scholarly journals Mass accumulation rate changes in Chinese loess during MIS 2, and asynchrony with records from Greenland ice cores and North Pacific Ocean sediments during the Last Glacial Maximum

2015 ◽  
Vol 19 ◽  
pp. 251-258 ◽  
Author(s):  
Shugang Kang ◽  
Helen M. Roberts ◽  
Xulong Wang ◽  
Zhisheng An ◽  
Min Wang
Keyword(s):  
Pacific Ocean ◽  
Last Glacial Maximum ◽  
North Pacific ◽  
Accumulation Rate ◽  
North Pacific Ocean ◽  
Ice Cores ◽  
Chinese Loess ◽  
The Last Glacial Maximum ◽  
Mass Accumulation ◽  
The Last Glacial

scholarly journals Atmospheric Fe supply has a negligible role in promoting marine productivity in the Glacial North Pacific Ocean

2020 ◽  
Author(s):  
Francois Burgay ◽  
Andrea Spolaor ◽  
Jacopo Gabrieli ◽  
Giulio Cozzi ◽  
Clara Turetta ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Ice Cores ◽  
The Arctic ◽  
High Concentration ◽  
Sea Ice Extent ◽  
Last Glacial ◽  
Marine Productivity ◽  
The Last Glacial

Abstract. Iron is a key element in the Earth climate system as it can enhance the marine primary productivity in the High-Nutrient Low-Chlorophyll (HNLC) regions where, despite a high concentration of major nutrients, the chlorophyll production is low due to iron limitation. One of the main Fe sources to the ocean is Aeolian dust. For this reason, ice cores provide a sensitive and continuous archive for reconstructing Fe fluxes over the last millennia. Here we show the first Northern Hemisphere Fe record retrieved from the NEEM ice core, which offers a unique opportunity to reconstruct the past Fe fluxes in the Arctic region over the last 108 kyr. Holocene Fe fluxes to the Arctic were three times lower than the average recorded over the last glacial period. They were greater during the Last Glacial Maximum (LGM) and the Marine Isotope Stage 4 (MIS 4). Comparing our data with palaeoceanographic records retrieved from the HNLC North Pacific, we demonstrated that during the coldest periods, characterized by the highest Fe fluxes, marine productivity in the subarctic Pacific Ocean did not increase due to a greater sea-ice extent and the absence of upwelling nutrient supply. This supports the hypothesis that Fe-fertilization was more effective in other regions, such as the transition zone of the North Pacific, where a closer relationship between marine productivity and the Aeolian Fe fluxes was observed.

scholarly journals N2O Measurements on Air Extracted from Antarctic Ice Cores (Abstract)

1988 ◽  
Vol 10 ◽  
pp. 222-222
Author(s):  
D. Zardini ◽  
D. Raynaud ◽  
D. Scharffe ◽  
W. Seiler
Keyword(s):  
Last Glacial Maximum ◽  
Ice Cores ◽  
Experimental Tests ◽  
Glacial Maximum ◽  
Recent Period ◽  
Air Samples ◽  
Last Glacial ◽  
Original Procedure ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A method has been developed for measuring N2O concentrations in the air extracted from the bubbles contained in ice cores. The air extraction is performed by cutting the ice into very small pieces with a rotating knife, in a controlled atmosphere. The N2O concentrations are measured by gas chromatography. The complete original procedure will be discussed, and the results of the different experimental tests given, with a discussion of the uncertainties.This method has been used to perform about 40 measurements on Antarctic ice samples. Ten air samples from the D57 core date approximately from the beginning of the seventeenth and twentieth centuries. The others were taken from the Dome C core and date from the Holocene and the period around the Last Glacial Maximum. The D57 results are in agreement with those of Pearman and others (1986), leading to a similar pre-industrial N2O level (270-290 ppb volume). Furthermore, our Dome C results suggest that during the Last Glacial Maximum atmospheric N2O content was not drastically different from the recent period.

scholarly journals A Radiocarbon Perspective on Greenland Ice-Core Chronologies: Can we Use Ice Cores for 14C Calibration?

Radiocarbon ◽  
2004 ◽  
Vol 46 (3) ◽  
pp. 1239-1259 ◽  
Author(s):  
John Southon
Keyword(s):  
Last Glacial Maximum ◽  
Northern Hemisphere ◽  
Time Scale ◽  
Ice Core ◽  
Ice Cores ◽  
Strong Correlations ◽  
Crucial Importance ◽  
Proxy Records ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Some of the most valuable paleoclimate archives yet recovered are the multi-proxy records from the Greenland GISP2 and GRIP ice cores. The crucial importance of these data arises in part from the strong correlations that exist between the Greenland δ18O records and isotopic or other proxies in numerous other Northern Hemisphere paleoclimate sequences. These correlations could, in principle, allow layer-counted ice-core chronologies to be transferred to radiocarbon-dated paleoclimate archives, thus providing a 14C calibration for the Last Glacial Maximum and Isotope Stage 3, back to the instrumental limits of the 14C technique. However, this possibility is confounded by the existence of numerous different chronologies, as opposed to a single (or even a “best”) ice-core time scale. This paper reviews how the various chronologies were developed, summarizes the differences between them, and examines ways in which further research may allow a 14C calibration to be established.

PMIP-carbon: towards a multi-models comparison of climate-carbon interactions at the Last Glacial Maximum

2020 ◽  
Author(s):  
Nathaelle Bouttes ◽  
Ruza Ivanovic ◽  
Ayako Abe-Ouchi ◽  
Hidetaka Kobayashi ◽  
Laurie Menviel ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Carbon Isotopes ◽  
Last Glacial Maximum ◽  
Ocean Circulation ◽  
Ice Cores ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Intercomparison Project ◽  
The Last Glacial Maximum ◽  
The Last Glacial

<p>More and more climate models now include the carbon cycle, but multi-models studies of climate-carbon simulations within the Climate Model Intercomparison Project (CMIP) are limited to present and future time periods. In addition, the carbon cycle is not considered in the simulations of past periods analysed within the Paleoclimate Modelling Intercomparison Project (PMIP). Yet, climate-carbon interactions are crucial to anticipate future atmospheric CO<sub>2</sub> concentrations and their impact on climate. Such interactions can change depending on the background climate, it is thus necessary to compare model results among themselves and to data for past periods with different climates such as the Last Glacial Maximum (LGM).</p><p>The Last Glacial Maximum, around 21,000 years ago, was about 4°C colder than the pre-industrial, and associated with large ice sheets on the American and Eurasian continents. It is one of the best documented periods thanks to numerous paleoclimate archives such as marine sediment cores and ice cores. Despite this period having been studied for years, no consensus on the causes of the lower atmospheric CO<sub>2</sub> concentration at the time (around 180 ppm) has been reached and models still struggle to simulate these low CO<sub>2</sub> values. The ocean, which contains around 40 times more carbon than the atmosphere, likely plays a key role, but models tend to simulate ocean circulation changes in disagreement with proxy data, such as carbon isotopes.</p><p>This new project aims at comparing, for the first time, the carbon cycle representation at the Last Glacial Maximum from general circulation models and intermediate complexity models. We will explain the protocol and present first results in terms of carbon storage in the main reservoirs (atmosphere, land and ocean) and their link to key climate variables such as temperature, sea ice and ocean circulation. The use of coupled climate-carbon models will not only allow to compare changes in the carbon cycle in models and analyse their causes, but it will also enable us to better compare to indirect data related to the carbon cycle such as carbon isotopes.</p>

scholarly journals High-resolution interpolar difference of atmospheric methane around the Last Glacial Maximum

2012 ◽  
Vol 9 (5) ◽  
pp. 5471-5508 ◽  
Author(s):  
M. Baumgartner ◽  
A. Schilt ◽  
O. Eicher ◽  
J. Schmitt ◽  
J. Schwander ◽  
...  
Keyword(s):  
High Resolution ◽  
Last Glacial Maximum ◽  
Methane Concentration ◽  
Ice Cores ◽  
Glacial Maximum ◽  
Atmospheric Methane ◽  
Before Present ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Reconstructions of past atmospheric methane concentrations are available from ice cores from both, Greenland and Antarctica. The difference observed between the two polar methane concentration levels is a valuable additional parameter which allows to constrain the geographical location of the responsible methane sources. Here we present new high-resolution methane records from the North Greenland Ice Core Project (NGRIP) and the European Project for Ice Coring in Antarctica (EPICA) Dronning Maud Land (EDML) ice cores covering Termination 1, the Last Glacial Maximum, and parts of the last glacial back to 32 000 years before present. Due to the high-resolution records the synchronisation between the ice cores from NGRIP and EDML is considerably improved and the interpolar concentration difference of methane is determined with unprecedented precision and temporal resolution. Relative to the mean methane concentration, we find a rather stable positive interpolar difference throughout the record with its minimum value of 3.7 ± 0.7 % between 21 900–21 200 years before present, which is higher than previously estimated in this interval close to the Last Glacial Maximum. This implies that Northern Hemisphere boreal wetland sources were never completely shut off during the peak glacial. Starting at 21 000 years before present, i.e. severval millenia prior to the transition into the Holocene, the relative interpolar difference becomes even more positive and stays at a fairly stable level of 6.5 ± 0.8 % during Termination 1. We hypothesise that the anti-correlation observed in the monsoon records from the Northern and Southern Hemispheres induces a methane source redistribution within lower latitudes, which could explain parts of the variations in the interpolar difference.

scholarly journals Reconstruction of Pacific Ocean bottom water salinity during the Last Glacial Maximum

2014 ◽  
Vol 41 (8) ◽  
pp. 2914-2920 ◽  
Author(s):  
Tania Lado Insua ◽  
Arthur J. Spivack ◽  
Dennis Graham ◽  
Steven D'Hondt ◽  
Kathryn Moran
Keyword(s):  
Pacific Ocean ◽  
Last Glacial Maximum ◽  
Bottom Water ◽  
Glacial Maximum ◽  
Water Salinity ◽  
Ocean Bottom ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial
Sign in / Sign up

Export Citation Format

Share Document