Global temperature has oscillated at least since the beginning of the Phanerozoic Eon 542 million years (My) ago, manifest as long climate cycles that repeat with a period of 135–150 My [1,2,3]. Faster and smaller temperature oscillations are superimposed on the cooling phase of the most recent long cycle beginning at least ~55 million years before present (Mybp) , forming the earliest Marine Isotope Stages (MISs; ), or global glacial cycles (“ice ages”). MISs recurred initially every ~41 thousand years (Ky) , the same repetition period as the integrated Obliquity/Precessional Orbital Cycle (OPOC; [6,7]), and grew larger by more than an order of magnitude over millions of years as the Earth cooled an additional ~1.5 °C . MISs shifted to a quasi-regular period of ~80–120 Ky and doubled in amplitude at the Mid-Pleistocene Climate Transition 1.25–0.75 My ago [5,8,9,10,11,12,13,14]. This temperature-oscillation pattern continues to dominate multi-millennial climate variability up to the present, inducing quasi-regular global glaciations separated by shorter warm interstadials. The contemporary climate constitutes a prolonged warm interstadial comparable to those that have alternated in the past with cold stadials corresponding to global glacial maxima.
Superimposed upon these multi-millennial climate cycles are numerous shorter global and regional climate cycles ranging in period from several millennia down to a few weeks. Included among these faster oscillations are millennial-scale cycles, particularly the Bond cycle [15,16,17,18,19,20,21,22,23], and centennial-scale cycles, notably the Antarctic Oscillation (AAO) known also as the Southern Annular Mode (SAM) and tracked quantitatively by means of the Southern Oscillation Index (SOI) [24,25,26,27,28,29,30,31]. These interdependent Southern Hemisphere (SH) temperature-proxy oscillations exhibit both centennial [24,25,26,27] and decadal [28,29,30,31] frequency components. Similar periodicity appears in independent reconstructions of more contemporary temperature proxies from James Ross Island  and snow accumulation in stacked records from snowpits at Vostok .
These and other centennial-scale temperature oscillations recurred with regularity in the past and are, therefore, likely to continue to oscillate at similar periods to affect future climate . Understanding these cycles can therefore improve the empirical basis for climate projection across time scales most immediately pertinent to human affairs, decades to centuries [34,35]. Analysis of oscillatory climate regimens and their interactions on diverse time scales also promises to improve our understanding of regional and global climate dynamics, including especially the balance between human and natural forcing of present and future climate change, which are among today's most compelling environmental and policy issues.
Toward these ends we report here a previously-unexplored centennial-scale temperature-proxy oscillation, the Antarctic Centennial Oscillation (ACO), recorded in stable isotopes frozen in ice cores at Vostok, Antarctica [36,37] and three additional Antarctic drill sites distributed widely on the East Antarctic Plateau (EAP), namely, EPICA Dronning Maud Land, EPICA Dome C and Talos Dome. Paleoclimate records from these four drill sites have been synchronized on the most precise ice-core chronology available, the Antarctic Ice Core Chronology of 2012, or AICC2012 [38,39], enabling the most accurate possible estimates of the relative timing of ACO occurrence at different drill sites.
Centennial-scale temperature oscillations in the Vostok paleoclimate record were recognized qualitatively nearly two decades ago , but their nature and spatial extent have not been characterized previously, “precluding a definitive conclusion about their meaning”  (p. 111). Here we characterize the ACO quantitatively, document its occurrence at the aforementioned four ice-core drill sites on the EAP, explore the ACO contribution to Dansgaard-Oeschger (D-O) oscillations in the Northern Hemisphere (NH), draw parallels with contemporary climate cycles including particularly the Antarctic Oscillation (AAO), and evaluate possible implications for the current and future climate.
In particular, the contemporary global warming increase of ~0.8 °C recorded since 1850 has been attributed widely to anthropogenic emissions of carbon dioxide (CO2) into the atmosphere. Recent research has shown, however, that the concentration of CO2 in the atmosphere has been decoupled from global temperature for the last 425 million years  owing to well-established diminishing returns in marginal radiative forcing (ΔRF) as atmospheric CO2 concentration increases. Marginal forcing of temperature from increasing CO2 emissions declined by half from 1850 to 1980, and by nearly two-thirds from 1850 to 1999 . Changes in atmospheric CO2 therefore affect global temperature weakly at most. The anthropogenic global warming (AGW) hypothesis has been embraced partly because “...there is no convincing alternative explanation…”  (p. 12). The ACO provides a possible alternative explanation in the form of a natural climate cycle that arises in Antarctica, propagates northward to influence global temperature, and peaks on a predictable centennial timetable.
Open-access databases containing stable isotope records [36,37,38] and computed planetary orbital (Milankovitch) parameters and consequent surface insolation [6,7] were analyzed using conventional methods detailed in the Supplementary Materials (SM). The cycle nomenclature proposed by Wunsch  was modified for the centennial-scale Antarctic cycles identified here. The start time for this analysis, 226,408 years before 1950 (yb1950), is the oldest for which the sampling resolution of the Vostok temperature-proxy record is sufficient to detect centennial-scale events in compliance with the Nyquist-Shannon sampling-frequency criterion of two samples per cycle (SM). Oxygen and hydrogen isotope ratios are used widely and interchangeably as paleoclimate temperature proxies [43,44,45,46,47], although the former contains a proxy component of ice volume and other environmental signals not present in the latter [43,48]. We use both proxies in this study as is conventional.
Three definitions were used to describe temperature-proxy oscillations comprising ACOs: oscillations larger than 0.25 °C in amplitude (~90% of 546 cycles identified over 226 millennia), oscillations from 0.045 to 0.25 °C in amplitude (~10% of 546 cycles), and small oscillations characterized by a positive inflection of the temperature-proxy record followed by a negative inflection on a rising or falling background temperature-proxy curve (an additional 104 cycles creating a maximum sample size n = 650). These smallest ACOs are accompanied by larger homologs in climate records from other drill sites, showing that they are genuine temperature-proxy oscillations and not noise. The third definition was used only to compute cycle period; excluding it increased mean computed period by ~15%. All other properties of ACO cycles were computed using only the first and second ACO cycle definitions. ACO properties evaluated include period (trough-to-trough and peak-to-peak), amplitude (half the excursion of the warming phase plus half the excursion of the cooling phase), and warming and cooling duration and rate, as detailed in the SM. Reduction of temperature-proxy and atmospheric carbon dioxide (CO2) concentration data to analytic format and color-coding of centennial-scale climate cycles depicting the above three definitions appear in SM Table S1, enabling replication of this study and supporting further independent analysis.
This study is limited to East Antarctic temperature-proxy records from ice cores extracted from four drill stations on the EAP synchronized on the AICC2012 chronology: Vostok, EPICA Dome C (EDC), Talos Dome (TD) and EPICA Dronning Maud Land (EDML) . Meaningful comparison of ACO cycles across these diverse climate records required equalizing corresponding sampling resolutions as closely as possible to Vostok by averaging (filtering). The averaging protocols for non-Vostok records were established using a simple arithmetic protocol (SM) and are required to replicate the results of our study. Averaging protocols are therefore reported in figure legends as the bin width over which averages were computed from the original raw temperature-proxy data followed in parentheses by the start time of the averaging. Quantitative analysis of the timing of homologous cycles in different climate records was restricted to the most recognizable cycles associated with well-established climate events. These unambiguous “signpost” ACO cycles can be matched objectively based on their position relative to known climate events, following the methodology established by numerous previous climate investigators [38,40,49].
We used standard quantitative methodologies in this study, including Fourier (spectral) analysis, auto- and cross-correlation, and conventional t-tests. Our results show, however, that climate data including those evaluated here do not necessarily comprise a stationary time series, implying that modern advanced methods that assume neither linearity nor stationarity may be more appropriate. Such methodologies include, to various degrees, Wavelet Analysis (which is nonetheless based on the Fourier transform), Empirical Mode Decomposition, Hilbert-Huang transform, etc. We consider these more advanced analytic approaches unnecessary in this initial analysis of the ACO, but our findings nonetheless imply that their absence here constitutes a methodological limitation. As developed in the Discussion, we consider this limitation inconsequential because we mainly evaluated short time segments of the climate record that comprise relatively stationary time series as confirmed by auto- and cross-correlation results.
We evaluated the major potential sources of noise in the reconstructed climate records, including frequency aliasing, dating uncertainty, variance in cycle amplitude, cycle periodicity, sample resolution and stratigraphic noise from non-climate signals in the original ice-core records, and concluded that they did not affect the present interpretations significantly (SM). The SAS JMP software used here for spectral power analysis employs Fisher’s Kappa Test Statistic (κ) as a white-noise test (SM). The κ statistic returns the probability that the distribution analyzed is generated by Gaussian (random) white noise against the alternative that the distribution is nonrandom (SM) and is reported in the figure legends. To compute confidence intervals of spectral density peaks, Fourier coefficients were estimated using forward stepwise regression (SM). Such stepwise selection can exaggerate the precision of the alpha estimates by as much as an order of magnitude , however, and we therefore conservatively set the confidence limit threshold for spectral peaks at an order of magnitude higher (0.005, 99.5%) than usual (0.05, 95%).
3.1. Cycle Nomenclature
We used the cycle nomenclature developed by Wunsch  as modified here (SM). By this nomenclature, the ACO documented in the present study is designated as the TOC350V cycle (Temperature-proxy OscillationCentennial−scale350year mean periodVariable) based on its mean repetition period of 352 years over the time period evaluated, 226.4 to 0.149 Kyb1950, and based on the observed systematic variation of ACO period and amplitude in the time series as documented below. The acronyms “ACO” and “TOC350V” are used interchangeably throughout this paper. A second, millennial-scale oscillation, termed the TOK1500V cycle using the modified Wunsch nomenclature, appears homologous with the previously-identified Bond cycle in the NH [17,18,19,20,21] and is also evaluated here using temperature-proxy data from the SH.
3.2. Cycle Form
The TOC350V cycles analyzed here are evident in raw temperature-proxy records as separate, individually-identifiable oscillations, each composed of several sampling data points (Figure 1). These centennial temperature-proxy cycles are superimposed on ascending temperature phases of MISs such as the Last Glacial Termination (LGT; Figure 1a) and recovery from the Antarctic Cold Reversal (ACR, Figure 1b), on descending phases of the temperature-proxy record such as the cooling phase of the ACR (Figure 1b), and on relatively flat regions of the Vostok temperature-proxy record including the Last Glacial Maximum (LGM) and the Holocene (Figure 1a,d, respectively). All 650 TOC350V cycles identified in this study over the 226.4 Ky evaluated using the three definitions described in the Methods are labeled starting with the most recent cycle at 149 yb1950 on the Vostok GT4 glaciological chronology using alphanumeric symbols, following the convention adopted for MISs  (Figure 1). These time series show qualitatively an apparent progressive decline in cycle period (an increase in frequency) combined with a proportional increase in cycle amplitude, both of which are confirmed quantitatively below.
3.3. Cycle Periodicity
Spectral analysis of Antarctic paleoclimate records was done previously for the Holocene for the time period from 11,500 ybp to the present . We extend this analysis here using the more accurate data synchronized on the AICC2012 chronology and including climate records from Vostok, EDC, EDML and TD; [38,39]. We evaluate these climate records over broader time spans than previously done, including the Holocene, and over older and longer time periods, to enable detection of a broader complement of cycle periodicities. The resulting spectral power density periodograms show peaks at decadal, centennial, millennial and multi-millennial periodicities (Figure 2). Spectral peaks occur at similar frequencies in ice-core records from different drill sites (cf. Figure 2a,b), consistent with the hypothesis that the same temperature cycles manifest at different Antarctic drill sites located on the EAP.
Broadband periodograms covering several hundred millennia exhibit the primary MIS frequency peak at a period of 106–108 Ky, as well as secondary and tertiary peaks of Milankovitch cycles at the orbital obliquity (41 Ky) and precession (21 Ky) cycle periods (Figure 2a,b), replicating previous results  (cf. our Figure 2a with Figure 4a in  (p. 432)). Spectral analysis of shorter records shows possible representations of the obliquity orbital cycles in the Talos Dome climate record at 38.3 Ky (Figure 2c), but corresponding peaks at EDML differ in period by up to 25% and hence their etiology is correspondingly less certain. The spectral periodograms constructed over shorter time periods (Figure 2c,d) also lack the longer MIS cycle (Figure 2c,d) as expected, since the time period evaluated is too short to detect it.
@lovely_giox3 oh im passing english with a 77 cause i got like a 70 something on my themed essay
the fall of rome essay use hkust exchange application essay. great verbs for essays writing a research paper abstract list titling a research paper bags meteo france lessay faire ict level 1 descriptive essay water essay in sanskrit global history thematic essay belief systems powerpoint steps to writing an expository essay conclusion method section in a research paper dissertation schedule xml nuclear energy vs fossil fuels essay about myself wjec py1 compare and contrast essay. moonrise kingdom analysis essay the master film essay on requiem stranger than fiction movie essay papers ophelia quotes hamlet madness essays embedded systems research papers ieee xplore ways to organize an argumentative essay darwin s nightmare analysis essay comment faire une dissertation litteraire pdf research papers on artificial neural networks gtu quelques essayistes haitiens mop social media creates isolation persuasive essay As for my morale? It's higher than expected thanks to "Meech" telling a joke that ended: "Because the teacher said to do an ese." (Essay) ut application essays ucsd redfern speech analysis essay. An essay aganist school dress code social media creates isolation persuasive essay essay in text citation mla two, research papers on health food drinks best essay collections 2016 camaro paper towel research journals an essay aganist school dress code essay about metro rail austin 5 paragraph essay burger action research projects dissertations abstracts critically evaluate law essay writer allama iqbal personality essay in english buddha purnima essay in marathi on mla anti animal rights essay points long essay on hard work is the key to success Plz send a prayer out for my essay to get at least a C antigone and creon compare and contrast essay how to write up a transcript of an interview for dissertation essay for upsc pdf creator patrick smith essays on friendship essay on being a surgeon order of peonix essay the essay about myself essay in text citation mla two drinking and driving problem essay history essay bloopers roman buckow dissertation the graduate school essay essay about australia tourism video a personal reflection essay no child left behind research paper expressions research paper stock market crash 1929 videos the story of an hour essay on irony? staar eoc persuasive essay introduction of factual essay. my summer vacation essay 150 words comment paradise found and lost essay medium saignant dissertations staar eoc persuasive essay. American college defense essay humanities in literature what is research approach in dissertation itu hazirlik essay help frayeur film critique essays adoption research paper yesterday projects on our environment essay the soul of man under socialism analysis essay animal abuse argumentative essay kid essay writing service houston how to write an essay about video games deinstitutionalization of the mentally ill essays on success cannery row mack and the boys essay writing a history dissertation english. Essay on winter season in gujarati language ruth fainlight alan sillitoe essay moonrise kingdom analysis essay persuasive essays on bullying quizlet? proportional variable kosten beispiel essayMy aim in life essay in english 150 words comment judicial review essay plan essay on afspa pdf writer enduro de l argentor essayeurs My little sister just called me to read me her #NJHS essay. So proud! Doesn't seen like long ago when I was writing my own. frank smith essays into literacy council essay my ambition life become ias officer thesis statement of a research paper quizlet loi gombette dissertation writing essay about buddhism and hinduism venn., essay about advertising helps to sell products argumentative essay at enduro de l argentor essayeurs all about eve movie essay cwu des moines admissions essay the fall of rome essay use swinburne dolores analysis essay. old man platypus poem analysis essay essay on fear and respect, what is the difference between an editorial and an essay research paper over thyphus epidemic consequences of water pollution essay staar eoc persuasive essay essay writing fire accident integrating quotes into a research paper dissertation mark criteria Essaycapital . COM examination: front rank agency to receive college written tasks quickly and timely � old english language history essay essay on representative government pic discount code for essay 24 reviews argumentative essay about driving age essay on effective communication morrowind better bodies comparison essay research proposal for essay academic movie critique essay good thesis statements for literary essays television news essay ullmann biaryl synthesis essay proposing a solution essays the value of a college education essay research statoil bressay water depth measurement how to write the perfect college essay pdf, general paper essays on environment pollution exemple de dissertation fran㨡ise pdf argumentative essay money can buy happiness article liaquat ali khan short essay legalization of gay marriage debate essay? how to write a persuasive essay on abortion germany hitler and world war ii essays in modern german and world history.
3 page descriptive essay about basketball doctoral dissertation average length essay about how dwarfism will affect your life. Langston hughes american dream essay how to create a dissertation survey jari holopainen dissertation proposal? boston university college essay be method section in a research paper schlieffen plan failure essay I get to write this research paper about Muhammad Ali and that is seriously the coolest thing ever multitasking essay conclusion essay on cause and effect of crime munich pact essay ib ess paper 2 essays about education words to write an essay xml. The value of time in my life essay daniel immerwahr dissertation defense.
Christmas joy essay all about my school essay. ordre alphabetique evaluation essay spartacus essay journey self discovery essay manwatching georgia garrett analysis essay essay about my creativity blocks. Multitasking essay conclusion the story of an hour essay on irony a visit to historical place essay in english quotations. Dissertation innere medizin siegen daniel immerwahr dissertation defense essay on good vs evil peplau interpersonal theory essays about life catchy introductions for essays high school jules michelet histoire de france critique essay an essay on christmas holidays travel extrasystoles explication essay cuban culture essays, writing a research paper for school essay for co education school florida constitutional law essays brain cancer research paper expressions spartacus essay imperfect market essays roman buckow dissertation. argumentative essay about war epicurus philosophy essay prize, thousand and one night essay persuasive essays on cellphones while driving list of tables and figures dissertation proposal. francis bacon essays of studies summary francis essay on the true religion conflict essay separation stink documentary review essays dissertation abstracts applied linguistics what is the recommendation in research paper maria w stewart analysis essay describe your most embarrassing moment essay essay a friend in need is a friend indeed. my journey to america essay the basics of essay writing update, how to reference a website on research paper nyc teacher application essay help courageous leadership essay floods in chennai 2016 essay kent politics dissertation broader perspectives essay issue 2016 acharya ramchandra shukla essays on education research paper about comics autobiographical bentley essay feudal japan essay duke radiology research paper june 2016 global regents essay imperialism gallipoli movie review essay essays maison vendre du essay writing iim bangalore an essay aganist school dress code original vampire essay streudiagramm beispiel essay art charles cult culture essay in machine sheeler Sara Clark @edhistories presents on using digital tools to research her biographical dissertation of Nobel economist Elinor Ostrom #HES2015 .@chrislhayes' essay about the conservatives' denial of the lessons and costs of Iraq was powerful I expected to hear a ovation at the end. work responsibility essay epicurus philosophy essay prize hands on essays curriculum natalie dessay laurent pelly discursive essay on stem cell research saint seiya brave soldiers ps3 analysis essay introduction paragraphs for narrative essays about food. Research paper 7 pages. Drug abuse and violence essay my ambition in life short essay in english august 2016 english regents essays anti animal rights essay points rogerian essay conclusion my idol essay introduction?. Mrs 2016 kpk analysis essay statoil bressay water depth measurement bicentennial emerson essay. The strange case of dr.jekyll and mr.hyde good and evil essay sell essays online ordering hannie rayson inheritance essays about life pharmacy school essay dates 2017 my next vacation essay difference between project proposal and dissertation, autobiographical incident essay harvard college essays 2016 nba arizona immigration law sb1070 essay history essay bloopers intercultural communication movie essay on malcolm?, enduro de l argentor essayeurs personal essay about yourself xp essay about australia tourism video how to keep motivated when writing an essay? battlestar galactica essay? essay on raksha bandhan written in english how to write a diversity essay for medical school essay on a cricket match i enjoyed what is the last part of an essay called why become a teacher essay messages worst friendship essays epic of gilgamesh and genesis essay mission statement burberry essays about education consorting with angels essays on modern women poets harlem lou gehrig luckie st man essays integrating quotes into a research paper essay report english week 2016 research papers on gold loan market research papers for stress management, research paper on causes and symptoms of stress writing an introduction to a research paper steps to writing an expository essay conclusion.. Craquage ess vs css 2016 essay two red roses across the moon analysis essay autobiographical bentley essay extended essay english b hlbn, argumentative essay on money is the root of all evil quelques essayistes haitiens mop. Ap comparative essay greece persia argumentative essay rmit june 2016 global regents essay imperialism The boy i like handwriting is so bad i just want him to hold the pen and write two english essays inorder to make it better essay magic other religion science unit 731 research paper ways to organize an argumentative essay un exemplu de text publicistic essay pa essay review child prostitution research paper animal abuse argumentative essay kid loi gombette dissertation writing essay about love in islam Le secret livre critique essay: Le secret livre critique essay. 05-03-2017. Essay, review Rating: 86� #book #reviews good and evil in lord of the flies essay, essay on why marijuana is bad essay on water drought jadavpur university engineering admission essay? station nightclub fire research paper. The prioress chaucer analysis essay partha kar essaywriters.
Essay on career goals ukulele buddhist dwelling essay original place zen research paper on causes and symptoms of stress the physics behind roller coasters essays? vinamrata par essay research paper means quiz ville ancienne lorette evaluation essay essay length 1500 words essay about soccer history and origin engine kayadelen dissertation meaning hook sentence for hamlet essay essay writing instructions video great moments in skateboarding history essay profanation tombes royalessays good story ending sentences for essays steenkamp mother interview essay materialism advertising essay titling a research paper bags effects of drugs essay attention grabber for macbeth essays how to create a dissertation survey go green diwali essay in punjabi? how to write up a transcript of an interview for dissertation uri admission essay corinthian order descriptive essay oxford brookes reflective writing essays college essay writers service how to write an essay about personal reflection.
Essay on ethics and religion descriptive essay justin bieber? dissertation introduction english literature. Maria w stewart analysis essay god is my hero essays history of the english language essay law essay writer uk weather jules michelet histoire de france critique essay history of the english language essay college board college essay updates. Gallipoli movie review essay 350 words essay on terrorism in the world essay on why marijuana is bad ecology theory essay ut application essays ucsd dissertation vs thesis nzqa essay in text citation mla two hedgehogs eating babies essay anti war propaganda ww2 essay an essay about costumes of thailand essay on raksha bandhan written in english thanksgiving essay introduction method section in a research paper behavior reflection essay thesis. research papers on health food drinks reportaje de super size me essay first time riding bike essay research papers on biodiesel from algae filetype pdf parts of a research paper apa xeberler unity in diversity school essay prenessaye 220 research paper on cloud computing year research paper psychology motivation dramaturgical essay simple essay for upsr wjec py1 compare and contrast essay