Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

2007 ◽  
Vol 365 (1856) ◽  
pp. 1793-1828 ◽  
Author(s):  
Michael Whiticar ◽  
Hinrich Schaefer
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
Mixing Ratio ◽  
Mass Balances ◽  
Late Glacial Period ◽  
The Past ◽  
Methane Budget ◽  
Hydrogen Isotope Ratios ◽  
Palaeoenvironmental Conditions ◽  
Carbon And Hydrogen Isotope

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 (<50 kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10 kyr BP. The δ 13 CH 4 and δD-CH 4 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 δ 13 CH 4 and δD-CH 4 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 13 C- and 2 H-enriched, relative to Modern. The shift is small for δ 13 CH 4 (approx. 1‰) but greater for δD-CH 4 (approx. 9‰). The YD δ 13 CH 4 –δD-CH 4 record shows a remarkable relationship between them from 12.15 to 11.52 kyr BP. The corresponding C- and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This δ 13 CH 4 –δD-CH 4 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.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

2019 ◽  
Vol 15 (2) ◽  
pp. 713-733 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
The Past ◽  
Natural Climate

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

Evidence for high-frequency late Glacial to mid-Holocene (16,800 to 5500 cal yr B.P.) climate variability from oxygen isotope values of Lough Inchiquin, Ireland

2006 ◽  
Vol 65 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Aaron F. Diefendorf ◽  
William P. Patterson ◽  
Henry T. Mullins ◽  
Neil Tibert ◽  
Anna Martini
Keyword(s):  
Climate Variability ◽  
High Frequency ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climate Anomaly ◽  
Climate Conditions ◽  
Late Glacial Period ◽  
High Frequency Variability ◽  
Western Ireland

AbstractA 7.6-m core recovered from Lough Inchiquin, western Ireland provides evidence for rapid and long-term climate change from the Late Glacial period to the Mid-Holocene. We determined percentage of carbonate, total organic matter, mineralogy, and δ18Ocalcite values to provide the first high-resolution record of climate variability for this period in Ireland. Following deglaciation, rapid climate amelioration preceded large increases in GISP2 δ18Oice values by ∼2300 yr. The Oldest Dryas (15,100 to 14,500 cal yr B.P.) Late Glacial event is documented in this record as a decrease in δ18Ocalcite values. Brief warming at ∼12,700 cal yr B.P. was followed by characteristic Younger Dryas cold and dry climate conditions. A rapid increase in δ18Ocalcite values at ∼10,500 cal yr B.P. marked the onset of Boreal warming in western Ireland. The 8200 cal yr B.P. event is represented by a brief cooling in our record. Prior to general warming, a larger and previously undescribed climate anomaly between 7300 and 6700 cal yr B.P. is characterized by low δ18Ocalcite values with high-frequency variability.

Jura glacial lakes: a paleoclimatic and paleoenvironmental evolution since the Late Glacial Period.

2020 ◽  
Author(s):  
Brahimsamba Bomou ◽  
Damien Zappa ◽  
Anne-Marie Rachoud-Schneider ◽  
Jean-Nicolas Haas ◽  
Marina Gärtner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Lacustrine Sediments ◽  
Younger Dryas ◽  
Late Glacial ◽  
Glacial Period ◽  
Glacial Lakes ◽  
Late Glacial Period ◽  
Paleoenvironmental Evolution ◽  
Multiproxy Approach

&lt;p&gt;During the retreat of a W&amp;#252;rm ice sheet, numerous glacial paleolakes took place in the Swiss and French Jura. Two sites were investigated: the Amburnex Valley site (Switzerland), which evolved in well-developed peatland and the Lake Val (France), which is still persisted as a lacustrine system. During the Late Glacial period, both sites were glacial lakes characterized by a significant accumulation of lacustrine sediments.&lt;/p&gt;&lt;p&gt;Using a multiproxy approach, this project aims to reconstruct the paleoclimatic and the paleoenvironmental evolution recorded in lacustrine sediments and peatbog deposits since the last 13&amp;#8217;000 years.&lt;/p&gt;&lt;p&gt;The Amburnex core (7m) exhibit a basal morainic deposit from the W&amp;#252;rm period, overlain by three meters of lacustrine deposits and four meters of peatland deposits. The Lake Val core (4.5m) consists of the same lithological succession.&lt;/p&gt;&lt;p&gt;A multiproxy approach based on palynological analyses, grain-size analyses, mineralogical analyses (XRD) and geochemical analyses (TOC, Nitrogen, Phosphorus and Mercury contents; major and trace elements; organic carbon isotopes) have been used to characterize the hydrological and climatic fluctuations, the trophic level and the origin of organic matter in order to reconstruct the paleoenvironmental and paleoclimatic evolution of this area.&lt;/p&gt;&lt;p&gt;In the Amburnex site, the B&amp;#248;lling-Aller&amp;#248;d, the Younger Dryas and the beginning of the Preboreal period have been recognized by palynological analyses and confirmed by carbon 14 dating. During the Oldest Dryas, oligotrophic conditions took place as suggested by the very low concentrations in nitrogen and organic matter. Then, during the warmer B&amp;#248;lling period, an enrichment in total organic carbon (TOC) associated with a decrease in phosphorus content are observed, implying the development of eutrophic conditions and maybe phosphorus recycling. Later in the Aller&amp;#248;d period, low TOC and phosphorus contents, associated with varved carbonate deposits, indicate a return to more oligotrophic conditions. New organic matter enrichments are observed in the interval corresponding to the colder Younger Dryas period. These trends are quite consistent with those observed in the Lake Val and reflect significant changes in runoff and nutrient inputs at least at regional scale.&lt;/p&gt;

Late-Glacial to Holocene Changes in Winds, Upwelling, and Seasonal Production of the Northern California Current System

1992 ◽  
Vol 38 (3) ◽  
pp. 359-370 ◽  
Author(s):  
Constance Sancetta ◽  
Michell Lyle ◽  
Linda Heusser ◽  
Rainer Zahn ◽  
J.Platt Bradbury
Keyword(s):  
Late Pleistocene ◽  
Climate Model ◽  
Current System ◽  
Younger Dryas ◽  
California Current ◽  
Late Glacial ◽  
California Current System ◽  
The Past ◽  
Northern California Current ◽  
Continental Interior

AbstractA core 120 km off the coast of southern Oregon was examined for changes in lithology, diatoms, and pollen over the past 30,000 yr. Primary production during the late Pleistocene was about half that of the Holocene. Evidence from diatoms and pollen indicates that summer upwelling was much weaker, implying an absence of strong northerly winds. Early Pliocene diatoms found throughout the late Pleistocene section were probably derived from diatomites east of the Cascades and provide evidence for strong easterly winds over a dry continental interior. The findings verify predictions of a climate model based on glacial maximum conditions. There is no compelling evidence for a climatic reversal corresponding to the European Younger Dryas chron. During the early Holocene (9000−7000 yr B.P.) there may have been years when winds were insufficiently strong to support upwelling, so that warm stratified waters lay closer to the coast.

Last glacial–interglacial environments in the southern Rocky Mountains, USA and implications for Younger Dryas-age human occupation

2012 ◽  
Vol 77 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Christy E. Briles ◽  
Cathy Whitlock ◽  
David J. Meltzer
Keyword(s):  
Rocky Mountains ◽  
Fire History ◽  
Younger Dryas ◽  
Late Glacial ◽  
Subalpine Forest ◽  
Glacial Period ◽  
Last Glacial ◽  
Southern Rocky Mountains ◽  
Late Glacial Period ◽  
Fire Activity

The last glacial-interglacial transition (LGIT; 19–9 ka) was characterized by rapid climate changes and significant ecosystem reorganizations worldwide. In western Colorado, one of the coldest locations in the continental US today, mountain environments during the late-glacial period are poorly known. Yet, archaeological evidence from the Mountaineer site (2625 m elev.) indicates that Folsom-age Paleoindians were over-wintering in the Gunnison Basin during the Younger Dryas Chronozone (YDC; 12.9–11.7 ka). To determine the vegetation and fire history during the LGIT, and possible explanations for occupation during a period thought to be harsher than today, a 17-ka-old sediment core from Lily Pond (3208 m elev.) was analyzed for pollen and charcoal and compared with other high-resolution records from the southern Rocky Mountains. Widespread tundra and Picea parkland and low fire activity in the cold wet late-glacial period transitioned to open subalpine forest and increased fire activity in the Bølling–Allerød period as conditions became warmer and drier. During the YDC, greater winter snowpack than today and prolonged wet springs likely expanded subalpine forest to lower elevations than today, providing construction material and fuel for the early inhabitants. In the early to middle Holocene, arid conditions resulted in xerophytic vegetation and frequent fire.

Fluctuations of Outlet and Valley Glaciers in the Southern Andes (Argentina) during the Past 13,000 Years

1999 ◽  
Vol 51 (3) ◽  
pp. 238-247 ◽  
Author(s):  
Gerd Wenzens
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
The South ◽  
Southern Andes ◽  
Outlet Glacier ◽  
The Holocene ◽  
The Past ◽  
Late Glacial And Holocene ◽  
Glacial Time

AbstractIn the southern Argentine Andes, ten advances of valley glaciers were used to reconstruct the late-glacial and Holocene glacier history. The accumulation areas of these glaciers lie in the Precordillera and are thus independent of fluctuations of the South Patagonian Icefield. Like the Viedma outlet glacier, the valley glaciers advanced three times during late-glacial time (14,000–10,000 yr B.P.). The youngest advance correlates with the Younger Dryas Stade, based on two minimum AMS14C dates of 9588 and 9482 yr B.P. The second oldest advance occurred before 11,800 yr B.P. During the first half of the Holocene, (ca. 10,000–5000 yr B.P.), advances culminated about 8500, 8000–7500, and 5800–5500 yr B.P. During the second half of the Holocene, advances occurred between ca. 4500 and 4200 yr B.P., as well as between 3600 and 3300 yr B.P. In the Rı́o Cóndor valley three subsequent advances have been identified.

scholarly journals Illuminating Intcal During the Younger Dryas

Radiocarbon ◽  
2020 ◽  
Vol 62 (4) ◽  
pp. 883-889 ◽  
Author(s):  
Frederick Reinig ◽  
Adam Sookdeo ◽  
Jan Esper ◽  
Michael Friedrich ◽  
Giulia Guidobaldi ◽  
...  
Keyword(s):  
Environmental Change ◽  
Calibration Curve ◽  
Younger Dryas ◽  
Late Glacial ◽  
Precision Data ◽  
The Past ◽  
Climate And Environmental Change ◽  
Absolute Dating ◽  
High Precision Data ◽  
Geochronological Dating

ABSTRACTAs the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any other contribution during any other period of time. Thus, our results now provide unique geochronological dating into the Younger Dryas, a pivotal period of climate and environmental change at the transition from LG into Early Holocene conditions.

Late-Glacial climatic changes in Eastern France (Lake Lautrey) from pollen, lake-levels, and chironomids

2005 ◽  
Vol 64 (2) ◽  
pp. 197-211 ◽  
Author(s):  
O. Peyron ◽  
C. Bégeot ◽  
S. Brewer ◽  
O. Heiri ◽  
M. Magny ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
High Temporal Resolution ◽  
Lake Levels ◽  
Late Glacial Period ◽  
Climate Reconstructions ◽  
Quantitative Estimates ◽  
Abrupt Changes ◽  
Cold Events ◽  
Climate Signals

AbstractHigh-temporal resolution analyses of pollen, chironomid, and lake-level records from Lake Lautrey provide multi-proxy, quantitative estimates of climatic change during the Late-Glacial period in eastern France. Past temperature and moisture parameters were estimated using modern analogues and ‘plant functional types’ transfer-function methods for three pollen records obtained from different localities within the paleolake basin. The comparison of these methods shows that they provide generally similar climate signals, with the exception of the Bölling. Comparison of pollen- and chironomid-based temperature of the warmest month reconstructions generally agree, except during the Bölling. Major abrupt changes associated with the Oldest Dryas/Bölling, Alleröd/Younger Dryas, and the Younger Dryas/Preboreal transitions were quantified as well as other minor fluctuations related to the cold events (e.g., Preboreal oscillation). The temperature of the warmest month increased by ∼5°C at the start of Bölling, and by 1.5°�"3°C at the onset of the Holocene, while it fell by ca. 3° to 4°C at the beginning of Younger Dryas. The comparative analysis of the results based on the three Lautrey cores have highlighted significant differences in the climate reconstructions related to the location of each core, underlining the caution that is needed when studying single cores not taken from deepest part of lake basins.

A midge-based late-glacial temperature reconstruction from southwestern Nova Scotia

2005 ◽  
Vol 42 (11) ◽  
pp. 2051-2057 ◽  
Author(s):  
Bronwen S Whitney ◽  
Jessie H Vincent ◽  
Les C Cwynar
Keyword(s):  
Nova Scotia ◽  
Younger Dryas ◽  
Temperature Reconstruction ◽  
Late Glacial ◽  
Organic Content ◽  
Eastern North America ◽  
Quantitative Reconstruction ◽  
Late Glacial Period ◽  
Maritime Canada ◽  
Glacial Climate

We present a quantitative reconstruction of the thermal regime spanning the late-glacial period of Nova Scotia (14 700 to 11 600 BP) as inferred by analyzing fossil midges from a small lake (Lac à Magie) in southwestern Nova Scotia. The GS-1 event (equivalent to the Younger Dryas, dating from 12 700 to 11 600 BP in Maritime Canada) was marked by a 5 °C decline in inferred mean July surface-water temperatures and a 15% drop in organic content. Previous pollen and plant macrofossil analyses of this site demonstrate a response of vegetation to GS-1 cooling. These data, coupled with a midge-inferred temperature reconstruction from a nearby site, suggest that late-glacial climate change was less pronounced in southern Nova Scotia than in other sites in Maritime Canada and adjacent eastern North America.

Variations in Sediment Yield from the Upper Doubs River Carbonate Watershed (Jura, France) since the Late-Glacial Period

1999 ◽  
Vol 51 (3) ◽  
pp. 267-279 ◽  
Author(s):  
Vincent Bichet ◽  
Michel Campy ◽  
Jean-François Buoncristiani ◽  
Christian Digiovanni ◽  
Michel Meybeck ◽  
...  
Keyword(s):  
Sediment Yield ◽  
Younger Dryas ◽  
Late Glacial ◽  
Glacial Period ◽  
Mean Values ◽  
Seismic Surveys ◽  
Forest Clearing ◽  
Late Glacial Period ◽  
Erosion Processes ◽  
Detrital Sediment

AbstractThe Upper Doubs River Valley is a 910-km2watershed feeding into Lake Chaillexon. The lake was formed by a natural rockfall at the end of the Bølling Chronozone (around 14,250 cal yr B.P.) and since then has trapped material eroded from the watershed. The filling process and variations in sediment yield have been investigated by mechanical coring, seismic surveys, and electric soundings. The detrital sediment yield of the upstream watershed can be calculated by quantifying the sedimentary stocks for each climatic stage of the Late-Glacial period and Holocene Epoch and estimating the lake's entrapment capacity. This enables us to determine the intensity of the erosion processes in relation to climate and environmental factors. The Bølling–Allerød Interstade produced the greatest yields with mean values of 19,500 metric tons per calendar year (t/yr). The Younger Dryas Chronozone saw a sharp fall (8900 t/yr) that continued into the Preboreal (2100 t/yr). Clastic supply increased during the Boreal (4500 t/yr) before declining again in the Early Atlantic (2400 t/yr). Since then, yields have risen from 4500 t/yr in the Late Atlantic to 6800 t/yr in the Subboreal and 11,100 t/yr in the Subatlantic. Comparison of quantitative data with the qualitative analysis of the deposits and with the paleohydrologic curve of the watershed based on level fluctuations in lakes around Chaillexon shows that climate was the controlling factor of sediment yield until the Late Atlantic. From the Late Atlantic–Subboreal around 5400 cal yr B.P. (470014C yr B.P.) and especially from the end of the Subboreal Chronozone and during the Subatlantic Chronozone (2770 cal yr B.P./270014C yr B.P.–present) climatic constraints have been compounded by human activity related to forest clearing and land use.

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