Quantifying molecular oxygen isotope variations during a Heinrich stadial

Abstract. δ18O of atmospheric oxygen (δ18Oatm) undergoes millennial-scale variations during the last glacial period, and systematically increases during Heinrich stadials (HSs). Changes in δ18Oatm combine variations in biospheric and water cycle processes. The identification of the main driver of the millennial variability in δ18Oatm is thus not straightforward. Here, we quantify the response of δ18Oatm to such millennial events using a freshwater hosing simulation performed under glacial boundary conditions. Our global approach takes into account the latest estimates of isotope fractionation factor for respiratory and photosynthetic processes and make use of atmospheric water isotope and vegetation changes. Our modeling approach allows to reproduce the main observed features of a HS in terms of climatic conditions, vegetation distribution and δ18O of precipitation. We use it to decipher the relative importance of the different processes behind the observed changes in δ18Oatm. The results highlight the dominant role of hydrology on δ18Oatm and confirm that δ18Oatm can be seen as a global integrator of hydrological changes over vegetated areas.

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Quantifying molecular oxygen isotope variations during a Heinrich Stadial

Climate of the Past Discussions ◽

10.5194/cpd-11-2281-2015 ◽

2015 ◽

Vol 11 (3) ◽

pp. 2281-2339

Author(s):

C. Reutenauer ◽

A. Landais ◽

T. Blunier ◽

C. Bréant ◽

M. Kageyama ◽

...

Keyword(s):

Water Cycle ◽

Atmospheric Oxygen ◽

Dominant Role ◽

Climatic Conditions ◽

Water Isotopes ◽

Fractionation Factor ◽

Last Glacial Period ◽

Main Driver ◽

The Last Glacial

Abstract. δ18O of atmospheric oxygen (δ18Oatm) undergoes millennial scale variations during the last glacial period, and systematically increases during Heinrich Stadials (HS). Changes in δ18Oatm combine variations in biospheric and water cycle processes. The identification of the main driver of the millennial variability of δ18Oatm is thus not straightforward. Here, we quantify the response of δ18Oatm to such millennial events using a freshwater hosing simulation (HS_exp) performed under glacial boundary conditions. Our global approach takes into account the latest estimates of isotope fractionation factor for respiratory and photosynthetic processes and make use of atmospheric water isotopes and vegetations changes. Our modeling approach allows to reproduce the main observed features of a HS in terms of climatic conditions, vegetation distribution and δ18O of precipitation. We use it to decipher the relative importance of the different processes behind the observed changes in δ18Oatm. The results highlight the dominant role of hydrology on δ18Oatm and confirm that δ18Oatm can be seen as a global integrator of hydrological changes over vegetated areas.

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Impacts of Heinrich events upon Human existence potential in Europe

10.5194/egusphere-egu2020-7778 ◽

2020 ◽

Author(s):

Masoud Rostami ◽

Konstantin Klein ◽

Christian Wegener ◽

Yaping Shao ◽

Gerd-Christian Weniger

Keyword(s):

Aridity Index ◽

Human Existence ◽

Climate Forcing ◽

Least Cost Path ◽

Last Glacial Period ◽

Climate Conditions ◽

Heinrich Events ◽

Extreme Cold ◽

The Last Glacial

Heinrich events are recognized as the dominant periods of extreme cold terrestrial climate conditions during the last glacial period. The role of climate forcing alone upon Human Existence Potential (HEP) during extreme events, e.g. Heinrich and Dansgaard-Oeschger events, is not yet sufficiently resolved. By reproducing climate variables during the two extreme cold and warm cycles by means of an Earth System Model, employing an improved HEP model, and utilizing archaeological excavation sites, we report the spatial distribution of HEP over Europe during both cold stadials and warm interstadials corresponding to the two Upper Palaeolithic technocomplexes: Late Gravettian and Aurignacian. By introducing some other diagnostics like Environmental Human Catchment, which is defined as an area delimited by low HEP, cooling-aridity index, and Least Cost Path among colonized people, we shed light into population dynamics in this epoch. Consecutive extreme cold and warm cycles, corresponding to contraction-expansion of HEP, supports the hypothesis of repetitive depopulation&#8211;repopulation cycles of habitats. Regarding the controversial issue of late survival location of Neanderthals, we illustrate that western coastlines had such a suitable and stable HEP scores for all human taxa including Neanderthals to survive during Heinrich events.

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Sequence of events at high resolution during deglaciations over the last 800ka from the EDC ice core

10.5194/egusphere-egu21-7850 ◽

2021 ◽

Author(s):

Antoine Grisart ◽

amaelle landais ◽

barbara stenni ◽

ilaria crotti ◽

valérie masson delmotte ◽

...

Keyword(s):

High Resolution ◽

Isotopic Composition ◽

Elemental Composition ◽

Water Cycle ◽

Atmospheric Oxygen ◽

Ice Core ◽

Ice Cores ◽

Climatic Conditions ◽

Low Latitude ◽

Sequence Of Events

The EPICA Dome C (EDC) ice core has been drilled from 1996 to 2004. Its study revealed a unique 800 ka long continuous climatic record including 9 deglaciations. Ice cores contain numerous proxies in the ice and in the air trapped in bubbles (chronological constraints, greenhouse gases concentration, local temperature proxies, mid to low latitude climate proxies). Here, we focus on information provided by the isotopic (and elemental) composition of water and oxygen archived in both ice and gas matrix. On one hand, the water isotopic composition brings information on past temperatures and water cycle re-organizations:&#160;&#160; d18O or dD records past temperature, whereas the combination of d18O with dD or d17O provide information on the past water cycle organization through d-excess and 17O-excess linked to climatic conditions of the evaporative regions. On the other hand, the elemental composition of oxygen expressed in the O2/N2 ratio provides key information for orbital dating over the last 800 ka in complement with the isotopic composition of atmospheric oxygen (d18O of O2 or d18Oatm) which is related as well to the low latitude water cycle.In this study, we present new high resolution records of water isotopes (d18O, d-excess and 17O-excess) as well as high resolution measurements of O2/N2 and d18Oatm over the last 9 deglaciations on the EDC ice core. We first use the high resolution records of O2/N2 and d18Oatm to improve absolute dating constrain over the glacial terminations and discuss the link between orbital forcing and climate variations recorded in the EDC ice core. In a second part, we use d-excess, 17O-excess and d18Oatm to constrain the relative chronology of high vs low latitude climatic events at sub-millennial scale over past deglaciations.

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43.—The Water Volume in Oceans and Seas.

Proceedings of the Royal Society of Edinburgh Section B Biology ◽

10.1017/s0080455x00002009 ◽

1972 ◽

Vol 72 (1) ◽

pp. 429-431

Author(s):

Eugenie Lisitzin

Keyword(s):

Sea Water ◽

Water Cycle ◽

Water Volume ◽

Roman Poet ◽

De Rerum Natura ◽

Last Glacial Period ◽

Special Cases ◽

Principal Factors ◽

Inland Ice ◽

The Last Glacial

Oceanography, as is well known, is considered a young science, lacking in old traditions. Nevertheless, the interest in oceans and seas may in some special cases be traced back as far as the centuries before the beginning of the Christian era. Reference may be made, for instance, to the Roman poet Lucretius, who in his work De rerum natura expressed astonishment that the amount of water in the seas does not augment in spite of the fact that the discharge of all the rivers in the world gathers there. Lucretius considered the effect of evaporation a possible explanation for this fact, thus mentioning one of the principal factors which determine the water cycle in nature, at least during periods in which average climatological conditions prevail. During periods characterised by more pronounced climatological deviations the equilibrium of the water cycle may be greatly disturbed. As an interesting example it may be mentioned that during the last glacial period considerable quantities of sea water were transformed into inland ice. It has been estimated that the water level in the oceans and seas at that epoch was approximately 100 metres lower than at the present time.

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The bearing of phyto-archaeological evidence on discussions of climatic change over recent millennia

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1990.0048 ◽

1990 ◽

Vol 330 (1615) ◽

pp. 671-677 ◽

Cited By ~ 6

Keyword(s):

Middle Ages ◽

Pinus Halepensis ◽

Western Mediterranean ◽

Neolithic Period ◽

Last Glacial Period ◽

Archaeological Data ◽

Buxus Sempervirens ◽

Late Mesolithic ◽

The Last Glacial

Phyto-archaeological data based on macro-remains studies, especially prehistoric charcoal, provide evidence concerning the changes in western Mediterranean vegetation during the last millennia. Comparisons are based on present vegetation levels as defined by Ozenda. From the last glacial period to the present time, differences between warm and cool vegetation were of about 8 °C in the south of France but less extreme in more southern regions. The late Pleistocene and early Holocene (Late Palaeolithic and part of Mesolithic) were a period of transition with pines and junipers. Then, the late Mesolithic and the early Neolithic are typically periods of good forestation. During the Neolithic period deciduous and holm oaks had a role of varying importance in all the present Mediterranean levels (thermomeso- and supramediterranean). Man’s influence on the vegetation became significant in the middle Neolithic (south of France) or earlier (south of Spain) and may be characterized by plants such as Buxus sempervirens, Quercus ilex, Pinus halepensis and heaths. The Chalcolithic, the Roman period and the Middle Ages are also periods during which Man’s influence was important.

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Burial of Different Types of Organic Carbon in Core 17962 from South China Sea since the Last Glacial Period

Quaternary Research ◽

10.1006/qres.2002.2346 ◽

2002 ◽

Vol 58 (1) ◽

pp. 93-100 ◽

Cited By ~ 17

Author(s):

Guodong Jia ◽

Ping'an Peng ◽

Dianyong Fang

Keyword(s):

Organic Carbon ◽

South China Sea ◽

South China ◽

Vegetation Cover ◽

Climatic Conditions ◽

Pyrolysis Gas ◽

Last Glacial Period ◽

China Sea ◽

Regional Land ◽

The Last Glacial

AbstractTotal organic carbon (TOC), black carbon (BC), and land-derived organic carbon (LOC) extracted from marine sediment core 17962 from the southern South China Sea and analyzed by pyrolysis gas chromatography, elemental analyzers, and mass spectroscopy can be interpreted in terms of regional land biomass burning, climatic conditions, vegetation cover, and ocean paleoproductivity. Carbon from terrestrial sources, including BC and LOC, appears to be a significant component of TOC (3.1–39.3% range, 16.5% average for BC; 4.4–56.6% range, 14.6% average for LOC). The production of BC and LOC was only slightly higher during the Last Maximum Glaciation (LGM) than during the Holocene. Therefore, dramatic changes in climate and vegetation cover do not seem to have occurred at the Pleistocene–Holocene boundary. Paleoproductivity data calculated from marine organic carbon, proved to be more accurate than those calculated from TOC and exhibit the same pattern of temporal variation. However, the glacial–interglacial contrast in the refined palaeoproductivity is less evident than that calculated from TOC.

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Possible role of dust-induced regional warming in abrupt climate change during the last glacial period

Nature ◽

10.1038/384447a0 ◽

1996 ◽

Vol 384 (6608) ◽

pp. 447-449 ◽

Cited By ~ 78

Author(s):

Jonathan Overpeck ◽

David Rind ◽

Andrew Lacis ◽

Richard Healy

Keyword(s):

Climate Change ◽

Abrupt Climate Change ◽

Glacial Period ◽

Regional Warming ◽

Last Glacial Period ◽

Last Glacial ◽

The Last Glacial

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The role of dew and radiation fog inputs in the local water cycling of a temperate grassland in Central Europe

10.5194/hess-2020-493 ◽

2020 ◽

Author(s):

Yafei Li ◽

Franziska Aemisegger ◽

Andreas Riedl ◽

Nina Buchmann ◽

Werner Eugster

Keyword(s):

Water Vapor ◽

Large Scale ◽

Water Cycle ◽

Dominant Role ◽

Temperate Grassland ◽

Ambient Water ◽

Radiation Fog ◽

Dew Formation ◽

Local Water

Abstract. In a warmer climate, non-rainfall water (hereafter NRW) formed from dew and fog potentially plays an increasingly important role in temperate grassland ecosystems under the scarcity of precipitation over prolonged periods. Dew and radiation fog occur in combination during clear and calm nights, and both use ambient water vapor as a source. Research on the combined mechanisms involved in NRW inputs to ecosystems are rare, and the condensation of soil-diffusing vapor, as one of the NRW input pathways for dew formation, has hardly been studied at all. The aim of this paper is thus to investigate the different NRW input pathways into a temperate Swiss grassland at Chamau during prolonged dry periods in summer 2018. We measured the isotopic compositions (δ18O, δ2H, and d = δ2H − 8 · δ18O) of both ambient water vapor and the NRW droplets on leaf surfaces combined with eddy covariance and meteorological measurements during one dew-only and two combined dew and radiation fog events. We employed a simple two end-member mixing model using δ18O and δ2H to split the dew input pathways from different sources. Our results showed a decrease of 0.8–5.5 mmol mol−1 in volumetric water vapor mixing ratio and a decrease of 4.8–16.7 ‰ in ambient water vapor δ2H due to dew formation and radiation fog droplet deposition. A nighttime maximum in ambient water vapor δ18O (−15.5 ‰ to −14.3 ‰) and a 3.4–3.7 ‰ decrease in ambient water vapor d were observed for dew formation in unsaturated conditions. In conditions of slight super-saturation, a stronger decrease of ambient water vapor δ18O (0.3–1.5 ‰) and a minimum of ambient water vapor d (−6.0 ‰ to −4.7 ‰) were observed. The combined foliage NRW and ambient water vapor δ18O and δ2H suggested two different input pathways: (1) condensation of ambient water vapor and (2) of soil-diffusing vapor. The latter contributed 9–42 % to the total foliage NRW. The dew and radiation fog potentially produced 0.06–0.39 mm night−1 NRW gain on foliage, which was comparable with 2.8 mm day−1 daytime evapotranspiration. The ambient water vapor d was correlated and anti-correlated with ambient temperature and ambient relative humidity respectively, suggesting an only minor influence of large-scale air advection and highlighted the dominant role of local moisture as a source for ambient water vapor. Our results thus highlight the importance of NRW inputs to temperate grasslands during prolonged dry periods and reveal the complexity of the local water cycle in such conditions including different pathways of water deposition.

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Seasonal variability of radiation tide in Gulf of Riga

10.5194/os-2020-7 ◽

2020 ◽

Author(s):

Vilnis Frishfelds ◽

Juris Sennikovs ◽

Uldis Bethers ◽

Andrejs Timuhins

Keyword(s):

Water Level ◽

Atmospheric Pressure ◽

Dominant Role ◽

Primary Source ◽

Sea Breeze ◽

The Sun ◽

Yearly Variation ◽

Main Driver ◽

Gulf Of Riga

Abstract. Diurnal oscillations of water level in Gulf of Riga are considered. It was found that there is distinct daily pattern of diurnal oscillations in certain seasons. The role of sea breeze, gravitational tides and atmospheric pressure gradient are analysed. The interference of the first two effects provide the dominant role in diurnal oscillations. The effect of gravitational tides is described both with sole tidal forcing and also in real case with atmospheric forcing and stratification. The yearly variation of the declination of the Sun and stratification leads to seasonal intensification of gravitational tides in Gulf of Riga. Correlation between gravitational tide of the Sun with its radiation caused wind effects appears to be main driver of oscillations in Gulf of Riga. Daily variation of wind is primary source of S1 tidal component with a water level maximum at 18:00 UTC in Gulf of Riga. Effect of solar radiation influences also K1 and P1 tidal components which are examined, too.

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Uncertainties modelling CH4 emissions from northern wetlands in glacial climates: the role of vegetation

Climate of the Past Discussions ◽

10.5194/cpd-6-2651-2010 ◽

2010 ◽

Vol 6 (6) ◽

pp. 2651-2685

Author(s):

C. Berrittella ◽

J. Van Huissteden

Keyword(s):

Large Scale ◽

High Sensitivity ◽

Climatic Conditions ◽

Ch4 Emissions ◽

Lack Of Information ◽

Emission Models ◽

Flux Estimation ◽

Vegetation Parameters ◽

The Last Glacial

Abstract. The PEATLAND-VU methane (CH4) model has been used to simulate emissions from continental Europe under different climatic conditions during the last glacial (LG) and modern climates. Such emissions are reactive to hydrology and the results presented by this paper demonstrate high sensitivity to vegetation parameters. Vegetation influences natural CH4 emissions and thus affects its modelling. In wetlands ecosystems various interactions between plants and CH4 do take place and each type of plant is able to affect fluxes in its own way. However, effects of vegetation factors are rarely properly assessed in detail for large scale emission models. Consequently, modelling of CH4 fluxes is currently suffering from lack of information regarding vegetation processes and parameter quantification, thus explaining uncertain estimations. Modelled wetland CH4 emissions during glacial climates are highly uncertain regarding the extent and type of vegetation cover. Paleobotanical data indicate that past (glacial) northern wetland plants associations differed considerably from present moss-rich tundra vegetations. This study examines the effects of wetland vegetation on CH4 emissions, aiming at more plausible flux estimation as well as identifying the sources and the processes governing CH4 emissions.

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Quantifying molecular oxygen isotope variations during a Heinrich stadial