance from the sun is constant so there is not a hugely significant precessional effect. -
Cryosphere: a Kingdom of Anomalies and Diversity
Atmos. Chem. Phys., 18, 6535–6542, 2018 https://doi.org/10.5194/acp-18-6535-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Cryosphere: a kingdom of anomalies and diversity Vladimir Melnikov1,2,3, Viktor Gennadinik1, Markku Kulmala1,4, Hanna K. Lappalainen1,4,5, Tuukka Petäjä1,4, and Sergej Zilitinkevich1,4,5,6,7,8 1Institute of Cryology, Tyumen State University, Tyumen, Russia 2Industrial University of Tyumen, Tyumen, Russia 3Earth Cryosphere Institute, Tyumen Scientific Center SB RAS, Tyumen, Russia 4Institute for Atmospheric and Earth System Research (INAR), Physics, Faculty of Science, University of Helsinki, Helsinki, Finland 5Finnish Meteorological Institute, Helsinki, Finland 6Faculty of Radio-Physics, University of Nizhny Novgorod, Nizhny Novgorod, Russia 7Faculty of Geography, University of Moscow, Moscow, Russia 8Institute of Geography, Russian Academy of Sciences, Moscow, Russia Correspondence: Hanna K. Lappalainen (hanna.k.lappalainen@helsinki.fi) Received: 17 November 2017 – Discussion started: 12 January 2018 Revised: 20 March 2018 – Accepted: 26 March 2018 – Published: 8 May 2018 Abstract. The cryosphere of the Earth overlaps with the 1 Introduction atmosphere, hydrosphere and lithosphere over vast areas ◦ with temperatures below 0 C and pronounced H2O phase changes. In spite of its strong variability in space and time, Nowadays the Earth system is facing the so-called “Grand the cryosphere plays the role of a global thermostat, keeping Challenges”. The rapidly growing population needs fresh air the thermal regime on the Earth within rather narrow limits, and water, more food and more energy. Thus humankind suf- affording continuation of the conditions needed for the main- fers from climate change, deterioration of the air, water and tenance of life. -
Causes of Sea Level Rise
FACT SHEET Causes of Sea OUR COASTAL COMMUNITIES AT RISK Level Rise What the Science Tells Us HIGHLIGHTS From the rocky shoreline of Maine to the busy trading port of New Orleans, from Roughly a third of the nation’s population historic Golden Gate Park in San Francisco to the golden sands of Miami Beach, lives in coastal counties. Several million our coasts are an integral part of American life. Where the sea meets land sit some of our most densely populated cities, most popular tourist destinations, bountiful of those live at elevations that could be fisheries, unique natural landscapes, strategic military bases, financial centers, and flooded by rising seas this century, scientific beaches and boardwalks where memories are created. Yet many of these iconic projections show. These cities and towns— places face a growing risk from sea level rise. home to tourist destinations, fisheries, Global sea level is rising—and at an accelerating rate—largely in response to natural landscapes, military bases, financial global warming. The global average rise has been about eight inches since the centers, and beaches and boardwalks— Industrial Revolution. However, many U.S. cities have seen much higher increases in sea level (NOAA 2012a; NOAA 2012b). Portions of the East and Gulf coasts face a growing risk from sea level rise. have faced some of the world’s fastest rates of sea level rise (NOAA 2012b). These trends have contributed to loss of life, billions of dollars in damage to coastal The choices we make today are critical property and infrastructure, massive taxpayer funding for recovery and rebuild- to protecting coastal communities. -
Global Warming Impacts on Severe Drought Characteristics in Asia Monsoon Region
water Article Global Warming Impacts on Severe Drought Characteristics in Asia Monsoon Region Jeong-Bae Kim , Jae-Min So and Deg-Hyo Bae * Department of Civil & Environmental Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-Gu, Seoul 05006, Korea; [email protected] (J.-B.K.); [email protected] (J.-M.S.) * Correspondence: [email protected]; Tel.: +82-2-3408-3814 Received: 2 April 2020; Accepted: 7 May 2020; Published: 12 May 2020 Abstract: Climate change influences the changes in drought features. This study assesses the changes in severe drought characteristics over the Asian monsoon region responding to 1.5 and 2.0 ◦C of global average temperature increases above preindustrial levels. Based on the selected 5 global climate models, the drought characteristics are analyzed according to different regional climate zones using the standardized precipitation index. Under global warming, the severity and frequency of severe drought (i.e., SPI < 1.5) are modulated by the changes in seasonal and regional precipitation − features regardless of the region. Due to the different regional change trends, global warming is likely to aggravate (or alleviate) severe drought in warm (or dry/cold) climate zones. For seasonal analysis, the ranges of changes in drought severity (and frequency) are 11.5%~6.1% (and 57.1%~23.2%) − − under 1.5 and 2.0 ◦C of warming compared to reference condition. The significant decreases in drought frequency are indicated in all climate zones due to the increasing precipitation tendency. In general, drought features under global warming closely tend to be affected by the changes in the amount of precipitation as well as the changes in dry spell length. -
Downloaded 10/01/21 10:31 PM UTC 874 JOURNAL of CLIMATE VOLUME 12
MARCH 1999 VAVRUS 873 The Response of the Coupled Arctic Sea Ice±Atmosphere System to Orbital Forcing and Ice Motion at 6 kyr and 115 kyr BP STEPHEN J. VAVRUS Center for Climatic Research, Institute for Environmental Studies, University of WisconsinÐMadison, Madison, Wisconsin (Manuscript received 2 February 1998, in ®nal form 11 May 1998) ABSTRACT A coupled atmosphere±mixed layer ocean GCM (GENESIS2) is forced with altered orbital boundary conditions for paleoclimates warmer than modern (6 kyr BP) and colder than modern (115 kyr BP) in the high-latitude Northern Hemisphere. A pair of experiments is run for each paleoclimate, one with sea-ice dynamics and one without, to determine the climatic effect of ice motion and to estimate the climatic changes at these times. At 6 kyr BP the central Arctic ice pack thins by about 0.5 m and the atmosphere warms by 0.7 K in the experiment with dynamic ice. At 115 kyr BP the central Arctic sea ice in the dynamical version thickens by 2±3 m, accompanied bya2Kcooling. The magnitude of these mean-annual simulated changes is smaller than that implied by paleoenvironmental evidence, suggesting that changes in other earth system components are needed to produce realistic simulations. Contrary to previous simulations without atmospheric feedbacks, the sign of the dynamic sea-ice feedback is complicated and depends on the region, the climatic variable, and the sign of the forcing perturbation. Within the central Arctic, sea-ice motion signi®cantly reduces the amount of ice thickening at 115 kyr BP and thinning at 6 kyr BP, thus serving as a strong negative feedback in both pairs of simulations. -
Ice Core Science 21
Science Highlights: Ice Core Science 21 Dating ice cores JAKOB SCHWANDER Climate and Environmental Physics, Physics Institute, University of Bern, Switzerland; [email protected] Introduction 200 [ppb An accurate chronology is the ba- NO 100 3 ] sis for a meaningful interpretation - 80 ] of any climate archive, including ice 2 0 O 2 40 [ppb cores. Until now, the oldest ice re- H 0 200 Dust covered from a continuous core is [ppb 100 that from Dome Concordia, Antarc- 2 ] ] tica, with an estimated age of over -1 1.6 0 Sm 1.2 µ 800,000 years (EPICA Community [ Conduct. 0.8 160 [ppb Members, 2004). But the recently SO 80 4 2 recovered cores from near bedrock ] 60 - ] at Kohnen Station (Dronning Maud + 40 0 Na Land, Antarctica) and Dome Fuji [ppb 20 40 [ 0 Ca (Antarctica) compete for the longest ppb 2 20 + climatic record. With the recovery of ] 80 0 + more and more ice cores, the task of ] 4 establishing a good common chro- 40 [ppb NH nology has become increasingly im- 0 portant for linking the fi ndings from 1425 1425 .5 1426 1426 .5 1427 the different records. Moreover, in Depth [m] order to create a comprehensive Fig. 1: Seasonal variations of impurities in early Holocene ice from the North GRIP ice core. picture of past climate dynamics, it Summer layers are indicated by grey lines. is crucial to aim at a common chro- al., 1993, Rasmussen et al., 2006). is assessed with such a model, then nology for all paleo-records. Here Ideally the counting uncertainty is one can construct a chronology of the different methods for dating ice on the order of 1%. -
Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents
Consultation Draft Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents Foreword............................................................................................................................. 3 PART 1 - OVERVIEW .............................................................................................................. 3 1. Introduction .............................................................................................................. 3 The Quaternary stratigraphical framework ........................................................................ 4 Palaeogeography ........................................................................................................... 6 Fitting the archaeological record into this dynamic landscape .............................................. 6 Shorter-timescale division of the Late Pleistocene .............................................................. 7 2. Scientific Dating methods for the Pleistocene ................................................................. 8 Radiometric methods ..................................................................................................... 8 Trapped Charge Methods................................................................................................ 9 Other scientific dating methods ......................................................................................10 Relative dating methods ................................................................................................10 -
The Global Monsoon Across Time Scales Mechanisms And
Earth-Science Reviews 174 (2017) 84–121 Contents lists available at ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev The global monsoon across time scales: Mechanisms and outstanding issues MARK ⁎ ⁎ Pin Xian Wanga, , Bin Wangb,c, , Hai Chengd,e, John Fasullof, ZhengTang Guog, Thorsten Kieferh, ZhengYu Liui,j a State Key Laboratory of Mar. Geol., Tongji University, Shanghai 200092, China b Department of Atmospheric Sciences, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96825, USA c Earth System Modeling Center, Nanjing University of Information Science and Technology, Nanjing 210044, China d Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China e Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455, USA f CAS/NCAR, National Center for Atmospheric Research, 3090 Center Green Dr., Boulder, CO 80301, USA g Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, China h Future Earth, Global Hub Paris, 4 Place Jussieu, UPMC-CNRS, 75005 Paris, France i Laboratory Climate, Ocean and Atmospheric Studies, School of Physics, Peking University, Beijing 100871, China j Center for Climatic Research, University of Wisconsin Madison, Madison, WI 53706, USA ARTICLE INFO ABSTRACT Keywords: The present paper addresses driving mechanisms of global monsoon (GM) variability and outstanding issues in Monsoon GM science. This is the second synthesis of the PAGES GM Working Group following the first synthesis “The Climate variability Global Monsoon across Time Scales: coherent variability of regional monsoons” published in 2014 (Climate of Monsoon mechanism the Past, 10, 2007–2052). -
The Effect of Orbital Forcing on the Mean Climate and Variability of the Tropical Pacific
15 AUGUST 2007 T I MMERMANN ET AL. 4147 The Effect of Orbital Forcing on the Mean Climate and Variability of the Tropical Pacific A. TIMMERMANN IPRC, SOEST, University of Hawaii at Manoa, Honolulu, Hawaii S. J. LORENZ Max Planck Institute for Meteorology, Hamburg, Germany S.-I. AN Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea A. CLEMENT RSMAS/MPO, University of Miami, Miami, Florida S.-P. XIE IPRC, SOEST, University of Hawaii at Manoa, Honolulu, Hawaii (Manuscript received 24 October 2005, in final form 22 December 2006) ABSTRACT Using a coupled general circulation model, the responses of the climate mean state, the annual cycle, and the El Niño–Southern Oscillation (ENSO) phenomenon to orbital changes are studied. The authors analyze a 1650-yr-long simulation with accelerated orbital forcing, representing the period from 142 000 yr B.P. (before present) to 22 900 yr A.P. (after present). The model simulation does not include the time-varying boundary conditions due to ice sheet and greenhouse gas forcing. Owing to the mean seasonal cycle of cloudiness in the off-equatorial regions, an annual mean precessional signal of temperatures is generated outside the equator. The resulting meridional SST gradient in the eastern equatorial Pacific modulates the annual mean meridional asymmetry and hence the strength of the equatorial annual cycle. In turn, changes of the equatorial annual cycle trigger abrupt changes of ENSO variability via frequency entrainment, resulting in an anticorrelation between annual cycle strength and ENSO amplitude on precessional time scales. 1. Introduction Recent greenhouse warming simulations performed with ENSO-resolving coupled general circulation mod- The El Niño–Southern Oscillation (ENSO) is a els (CGCMs) have revealed that the projected ampli- coupled tropical mode of interannual climate variability tude and pattern of future tropical Pacific warming that involves oceanic dynamics (Jin 1997) as well as (Timmermann et al. -
A New Mass Spectrometric Tool for Modelling Protein Diagenesis
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Institutional Research Information System University of Turin 114 Abstracts / Quaternary International 279-280 (2012) 9–120 budgets, preferably spanning an entire glacial cycle, remain the most by chiral amino acid analysis. However, this knowledge has not yet been accurate for extrapolating glacial erosion rates to the entire Pleistocene able to produce a model which is fully able to explain the patterns of and for assessing their impact on crustal uplift. In the Carlit massif, where breakdown at low (burial) temperatures. By performing high temperature topographic conditions have allowed the majority of Würmian sediments experiments on a range of biominerals (e.g. corals and marine gastropods) to remain trapped within the catchment, clastic volumes preserved and and comparing the racemisation patterns with those obtained in fossil widespread 10Be nuclide inheritance on ice-scoured bedrock steps in the samples of known age, some of our studies have highlighted a range of path of major iceways reveal that mean catchment-scale glacial denuda- discrepancies in the datasets which we attribute to the interplay of tion depths were low (5 m in w100 ka), non-uniform across the landscape, a network of diagenesis reactions which are not yet fully understood. In and unsteady through time. Extrapolating to the Pleistocene, the trans- particular, an accurate knowledge of the temperature sensitivity of the two formation of Cenozoic landscapes by glaciers has thus been limited, many main observable diagenetic reactions (hydrolysis and racemisation) is still cirques and valleys being pre-glacial landforms merely modified by glacial elusive. -
The WAIS Divide Deep Ice Core WD2014 Chronology – Part 2: Annual-Layer Counting (0–31 Ka BP)
Clim. Past, 12, 769–786, 2016 www.clim-past.net/12/769/2016/ doi:10.5194/cp-12-769-2016 © Author(s) 2016. CC Attribution 3.0 License. The WAIS Divide deep ice core WD2014 chronology – Part 2: Annual-layer counting (0–31 ka BP) Michael Sigl1,2, Tyler J. Fudge3, Mai Winstrup3,a, Jihong Cole-Dai4, David Ferris5, Joseph R. McConnell1, Ken C. Taylor1, Kees C. Welten6, Thomas E. Woodruff7, Florian Adolphi8, Marion Bisiaux1, Edward J. Brook9, Christo Buizert9, Marc W. Caffee7,10, Nelia W. Dunbar11, Ross Edwards1,b, Lei Geng4,5,12,d, Nels Iverson11, Bess Koffman13, Lawrence Layman1, Olivia J. Maselli1, Kenneth McGwire1, Raimund Muscheler8, Kunihiko Nishiizumi6, Daniel R. Pasteris1, Rachael H. Rhodes9,c, and Todd A. Sowers14 1Desert Research Institute, Nevada System of Higher Education, Reno, NV 89512, USA 2Laboratory for Radiochemistry and Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland 3Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA 4Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA 5Dartmouth College Department of Earth Sciences, Hanover, NH 03755, USA 6Space Science Laboratory, University of California, Berkeley, Berkeley, CA 94720, USA 7Department of Physics and Astronomy, PRIME Laboratory, Purdue University, West Lafayette, IN 47907, USA 8Department of Geology, Lund University, 223 62 Lund, Sweden 9College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA 10Department of Earth, Atmospheric,