scholarly journals Terrestrial stratigraphical division in the Quaternary and its correlation

2020 ◽  
pp. jgs2020-134
Author(s):  
P.L. Gibbard ◽  
P.D. Hughes
Keyword(s):  
Global Climate ◽  
Ice Core ◽  
Global Scale ◽  
Glacial Cycles ◽  
Climate Fluctuations ◽  
Global Correlation ◽  
Oxygen Isotope Stratigraphy ◽  
Isotope Record ◽  
Continental Ice Sheets ◽  
Ice Core Records

Initially, terrestrial evidence formed the foundation for the division of Quaternary time. However, since the 1970s there has been an abandonment of the terrestrial stage chronostratigraphy, which is based on locally dominated successions, in favour of the marine oxygen isotope stratigraphy which largely records global-scale changes in ice volume. However, it is now clear that glacial records around the world are asynchronous, even at the scale of the continental ice sheets which display marked contrasts in extent and timing in different glacial cycles. Consequently, the marine isotope record does not reflect global patterns of glaciation, or other terrestrial processes, on land. This has led to inappropriate correlation of terrestrial records with the marine isotopic record. The low resolution of the latter has led to a preferential shift towards high-resolution ice-core records for global correlation. However, even in the short term, most terrestrial records display spatial variation in response to global climate fluctuations, and changes recorded on land are often diachronous, asynchronous or both, leading to difficulties in global correlation. Thus, whilst the marine and the ice-core records are very useful in providing global frameworks through time, it must be recognized that there exist significant problems and challenges for terrestrial correlation.

scholarly journals A 3500-Year Ice Chemistry Record From The Dominion Range, Antarctica: Linkages Between Climatic Variations and Precipitation Chemistry

1990 ◽  
Vol 14 ◽  
pp. 358-358
Author(s):  
Mary Jo Spencer ◽  
Paul A. Mayewski ◽  
W. Berry Lyons ◽  
Mark S. Twickler ◽  
Pieter Grootes
Keyword(s):  
Oxygen Isotope ◽  
Global Climate ◽  
Ice Core ◽  
Precipitation Chemistry ◽  
Climate Forcing ◽  
Climatic Forcing ◽  
Climatic Variations ◽  
Oxygen Isotope Record ◽  
Isotope Record

In 1984 a 200-m ice core was collected from a local accumulation basin in the Dominion Range, Transantarctic Mountains, Antarctica. A complete oxygen isotope record has been obtained and a considerable portion of the core has been analyzed in detail for chloride, nitrate, sulfate, and sodium. About half of the chloride is due to sea salt with the remainder originating as gaseous HCl. Nitrate levels have increased markedly over the last 1000 years whereas the levels of the other constituents have remained fairly constant.The oxygen isotope results suggest that this region of Antarctica is responding to long-term global climate forcing as well as to shorter-term climatic variations. This data will be compared with the anion and sodium records in order to determine the effects of climatic forcing on these other records. In particular, nitrate appears to vary in concert with fluctuations in long-term climate. Additionally, variations in each constituent over the 3500 year period will be examined in detail to determine the influence of other processes which affect their concentrations.

scholarly journals Simulating ice core <sup>10</sup>Be on the glacial–interglacial timescale

2015 ◽  
Vol 11 (2) ◽  
pp. 115-133 ◽  
Author(s):  
C. Elsässer ◽  
D. Wagenbach ◽  
I. Levin ◽  
A. Stanzick ◽  
M. Christl ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Accumulation Rate ◽  
Ice Core ◽  
Global Scale ◽  
Snow Accumulation ◽  
Transfer Model ◽  
Ice Concentration ◽  
Model Measurement ◽  
Ice Core Records

Abstract. 10Be ice core measurements are an important tool for paleoclimate research, e.g., allowing for the reconstruction of past solar activity or changes in the geomagnetic dipole field. However, especially on multi-millennial timescales, the share of production and climate-induced variations of respective 10Be ice core records is still up for debate. Here we present the first quantitative climatological model of the 10Be ice concentration up to the glacial–interglacial timescale. The model approach is composed of (i) a coarse resolution global atmospheric transport model and (ii) a local 10Be air–firn transfer model. Extensive global-scale observational data of short-lived radionuclides as well as new polar 10Be snow-pit measurements are used for model calibration and validation. Being specifically configured for 10Be in polar ice, this tool thus allows for a straightforward investigation of production- and non-production-related modulation of this nuclide. We find that the polar 10Be ice concentration does not immediately record the globally mixed cosmogenic production signal. Using geomagnetic modulation and revised Greenland snow accumulation rate changes as model input, we simulate the observed Greenland Summit (GRIP and GISP2) 10Be ice core records over the last 75 kyr (on the GICC05modelext timescale). We show that our basic model is capable of reproducing the largest portion of the observed 10Be changes. However, model–measurement differences exhibit multi-millennial trends (differences up to 87% in case of normalized to the Holocene records) which call for closer investigation. Focusing on the (12–37) b2k (before the year AD 2000) period, mean model–measurement differences of 30% cannot be attributed to production changes. However, unconsidered climate-induced changes could likely explain the model–measurement mismatch. In fact, the 10Be ice concentration is very sensitive to snow accumulation changes. Here the reconstructed Greenland Summit (GRIP) snow accumulation rate record would require revision of +28% to solely account for the (12–37) b2k model–measurement differences.

scholarly journals The Antarctic ice core chronology (AICC2012): an optimized multi-parameter and multi-site dating approach for the last 120 thousand years

2013 ◽  
Vol 9 (4) ◽  
pp. 1733-1748 ◽  
Author(s):  
D. Veres ◽  
L. Bazin ◽  
A. Landais ◽  
H. Toyé Mahamadou Kele ◽  
B. Lemieux-Dudon ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Strong Basis ◽  
Last Glacial ◽  
Sequence Of Events ◽  
Global Correlation ◽  
Wide Range ◽  
The Antarctic ◽  
The Last Glacial ◽  
Ice Core Records

Abstract. The deep polar ice cores provide reference records commonly employed in global correlation of past climate events. However, temporal divergences reaching up to several thousand years (ka) exist between ice cores over the last climatic cycle. In this context, we are hereby introducing the Antarctic Ice Core Chronology 2012 (AICC2012), a new and coherent timescale developed for four Antarctic ice cores, namely Vostok, EPICA Dome C (EDC), EPICA Dronning Maud Land (EDML) and Talos Dome (TALDICE), alongside the Greenlandic NGRIP record. The AICC2012 timescale has been constructed using the Bayesian tool Datice (Lemieux-Dudon et al., 2010) that combines glaciological inputs and data constraints, including a wide range of relative and absolute gas and ice stratigraphic markers. We focus here on the last 120 ka, whereas the companion paper by Bazin et al. (2013) focuses on the interval 120–800 ka. Compared to previous timescales, AICC2012 presents an improved timing for the last glacial inception, respecting the glaciological constraints of all analyzed records. Moreover, with the addition of numerous new stratigraphic markers and improved calculation of the lock-in depth (LID) based on δ15N data employed as the Datice background scenario, the AICC2012 presents a slightly improved timing for the bipolar sequence of events over Marine Isotope Stage 3 associated with the seesaw mechanism, with maximum differences of about 600 yr with respect to the previous Datice-derived chronology of Lemieux-Dudon et al. (2010), hereafter denoted LD2010. Our improved scenario confirms the regional differences for the millennial scale variability over the last glacial period: while the EDC isotopic record (events of triangular shape) displays peaks roughly at the same time as the NGRIP abrupt isotopic increases, the EDML isotopic record (events characterized by broader peaks or even extended periods of high isotope values) reached the isotopic maximum several centuries before. It is expected that the future contribution of both other long ice core records and other types of chronological constraints to the Datice tool will lead to further refinements in the ice core chronologies beyond the AICC2012 chronology. For the time being however, we recommend that AICC2012 be used as the preferred chronology for the Vostok, EDC, EDML and TALDICE ice core records, both over the last glacial cycle (this study), and beyond (following Bazin et al., 2013). The ages for NGRIP in AICC2012 are virtually identical to those of GICC05 for the last 60.2 ka, whereas the ages beyond are independent of those in GICC05modelext (as in the construction of AICC2012, the GICC05modelext was included only via the background scenarios and not as age markers). As such, where issues of phasing between Antarctic records included in AICC2012 and NGRIP are involved, the NGRIP ages in AICC2012 should therefore be taken to avoid introducing false offsets. However for issues involving only Greenland ice cores, there is not yet a strong basis to recommend superseding GICC05modelext as the recommended age scale for Greenland ice cores.

scholarly journals A 1400-Year Oxygen Isotope History from the Ross Sea Area, Antarctica

1990 ◽  
Vol 14 ◽  
pp. 94-98 ◽  
Author(s):  
P.M. Grootes ◽  
M. Stuiver ◽  
T.L. Saling ◽  
P.A. Mayewski ◽  
M.J. Spencer ◽  
...  
Keyword(s):  
Ross Sea ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Cores ◽  
Local Conditions ◽  
Climate Fluctuations ◽  
Ross Ice Shelf ◽  
Isotope Record ◽  
Highly Correlated ◽  
Sea Area

Four ice cores from the Ross Sea drainage, Antarctica, show patterns of δ18O variations on a time scale of decades to centuries over the last 1400 years without change in the long-term average δ18O. Century scale δ18O fluctuations in the two cores drilled in the Ross Ice Shelf at Station J-9 (82°23′S, 168°38′W, elevation 60 m) are highly correlated (P < 2 × 10−4). The long isotope record (>30 000 a) of the 1978 J-9 core thus represents local conditions over at least 102 m and on time scales of 100 years and longer.Regional correlations between the J-9 δ18O records and those from Ridge BC (82°54′S, 136°40′W, elevation 509 m) and the Dominion Range (85°15′S, 166°10′E, elevation 2700 m) are barely significant (P ≈ 0.05 for J-9 '76 and Dominion Range, 580 to 1400 years ago) or absent. The failure to find clear regional isotope trends related to climate fluctuations may reflect the finding that between 1957 and 1982 the area was in the transition zone between areas with opposite temperature trends, and showed little or no temperature change. The fact that the records nevertheless show significant δ18O fluctuations highlights the need to base regional climate reconstructions on a regional suite of ice-core records.

scholarly journals A 1400-Year Oxygen Isotope History from the Ross Sea Area, Antarctica

1990 ◽  
Vol 14 ◽  
pp. 94-98 ◽  
Author(s):  
P.M. Grootes ◽  
M. Stuiver ◽  
T.L. Saling ◽  
P.A. Mayewski ◽  
M.J. Spencer ◽  
...  
Keyword(s):  
Ross Sea ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Cores ◽  
Local Conditions ◽  
Climate Fluctuations ◽  
Ross Ice Shelf ◽  
Isotope Record ◽  
Highly Correlated ◽  
Sea Area

Four ice cores from the Ross Sea drainage, Antarctica, show patterns of δ18O variations on a time scale of decades to centuries over the last 1400 years without change in the long-term average δ18O. Century scale δ18O fluctuations in the two cores drilled in the Ross Ice Shelf at Station J-9 (82°23′S, 168°38′W, elevation 60 m) are highly correlated (P &lt; 2 × 10−4). The long isotope record (&gt;30 000 a) of the 1978 J-9 core thus represents local conditions over at least 102 m and on time scales of 100 years and longer. Regional correlations between the J-9 δ18O records and those from Ridge BC (82°54′S, 136°40′W, elevation 509 m) and the Dominion Range (85°15′S, 166°10′E, elevation 2700 m) are barely significant (P ≈ 0.05 for J-9 '76 and Dominion Range, 580 to 1400 years ago) or absent. The failure to find clear regional isotope trends related to climate fluctuations may reflect the finding that between 1957 and 1982 the area was in the transition zone between areas with opposite temperature trends, and showed little or no temperature change. The fact that the records nevertheless show significant δ18O fluctuations highlights the need to base regional climate reconstructions on a regional suite of ice-core records.

A 3500-Year Ice Chemistry Record From The Dominion Range, Antarctica: Linkages Between Climatic Variations and Precipitation Chemistry

1990 ◽  
Vol 14 ◽  
pp. 358
Author(s):  
Mary Jo Spencer ◽  
Paul A. Mayewski ◽  
W. Berry Lyons ◽  
Mark S. Twickler ◽  
Pieter Grootes
Keyword(s):  
Oxygen Isotope ◽  
Global Climate ◽  
Ice Core ◽  
Precipitation Chemistry ◽  
Climate Forcing ◽  
Climatic Forcing ◽  
Climatic Variations ◽  
Oxygen Isotope Record ◽  
Isotope Record

In 1984 a 200-m ice core was collected from a local accumulation basin in the Dominion Range, Transantarctic Mountains, Antarctica. A complete oxygen isotope record has been obtained and a considerable portion of the core has been analyzed in detail for chloride, nitrate, sulfate, and sodium. About half of the chloride is due to sea salt with the remainder originating as gaseous HCl. Nitrate levels have increased markedly over the last 1000 years whereas the levels of the other constituents have remained fairly constant. The oxygen isotope results suggest that this region of Antarctica is responding to long-term global climate forcing as well as to shorter-term climatic variations. This data will be compared with the anion and sodium records in order to determine the effects of climatic forcing on these other records. In particular, nitrate appears to vary in concert with fluctuations in long-term climate. Additionally, variations in each constituent over the 3500 year period will be examined in detail to determine the influence of other processes which affect their concentrations.

scholarly journals Simulating ice core <sup>10</sup>Be on the glacial–interglacial timescale

2014 ◽  
Vol 10 (1) ◽  
pp. 761-808 ◽  
Author(s):  
C. Elsässer ◽  
D. Wagenbach ◽  
I. Levin ◽  
A. Stanzick ◽  
M. Christl ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Accumulation Rate ◽  
Ice Core ◽  
Global Scale ◽  
Snow Accumulation ◽  
Transfer Model ◽  
10Be Concentration ◽  
Ice Concentration ◽  
Ice Core Records

Abstract. 10Be ice core measurements are an important tool for paleoclimate research, e.g. allowing for the reconstruction of past solar activity or variation in the natural 14C production rate. However, especially on multi-millennial timescales, the share of production and climate induced variations of respective 10Be ice core records is still up to debate. Here we present the first quantitative climatological model of the 10Be ice concentration up to the glacial–interglacial timescale. The model approach is composed of (i) a coarse resolution global atmospheric transport model and (ii) a local 10Be air–firn-transfer model. Extensive global-scale observational data of short-lived radionuclides as well as new polar 10Be snow pit measurements are used for model calibration and validation. Being specifically configured for polar 10Be, this tool thus allows for a straight-forward investigation of production and non-production related modulation of this nuclide. We find that the polar 10Be ice concentration does not record a globally mixed cosmogenic production signal. In fact, the geomagnetic modulation of Greenland 10Be is up to 50% lower than in case of the global atmospheric 10Be inventory. Using geomagnetic modulation and revised Greenland snow accumulation rate changes as model input we simulate the observed Greenland Summit (GRIP and GISP2) 10Be ice core records over the last 75 kyr (on the GICC05modelext timescale). We show that our basic model is capable to reproduce the largest portion of the observed 10Be changes. However, model-measurements differences exhibit multi-millennial oscillations with amplitudes up to 87% of the mean observed Holocene 10Be concentration. Focusing on the (12–37) kyr b2k (before the year 2000 AD) period, mean model-measurements differences of 30% cannot be imputed to production changes. However, unconsidered climate-induced changes could likely explain the model shortcomings. In fact, the 10Be ice concentration is very sensitive to snow accumulation changes. Here the reconstructed Greenland Summit (GRIP) snow accumulation rate record would require revision of +28% to solely account for the (12–37) kyr b2k measurements-model differences.

scholarly journals Reduced resilience of terrestrial ecosystems locally is not reflected on a global scale

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Yuhao Feng ◽  
Haojie Su ◽  
Zhiyao Tang ◽  
Shaopeng Wang ◽  
Xia Zhao ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Vegetation Index ◽  
Global Climate ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Ecological Resilience ◽  
Terrestrial Vegetation ◽  
Ecosystem Resilience

AbstractGlobal climate change likely alters the structure and function of vegetation and the stability of terrestrial ecosystems. It is therefore important to assess the factors controlling ecosystem resilience from local to global scales. Here we assess terrestrial vegetation resilience over the past 35 years using early warning indicators calculated from normalized difference vegetation index data. On a local scale we find that climate change reduced the resilience of ecosystems in 64.5% of the global terrestrial vegetated area. Temperature had a greater influence on vegetation resilience than precipitation, while climate mean state had a greater influence than climate variability. However, there is no evidence for decreased ecological resilience on larger scales. Instead, climate warming increased spatial asynchrony of vegetation which buffered the global-scale impacts on resilience. We suggest that the response of terrestrial ecosystem resilience to global climate change is scale-dependent and influenced by spatial asynchrony on the global scale.

scholarly journals Global phosphorus dynamics in terms of phosphine

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Wanyi Fu ◽  
Xihui Zhang
Keyword(s):  
Wastewater Treatment ◽  
Human Activities ◽  
Wastewater Treatment Plants ◽  
Global Climate ◽  
Global Scale ◽  
Phosphorus Cycle ◽  
Natural Ecosystems ◽  
Driving Cycles ◽  
Global Cycles ◽  
Urban Wastewater Treatment

AbstractSince the detection of phosphine in the wastewater treatment plants in 1988, more and more investigations revealed that phosphine is closely related to ecological activities on a global scale. Here, we present perspectives on the whole dynamic cycles of phosphorus, particularly in terms of phosphine and its interactions with natural ecosystems, as well as the impacts from human activities. It may conclude that the phosphine-driving cycles of phosphorus depend on the coordination of human activities with natural ecosystems. Most importantly, the extensive recovery of phosphorus in numerous urban wastewater treatment plants may seriously obstruct its global cycles to catch up with the ecological needs in natural ecosystems. Phosphine gas plays an important role in the biogeochemical phosphorus cycle. Phosphorus might be one of the important elements participating in the global climate change together with carbon and nitrogen.

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