Climate evolution across the Mid-Brunhes Transition

Abstract. The Mid-Brunhes Transition (MBT) began ∼ 430 ka with an increase in the amplitude of the 100 kyr climate cycles of the past 800 000 years. The MBT has been identified in ice-core records, which indicate interglaciations became warmer with higher atmospheric CO2 levels after the MBT, and benthic oxygen isotope (δ18O) records, which suggest that post-MBT interglaciations had higher sea levels and warmer temperatures than pre-MBT interglaciations. It remains unclear, however, whether the MBT was a globally synchronous phenomenon that included other components of the climate system. Here, we further characterize changes in the climate system across the MBT through statistical analyses of ice-core and δ18O records as well as sea-surface temperature, benthic carbon isotope, and dust accumulation records. Our results demonstrate that the MBT was a global event with a significant increase in climate variance in most components of the climate system assessed here. However, our results indicate that the onset of high-amplitude variability in temperature, atmospheric CO2, and sea level at ∼430 ka was preceded by changes in the carbon cycle, ice sheets, and monsoon strength during Marine Isotope Stage (MIS) 14 and MIS 13.

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Climate evolution across the Mid-Brunhes Transition

10.5194/cp-2018-20 ◽

2018 ◽

Cited By ~ 2

Author(s):

Aaron M. Barth ◽

Peter U. Clark ◽

Nicholas S. Bill ◽

Feng He ◽

Nicklas G. Pisias

Keyword(s):

Ice Core ◽

Ice Sheets ◽

High Amplitude ◽

Climate System ◽

Atmospheric Co2 ◽

Sea Levels ◽

The Past ◽

Climate Evolution ◽

Monsoon Strength ◽

Climate Variance

Abstract. The Mid-Brunhes Transition (MBT) began ∼ 430 ka with an increase in the amplitude of the 100-kyr climate cycles of the past 800,000 years. The MBT has been identified in ice-core records, which indicate interglaciations became warmer with higher atmospheric CO2 levels after the MBT, and benthic oxygen isotope (δ18O) records, which suggest that post-MBT interglaciations had higher sea levels than pre-MBT interglaciations. It remains unclear, however, whether the MBT was a globally synchronous phenomenon that included other components of the climate system. Here we further characterize changes in the climate system across the MBT through statistical analyses of ice-core and δ18O records as well as sea-surface temperature, benthic carbon isotope, and dust accumulation records. Our results demonstrate that the MBT was a global event with a significant increase in climate variance in most components of the climate system assessed here. However, our results indicate that the onset of high-amplitude variability in temperature, atmospheric CO2, and sea level at ∼ 430 ka was preceded by changes in the carbon cycle, ice sheets, and monsoon strength during MIS 14 and 13.

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Supporting evidence from the EPICA Dronning Maud Land ice core for atmospheric CO2 changes during the past millennium

Tellus B ◽

10.1111/j.1600-0889.2005.00131.x ◽

2005 ◽

Vol 57 (1) ◽

pp. 51-57 ◽

Cited By ~ 49

Author(s):

URS SIEGENTHALER ◽

ERIC MONNIN ◽

KENJI KAWAMURA ◽

RENATO SPAHNI ◽

JAKOB SCHWANDER ◽

...

Keyword(s):

Ice Core ◽

Atmospheric Co2 ◽

Supporting Evidence ◽

The Past ◽

Dronning Maud Land ◽

Past Millennium

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8. Glaciers of the past

Glaciation: A Very Short Introduction ◽

10.1093/actrade/9780198745853.003.0008 ◽

2018 ◽

pp. 146-152

Author(s):

David J. A. Evans

Keyword(s):

Numerical Models ◽

Ice Core ◽

Three Dimensional ◽

Ice Sheets ◽

Ice Sheet ◽

Aerial Imagery ◽

The Past ◽

Glacial Landforms

To reconstruct the former extent and dynamics of ice sheets and glaciers requires a knowledge of process-form relationships that goes beyond individual landform types. Instead, glacial geomorphologists need to analyse large areas of glaciated terrain in a more holistic way, combining the whole range of glacial landforms and sediments to reconstruct glacier systems of the past, a subject now known as palaeoglaciology. ‘Glaciers of the past’ explains how the combination of aerial imagery and landform analysis is used in palaeoglaciological reconstruction. Increasingly powerful computers are making it possible to compile sophisticated numerical models that use our knowledge of glaciological processes and ice-core-derived palaeoclimate data to create three-dimensional glacier and ice sheet reconstructions.

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An Antarctic ice core reveals atmospheric CO2 variations over the past few centuries

Nature ◽

10.1038/315309a0 ◽

1985 ◽

Vol 315 (6017) ◽

pp. 309-311 ◽

Cited By ~ 100

Author(s):

D. Raynaud ◽

J. M. Barnola

Keyword(s):

Ice Core ◽

Atmospheric Co2 ◽

The Past

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Reconciling the surface temperature–surface mass balance relationship in models and ice cores in Antarctica over the last two centuries

10.5194/tc-2020-36 ◽

2020 ◽

Author(s):

Marie G. P. Cavitte ◽

Quentin Dalaiden ◽

Hugues Goosse ◽

Jan T. M. Lenaerts ◽

Elizabeth R. Thomas

Keyword(s):

Mass Balance ◽

Large Scale ◽

Ice Core ◽

Ice Sheets ◽

Ice Cores ◽

Surface Mass Balance ◽

Weak Correlation ◽

Surface Mass ◽

The Past ◽

Ice Core Records

Abstract. Ice cores are an important record of the past surface mass balance (SMB) of ice sheets, with SMB mitigating the ice sheets’ sea level impact over the recent decades. For the Antarctic Ice Sheet (AIS), SMB is dominated by large-scale atmospheric circulation, which collects warm moist air from further north and releases it in the form of snow as widespread accumulation or focused atmospheric rivers on the continent. This implies that the snow deposited at the surface of the AIS should record strongly coupled SMB and surface air temperature (SAT) variations. Ice cores use δ18O as a proxy for SAT as they do not record SAT directly. Here, using isotope-enabled global climate models and the RACMO2.3 regional climate model, we calculate positive SMB-SAT and δ18O-SMB correlations over ∼90 % of the AIS. The high spatial resolution of the RACMO2.3 model allows us to highlight a number of areas where SMB and SAT are not correlated, and show that wind-driven processes acting locally, such as Foehn and katabatic effects, can overwhelm the large-scale atmospheric input in SMB and SAT responsible for the positive SMB-SAT correlations. We focus in particular on Dronning Maud Land, East Antarctica, where the ice promontories clearly show these wind-induced effects. However, using the PAGES2k ice core compilations of SMB and δ18O of Thomas et al. (2017) and Stenni et al. (2017), we obtain a weak correlation, on the order of 0.1, between SMB and δ18O over the past ~150 years. We obtain an equivalently weak correlation between ice core SMB and the SAT reconstruction of Nicolas and Bromwich (2014) over the past ~50 years, although the ice core sites are not spatially co-located with the areas displaying a low SMB-SAT correlation in the models. To resolve the discrepancy between the measured and modeled signals, we show that averaging the ice core records in close spatial proximity increases their SMB-SAT correlation. This increase shows that the weak measured correlation likely results from random noise present in the ice core records, but is not large enough to match the correlation calculated in the models. Our results indicate thus a positive correlation between SAT and SMB in models and ice core reconstructions but with a weaker value in observations that may be due to missing processes in models or some systematic biases in ice core data that are not removed by a simple average.

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Change of the ice rheology with climatic transitions – implication on ice flow modelling and dating of the EPICA Dome C core

Climate of the Past Discussions ◽

10.5194/cpd-2-1187-2006 ◽

2006 ◽

Vol 2 (6) ◽

pp. 1187-1219 ◽

Cited By ~ 1

Author(s):

G. Durand ◽

F. Gillet-Chaulet ◽

A. Svensson ◽

O. Gagliardini ◽

S. Kipfstuhl ◽

...

Keyword(s):

Flow Model ◽

Ice Core ◽

Ice Sheets ◽

Ice Cores ◽

Horizontal Shear ◽

Ice Flow ◽

Flow Modelling ◽

The Past ◽

Ice Flows ◽

Crystallographic Orientations

Abstract. The study of the distribution of the crystallographic orientations (the fabric) along ice cores supplies information on the past and current ice flows of ice-sheets. Beside the usually observed formation of a vertical single maximum fabric, the EPICA Dome Concordia ice core (EDC) shows an abrupt and unexpected strenghtening of its fabric during termination II around 1750 m depth. Such strengthenings were already observed for sites located on an ice-sheet. This suggests that horizontal shear could occur along the EDC core. Moreover, the change in the fabric leads to a modification of the viscosity between neighbouring ice layers. Through the use of an anisotropic ice flow model, we quantify the change in viscosity and investigate its implication on ice flow and dating.

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The Influence On Atmospheric Composition of Volcanic Eruptions as Derived From Ice-Core Analysis

Annals of Glaciology ◽

10.1017/s0260305500006029 ◽

1985 ◽

Vol 7 ◽

pp. 125-129 ◽

Cited By ~ 9

Author(s):

C.U. Hammer

Keyword(s):

Ice Core ◽

Ice Sheets ◽

Ice Cores ◽

Volcanic Eruptions ◽

Atmospheric Composition ◽

Core Analysis ◽

Polar Ice ◽

Ice Caps ◽

The Past ◽

Polar Ice Sheets

Polar ice cores offer datable past snow deposits in the form of annual ice layers, which reflect the past atmospheric composition. Trace substances in the cores are related to the past mid-tropospheric impurity load, this being due to the vast extent of the polar ice sheets (or ice caps), their surface elevations and remoteness from most aerosol sources. Volcanic eruptions add to the rather low background impurity load via their eruptive products. This paper concentrates on the widespread influence on atmospheric impurity loads caused by the acid gas products from volcanic eruptions. In particular the following subjects are discussed: acid volcanic signals in ice cores, latitude of eruptions as derived by ice-core analysis, inter-hemispheric dating of the two polar ice sheets by equatorial eruptions, volcanic deposits in ice cores during the last glacial period and climatic implications.

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Glacier Melting, Disaster and Awareness Programme

SAMRIDDHI A Journal of Physical Sciences Engineering and Technology ◽

10.18090/samriddhi.v8i2.7147 ◽

2016 ◽

Vol 8 (02) ◽

pp. 131-138

Author(s):

Bharat Raj Singh ◽

Amar Bahadur Singh

Keyword(s):

Agricultural Soils ◽

Ice Sheets ◽

Storm Surges ◽

Past Century ◽

Sea Levels ◽

Ice Caps ◽

Ice Melt ◽

The Past ◽

Glacier Melting ◽

Awareness Programme

Large ice formations, like glaciers and the polar ice caps, naturally melt back a bit each summer. But, in the winter, snows, made primarily from evaporated seawater, are generally sufficient to balance out the melting. Recently, though, persistently higher temperatures caused by global warming have led to greaterthan- average summer melting as well as diminished snowfall due to later winters and earlier springs. This imbalance results in a significant net gain in runoff versus evaporation for the ocean, causing sea levels to rise. Satellite measurements tell us that over the past century, the Global Mean Sea Level (GMSL) has risen by 4 to 8 inches (10 to 20 centimeters). However, the annual rate of rise over the past 20 years has been 0.13 inches (3.2 millimeters) a year, roughly twice the average speed of the preceding 80 years. As with glaciers and the ice caps, increased heat is causing the massive ice sheets, that cover Greenland and Antarctica to melt at an accelerated pace. Scientists also believe ice-melt water from above and seawater from below is seeping beneath Greenland's and West Antarctica's ice sheets, effectively lubricating ice streams and causing them to move more quickly into the sea. Moreover, higher sea temperatures are causing the massive ice shelves that extend out from Antarctica to melt from below, weaken, and break off. When sea levels rise rapidly, as they have been doing, even a small increase can have devastating effect on coastal habitats. As seawater reaches farther inland, it can cause destructive erosion, flooding of wetlands, contamination of aquifers and agricultural soils, and lost habitat for fish, birds, and plants. When large storms hit land, higher sea levels mean bigger, more powerful storm surges that can strip away everything in their path. In addition, hundreds of millions of people live in areas that will become increasingly vulnerable to flooding. Higher sea levels would force them to abandon their homes and relocate. Low-lying islands could be submerged completely. Thus, it needs launching of serious awareness programme through print media, electronic media to curb the glacier melting by reducing heavy consumption of hydrocarbon and focus on zero pollution researches to develop energy production alternatives.

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Ice core record of the 13C/12C ratio of atmospheric CO2 in the past two centuries

Nature ◽

10.1038/324237a0 ◽

1986 ◽

Vol 324 (6094) ◽

pp. 237-238 ◽

Cited By ~ 807

Author(s):

H. Friedli ◽

H. Lötscher ◽

H. Oeschger ◽

U. Siegenthaler ◽

B. Stauffer

Keyword(s):

Ice Core ◽

Atmospheric Co2 ◽

The Past ◽

Ice Core Record

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Examining the strength of the link between surface temperature and surface mass balance in ice cores and models over the last centuries in Antarctica

10.5194/egusphere-egu2020-801 ◽

2020 ◽

Author(s):

Marie G. P. Cavitte ◽

Quentin Dalaiden ◽

Hugues Goosse ◽

Jan T.M. Lenaerts ◽

Elizabeth R. Thomas

Keyword(s):

Large Scale ◽

Ice Core ◽

Ice Sheets ◽

Ice Cores ◽

Regional Model ◽

Snow Accumulation ◽

Surface Mass Balance ◽

Weak Correlation ◽

Surface Mass ◽

The Past

Ice cores constitute an important record of the past surface mass balance (SMB) of the ice sheets, with SMB ultimately modulating the ice sheets&#8217; sea level impact. For the Antarctic Ice Sheet (AIS), SMB is dominated by snow accumulation and strongly controlled by atmospheric circulation. Large-scale atmospheric depressions collect warmth and moisture from further north that they then release over the AIS in the form of widespread accumulation or focused atmospheric rivers. This implies that snow deposited at the surface of the AIS should show strongly coupled SMB and surface air temperatures (SAT) variations. Ice cores do not record SAT directly but their d18O record is often used as a temperature proxy.&#160;Here, using the PAGES 2k Network ice core compilations of SMB and d18O of Thomas et al. (2017) and Stenni et al. (2017), we obtain a weak correlation between SMB and d18O over historical timescales, and an equivalently weak correlation between SMB and SAT based on the Nicolas & Bromwich (2014) SAT reconstructions. However, we calculate a strong and positive SMB-SAT correlation in the majority of regions of the AIS using Global Climate Models (GCM) and the regional model RACMO2.3p2.&#160;To resolve the discrepancy between measured and modeled signals, we show that averaging the ice core records in close spatial proximity increases their SMB-SAT correlation. This increase in measured SMB-SAT correlation likely results from noise present in the ice core records, but is not enough to match the strong correlation calculated in the models. On the model side, the high spatial resolution of the RACMO2.3p2 model allows us to highlight a number of areas of the AIS where SMB and SAT are not strongly correlated. We describe how wind-driven processes acting on the SMB and SAT locally, through Foehn and katabatic effects, can overwhelm the large-scale atmospheric input that induces the positive SMB-SAT correlations. In particular, we focus on Dronning Maud Land, East Antarctica, where each ice promontory clearly shows this wind-driven snow redistribution. Nevertheless, those regions displaying a low SMB-SAT correlation cover only a small fraction of the AIS and are not sufficient to explain the model-data discrepancy, suggesting a critical role of processes at a scale smaller than the one resolved by the regional model.&#160;References:Thomas, E. R., 2017, Regional Antarctic snow accumulation over the past 1000 years, Climate of the Past, 13, 1491&#8211;1513.Stenni, B. et al., 2017, Antarctic climate variability on regional and continental scales over the last 2000 years, Climate of the Past, 13, 1609&#8211;1634.Nicolas, J. P. & Bromwich, D. H., 2014, New reconstruction of Antarctic near-surface temperatures: Multidecadal trends and reliability of global reanalyses, Journal of Climate, 27, 8070&#8211;8093.

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