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1: Geological Time Periods During the Cenozoic Era. Dates listed on the right hand side are taken from Gradstein et al. (2004).
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... Antarctic Ice Sheet has existed for approximately 35 million years, but it has fluctuated considerably and has been one of the major driving forces for E-mail: m.j.siegert@ed.ac.uk (M.J. Siegert). changes in global sea level and climate throughout the Cenozoic ( Fig. 1.1). The rates, size and frequencies of these fluctuations have been the subjects of considerable debate. Determination of the scale and rapidity of the response of large ice masses and associated sea ice to climatic forcing is of vital importance, because ice-volume variations lead to: (1) changing global sea levels on a scale of tens of ...
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... and (2) alteration to the capacity of ice sheets and sea ice as major heat sinks/insulators. It is thus important to assess the stability of the cryosphere under a warming climate (IPCC, 2007), particularly as ice- core records have yielded evidence of a strong correlation between CO 2 concentrations in the atmosphere and palaeotemperatures ( Fig. 1.2). This concern is justified when CO 2 levels are compared with those of the past. Since Antarctica is a major driver of Earth's climate and sea level, much effort has been expended in deriving models of its behaviour. Some of these models have been successfully evaluated against modern conditions. In 2004, modelling the past record of ...
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... continental landmasses with the repositioning of Antarctica at southern polar latitudes in the Early Cretaceous (ca. 120 Ma). In spite of its polar position, Antarctica is thought to have remained mostly ice-free, vegetated, and with mean annual temperatures above freezing until the latter half of the Cenozoic (around 34 million years ago, Fig. 1.1), whereupon the continent became subject to repeated phases of glaciation at a variety of temporal and spatial scales. The southern continent and its surrounding ocean basins have been the target of numerous scientific expeditions and several scientific drilling project efforts that have led to significant advances in understanding of ...
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Polar mesosphere summer echoes (PMSE) have been observed for more than 30 years with 50 MHz VHF radars at various locations in the Northern Hemisphere. Continuous observation of PMSE is conducted on the northern Norwegian island of Andøya (69.3° N) using the ALWIN radar (1999–2008) and MAARSY (since 2010). The same kind of PMSE measurements began i...
We study palaeoclimatic records from various sites spread around the earth, focusing on the start of the last glacial-interglacial transition. The warming, as recorded in the δ18O record started First in the trop- ics, then propagated to the Antarctic and then finally to the Arctic. Our analysis of the data suggests that it took about 7.6 ka for on...
Based on the data and method offered by Liu et al. (2009), the direct wind and Stokes drift-induced energy inputs into the Ekman layer within the Antarctic Circumpolar Current (ACC) area are reestimated since the results of the former have been proved to be underestimated. And the result shows that the total rate of energy input into the Ekman-Stok...
Citations
... ACE grew out of the ANTOSTRAT (ANTarctic Offshore STRATigraphy) project, which was sanctioned by SCAR in 1990, to reconstruct the Cenozoic palaeoclimatic and glacial history of the Antarctic region from the study of the sedimentary record surrounding the continent. The main achievements of ANTOSTRAT and ACE were published in a set of special issues (Florindo et al., 2003(Florindo et al., , 2005(Florindo et al., , 2009Barrett et al., 2006;Escutia et al., 2012) and summarized in the first edition of this book published in December 2008 (Florindo and Siegert, 2008). ACE was followed from 2013 to 2020 by the Past Antarctic Ice Sheet dynamics (PAIS) programme, which continued work on constraining Antarctica's contribution to sea level resulting from past changes in ice sheet mass loss, and understanding its impacts on global environments through changes to atmospheric and oceanic circulation. ...
Antarctic Climate Evolution - second edition is a result of both SCAR pro�grammes and documents the state of knowledge concerning the ice and climate evolution of the Antarctic continent and its surrounding seas through the Cenozoic era to present day and into the future. Most of the subcommit�tees in ACE and PAIS have been responsible for individual chapters and, in this way, we have been able to cover the complete history of the Antarctic Ice Sheet and its climate evolution. The book will be of interest to research scientists from a wide range of disci�plines including glaciology, palaeoclimatology, sedimentology, climate change, environmental science, oceanography and palaeontology. It will also be valuable as a supplementary text for undergraduate courses.
... This special issue of Palaeogeography, Palaeoclimatology, Palaeoecology continues a series of related special issues and a book ( Florindo et al., 2003Florindo et al., , 2005Barrett et al., 2006;Florindo et al., 2008;Florindo and Siegert, 2009;), all of which are linked to the ACE program and data-model integration. ...
... In addition, ACE has established linkages to other communities, including those involved in ice core drilling, physical oceanography of the Southern Ocean, and glaciology. This special issue of Palaeogeography, Palaeoclimatology, Palaeoecology continues a series of related special issues and a book (Florindo et al., 2003Florindo et al., , 2005 Barrett et al., 2006; Florindo et al., 2008; Florindo and Siegert, 2009;), all of which are linked to the ACE program and data‐model integration.) Neogene (the past 23 million years) climate and ice sheet variability and implications for future sea level. ...
... This special issue of Palaeogeography, Palaeoclimatology, Palaeoecology continues a series of related special issues and a book (Florindo et al., 2003(Florindo et al., , 2005Barrett et al., 2006;Florindo et al., 2008;Florindo and Siegert, 2009;, all of which are linked to the ACE program and data-model integration. ...
The Antarctic cryosphere is an important component of the modern global climate system. Interactions and feedbacks between ice, ocean, atmosphere, and biosphere result in changes in sea level, ocean circulation and heat transport, marine productivity, air–sea gas exchange, and planetary albedo. The modern Antarctic ice sheets developed ~ 34 m.y. ago, whereas major Northern Hemisphere continental ice caps formed only ~ 3 m.y. ago (Zachos et al., 2008). Coupled climate and ice sheet models (DeConto and Pollard, 2003a, DeConto and Pollard, 2003b, Huber et al., 2004, DeConto et al., 2007 and DeConto et al., 2008) and paleoclimatic and CO2 proxy data (Coxall et al., 2005, Pagani et al., 2005, Liu et al., 2009 and Pearson et al., 2009) suggest decreasing levels of greenhouse gases combined with orbital forcing was the most likely triggering mechanism for inception and development of the Antarctic ice sheet. This implies that the opening of Southern Ocean gateways played only a secondary role (Kennett, 1977, DeConto and Pollard, 2003a and Huber et al., 2004), however the possible connection between the gateways, the marine carbon cycle, and declining Cenozoic CO2 remains unresolved (Mikolajewicz et al., 1993 and DeConto et al., 2007). Since their inception, the Antarctic ice sheets appear to have been very dynamic, waxing and waning in response to global climate change over intermediate and even short (orbital) timescales (Wise et al., 1991, Zachos et al., 1997 and Pollard and DeConto, 2009). While geological evidence of Pliocene–Pleistocene variability of the marine-based West Antarctic Ice Sheet (WAIS) has been simulated by state of the art ice sheet models, the apparent Cenozoic variability of the bigger, terrestrial East Antarctic Ice Sheet (EAIS) has proven much more difficult to reconcile with existing climate and ice models (Pollard and DeConto, 2005), reminding us that much still needs to be learned about the nature, cause, timing, and rate of processes involved in these changes.
In light of the current rising levels of atmospheric greenhouse gases, it is particularly important to assess past Antarctic ice sheet dynamics and stability that can be used as an analogue for future changes. Based on IPCC (2007) forecasts, atmospheric CO2 doubling and a 1.8 °C–4.2 °C temperature rise are expected by the end of this century. The lower values of these estimates have not been experienced on our planet for 10–15 million years, and the higher estimates have not been experienced since before ice sheets formed on Antarctica.
The Antarctic Climate Evolution (ACE) Program is one of the Scientific Research Programs (SRPs) of the Scientific Committee on Antarctic Research (SCAR), and is a core International Polar Year (IPY) Project. ACE aims to facilitate the study of Antarctic climate and glacial history (i.e., greenhouse Antarctica, the onset of glaciation, and the response of the Antarctic ice sheets to past climate changes across a range of timescales) through integration of numerical modeling with geophysical and geological data. This data-model philosophy allows for observations from field data to gain much greater explanatory power and to explore forcing factors and mechanisms of change. The work conducted by ACE is highlighting the relevance of past climate change and ice sheet evolution on timescales of thousands, hundreds of thousands, and millions of years for understanding climate and ice sheet variability, and the forcing mechanisms that control future change. ACE science depends on a range of regional field programs including both onshore and offshore geophysical and geological records from field geology, ocean–ice shelf–continental drilling, and marine and airborne geophysical surveys. In addition, ACE has established linkages to other communities, including those involved in ice core drilling, physical oceanography of the Southern Ocean, and glaciology.
This special issue of Palaeogeography, Palaeoclimatology, Palaeoecology continues a series of related special issues and a book (Florindo et al., 2003, Florindo et al., 2005, Barrett et al., 2006, Florindo et al., 2008, Florindo and Siegert, 2009 and Florindo et al., 2009), all of which are linked to the ACE program and data‐model integration.
... This special issue of Palaeogeography, Palaeoclimatology, Palaeoecology continues a series of related special issues and a book (Florindo et al., 2003(Florindo et al., , 2005Barrett et al., 2006;Florindo et al., 2008;Florindo and Siegert, 2009;, all of which are linked to the ACE program and data-model integration. ...
... The main objectives of our study are to: (1) provide robust identification of the main magnetic 80 carriers in the drift sediments, which is important for understanding the paleomagnetic recording 81 process, and (2) construct a robust chronostratigraphic framework for cores SED-7, SED-12, and 82 SED-13, which is which is important for reconstructing Late Pleistocene paleoenvironments of the 83 Antarctic Peninsula. The Antarctic Peninsula may represent the best natural laboratory to 84 investigate the interaction of atmosphere, hydrosphere and cryosphere and the response of Earth's 85 climate system to rapid regional warming [e.g., Florindo and Siegert, 2009]. Over the past 50 years, 86 the Antarctic Peninsula has experienced the greatest atmospheric temperature increase on Earth, 87 rising by nearly 3°C [e.g., King et al., 2003; Turner et al., 2005], which is approximately 10 times 88 the mean rate of present global warming [IPCC, 2007] ...
We present results of detailed paleomagnetic investigations on deep-sea
cores from sediment drifts located along the Pacific continental margin
of the Antarctic Peninsula. High-resolution magnetic measurements on u
channel samples provide detailed age models for three cores collected
from drift 7, which document an age of 122 ka for the oldest sediments
recovered near the drift crest at site SED-07 and a high sedimentation
rate (11 cm/kyr) at site SED-12 located close to the Alexander Channel
system. Low- and high-temperature magnetic measurements in conjunction
with microscopic and mineralogic observations from drifts 4, 5 and 7
indicate that pseudosingle-domain detrital titanomagnetite (partially
oxidized and with limited Ti substitution) is the dominant magnetic
mineral in the drift sediments. The titanomagnetite occurs in two
magnetic forms: (1) a low-coercivity form similar to
laboratory-synthesized titanomagnetite and (2) a high-coercivity form
(Bcr > 60 mT). These two forms vary in amount and
stratigraphic distribution across the drifts. We did not find evidence
for diagenetic magnetic iron sulfides as has been previously suggested
for these drift deposits. The observed change of magnetic mineralogy in
sediments deposited during Heinrich events on drift 7 appears to be
related to warming periods, which temporarily modified the normal
glacial transport pathways of glaciogenic detritus to and along the
continental rise and thus resulted in deposition of sediments with a
different provenance. Understanding this sediment provenance delivery
signature at a wider spatial scale should provide information about ice
sheet dynamics in West Antarctica over the last ˜100 kyr.
... The data presented in the present Initial Report volume are vital to the Scientific Committee on Antarctic Research (SCAR) scientific research programme -Antarctic Climate Evolution (ACE -http://www.ace.scar.org/) (Florindo & Siegert, 2008), whose objective is the integration of new Antarctic geological and paleoclimatic data into climate and ice sheet models. Empirical data generated from ANDRILL studies will help calibrate these numerical models, enabling new constraint to be placed on estimates of ice volume variability, sea-level change, terrestrial and marine paleotemperature, and the timing of development and paleodistribution of Antarctica's terrestrial and marine biota. ...
The history of glaciations on Southern Hemisphere sub-polar islands is unclear. Debate surrounds the extent and timing of the last glacial advance and termination on sub-Antarctic South Georgia in particular. Here, using sea-floor geophysical data and marine sediment cores, we resolve the record of glaciation offshore of South Georgia through the transition from the Last Glacial Maximum to Holocene. We show a sea-bed landform imprint of a shelf-wide last glacial advance and progressive deglaciation. Renewed glacier resurgence in the fjords between c. 15,170 and 13,340 yr ago coincided with a period of cooler, wetter climate known as the Antarctic Cold Reversal, revealing a cryospheric response to an Antarctic climate pattern extending into the Atlantic sector of the Southern Ocean. We conclude that the last glaciation of South Georgia was extensive, and the sensitivity of its glaciers to climate variability during the last termination more significant than implied by previous studies.
Penguin bones from the Eocene La Meseta Formation (Seymour Island, Antarctic Peninsula) constitute the only extensive fossil record of Antarctic Sphenisciformes. Here, we synonymize some of the recognized genera (Anthropornis with Orthopteryx, Delphinornis with Ichtyopteryx) and species (Anthropornis nordenskjoeldi with Orthopteryx gigas, Delphinornis gracilis with Ichtyopteryx gracilis). Moreover, we suggest that Antarctic species of Anthropornis and Palaeeudyptes, so-called giant penguins, may in fact comprise only one species each instead of two, based on evidence of well-marked sexual dimorphism. We also present new estimates of body mass based on femora testifying to the impressive scope of interspecific body-size variation in Eocene Antarctic penguins.
