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Compression complexity with ordinal patterns for robust causal inference in irregularly sampled time series. Sci Rep 2022; 12:14170. [PMID: 35986037 PMCID: PMC9391387 DOI: 10.1038/s41598-022-18288-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 08/09/2022] [Indexed: 11/08/2022] Open
Abstract
AbstractDistinguishing cause from effect is a scientific challenge resisting solutions from mathematics, statistics, information theory and computer science. Compression-Complexity Causality (CCC) is a recently proposed interventional measure of causality, inspired by Wiener–Granger’s idea. It estimates causality based on change in dynamical compression-complexity (or compressibility) of the effect variable, given the cause variable. CCC works with minimal assumptions on given data and is robust to irregular-sampling, missing-data and finite-length effects. However, it only works for one-dimensional time series. We propose an ordinal pattern symbolization scheme to encode multidimensional patterns into one-dimensional symbolic sequences, and thus introduce the Permutation CCC (PCCC). We demonstrate that PCCC retains all advantages of the original CCC and can be applied to data from multidimensional systems with potentially unobserved variables which can be reconstructed using the embedding theorem. PCCC is tested on numerical simulations and applied to paleoclimate data characterized by irregular and uncertain sampling and limited numbers of samples.
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Abstract
Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores1; these interhemispheric connections may have existed during previous glacial cycles. Analysis of a continuous and independently dated record of glaciation in the tropical Andes spanning 700,000 years shows that Andean glaciation follows patterns of global ice volume change, with a periodicity of approximately 100,000 years.
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3
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Antarctic and global climate history viewed from ice cores. Nature 2018; 558:200-208. [DOI: 10.1038/s41586-018-0172-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 03/19/2018] [Indexed: 11/08/2022]
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4
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Bock M, Schmitt J, Beck J, Seth B, Chappellaz J, Fischer H. Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH 4 ice core records. Proc Natl Acad Sci U S A 2017; 114:E5778-E5786. [PMID: 28673973 PMCID: PMC5530640 DOI: 10.1073/pnas.1613883114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atmospheric methane (CH4) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [δ13CH4 and δD(CH4)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our δD(CH4) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH4 changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial variations is a marked difference in both isotope records, with systematically higher values during the last 25,000 y compared with older time periods. This shift cannot be explained by climatic changes. Rather, our isotopic methane budget points to a marked increase in fire activity, possibly caused by biome changes and accumulation of fuel related to the late Pleistocene megafauna extinction, which took place in the course of the last glacial.
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Affiliation(s)
- Michael Bock
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland;
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jochen Schmitt
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jonas Beck
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Barbara Seth
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jérôme Chappellaz
- CNRS, IGE (Institut des Géosciences de l'Environnement), F-38000 Grenoble, France
- University of Grenoble Alpes, IGE, F-38000 Grenoble, France
- IRD (Institut de Recherche pour le Développement), IGE, F-38000 Grenoble, France
- Grenoble INP (Institut National Polytechnique), IGE, F-38000 Grenoble, France
| | - Hubertus Fischer
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland;
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
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5
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Isotopic evidence of multiple controls on atmospheric oxidants over climate transitions. Nature 2017; 546:133-136. [DOI: 10.1038/nature22340] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 03/30/2017] [Indexed: 11/08/2022]
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6
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Kobashi T, Menviel L, Jeltsch-Thömmes A, Vinther BM, Box JE, Muscheler R, Nakaegawa T, Pfister PL, Döring M, Leuenberger M, Wanner H, Ohmura A. Volcanic influence on centennial to millennial Holocene Greenland temperature change. Sci Rep 2017; 7:1441. [PMID: 28469185 PMCID: PMC5431187 DOI: 10.1038/s41598-017-01451-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/30/2017] [Indexed: 11/23/2022] Open
Abstract
Solar variability has been hypothesized to be a major driver of North Atlantic millennial-scale climate variations through the Holocene along with orbitally induced insolation change. However, another important climate driver, volcanic forcing has generally been underestimated prior to the past 2,500 years partly owing to the lack of proper proxy temperature records. Here, we reconstruct seasonally unbiased and physically constrained Greenland Summit temperatures over the Holocene using argon and nitrogen isotopes within trapped air in a Greenland ice core (GISP2). We show that a series of volcanic eruptions through the Holocene played an important role in driving centennial to millennial-scale temperature changes in Greenland. The reconstructed Greenland temperature exhibits significant millennial correlations with K+ and Na+ ions in the GISP2 ice core (proxies for atmospheric circulation patterns), and δ18O of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Therefore, we conclude that volcanic activity played a critical role in driving centennial to millennial-scale Holocene temperature variability in Greenland and likely beyond.
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Affiliation(s)
- Takuro Kobashi
- Climate and Environmental Physics, University of Bern, 3012, Bern, Switzerland. .,Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland. .,Renewable Energy Institute, Minato-ku, 105-0003, Tokyo, Japan.
| | - Laurie Menviel
- Climate Change Research Centre and PANGEA Research Centre, University of New South Wales, New South Wales, 2052, Australia.,ARC Centre of Excellence for Climate System Science, New South Wales, Sydney, Australia
| | - Aurich Jeltsch-Thömmes
- Climate and Environmental Physics, University of Bern, 3012, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland
| | - Bo M Vinther
- Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jason E Box
- Geological Survey of Greenland and Denmark, 1350, Copenhagen, Denmark
| | - Raimund Muscheler
- Department of Geology, Quaternary Sciences, Lund University, 22362, Lund, Sweden
| | | | - Patrik L Pfister
- Climate and Environmental Physics, University of Bern, 3012, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland
| | - Michael Döring
- Climate and Environmental Physics, University of Bern, 3012, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland
| | - Markus Leuenberger
- Climate and Environmental Physics, University of Bern, 3012, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland
| | - Heinz Wanner
- Oeschger Centre for Climate Change Research, University of Bern, 3012, Bern, Switzerland
| | - Atsumu Ohmura
- Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology ETH Zurich, 8092, Zurich, Switzerland
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7
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Vasanth M, Muralidhar M, Saraswathy R, Nagavel A, Dayal JS, Jayanthi M, Lalitha N, Kumararaja P, Vijayan KK. Methodological approach for the collection and simultaneous estimation of greenhouse gases emission from aquaculture ponds. ENVIRONMENTAL MONITORING AND ASSESSMENT 2016; 188:671. [PMID: 27848111 DOI: 10.1007/s10661-016-5646-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 10/14/2016] [Indexed: 06/06/2023]
Abstract
Global warming/climate change is the greatest environmental threat of our time. Rapidly developing aquaculture sector is an anthropogenic activity, the contribution of which to global warming is little understood, and estimation of greenhouse gases (GHGs) emission from the aquaculture ponds is a key practice in predicting the impact of aquaculture on global warming. A comprehensive methodology was developed for sampling and simultaneous analysis of GHGs, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from the aquaculture ponds. The GHG fluxes were collected using cylindrical acrylic chamber, air pump, and tedlar bags. A cylindrical acrylic floating chamber was fabricated to collect the GHGs emanating from the surface of aquaculture ponds. The sampling methodology was standardized and in-house method validation was established by achieving linearity, accuracy, precision, and specificity. GHGs flux was found to be stable at 10 ± 2 °C of storage for 3 days. The developed methodology was used to quantify GHGs in the Pacific white shrimp Penaeus vannamei and black tiger shrimp Penaeus monodon culture ponds for a period of 4 months. The rate of emission of carbon dioxide was found to be much greater when compared to other two GHGs. Average GHGs emission in gha-1 day-1 during the culture was comparatively high in P.vannamei culture ponds.
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Affiliation(s)
- Muthuraman Vasanth
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
| | - Moturi Muralidhar
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India.
| | - Ramamoorthy Saraswathy
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
| | - Arunachalam Nagavel
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
| | - Jagabattula Syama Dayal
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
| | - Marappan Jayanthi
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
| | - Natarajan Lalitha
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
| | - Periyamuthu Kumararaja
- ICAR-Central Institute of Brackishwater Aquaculture, 75, Santhome High Road, R.A. Puram, Chennai, 600028, India
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8
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Xu H, Lan J, Sheng E, Liu Y, Liu B, Yu K, Ye Y, Cheng P, Qiang X, Lu F, Wang X. Tropical/Subtropical Peatland Development and Global CH4 during the Last Glaciation. Sci Rep 2016; 6:30431. [PMID: 27465566 PMCID: PMC4964359 DOI: 10.1038/srep30431] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/01/2016] [Indexed: 11/09/2022] Open
Abstract
Knowledge of peatland development over the tropical/subtropical zone during the last glaciation is critical for understanding the glacial global methane cycle. Here we present a well-dated ‘peat deposit-lake sediment’ alternate sequence at Tengchong, southwestern China, and discuss the peatland development and its linkage to the global glacial methane cycle. Peat layers were formed during the cold Marine Isotope Stage (MIS)-2 and -4, whereas lake sediments coincided with the relatively warm MIS-3, which is possibly related to the orbital/suborbital variations in both temperature and Asian summer monsoon intensity. The Tengchong peatland formation pattern is broadly synchronous with those over subtropical southern China and other tropical/subtropical areas, but it is clearly in contrast to those over the mid-high Northern Hemisphere. The results of this work suggest that the shifts of peatland development between the tropical/subtropical zone and mid-high Northern Hemisphere may have played important roles in the glacial/interglacial global atmospheric CH4 cycles.
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Affiliation(s)
- Hai Xu
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China.,Department of Environment Science and Technology, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Jianghu Lan
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
| | - Enguo Sheng
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
| | - Yong Liu
- College of Tourism and Geographical Sciences, Yunnan Normal University, Kunming, China
| | - Bin Liu
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
| | - Keke Yu
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China.,Graduate university of Chinese Academy of Sciences. Beijing, China
| | - Yuanda Ye
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China.,Graduate university of Chinese Academy of Sciences. Beijing, China
| | - Peng Cheng
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
| | - Xiaoke Qiang
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
| | - Fengyan Lu
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
| | - Xulong Wang
- State key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of Sciences. Xi'an, China
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9
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Exploring the influence of ancient and historic megaherbivore extirpations on the global methane budget. Proc Natl Acad Sci U S A 2015; 113:874-9. [PMID: 26504225 DOI: 10.1073/pnas.1502547112] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Globally, large-bodied wild mammals are in peril. Because "megamammals" have a disproportionate influence on vegetation, trophic interactions, and ecosystem function, declining populations are of considerable conservation concern. However, this is not new; trophic downgrading occurred in the past, including the African rinderpest epizootic of the 1890s, the massive Great Plains bison kill-off in the 1860s, and the terminal Pleistocene extinction of megafauna. Examining the consequences of these earlier events yields insights into contemporary ecosystem function. Here, we focus on changes in methane emissions, produced as a byproduct of enteric fermentation by herbivores. Although methane is ∼ 200 times less abundant than carbon dioxide in the atmosphere, the greater efficiency of methane in trapping radiation leads to a significant role in radiative forcing of climate. Using global datasets of late Quaternary mammals, domestic livestock, and human population from the United Nations as well as literature sources, we develop a series of allometric regressions relating mammal body mass to population density and CH4 production, which allows estimation of methane production by wild and domestic herbivores for each historic or ancient time period. We find the extirpation of megaherbivores reduced global enteric emissions between 2.2-69.6 Tg CH4 y(-1) during the various time periods, representing a decrease of 0.8-34.8% of the overall inputs to tropospheric input. Our analyses suggest that large-bodied mammals have a greater influence on methane emissions than previously appreciated and, further, that changes in the source pool from herbivores can influence global biogeochemical cycles and, potentially, climate.
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10
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Maslin M, Owen M, Betts R, Day S, Dunkley Jones T, Ridgwell A. Gas hydrates: past and future geohazard? PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:2369-2393. [PMID: 20403833 DOI: 10.1098/rsta.2010.0065] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Gas hydrates are ice-like deposits containing a mixture of water and gas; the most common gas is methane. Gas hydrates are stable under high pressures and relatively low temperatures and are found underneath the oceans and in permafrost regions. Estimates range from 500 to 10,000 giga tonnes of carbon (best current estimate 1600-2000 GtC) stored in ocean sediments and 400 GtC in Arctic permafrost. Gas hydrates may pose a serious geohazard in the near future owing to the adverse effects of global warming on the stability of gas hydrate deposits both in ocean sediments and in permafrost. It is still unknown whether future ocean warming could lead to significant methane release, as thermal penetration of marine sediments to the clathrate-gas interface could be slow enough to allow a new equilibrium to occur without any gas escaping. Even if methane gas does escape, it is still unclear how much of this could be oxidized in the overlying ocean. Models of the global inventory of hydrates and trapped methane bubbles suggest that a global 3( degrees )C warming could release between 35 and 940 GtC, which could add up to an additional 0.5( degrees )C to global warming. The destabilization of gas hydrate reserves in permafrost areas is more certain as climate models predict that high-latitude regions will be disproportionately affected by global warming with temperature increases of over 12( degrees )C predicted for much of North America and Northern Asia. Our current estimates of gas hydrate storage in the Arctic region are, however, extremely poor and non-existent for Antarctica. The shrinking of both the Greenland and Antarctic ice sheets in response to regional warming may also lead to destabilization of gas hydrates. As ice sheets shrink, the weight removed allows the coastal region and adjacent continental slope to rise through isostacy. This removal of hydrostatic pressure could destabilize gas hydrates, leading to massive slope failure, and may increase the risk of tsunamis.
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Affiliation(s)
- Mark Maslin
- Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, UK.
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11
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Bock M, Schmitt J, Behrens M, Möller L, Schneider R, Sapart C, Fischer H. A gas chromatography/pyrolysis/isotope ratio mass spectrometry system for high-precision deltaD measurements of atmospheric methane extracted from ice cores. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2010; 24:621-633. [PMID: 20155754 DOI: 10.1002/rcm.4429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Air enclosures in polar ice cores represent the only direct paleoatmospheric archive. Analysis of the entrapped air provides clues to the climate system of the past in decadal to centennial resolution. A wealth of information has been gained from measurements of concentrations of greenhouse gases; however, little is known about their isotopic composition. In particular, stable isotopologues (deltaD and delta(13)C) of methane (CH(4)) record valuable information on its global cycle as the different sources exhibit distinct carbon and hydrogen isotopic composition. However, CH(4) isotope analysis is limited by the large sample size required and the demanding analysis as high precision is required. Here we present a highly automated, high-precision online gas chromatography/pyrolysis/isotope ratio monitoring mass spectrometry (GC/P/irmMS) technique for the analysis of deltaD(CH(4)). It includes gas extraction from ice, preconcentration, gas chromatographic separation and pyrolysis of CH(4) from roughly 500 g of ice with CH(4) concentrations as low as 350 ppbv. Ice samples with approximately 40 mL air and only approximately 1 nmol CH(4) can be measured with a precision of 3.4 per thousand. The precision for 65 mL air samples with recent atmospheric concentration is 1.5 per thousand. The CH(4) concentration can be obtained along with isotope data which is crucial for reporting ice core data on matched time scales and enables us to detect flaws in the measurement procedure. Custom-made script-based processing of MS raw and peak data enhance the system's performance with respect to stability, peak size dependency, hence precision and accuracy and last but not least time requirement.
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Affiliation(s)
- Michael Bock
- Climate and Environmental Physics and Oeschger Centre for Climate Change Research, University of Bern, Switzerland.
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12
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Thomas ER, Wolff EW, Mulvaney R, Johnsen SJ, Steffensen JP, Arrowsmith C. Anatomy of a Dansgaard‐Oeschger warming transition: High‐resolution analysis of the North Greenland Ice Core Project ice core. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jd011215] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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14
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Miteva V, Teacher C, Sowers T, Brenchley J. Comparison of the microbial diversity at different depths of the GISP2 Greenland ice core in relationship to deposition climates. Environ Microbiol 2009; 11:640-56. [DOI: 10.1111/j.1462-2920.2008.01835.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Reagan MT, Moridis GJ. Dynamic response of oceanic hydrate deposits to ocean temperature change. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008jc004938] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Matthew T. Reagan
- Earth Sciences Division; Lawrence Berkeley National Laboratory; Berkeley California USA
| | - George J. Moridis
- Earth Sciences Division; Lawrence Berkeley National Laboratory; Berkeley California USA
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16
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Abstract
Isolated spikes of anomalously high concentrations of N(2)O have been reported at depths in Greenland and Antarctic ice cores corresponding to narrow time intervals over the past approximately 10(5) years. Now, using a calibrated spectrofluorimeter to map protein-bound Trp, a proxy for microbes, versus depth in the 3,053-m GISP2 ice core, we find six depths at which localized spikes of high cell concentrations coincide with N(2)O spikes. We show that the excess gases are consistent with accumulation of in situ metabolic wastes during residence times of the excess microbes in the ice. Because of sparseness of N(2)O measurements and our spectrofluorimetry versus depth, the total number of microbially produced N(2)O spikes in GISP2 is probably much larger than six. Spikes of excess methanogens coincident with CH(4) spikes are found at three depths in the bottom 3% of GISP2, most likely because of methanogenic metabolism in the underlying silty ice, followed by turbulent flow of the lowest approximately 90 m of ice. The apparent rates of in situ production of N(2)O and CH(4) spikes by metabolism are observed to be consistent with a single activation energy, U, and maintain proportionality to exp(-U/RT) over the entire temperature range down to -40 degrees C. Fluorescence of nonmicrobial aerosols in GISP2 ice is distinguishable from microbial fluorescence by its different emission spectra. Our spectrofluorimetric scans throughout the GISP2 ice core lead us to conclude that both microbes and nonmicrobial aerosols are deposited in discontinuous bursts, which may provide a tool for studying wind storms in the distant past.
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17
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Diffusion-controlled metabolism for long-term survival of single isolated microorganisms trapped within ice crystals. Proc Natl Acad Sci U S A 2007; 104:16592-7. [PMID: 17940052 DOI: 10.1073/pnas.0708183104] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two known habitats for microbial metabolism in ice are surfaces of mineral grains and liquid veins along three-grain boundaries. We propose a third, more general, habitat in which a microbe frozen in ice can metabolize by redox reactions with dissolved small molecules such as CO(2), O(2), N(2), CO, and CH(4) diffusing through the ice lattice. We show that there is an adequate supply of diffusing molecules throughout deep glacial ice to sustain metabolism for >10(5) yr. Using scanning fluorimetry to map proteins (a proxy for cells) and F420 (a proxy for methanogens) in ice cores, we find isolated spikes of fluorescence with intensity consistent with as few as one microbial cell in a volume of 0.16 microl with the protein mapper and in 1.9 microl with the methanogen mapper. With such precise localization, it should be possible to extract single cells for molecular identification.
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Whiticar M, Schaefer H. Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2007; 365:1793-828. [PMID: 17513274 DOI: 10.1098/rsta.2007.2048] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Upon closer inspection, the classical view of the synchronous relationship between tropospheric methane mixing ratio and Greenland temperature observed in ice samples reveals clearly discernable variations in the magnitude of this response during the Late Pleistocene (<50kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10kyr BP. The delta13CH4 and deltaD-CH4 of tropospheric methane recorded in ice samples provide a useful constraint on the palaeomethane budget estimations. Anticipated changes in palaeoenvironmental conditions are recorded as changes in the isotope signals of the methane precursors, which are then translated into past global delta13CH4 and deltaD-CH4 signatures. We present the first methane budgets for the late glacial period that are constrained by dual stable isotopes. The overall isotope variations indicate that the Younger Dryas (YD) and Preindustrial Holocene have methane that is 13C- and 2H-enriched, relative to Modern. The shift is small for delta13CH4 (approx. 1 per thousand) but greater for deltaD-CH4 (approx. 9 per thousand). The YD delta13CH4-deltaD-CH4 record shows a remarkable relationship between them from 12.15 to 11.52kyr BP. The corresponding C- and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This delta13CH4-deltaD-CH4 relationship breaks down during the YD-Preboreal transition. In both age cases, catastrophic releases of hydrates with Archaeal isotope signatures can be ruled out. Thermogenic clathrate releases are possible during the YD period, but so are conventional natural gas seepages.
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Affiliation(s)
- Michael Whiticar
- School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada.
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19
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Wolff E, Spahni R. Methane and nitrous oxide in the ice core record. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2007; 365:1775-92. [PMID: 17513260 DOI: 10.1098/rsta.2007.2044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Polar ice cores contain, in trapped air bubbles, an archive of the concentrations of stable atmospheric gases. Of the major non-CO2 greenhouse gases, methane is measured quite routinely, while nitrous oxide is more challenging, with some artefacts occurring in the ice and so far limited interpretation. In the recent past, the ice cores provide the only direct measure of the changes that have occurred during the industrial period; they show that the current concentration of methane in the atmosphere is far outside the range experienced in the last 650,000 years; nitrous oxide is also elevated above its natural levels. There is controversy about whether changes in the pre-industrial Holocene are natural or anthropogenic in origin. Changes in wetland emissions are generally cited as the main cause of the large glacial-interglacial change in methane. However, changing sinks must also be considered, and the impact of possible newly described sources evaluated. Recent isotopic data appear to finally rule out any major impact of clathrate releases on methane at these time-scales. Any explanation must take into account that, at the rapid Dansgaard-Oeschger warmings of the last glacial period, methane rose by around half its glacial-interglacial range in only a few decades. The recent EPICA Dome C (Antarctica) record shows that methane tracked climate over the last 650,000 years, with lower methane concentrations in glacials than interglacials, and lower concentrations in cooler interglacials than in warmer ones. Nitrous oxide also shows Dansgaard-Oeschger and glacial-interglacial periodicity, but the pattern is less clear.
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Affiliation(s)
- Eric Wolff
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, UK.
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20
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Weldeab S, Lea DW, Schneider RR, Andersen N. 155,000 Years of West African Monsoon and Ocean Thermal Evolution. Science 2007; 316:1303-7. [PMID: 17540896 DOI: 10.1126/science.1140461] [Citation(s) in RCA: 334] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A detailed reconstruction of West African monsoon hydrology over the past 155,000 years suggests a close linkage to northern high-latitude climate oscillations. Ba/Ca ratio and oxygen isotope composition of planktonic foraminifera in a marine sediment core from the Gulf of Guinea, in the eastern equatorial Atlantic (EEA), reveal centennial-scale variations of riverine freshwater input that are synchronous with northern high-latitude stadials and interstadials of the penultimate interglacial and the last deglaciation. EEA Mg/Ca-based sea surface temperatures (SSTs) were decoupled from northern high-latitude millennial-scale fluctuation and primarily responded to changes in atmospheric greenhouse gases and low-latitude solar insolation. The onset of enhanced monsoon precipitation lags behind the changes in EEA SSTs by up to 7000 years during glacial-interglacial transitions. This study demonstrates that the stadial-interstadial and deglacial climate instability of the northern high latitudes exerts dominant control on the West African monsoon dynamics through an atmospheric linkage.
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Affiliation(s)
- Syee Weldeab
- Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106-9630, USA.
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21
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Abstract
Application of physical and chemical concepts, complemented by studies of prokaryotes in ice cores and permafrost, has led to the present understanding of how microorganisms can metabolize at subfreezing temperatures on Earth and possibly on Mars and other cold planetary bodies. The habitats for life at subfreezing temperatures benefit from two unusual properties of ice. First, almost all ionic impurities are insoluble in the crystal structure of ice, which leads to a network of micron-diameter veins in which microorganisms may utilize ions for metabolism. Second, ice in contact with mineral surfaces develops a nanometre-thick film of unfrozen water that provides a second habitat that may allow microorganisms to extract energy from redox reactions with ions in the water film or ions in the mineral structure. On the early Earth and on icy planets, prebiotic molecules in veins in ice may have polymerized to RNA and polypeptides by virtue of the low water activity and high rate of encounter with each other in nearly one-dimensional trajectories in the veins. Prebiotic molecules may also have utilized grain surfaces to increase the rate of encounter and to exploit other physicochemical features of the surfaces.
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Affiliation(s)
- P Buford Price
- Physics Department, University of California, Berkeley, CA 94720, USA.
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22
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Affiliation(s)
- William S Reeburgh
- Department of Earth System Science, University of California, Irvine, California 92697-3100, USA.
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23
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To What Extent Can Ice Core Data Contribute to the Understanding of Plant Ecological Developments of the Past? STABLE ISOTOPES AS INDICATORS OF ECOLOGICAL CHANGE 2007. [DOI: 10.1016/s1936-7961(07)01014-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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24
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Bender ML, Floch G, Chappellaz J, Suwa M, Barnola JM, Blunier T, Dreyfus G, Jouzel J, Parrenin F. Gas age–ice age differences and the chronology of the Vostok ice core, 0–100 ka. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006488] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Sowers T. Late Quaternary Atmospheric CH4 Isotope Record Suggests Marine Clathrates Are Stable. Science 2006; 311:838-40. [PMID: 16469923 DOI: 10.1126/science.1121235] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
One explanation for the abrupt increases in atmospheric CH4, that occurred repeatedly during the last glacial cycle involves clathrate destabalization events. Because marine clathrates have a distinct deuterium/hydrogen (D/H) isotope ratio, any such destabilization event should cause the D/H ratio of atmospheric CH4 (deltaD(CH4)) to increase. Analyses of air trapped in the ice from the second Greenland ice sheet project show stable and/or decreasing deltaD(CH4) values during the end of the Younger and Older Dryas periods and one stadial period, suggesting that marine clathrates were stable during these abrupt warming episodes. Elevated glacial deltaD(CH4) values may be the result of a lower ratio of net to gross wetland CH4 emissions and an increase in petroleum-based emissions.
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Affiliation(s)
- Todd Sowers
- Department of Geosciences and the Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA.
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27
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Tung HC, Price PB, Bramall NE, Vrdoljak G. Microorganisms metabolizing on clay grains in 3-km-deep Greenland basal ice. ASTROBIOLOGY 2006; 6:69-86. [PMID: 16551227 DOI: 10.1089/ast.2006.6.69] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We have discovered > 10(8) microbial cells/cm3 attached to clay grains in the bottom 13 m of the GISP2 (Greenland Ice Sheet Project) ice core. Their concentration correlates with huge excesses of CO2 and CH4. We show that Fe-reducing bacteria produce most of the excess CO2 and methanogenic archaea produce the excess CH4. The number of attached cells per clay grain is proportional to grain perimeter rather than to area, which implies that nutrients are accessed at grain edges. We conclude that Fe-reducing microbes immobilized on clay surfaces metabolize via "shuttle" molecules that transport electrons to grain edges, where they reduce Fe(III) ions at edges to Fe(II) while organic acid ions are oxidized to CO2. Driven by the concentration gradient, electrons on Fe(II) ions at grain edges "hop" to Fe(III) ions inward in the same edges and oxidize them. The original Fe(III) ions can then attach new electrons from shuttle molecules at the edges. Our mechanism explains how Fe-reducers can reduce essentially all Fe(III) in clay minerals. We estimate that the Fe(III) in clay grains in the GISP2 silty ice can sustain Fe-reducing bacteria at the ambient temperature of -9 degrees C for approximately 10(6) years. F420 autofluorescence imaging shows that > 2.4% of the cells are methanogens, which account for the excess methane.
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Affiliation(s)
- H C Tung
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California 94720, USA
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28
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Suwa M, von Fischer JC, Bender ML, Landais A, Brook EJ. Chronology reconstruction for the disturbed bottom section of the GISP2 and the GRIP ice cores: Implications for Termination II in Greenland. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006032] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Spahni R, Chappellaz J, Stocker TF, Loulergue L, Hausammann G, Kawamura K, Flückiger J, Schwander J, Raynaud D, Masson-Delmotte V, Jouzel J. Atmospheric methane and nitrous oxide of the Late Pleistocene from Antarctic ice cores. Science 2005; 310:1317-21. [PMID: 16311333 DOI: 10.1126/science.1120132] [Citation(s) in RCA: 357] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The European Project for Ice Coring in Antarctica Dome C ice core enables us to extend existing records of atmospheric methane (CH4) and nitrous oxide (N2O) back to 650,000 years before the present. A combined record of CH4 measured along the Dome C and the Vostok ice cores demonstrates, within the resolution of our measurements, that preindustrial concentrations over Antarctica have not exceeded 773 +/- 15 ppbv (parts per billion by volume) during the past 650,000 years. Before 420,000 years ago, when interglacials were cooler, maximum CH4 concentrations were only about 600 ppbv, similar to lower Holocene values. In contrast, the N2O record shows maximum concentrations of 278 +/- 7 ppbv, slightly higher than early Holocene values.
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Affiliation(s)
- Renato Spahni
- Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
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Abrupt climate change of East Asian Monsoon at 130 kaBP inferred from a high resolution stalagmite δ18O record. CHINESE SCIENCE BULLETIN-CHINESE 2005. [DOI: 10.1007/bf02899648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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31
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Cruz FW, Burns SJ, Karmann I, Sharp WD, Vuille M, Cardoso AO, Ferrari JA, Dias PLS, Viana O. Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil. Nature 2005; 434:63-6. [PMID: 15744298 DOI: 10.1038/nature03365] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 01/11/2005] [Indexed: 11/09/2022]
Abstract
During the last glacial period, large millennial-scale temperature oscillations--the 'Dansgaard/Oeschger' cycles--were the primary climate signal in Northern Hemisphere climate archives from the high latitudes to the tropics. But whether the influence of these abrupt climate changes extended to the tropical and subtropical Southern Hemisphere, where changes in insolation are thought to be the main direct forcing of climate, has remained unclear. Here we present a high-resolution oxygen isotope record of a U/Th-dated stalagmite from subtropical southern Brazil, covering the past 116,200 years. The oxygen isotope signature varies with shifts in the source region and amount of rainfall in the area, and hence records changes in atmospheric circulation and convective intensity over South America. We find that these variations in rainfall source and amount are primarily driven by summer solar radiation, which is controlled by the Earth's precessional cycle. The Dansgaard/Oeschger cycles can be detected in our record and therefore we confirm that they also affect the tropical hydrological cycle, but that in southern subtropical Brazil, millennial-scale climate changes are not as dominant as they are in the Northern Hemisphere.
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Affiliation(s)
- Francisco W Cruz
- Department of Geosciences, University of Massachusetts, Amherst, 01002 Massachusetts, USA.
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32
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Andersen KK, Azuma N, Barnola JM, Bigler M, Biscaye P, Caillon N, Chappellaz J, Clausen HB, Dahl-Jensen D, Fischer H, Flückiger J, Fritzsche D, Fujii Y, Goto-Azuma K, Grønvold K, Gundestrup NS, Hansson M, Huber C, Hvidberg CS, Johnsen SJ, Jonsell U, Jouzel J, Kipfstuhl S, Landais A, Leuenberger M, Lorrain R, Masson-Delmotte V, Miller H, Motoyama H, Narita H, Popp T, Rasmussen SO, Raynaud D, Rothlisberger R, Ruth U, Samyn D, Schwander J, Shoji H, Siggard-Andersen ML, Steffensen JP, Stocker T, Sveinbjörnsdóttir AE, Svensson A, Takata M, Tison JL, Thorsteinsson T, Watanabe O, Wilhelms F, White JWC. High-resolution record of Northern Hemisphere climate extending into the last interglacial period. Nature 2004; 431:147-51. [PMID: 15356621 DOI: 10.1038/nature02805] [Citation(s) in RCA: 313] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Accepted: 06/30/2004] [Indexed: 11/08/2022]
Abstract
Two deep ice cores from central Greenland, drilled in the 1990s, have played a key role in climate reconstructions of the Northern Hemisphere, but the oldest sections of the cores were disturbed in chronology owing to ice folding near the bedrock. Here we present an undisturbed climate record from a North Greenland ice core, which extends back to 123,000 years before the present, within the last interglacial period. The oxygen isotopes in the ice imply that climate was stable during the last interglacial period, with temperatures 5 degrees C warmer than today. We find unexpectedly large temperature differences between our new record from northern Greenland and the undisturbed sections of the cores from central Greenland, suggesting that the extent of ice in the Northern Hemisphere modulated the latitudinal temperature gradients in Greenland. This record shows a slow decline in temperatures that marked the initiation of the last glacial period. Our record reveals a hitherto unrecognized warm period initiated by an abrupt climate warming about 115,000 years ago, before glacial conditions were fully developed. This event does not appear to have an immediate Antarctic counterpart, suggesting that the climate see-saw between the hemispheres (which dominated the last glacial period) was not operating at this time.
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Affiliation(s)
- K K Andersen
- Niels Bohr Institute for Astronomy, Physics and Geophysics, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen OE, Denmark
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33
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Abstract
Identifying leads and lags between high- and low-latitude abrupt climate shifts is needed to understand where and how such events were triggered. Vascular plant biomarkers preserved in Cariaco basin sediments reveal rapid vegetation changes in northern South America during the last deglaciation, 15,000 to 10,000 years ago. Comparing the biomarker records to climate proxies from the same sediment core provides a precise measure of the relative timing of changes in different regions. Abrupt deglacial climate shifts in tropical and high-latitude North Atlantic regions were synchronous, whereas changes in tropical vegetation consistently lagged climate shifts by several decades.
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Affiliation(s)
- Konrad A Hughen
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
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34
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Delmotte M. Atmospheric methane during the last four glacial-interglacial cycles: Rapid changes and their link with Antarctic temperature. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003jd004417] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Lea DW, Pak DK, Peterson LC, Hughen KA. Synchroneity of tropical and high-latitude Atlantic temperatures over the last glacial termination. Science 2003; 301:1361-4. [PMID: 12958356 DOI: 10.1126/science.1088470] [Citation(s) in RCA: 346] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A high-resolution western tropical Atlantic sea surface temperature (SST) record from the Cariaco Basin on the northern Venezuelan shelf, based on Mg/Ca values in surface-dwelling planktonic foraminifera, reveals that changes in SST over the last glacial termination are synchronous, within +/-30 to +/-90 years, with the Greenland Ice Sheet Project 2 air temperature proxy record and atmospheric methane record. The most prominent deglacial event in the Cariaco record occurred during the Younger Dryas time interval, when SSTs dropped by 3 degrees to 4 degrees C. A rapid southward shift in the atmospheric intertropical convergence zone could account for the synchroneity of tropical temperature, atmospheric methane, and high-latitude changes during the Younger Dryas.
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Affiliation(s)
- David W Lea
- Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
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36
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Sowers T, Alley RB, Jubenville J. Ice core records of atmospheric N2O covering the last 106,000 years. Science 2003; 301:945-8. [PMID: 12920293 DOI: 10.1126/science.1085293] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Paleoatmospheric records of trace-gas concentrations recovered from ice cores provide important sources of information on many biogeochemical cycles involving carbon, nitrogen, and oxygen. Here, we present a 106,000-year record of atmospheric nitrous oxide (N2O) along with corresponding isotopic records spanning the last 30,000 years, which together suggest minimal changes in the ratio of marine to terrestrial N2O production. During the last glacial termination, both marine and oceanic N2O emissions increased by 40 +/- 8%. We speculate that our records do not support those hypotheses that invoke enhanced export production to explain low carbon dioxide values during glacial periods.
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Affiliation(s)
- Todd Sowers
- Department of Geosciences and the EMS Environment Institute, Pennsylvania State University, UniversityPark, PA 16802, USA.
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37
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Broecker WS. Does the trigger for abrupt climate change reside in the ocean or in the atmosphere? Science 2003; 300:1519-22. [PMID: 12791974 DOI: 10.1126/science.1083797] [Citation(s) in RCA: 271] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Two hypotheses have been put forward to explain the large and abrupt climate changes that punctuated glacial time. One attributes such changes to reorganizations of the ocean's thermohaline circulation and the other to changes in tropical atmosphere-ocean dynamics. In an attempt to distinguish between these hypotheses, two lines of evidence are examined. The first involves the timing of the freshwater injections to the northern Atlantic that have been suggested as triggers for the global impacts associated with the Younger Dryas and Heinrich events. The second has to do with evidence for precursory events associated with the Heinrich ice-rafted debris layers in the northern Atlantic and with the abrupt Dansgaard-Oeschger warmings recorded in the Santa Barbara Basin.
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Affiliation(s)
- W S Broecker
- Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Post Office Box 1000, Palisades, NY 10964-8000, USA.
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38
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Nisbet EG. Have sudden large releases of methane from geological reservoirs occurred since the Last Glacial Maximum, and could such releases occur again? PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2002; 360:581-607. [PMID: 12804295 DOI: 10.1098/rsta.2001.0958] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Methane emissions from geological reservoirs may have played a major role in the sudden events terminating glaciation, both at the start of the Bølling/Allerød and also at the end of the Younger Dryas. These reservoirs include Arctic methane hydrates and also methane hydrate stored in offshore marine sediments in tropical and temperate latitudes. Emissions from hydrate stores may have resonated with tropical wetland emissions, each reinforcing the other. Because methane is such a powerful greenhouse gas, much smaller emissions of methane, compared with carbon dioxide, are required in order to have the same short-term impact by climate forcing. The methane-linked hypothesis has much geological support from sea-floor evidence of emission. However, Greenland ice-core records have been interpreted as showing methane as a consequential factor, rather than the leader, of change. This interpretation can be challenged on the grounds that temperature gradients in Greenland ice record local changes and local timing of a step-like shift in weather fronts, while methane concentrations record changes on a hemispheric and global scale. There are large remaining hydrate reservoirs in the Arctic and in shelf sediments globally, and there is substantial risk of further emissions.
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Affiliation(s)
- Euan G Nisbet
- Department of Geology, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
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39
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Dwyer GS, Cronin TM, Baker PA. Trace elements in marine ostracodes. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/131gm11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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40
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Sowers T. N2O record spanning the penultimate deglaciation from the Vostok ice core. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000jd900707] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Bréas O, Guillou C, Reniero F, Wada E. The global methane cycle: isotopes and mixing ratios, sources and sinks. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2001; 37:257-379. [PMID: 12723792 DOI: 10.1080/10256010108033302] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A review of the global cycle of methane is presented with emphasis on its isotopic composition. The history of methane mixing ratios, reconstructed from measurements of air trapped in ice-cores is described. The methane record now extends back to 420 kyr ago in the case of the Vostok ice cores from Antarctica. The trends in mixing ratios and in delta13C values are reported for the two Hemispheres. The increase of the atmospheric methane concentration over the past 200 years, and by 1% per year since 1978, reaching 1.7 ppmv in 1990 is underlined. The various methane sources are presented. Indeed the authors describe the methane emissions by bacterial activity under anaerobic conditions in wet environments (wetlands, bogs, tundra, rice paddies), in ruminant stomachs and termite guts, and that originating from fossil carbon sources, such as biomass burning, coal mining, industrial losses, automobile exhaust, sea floor vent, and volcanic emissions. Furthermore, the main sinks of methane in the troposphere, soils or waters via oxidation are also reported, and the corresponding kinetic isotope effects.
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Affiliation(s)
- O Bréas
- European Commission Joint Research Centre, Institute for Reference Materials and Measurements, Isotope Measurements Unit, B-2440 Geel, Belgium
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42
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Sowers T, Jubenville J. A modified extraction technique for liberating occluded gases from ice cores. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jd900335] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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43
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Betancourt JL, Latorre C, Rech JA, Quade J, Rylander KA. A 22,000-Year Record of Monsoonal Precipitation from Northern Chile's Atacama Desert. Science 2000; 289:1542-1546. [PMID: 10968788 DOI: 10.1126/science.289.5484.1542] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Fossil rodent middens and wetland deposits from the central Atacama Desert (22 degrees to 24 degrees S) indicate increasing summer precipitation, grass cover, and groundwater levels from 16.2 to 10.5 calendar kiloyears before present (ky B.P.). Higher elevation shrubs and summer-flowering grasses expanded downslope across what is now the edge of Absolute Desert, a broad expanse now largely devoid of rainfall and vegetation. Paradoxically, this pluvial period coincided with the summer insolation minimum and reduced adiabatic heating over the central Andes. Summer precipitation over the central Andes and central Atacama may depend on remote teleconnections between seasonal insolation forcing in both hemispheres, the Asian monsoon, and Pacific sea surface temperature gradients. A less pronounced episode of higher groundwater levels in the central Atacama from 8 to 3 ky B.P. conflicts with an extreme lowstand of Lake Titicaca, indicating either different climatic forcing or different response times and sensitivities to climatic change.
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Affiliation(s)
- JL Betancourt
- U.S. Geological Survey, 1675 West Anklam Road, Tucson, AZ 85745, USA. Laboratorio de Botanica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile. Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA
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Kennett JP, Cannariato KG, Hendy IL, Behl RJ. Carbon isotopic evidence for methane hydrate instability during quaternary interstadials. Science 2000; 288:128-33. [PMID: 10753115 DOI: 10.1126/science.288.5463.128] [Citation(s) in RCA: 427] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Large (about 5 per mil) millennial-scale benthic foraminiferal carbon isotopic oscillations in the Santa Barbara Basin during the last 60,000 years reflect widespread shoaling of sedimentary methane gradients and increased outgassing from gas hydrate dissociation during interstadials. Furthermore, several large, brief, negative excursions (up to -6 per mil) coinciding with smaller shifts (up to -3 per mil) in depth-stratified planktonic foraminiferal species indicate massive releases of methane from basin sediments. Gas hydrate stability was modulated by intermediate-water temperature changes induced by switches in thermohaline circulation. These oscillations were likely widespread along the California margin and elsewhere, affecting gas hydrate instability and contributing to millennial-scale atmospheric methane oscillations.
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Affiliation(s)
- JP Kennett
- Geological Sciences and Marine Science Institute, University of California, Santa Barbara, CA 93106, USA. Department of Geological Sciences, California State University, Long Beach, CA 90840, USA
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45
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Abstract
Ice-core records show that climate changes in the past have been large, rapid, and synchronous over broad areas extending into low latitudes, with less variability over historical times. These ice-core records come from high mountain glaciers and the polar regions, including small ice caps and the large ice sheets of Greenland and Antarctica.
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Affiliation(s)
- R B Alley
- Environment Institute and Department of Geosciences, Pennsylvania State University, Deike Building, University Park, PA 16802, USA
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46
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Ice Sheets and the Ice-Core Record of Climate Change. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0074-6142(00)80124-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Smith LC, MacDonald GA, Frey KE, Velichko A, Kremenetski K, Borisova O, Dubinin P, Forster RR. U.S.-Russia venture probes Siberian peatlands' sensitivity to climate. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/00eo00357] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lang C, Leuenberger M, Schwander J, Johnsen S. 16 degrees C rapid temperature variation in central greenland 70,000 years Ago. Science 1999; 286:934-7. [PMID: 10542142 DOI: 10.1126/science.286.5441.934] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Variations in the (29)N(2)/(28)N(2) ratio of air bubbles trapped in polar ice cores and their relation to variations of the (18)O/(16)O of the ice allow past surface temperature variations and ice age-gas age differences to be determined. High-resolution measurements of (29)N(2)/(28)N(2) in Dansgaard-Oeschger event 19 (around 70,000 years before the present) in ice from Central Greenland show that at the beginning of the event, the ice age-gas age difference was 1090 +/- 100 years. With the use of a combined firn densification, temperature, and gas diffusion model, the delta(18)O(ice)-temperature coefficient alpha was determined to be 0. 42 +/- 0.05 per mil per kelvin. This coefficient implies a mean surface temperature change of 16.0 kelvin (between 14.3 and 18.1 kelvin), which differs substantially from values derived from borehole temperatures and modern spatial delta(18)O(ice)-surface temperature correlations.
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Affiliation(s)
- C Lang
- Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, Bern CH-3012, Switzerland. Niels Bohr Institute, Department of Geophysics, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, Den
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Severinghaus JP, Brook EJ. Abrupt climate change at the end of the last glacial period inferred from trapped air in polar Ice. Science 1999; 286:930-4. [PMID: 10542141 DOI: 10.1126/science.286.5441.930] [Citation(s) in RCA: 423] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The last glacial period was terminated by an abrupt warming event in the North Atlantic approximately 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 degrees C over a period of several decades, beginning 14,672 years ago. Atmospheric methane concentrations rose abruptly over a approximately 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) approximately 20 to 80 years after the onset of Greenland warming, supporting a North Atlantic rather than a tropical trigger for the climate event.
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Affiliation(s)
- JP Severinghaus
- Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA. Department of Geology, Washington State University, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686, USA
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