ORCID Profile
0000-0002-6471-1106
Current Organisations
Keele University
,
University of New South Wales
,
Cranfield University
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Palaeoclimatology | Glaciology | Physical Geography and Environmental Geoscience | Climate Change Processes | Geochronology
Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Global Effects of Climate Change and Variability (excl. Australia, New Zealand, Antarctica and the South Pacific) (excl. Social Impacts) |
Publisher: American Geophysical Union (AGU)
Date: 10-2015
DOI: 10.1002/2015JC010972
Publisher: Informa UK Limited
Date: 03-2006
Publisher: Elsevier BV
Date: 10-2007
Publisher: Proceedings of the National Academy of Sciences
Date: 17-09-2012
Abstract: Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the Antarctic ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-Antarctic terrestrial and marine geological data for constraint, then perturb the system with sea level and ocean heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to ocean forcings, in agreement with empirical data. Most significantly, we find that although ocean warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments—a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.
Publisher: Copernicus GmbH
Date: 30-07-2015
Abstract: Abstract. Future changes in atmospheric circulation and associated modes of variability are a major source of uncertainty in climate projections. Nowhere is this issue more acute than across the mid- to high-latitudes of the Southern Hemisphere (SH) which over the last few decades has experienced extreme and regional variable trends in precipitation, ocean circulation, and temperature, with major implications for Antarctic ice melt and surface mass balance. Unfortunately there is a relative dearth of observational data, limiting our understanding of the driving mechanism(s). Here we report a new 130-year annually-resolved record of δ D – a proxy for temperature – from the South Geographic Pole where we find a significant influence from extra-tropical pressure anomalies which act as "gatekeepers" to the meridional exchange of air masses. Reanalysis of global atmospheric circulation suggests these pressure anomalies play a considerably larger influence on mid- to high-latitude SH climate than hitherto believed, modulated by the tropical Pacific Ocean. Our findings suggest that future increasing tropical warmth will strengthen meridional circulation, exaggerating current trends, with potentially significant impacts on Antarctic surface mass balance.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Copernicus GmbH
Date: 25-04-2017
DOI: 10.5194/TC-2017-51
Abstract: Abstract. Satellite observations demonstrate Antarctic sea ice extent increased between late-1978 and 2015, with significant spatial and seasonal variability. Late spring retreat off George V Land is a major component of the observed increase, but the paucity of proxy records makes interpretation of trends (and impacts) challenging. Here Earth-system modelling and reanalysis demonstrate tropical Pacific warming can trigger an atmospheric Rossby wave response during the austral spring, delaying sea-ice retreat off George V Land. Our results provide new insights into the spatial and temporal role low latitudes play in Antarctic sea-ice production, drift and ocean circulation on decadal to centennial timescales.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7DT02930F
Abstract: The distribution of Fe( ii ) and Ni( ii ) over two distinct metal sites in [Fe 9−x Ni x ] clusters is studied by X-ray crystallography, Mössbauer and XRF spectroscopies, and DFT calculations.
Publisher: American Geophysical Union (AGU)
Date: 02-03-2016
DOI: 10.1002/2015GL066476
Publisher: Copernicus GmbH
Date: 04-06-2016
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 02-2008
Publisher: Copernicus GmbH
Date: 10-12-2020
DOI: 10.5194/ESSD-12-3341-2020
Abstract: Abstract. A valuable analogue for assessing Earth's sensitivity to warming is the Last Interglacial (LIG 129–116 ka), when global temperatures (0 to +2 ∘C) and mean sea level (+6 to 11 m) were higher than today. The direct contribution of warmer conditions to global sea level (thermosteric) is uncertain. We report here a global network of LIG sea surface temperatures (SST) obtained from various published temperature proxies (e.g. faunal and floral plankton assemblages, Mg ∕ Ca ratios of calcareous organisms, and alkenone U37K′). We summarize the current limitations of SST reconstructions for the LIG and the spatial temperature features of a naturally warmer world. Because of local δ18O seawater changes, uncertainty in the age models of marine cores, and differences in s ling resolution and/or sedimentation rates, the reconstructions are restricted to mean conditions. To avoid bias towards in idual LIG SSTs based on only a single (and potentially erroneous) measurement or a single interpolated data point, here we report average values across the entire LIG. Each site reconstruction is given as an anomaly relative to 1981–2010, corrected for ocean drift, and where available seasonal estimates are provided (189 annual, 99 December–February, and 92 June–August records). To investigate the sensitivity of the reconstruction to high temperatures, we also report maximum values during the first 5 millennia of the LIG (129–124 ka). We find mean global annual SST anomalies of 0.2 ± 0.1 ∘C averaged across the LIG and an early maximum peak of 0.9 ± 0.1 ∘C, respectively. The global dataset provides a remarkably coherent pattern of higher SST increases at polar latitudes than in the tropics (demonstrating the polar lification of surface temperatures during the LIG), with comparable estimates between different proxies. Polewards of 45∘ latitude, we observe annual SST anomalies averaged across the full LIG of 0.8 ± 0.3 ∘C in both hemispheres with an early maximum peak of 2.1 ± 0.3 ∘C. Using the reconstructed SSTs suggests a mean LIG global thermosteric sea level rise of 0.08 ± 0.1 m and a peak contribution of 0.39 ± 0.1 m, respectively (assuming warming penetrated to 2000 m depth). The data provide an important natural baseline for a warmer world, constraining the contributions of Greenland and Antarctic ice sheets to global sea level during a geographically widespread expression of high sea level, and can be used to test the next inter-comparison of models for projecting future climate change. The dataset described in this paper, including summary temperature and thermosteric sea level reconstructions, is available at 0.1594/PANGAEA.904381 (Turney et al., 2019).
Publisher: Informa UK Limited
Date: 06-2005
Publisher: Springer Science and Business Media LLC
Date: 02-07-2013
DOI: 10.1038/SREP02118
Publisher: Copernicus GmbH
Date: 07-03-2016
DOI: 10.5194/TC-2016-19
Abstract: Abstract. The dramatic calving of the Mertz Glacier Tongue in 2010, triggered by the impact of iceberg B09B, reshaped the oceanographic regime across the Mertz Polynya and Commonwealth Bay, regions where high salinity shelf water (HSSW) is formed, the precursor to Antarctic bottom water (AABW). Here we compare post-calving observations with high-resolution ocean modelling which suggest that this reconfiguration has led to the development of a new polynya off Commonwealth Bay, where HSSW production continues by the grounding of B09B. Our findings demonstrate how local changes in icescape can impact formation of AABW, with implications for large-scale ocean circulation and climate.
Publisher: Wiley
Date: 26-12-2014
DOI: 10.1002/JQS.2683
Publisher: Research Square Platform LLC
Date: 25-10-2021
DOI: 10.21203/RS.3.RS-1008132/V1
Abstract: Beneficiaries prefer renewable energy-based systems over grid-connected electricity. The cost of energy is viewed as the most influential factor while choosing renewable energy systems. Beneficiaries chose to stay linked with renewable energy systems even when they received grid-connected electricity at a lower tariff.Net-metering and feed-in tariff mechanisms, as well as tax cuts and subsidies for renewable energy projects, could be the catalyst for fostering greater uptake of renewables in the electricity generation mix.
Publisher: Research Square Platform LLC
Date: 28-10-2021
DOI: 10.21203/RS.3.RS-1008132/V2
Abstract: Beneficiaries prefer renewable energy-based systems over grid-connected electricity. The cost of energy is viewed as the most influential factor while choosing renewable energy systems. Beneficiaries chose to stay linked with renewable energy systems even when they received grid-connected electricity at a lower tariff.Net-metering and feed-in tariff mechanisms, as well as tax cuts and subsidies for renewable energy projects, could be the catalyst for fostering greater uptake of renewables in the electricity generation mix.
Publisher: Springer Science and Business Media LLC
Date: 22-06-2020
Publisher: MDPI AG
Date: 05-08-2021
DOI: 10.3390/RS13163091
Abstract: Ground deformation related to mining activities may occur immediately or many years later, leading to a series of mine geological disasters, such as ground fissures, collapses, and even mining earthquakes. Deformation monitoring has been carried out with techniques, such as multitemporal interferometric synthetic aperture radar (MTInSAR). Over the past decade, MTInSAR has been widely used in monitoring mining deformation, and it is still difficult to retrieve mining deformation over dense vegetation areas. In this study, we use multiple-platform SAR images to retrieve mining deformation over dense vegetation areas. The high-quality interferograms are selected by the coherence map, and the mining deformation is retrieved by the MSBAS-InSAR technique. SAR images from TerraSAR-X, Sentinel-1A, Radarsat-2, and PALSAR-2 over the Fengfeng mining area, Heibei, China, are used to retrieve the deformation of mining activities covered with dense vegetation. The results show that the subsidence in the Fengfeng mining area reaches up to 90 cm over the period from July 2015 to April 2016. The root-mean-square error (RMSE) between the results from InSAR and leveling is 83.5 mm/yr at two mining sites, i.e., Wannian and Jiulong Mines.
Publisher: Copernicus GmbH
Date: 26-05-2016
DOI: 10.5194/TC-2016-111
Abstract: Abstract. Recent observations and modelling studies have demonstrated the potential for rapid and substantial retreat of large sectors of the East Antarctic Ice Sheet (EAIS). This has major implications for ocean circulation and global sea level. Here we examine the effects of increasing meltwater from the Wilkes Basin, one of the major marine-based sectors of the EAIS, on Southern Ocean dynamics. Climate model simulations reveal that the meltwater flux rapidly stratifies surface waters, leading to a dramatic decrease in the rate of Antarctic Bottom Water formation. The surface ocean cools but, critically, the Southern Ocean warms by more than 1 ºC at depth. This warming is accompanied by a Southern Ocean-wide "domino effect", whereby the warming signal propagates westward with depth. Our results suggest that melting of one sector of the EAIS could result in accelerated warming across other sectors, including the Weddell Sea sector of the West Antarctic Ice Sheet. Thus localised melting of the EAIS could potentially destabilise the wider Antarctic Ice Sheet.
Publisher: California Digital Library (CDL)
Date: 07-12-2018
Publisher: Copernicus GmbH
Date: 13-11-2018
Abstract: Abstract. The Amundsen Sea Low (ASL) plays a major role in the climate and environment of Antarctica and the Southern Ocean, including surface air temperature and sea ice concentration changes. Unfortunately, a relative dearth of observational data across the Amundsen and Bellingshausen seas prior to the satellite era (post-1979) limits our understanding of the past behaviour and impact of the ASL. The limited proxy evidence for changes in the ASL are primarily restricted to the Antarctic where ice core evidence suggests a deepening of the atmospheric pressure system during the late Holocene. However, no data have previously been reported from the northern side of the ASL. Here we report a high-resolution, multi-proxy study of a 5000-year-long peat record from the Falkland Islands, a location sensitive to contemporary ASL dynamics which modulates northerly and westerly airflow across the southwestern South Atlantic sector of the Southern Ocean. In combination with climate reanalysis, we find a marked period of wetter, colder conditions most likely the result of enhanced southerly airflow between 5000 and 2500 years ago, suggesting limited ASL influence over the region. After 2500 years ago, drier and warmer conditions were established, implying more westerly airflow and the increased projection of the ASL onto the South Atlantic. The possible role of the equatorial Pacific via atmospheric teleconnections in driving this change is discussed. Our results are in agreement with Antarctic ice core records and fjord sediments from the southern South American coast, and suggest that the Falkland Islands provide a valuable location for reconstructing high southern latitude atmospheric circulation changes on multi-decadal to millennial timescales.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-11-2021
Abstract: Our paper about the impacts of the Lasch s Geomagnetic Excursion 42,000 years ago has provoked considerable scientific and public interest, particularly in the so-called Adams Event associated with the initial transition of the magnetic poles. Although we welcome the opportunity to discuss our new ideas, Hawks’ assertions of misrepresentation are especially disappointing given his limited examination of the material.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Copernicus GmbH
Date: 03-02-2016
Abstract: Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high latitudes with potentially global climate implications. Unfortunately, historic observations only extend back to the late 19th century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30-year) record of past westerly wind strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated within the core latitude of Southern Hemisphere westerly airflow (the so-called furious fifties), we identify highly variable changes in exotic pollen and charcoal derived from South America which can be used to inform on past westerly air strength. We find a period of high charcoal content between 2000 and 1000 cal. years BP, associated with increased burning in Patagonia, most probably as a result of higher temperatures and stronger westerly airflow. Spectral analysis of the charcoal record identifies a pervasive ca. 250-year periodicity that is coherent with radiocarbon production rates, suggesting that solar variability has a modulating influence on Southern Hemisphere westerly airflow. Our results have important implications for understanding global climate change through the late Holocene.
Publisher: Geological Society of America
Date: 09-2006
DOI: 10.1130/B25735.1
Publisher: Elsevier BV
Date: 10-2013
Publisher: Microbiology Society
Date: 13-04-2022
DOI: 10.1099/MIC.0.001176
Abstract: Antarctic sea-ice forms a complex and dynamic system that drives many ecological processes in the Southern Ocean. Sea-ice microalgae and their associated microbial communities are understood to influence nutrient flow and allocation in marine polar environments. Sea-ice microalgae and their microbiota can have high seasonal and regional ( km 2 ) compositional and abundance variation, driven by factors modulating their growth, symbiotic interactions and function. In contrast, our knowledge of small-scale variation in these communities is limited. Understanding variation across multiple scales and its potential drivers is critical for informing on how multiple stressors impact sea-ice communities and the functions they provide. Here, we characterized bacterial communities associated with sea-ice microalgae and the potential drivers that influence their variation across a range of spatial scales (metres to kms) in a previously understudied area in Commonwealth Bay, East Antarctica where anomalous events have substantially and rapidly expanded local sea-ice coverage. We found a higher abundance and different composition of bacterial communities living in sea-ice microalgae closer to the shore compared to those further from the coast. Variation in community structure increased linearly with distance between s les. Ice thickness and depth to the seabed were found to be poor predictors of these communities. Further research on the small-scale environmental drivers influencing these communities is needed to fully understand how large-scale regional events can affect local function and ecosystem processes.
Publisher: Proceedings of the National Academy of Sciences
Date: 11-02-2020
Abstract: The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice–climate feedbacks that further lify warming.
Publisher: Springer Science and Business Media LLC
Date: 12-09-2017
DOI: 10.1038/S41467-017-00577-6
Abstract: Contrasting Greenland and Antarctic temperatures during the last glacial period (115,000 to 11,650 years ago) are thought to have been driven by imbalances in the rates of formation of North Atlantic and Antarctic Deep Water (the ‘bipolar seesaw’). Here we exploit a bidecadally resolved 14 C data set obtained from New Zealand kauri ( Agathis australis ) to undertake high-precision alignment of key climate data sets spanning iceberg-rafted debris event Heinrich 3 and Greenland Interstadial (GI) 5.1 in the North Atlantic (~30,400 to 28,400 years ago). We observe no ergence between the kauri and Atlantic marine sediment 14 C data sets, implying limited changes in deep water formation. However, a Southern Ocean (Atlantic-sector) iceberg rafted debris event appears to have occurred synchronously with GI-5.1 warming and decreased precipitation over the western equatorial Pacific and Atlantic. An ensemble of transient meltwater simulations shows that Antarctic-sourced salinity anomalies can generate climate changes that are propagated globally via an atmospheric Rossby wave train.
Publisher: Copernicus GmbH
Date: 04-11-2016
Abstract: Abstract. The dramatic calving of the Mertz Glacier tongue in 2010, precipitated by the movement of iceberg B09B, reshaped the oceanographic regime across the Mertz Polynya and Commonwealth Bay, regions where high-salinity shelf water (HSSW) – the precursor to Antarctic bottom water (AABW) – is formed. Here we present post-calving observations that suggest that this reconfiguration and subsequent grounding of B09B have driven the development of a new polynya and associated HSSW production off Commonwealth Bay. Supported by satellite observations and modelling, our findings demonstrate how local icescape changes may impact the formation of HSSW, with potential implications for large-scale ocean circulation.
Publisher: Copernicus GmbH
Date: 03-06-2015
Abstract: Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high-latitudes with potentially global climate implications. Unfortunately historic observations only extend back to the late nineteenth century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30 yr) record of past westerly air strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated under the core latitude of Southern Hemisphere westerly airflow, we identify highly variable changes in exotic pollen derived from South America which can be used to inform on past westerly air strength and location. The results indicate enhanced airflow over the Falklands between 2000 and 1000 cal. yr BP, and associated with increased burning, most probably as a result of higher temperatures and/or reduced precipitation, comparable to records in South America. Spectral analysis of the charcoal record identifies a 250 year periodicity within the data, suggesting solar variability has a modulating influence on Southern Hemisphere westerly airflow with potentially important implications for understanding global climate change through the late Holocene.
Publisher: Springer Science and Business Media LLC
Date: 10-2015
DOI: 10.1038/NATURE15706
Abstract: Atmospheric warming is projected to increase global mean surface temperatures by 0.3 to 4.8 degrees Celsius above pre-industrial values by the end of this century. If anthropogenic emissions continue unchecked, the warming increase may reach 8-10 degrees Celsius by 2300 (ref. 2). The contribution that large ice sheets will make to sea-level rise under such warming scenarios is difficult to quantify because the equilibrium-response timescale of ice sheets is longer than those of the atmosphere or ocean. Here we use a coupled ice-sheet/ice-shelf model to show that if atmospheric warming exceeds 1.5 to 2 degrees Celsius above present, collapse of the major Antarctic ice shelves triggers a centennial- to millennial-scale response of the Antarctic ice sheet in which enhanced viscous flow produces a long-term commitment (an unstoppable contribution) to sea-level rise. Our simulations represent the response of the present-day Antarctic ice-sheet system to the oceanic and climatic changes of four representative concentration pathways (RCPs) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We find that substantial Antarctic ice loss can be prevented only by limiting greenhouse gas emissions to RCP 2.6 levels. Higher-emissions scenarios lead to ice loss from Antarctic that will raise sea level by 0.6-3 metres by the year 2300. Our results imply that greenhouse gas emissions in the next few decades will strongly influence the long-term contribution of the Antarctic ice sheet to global sea level.
Publisher: IOP Publishing
Date: 06-2016
Publisher: Wiley
Date: 2016
DOI: 10.1002/JQS.2828
Publisher: Geological Society of America
Date: 08-11-2017
DOI: 10.1130/G38402.1
Publisher: Springer Science and Business Media LLC
Date: 26-06-2015
DOI: 10.1038/SREP11673
Abstract: Recent paleoclimate reconstructions have challenged the traditional view that Northern Hemisphere insolation and associated feedbacks drove synchronous global climate and ice-sheet volume during the last glacial cycle. Here we focus on the response of the Patagonian Ice Sheet and demonstrate that its maximum expansion culminated at 28,400 ± 500 years before present (28.4 ± 0.5 ka), more than 5,000 years before the minima in 65°N summer insolation and the formally-defined Last Glacial Maximum (LGM) at 21,000 ± 2,000 years before present. To investigate the potential drivers of this early LGM (eLGM), we simulate the effects of orbital changes using a suite of climate models incorporating prescribed and evolving sea-ice anomalies. Our analyses suggest that Antarctic sea-ice expansion at 28.5 ka altered the location and intensity of the Southern Hemisphere storm track, triggering regional cooling over Patagonia of 5°C that extends across the wider mid-southern latitudes. In contrast, at the LGM, continued sea-ice expansion reduced regional temperature and precipitation further, effectively starving the ice sheet and resulting in reduced glacial expansion. Our findings highlight the dominant role that orbital changes can play in driving Southern Hemisphere glacial climate via the sensitivity of mid-latitude regions to changes in Antarctic sea-ice extent.
Publisher: Wiley
Date: 07-2014
DOI: 10.1002/JQS.2700
Publisher: Copernicus GmbH
Date: 30-07-2015
Publisher: Wiley
Date: 10-2013
DOI: 10.1002/JQS.2668
Publisher: Elsevier BV
Date: 03-2014
Publisher: American Geophysical Union (AGU)
Date: 10-2015
DOI: 10.1002/2015EF000306
Publisher: Springer Science and Business Media LLC
Date: 09-08-2018
DOI: 10.1038/S41598-018-29226-8
Abstract: Understanding feedbacks between the Greenland Ice Sheet (GrIS) and the Atlantic Meridional Overturning Circulation (AMOC) is crucial for reducing uncertainties over future sea level and ocean circulation change. Reconstructing past GrIS dynamics can extend the observational record and elucidate mechanisms that operate on multi-decadal timescales. We report a highly-constrained last glacial vertical profile of cosmogenic isotope exposure ages from Sermilik Fjord, a marine-terminating ice stream in the southeast sector of the GrIS. Our reconstruction reveals substantial ice-mass loss throughout the Younger Dryas (12.9-11.7 ka), a period of marked atmospheric and sea-surface cooling. Earth-system modelling reveals that southern GrIS marginal melt was likely driven by strengthening of the Irminger Current at depth due to a weakening of the AMOC during the Younger Dryas. This change in North Atlantic circulation appears to have drawn warm subsurface waters to southeast Greenland despite markedly cooler sea surface temperatures, enhancing thermal erosion at the grounding lines of palaeo ice-streams, supporting interpretation of regional marine-sediment cores. Given current rates of GrIS meltwater input into the North Atlantic and the vulnerability of major ice streams to water temperature changes at the grounding line, this mechanism has important implications for future AMOC changes and northern hemisphere heat transport.
Publisher: Cambridge University Press (CUP)
Date: 02-02-2016
DOI: 10.1017/S0954102015000644
Abstract: The arrival of iceberg B09B in Commonwealth Bay, East Antarctica, and subsequent fast ice expansion has dramatically increased the distance Adélie penguins ( Pygoscelis adeliae ) breeding at Cape Denison must travel in search of food. This has provided a natural experiment to investigate the impact of iceberg stranding events and sea ice expansion along the East Antarctic coast. As part of the Australasian Antarctic Expedition 2013–14, the Adélie penguin colony at Cape Denison was censused to compare to historic counts. Whilst some 5520 pairs still bred at Cape Denison there has been an order of magnitude decline in Adélie numbers in the area in comparison to the first counts a century ago and, critically, recent estimates based on satellite images and a census in 1997. In contrast, an Adélie population on the eastern fringe of Commonwealth Bay just 8 km from the fast ice edge was thriving, indicating the arrival of B09B and fast ice expansion was probably responsible for the observed recent population decline. In conclusion, the Cape Denison population could be extirpated within 20 years unless B09B relocates or the now perennial fast ice within the bay breaks out. Our results have important implications for wider East Antarctic if the current increasing sea ice trend continues.
Publisher: Springer Science and Business Media LLC
Date: 18-11-2021
DOI: 10.1038/S41467-021-27053-6
Abstract: Emerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and timescale of responses. Iceberg-rafted debris data from Iceberg Alley identify eight retreat phases after the Last Glacial Maximum that each destabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently re-stabilized equally rapidly. This dynamic response of the AIS is supported by (i) a West Antarctic blue ice record of ice-elevation drawdown m during three such retreat events related to globally recognized deglacial meltwater pulses, (ii) step-wise retreat up to 400 km across the Ross Sea shelf, (iii) independent ice sheet modeling, and (iv) tipping point analysis. Our findings are consistent with a growing body of evidence suggesting the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat and substantial global sea level rise.
Publisher: American Meteorological Society
Date: 02-2016
Publisher: Springer Science and Business Media LLC
Date: 10-10-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2021
Publisher: Geological Society of America
Date: 05-2010
DOI: 10.1130/G30754.1
Publisher: Informa UK Limited
Date: 02-04-2020
Publisher: Informa UK Limited
Date: 06-2005
Publisher: American Geophysical Union (AGU)
Date: 29-08-2021
DOI: 10.1029/2021GL094513
Abstract: The Antarctic Ice Sheet (AIS) response to past warming consistent with the 1.5–2°C “safe limit” of the United Nations Paris Agreement is currently not well known. Empirical evidence from the most recent comparable period, the Last Interglaciation, is sparse, and transient ice‐sheet experiments are few and inconsistent. Here, we present new, transient, GCM‐forced ice‐sheet simulations validated against proxy reconstructions. This is the first time such an evaluation has been attempted. Our empirically constrained simulations indicate that the AIS contributed 4 m to global mean sea level by 126 ka BP, with ice lost primarily from the Amundsen, but not Ross or Weddell Sea, sectors. We resolve the conflict between previous work and show that the AIS thinned in the Wilkes Subglacial Basin but did not retreat. We also find that the West AIS may be predisposed to future collapse even in the absence of further environmental change, consistent with previous studies.
Publisher: Elsevier BV
Date: 02-2016
Publisher: Elsevier BV
Date: 07-2011
Publisher: California Digital Library (CDL)
Date: 24-05-2019
Publisher: Copernicus GmbH
Date: 15-03-2017
Abstract: Abstract. Occupying about 14 % of the world's surface, the Southern Ocean plays a fundamental role in ocean and atmosphere circulation, carbon cycling and Antarctic ice-sheet dynamics. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine–atmosphere–ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54° S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes.
Publisher: Springer Science and Business Media LLC
Date: 29-09-2014
DOI: 10.1038/NCOMMS6107
Abstract: During the last glacial termination, the upwelling strength of the southern polar limb of the Atlantic Meridional Overturning Circulation varied, changing the ventilation and stratification of the high-latitude Southern Ocean. During the same period, at least two phases of abrupt global sea-level rise--meltwater pulses--took place. Although the timing and magnitude of these events have become better constrained, a causal link between ocean stratification, the meltwater pulses and accelerated ice loss from Antarctica has not been proven. Here we simulate Antarctic ice sheet evolution over the last 25 kyr using a data-constrained ice-sheet model forced by changes in Southern Ocean temperature from an Earth system model. Results reveal several episodes of accelerated ice-sheet recession, the largest being coincident with meltwater pulse 1A. This resulted from reduced Southern Ocean overturning following Heinrich Event 1, when warmer subsurface water thermally eroded grounded marine-based ice and instigated a positive feedback that further accelerated ice-sheet retreat.
Publisher: Copernicus GmbH
Date: 21-12-2015
Abstract: Abstract. Future changes in atmospheric circulation and associated modes of variability are a major source of uncertainty in climate projections. Nowhere is this issue more acute than across the mid-latitudes to high latitudes of the Southern Hemisphere (SH), which over the last few decades have experienced extreme and regionally variable trends in precipitation, ocean circulation and temperature, with major implications for Antarctic ice melt and surface mass balance. Unfortunately there is a relative dearth of observational data, limiting our understanding of the driving mechanism(s). Here we report a new 130-year annually resolved record of δD – a proxy for temperature – from the geographic South Pole where we find a significant influence from extratropical pressure anomalies which act as "gatekeepers" to the meridional exchange of air masses. Reanalysis of global atmospheric circulation suggests these pressure anomalies play a significant influence on mid- to high-latitude SH climate, modulated by the tropical Pacific Ocean. This work adds to a growing body of literature confirming the important roles of tropical and mid-latitude atmospheric circulation variability on Antarctic temperatures. Our findings suggest that future increasing tropical warmth will strengthen meridional circulation, exaggerating current trends, with potentially significant impacts on Antarctic surface mass balance.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-11-2021
Abstract: Our study on the exact timing and the potential climatic, environmental, and evolutionary consequences of the Lasch s Geomagnetic Excursion has generated the hypothesis that geomagnetism represents an unrecognized driver in environmental and evolutionary change. It is important for this hypothesis to be tested with new data, and encouragingly, none of the studies presented by Picin et al . undermine our model.
Publisher: Copernicus GmbH
Date: 07-03-2016
Publisher: American Geophysical Union (AGU)
Date: 11-11-2020
DOI: 10.1029/2019RG000663
Abstract: The Antarctic Ice Sheet (AIS) is out of equilibrium with the current anthropogenic‐enhanced climate forcing. Paleoenvironmental records and ice sheet models reveal that the AIS has been tightly coupled to the climate system during the past and indicate the potential for accelerated and sustained Antarctic ice mass loss into the future. Modern observations by contrast suggest that the AIS has only just started to respond to climate change in recent decades. The maximum projected sea level contribution from Antarctica to 2100 has increased significantly since the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report, although estimates continue to evolve with new observational and theoretical advances. This review brings together recent literature highlighting the progress made on the known processes and feedbacks that influence the stability of the AIS. Reducing the uncertainty in the magnitude and timing of the future sea level response to AIS change requires a multidisciplinary approach that integrates knowledge of the interactions between the ice sheet, solid Earth, atmosphere, and ocean systems and across time scales of days to millennia. We start by reviewing the processes affecting AIS mass change, from atmospheric and oceanic processes acting on short time scales (days to decades), through to ice processes acting on intermediate time scales (decades to centuries) and the response to solid Earth interactions over longer time scales (decades to millennia). We then review the evidence of AIS changes from the Pliocene to the present and consider the projections of global sea level rise and their consequences. We highlight priority research areas required to improve our understanding of the processes and feedbacks governing AIS change.
Publisher: Geological Society of America
Date: 19-03-2012
DOI: 10.1130/G32730.1
Publisher: Springer Science and Business Media LLC
Date: 19-04-2022
DOI: 10.1038/S41467-022-29642-5
Abstract: The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO 2 levels.
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 11-2022
Publisher: Copernicus GmbH
Date: 27-07-2017
Abstract: Abstract. The geometry of Antarctic ice sheets during warm periods of the geological past is difficult to determine from geological evidence, but is important to know because such reconstructions enable a more complete understanding of how the ice-sheet system responds to changes in climate. Here we investigate how Antarctica evolved under orbital and greenhouse gas conditions representative of an interglacial in the early Pliocene at 4.23 Ma, when Southern Hemisphere insolation reached a maximum. Using offline-coupled climate and ice-sheet models, together with a new synthesis of high-latitude palaeoenvironmental proxy data to define a likely climate envelope, we simulate a range of ice-sheet geometries and calculate their likely contribution to sea level. In addition, we use these simulations to investigate the processes by which the West and East Antarctic ice sheets respond to environmental forcings and the timescales over which these behaviours manifest. We conclude that the Antarctic ice sheet contributed 8.6 ± 2.8 m to global sea level at this time, under an atmospheric CO2 concentration identical to present (400 ppm). Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points.
Publisher: Elsevier BV
Date: 04-2016
Publisher: American Geophysical Union (AGU)
Date: 02-2016
DOI: 10.1002/2015GB005257
Publisher: Geological Society of America
Date: 05-2011
DOI: 10.1130/G32140Y.1
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2021
Publisher: Copernicus GmbH
Date: 14-03-2019
Abstract: Abstract. The New Zealand subantarctic islands of Auckland and C bell, situated between the subtropical front and the Antarctic Convergence in the Pacific sector of the Southern Ocean, provide valuable terrestrial records from a globally important climatic region. Whilst the islands show clear evidence of past glaciation, the timing and mechanisms behind Pleistocene environmental and climate changes remain uncertain. Here we present a multidisciplinary study of the islands – including marine and terrestrial geomorphological surveys, extensive analyses of sedimentary sequences, a comprehensive dating programme, and glacier flow line modelling – to investigate multiple phases of glaciation across the islands. We find evidence that the Auckland Islands hosted a small ice cap 384 000 ± 26 000 years ago (384±26 ka), most likely during Marine Isotope Stage 10, a period when the subtropical front was reportedly north of its present-day latitude by several degrees, and consistent with hemispheric-wide glacial expansion. Flow line modelling constrained by field evidence suggests a more restricted glacial period prior to the LGM that formed substantial valley glaciers on the C bell and Auckland Islands around 72–62 ka. Despite previous interpretations that suggest the maximum glacial extent occurred in the form of valley glaciation at the Last Glacial Maximum (LGM ∼21 ka), our combined approach suggests minimal LGM glaciation across the New Zealand subantarctic islands and that no glaciers were present during the Antarctic Cold Reversal (ACR ∼15–13 ka). Instead, modelling implies that despite a regional mean annual air temperature depression of ∼5 ∘C during the LGM, a combination of high seasonality and low precipitation left the islands incapable of sustaining significant glaciation. We suggest that northwards expansion of winter sea ice during the LGM and subsequent ACR led to precipitation starvation across the middle to high latitudes of the Southern Ocean, resulting in restricted glaciation of the subantarctic islands.
Publisher: Copernicus GmbH
Date: 25-04-2017
Publisher: Informa UK Limited
Date: 06-2005
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2021
Publisher: Elsevier BV
Date: 06-2012
Publisher: Springer Science and Business Media LLC
Date: 19-02-2018
DOI: 10.1038/S41598-018-20970-5
Abstract: Anthropogenic activity is now recognised as having profoundly and permanently altered the Earth system, suggesting we have entered a human-dominated geological epoch, the ‘Anthropocene’. To formally define the onset of the Anthropocene, a synchronous global signature within geological-forming materials is required. Here we report a series of precisely-dated tree-ring records from C bell Island (Southern Ocean) that capture peak atmospheric radiocarbon ( 14 C) resulting from Northern Hemisphere-dominated thermonuclear bomb tests during the 1950s and 1960s. The only alien tree on the island, a Sitka spruce ( Picea sitchensis ), allows us to seasonally-resolve Southern Hemisphere atmospheric 14 C, demonstrating the ‘bomb peak’ in this remote and pristine location occurred in the last-quarter of 1965 (October-December), coincident with the broader changes associated with the post-World War II ‘Great Acceleration’ in industrial capacity and consumption. Our findings provide a precisely-resolved potential Global Stratotype Section and Point (GSSP) or ‘golden spike’, marking the onset of the Anthropocene Epoch.
Publisher: Elsevier BV
Date: 03-2007
Publisher: Elsevier BV
Date: 02-2014
Publisher: MDPI AG
Date: 07-06-2019
DOI: 10.3390/GEOSCIENCES9060255
Abstract: Quantitative estimates of future Antarctic climate change are derived from numerical global climate models. Evaluation of the reliability of climate model projections involves many lines of evidence on past performance combined with knowledge of the processes that need to be represented. Routine model evaluation is mainly based on the modern observational period, which started with the establishment of a network of Antarctic weather stations in 1957/58. This period is too short to evaluate many fundamental aspects of the Antarctic and Southern Ocean climate system, such as decadal-to-century time-scale climate variability and trends. To help address this gap, we present a new evaluation of potential ways in which long-term observational and paleo-proxy reconstructions may be used, with a particular focus on improving projections. A wide range of data sources and time periods is included, ranging from ship observations of the early 20th century to ice core records spanning hundreds to hundreds of thousands of years to sediment records dating back 34 million years. We conclude that paleo-proxy records and long-term observational datasets are an underused resource in terms of strategies for improving Antarctic climate projections for the 21st century and beyond. We identify priorities and suggest next steps to addressing this.
Publisher: Geological Society of America
Date: 2004
DOI: 10.1130/G19795.1
Publisher: SAGE Publications
Date: 24-02-2022
Abstract: Satellite observations offering detailed records of global environmental change are only available from 1979. Emerging studies combining high-quality instrumental and natural observations highlight that the Earth system experienced a substantial shift across the mid-20th century, one that appears to have taken place before the Great Acceleration of human activities from the 1950s. These new results have far-reaching implications for understanding ice-ocean-atmospheric interactions in the Anthropocene and highlight the urgent need for drastic cuts in carbon emissions to limit the impact of future warming.
Publisher: Springer Science and Business Media LLC
Date: 02-10-2022
DOI: 10.1038/S41467-022-33494-4
Abstract: Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA ( sed aDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive contamination control and sed aDNA damage analysis) metagenomic marine eukaryote sed aDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote sed aDNA record of ~1 Mio. years and diatom and chlorophyte sed aDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU, psbO ). We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising % of all eukaryotes prior to ~14.5 ka, to ~50% after this time, i.e., following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species. Our study demonstrates that sed aDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.
Publisher: Copernicus GmbH
Date: 05-12-2016
DOI: 10.5194/CP-2016-123
Abstract: Abstract. The geometry of Antarctic ice sheets during warm periods of the geological past is difficult to determine from geological evidence, but is important to know because such reconstructions enable a more complete understanding of how the ice-sheet system responds to changes in climate. Here we investigate how Antarctica evolved under orbital and greenhouse gas conditions representative of a peak warmth interglacial in the early Pliocene at 4.23 Ma. Using offline-coupled climate and ice-sheet models, together with palaeoenvironmental proxy data to define a likely climate envelope, we simulate a range of ice-sheet geometries and calculate their likely contribution to sea level. In addition, we use these simulations to investigate the processes by which the West and East Antarctic ice sheets respond to environmental forcings and the timescales over which these behaviours manifest. We conclude that the Antarctic ice sheet contributed approximately 8.5 m to global sea level at this time, under an atmospheric CO2 concentration identical to present (400 ppm). Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points.
Publisher: Copernicus GmbH
Date: 21-11-2016
Publisher: Springer Science and Business Media LLC
Date: 05-01-2017
DOI: 10.1038/SREP39979
Abstract: Reconstructing the dynamic response of the Antarctic ice sheets to warming during the Last Glacial Termination (LGT 18,000–11,650 yrs ago) allows us to disentangle ice-climate feedbacks that are key to improving future projections. Whilst the sequence of events during this period is reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records, making it difficult to assess relationships between Antarctic ice-sheet (AIS) dynamics, climate change and sea level. Here we present results from a highly-resolved ‘horizontal ice core’ from the Weddell Sea Embayment, which records millennial-scale AIS dynamics across this extensive region. Counterintuitively, we find AIS mass-loss across the full duration of the Antarctic Cold Reversal (ACR 14,600–12,700 yrs ago), with stabilisation during the subsequent millennia of atmospheric warming. Earth-system and ice-sheet modelling suggests these contrasting trends were likely Antarctic-wide, sustained by feedbacks lified by the delivery of Circumpolar Deep Water onto the continental shelf. Given the anti-phase relationship between inter-hemispheric climate trends across the LGT our findings demonstrate that Southern Ocean-AIS feedbacks were controlled by global atmospheric teleconnections. With increasing stratification of the Southern Ocean and intensification of mid-latitude westerly winds today, such teleconnections could lify AIS mass loss and accelerate global sea-level rise.
Publisher: Springer Science and Business Media LLC
Date: 26-11-2015
DOI: 10.1038/NCOMMS9910
Abstract: Outlet glaciers grounded on a bed that deepens inland and extends below sea level are potentially vulnerable to ‘marine ice sheet instability’. This instability, which may lead to runaway ice loss, has been simulated in models, but its consequences have not been directly observed in geological records. Here we provide new surface-exposure ages from an outlet of the East Antarctic Ice Sheet that reveal rapid glacier thinning occurred approximately 7,000 years ago, in the absence of large environmental changes. Glacier thinning persisted for more than two and a half centuries, resulting in hundreds of metres of ice loss. Numerical simulations indicate that ice surface drawdown accelerated when the otherwise steadily retreating glacier encountered a bedrock trough. Together, the geological reconstruction and numerical simulations suggest that centennial-scale glacier thinning arose from unstable grounding line retreat. Capturing these instability processes in ice sheet models is important for predicting Antarctica’s future contribution to sea level change.
Publisher: Springer Science and Business Media LLC
Date: 08-04-2015
Publisher: Copernicus GmbH
Date: 21-11-2016
DOI: 10.5194/CP-2016-114
Abstract: Abstract. Occupying 14% of the world’s surface, the Southern Ocean plays a fundamental role in global climate, ocean circulation, carbon cycling and Antarctic ice-sheet stability. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54˚S). Our annually-resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the mid-twentieth century, a phenomenon predating the observational record. Climate reanalysis and modelling shows a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Copernicus GmbH
Date: 30-09-2016
Abstract: Abstract. Recent observations and modelling studies have demonstrated the potential for rapid and substantial retreat of large sectors of the East Antarctic Ice Sheet (EAIS). This has major implications for ocean circulation and global sea level. Here we examine the effects of increasing meltwater from the Wilkes Basin, one of the major marine-based sectors of the EAIS, on Southern Ocean dynamics. Climate model simulations reveal that the meltwater flux rapidly stratifies surface waters, leading to a dramatic decrease in the rate of Antarctic Bottom Water (AABW) formation. The surface ocean cools but, critically, the Southern Ocean warms by more than 1 °C at depth. This warming is accompanied by a Southern Ocean-wide “domino effect”, whereby the warming signal propagates westward with depth. Our results suggest that melting of one sector of the EAIS could result in accelerated warming across other sectors, including the Weddell Sea sector of the West Antarctic Ice Sheet. Thus, localised melting of the EAIS could potentially destabilise the wider Antarctic Ice Sheet.
Publisher: Cambridge University Press (CUP)
Date: 13-11-2014
Publisher: Informa UK Limited
Date: 06-2005
Publisher: Wiley
Date: 20-12-2014
DOI: 10.1111/JOCN.12520
Abstract: To describe healthcare providers' attitudes to family involvement during routine care and family presence during resuscitation or other invasive procedures in adult intensive care units in Saudi Arabia. Previous research has shown that healthcare professionals have revealed a ersity of opinions on family involvement during routine care and family presence during resuscitation or other invasive procedures. Attitude assessment can provide an indication of staff acceptance or rejection of the practice and also help identify key potential barriers that will need to be addressed. It has also been evident that participation in the care has potential benefits for patients and families as well as healthcare providers. A quantitative descriptive design. A questionnaire was used with a convenience s le of 468 healthcare providers who were recruited from eight intensive care units. The analysis found that healthcare providers had positive attitudes towards family involvement during routine care, but negative attitudes towards family presence during resuscitation or other invasive procedures. Physicians expressed more opposition to the practice than did nurses and respiratory therapists. Staff indicated a need to develop written guidelines and policies, as well as educational programmes, to address this sensitive issue in clinical practice. Family is an important resource in patient care in the context of the critical care environment. Clinical barriers including resources, hospital policies and guidelines, staff and public education should be taken into account to facilitate family integration to the care model. The findings can help to develop policies and guidelines for safe implementation of the practice. They can also encourage those who design nursing and other medical curricula to place more emphasis on the role of the family especially in critical care settings.
Publisher: Public Library of Science (PLoS)
Date: 17-07-2019
Publisher: Copernicus GmbH
Date: 04-06-2016
Publisher: Elsevier BV
Date: 09-2011
Publisher: New Zealand Ecological Society
Date: 2018
Publisher: American Geophysical Union (AGU)
Date: 10-12-2015
DOI: 10.1002/2015GL066344
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-02-2021
Abstract: Do terrestrial geomagnetic field reversals have an effect on Earth's climate? Cooper et al. created a precisely dated radiocarbon record around the time of the Lasch s geomagnetic reversal about 41,000 years ago from the rings of New Zealand sw kauri trees. This record reveals a substantial increase in the carbon-14 content of the atmosphere culminating during the period of weakening magnetic field strength preceding the polarity switch. The authors modeled the consequences of this event and concluded that the geomagnetic field minimum caused substantial changes in atmospheric ozone concentration that drove synchronous global climate and environmental shifts. Science , this issue p. 811
Publisher: Cambridge University Press (CUP)
Date: 10-06-2019
DOI: 10.1017/RDC.2019.54
Abstract: Precise radiocarbon ( 14 C) dating of sedimentary sequences is important for developing robust chronologies of environmental change, but s ling of suitable components can be challenging in highly dynamic landscapes. Here we investigate radiocarbon determinations of different peat size fractions from six peat sites, representing a range of geomorphological contexts on the South Atlantic subantarctic islands of the Falklands and South Georgia. To investigate the most suitable fraction for dating, 112 measurements were obtained from three components within selected horizons: a fine fraction .2 mm, a coarse fraction .2 mm, and bulk material. We find site selection is critical, with locations surrounded by high-ground and/or relatively slowly accumulating sites more susceptible to the translocation of older carbon. Importantly, in locations with reduced potential for redeposition of material, our results show that there is no significant or systematic difference between ages derived from bulk material, fine or coarse (plant macrofossil) material, providing confidence in the resulting age model. Crucially, in areas comprising complex terrain with extreme relief, we recommend dating macrofossils or bulk carbon rather than a fine fraction, or employing comprehensive dating of multiple sedimentary fractions to determine the most reliable fraction(s) for developing a robust chronological framework.
Publisher: Cambridge University Press (CUP)
Date: 13-11-2014
DOI: 10.1017/S0954102014000613
Abstract: Determining the millennial-scale behaviour of marine-based sectors of the West Antarctic Ice Sheet (WAIS) is critical to improve predictions of the future contribution of Antarctica to sea level rise. Here high-resolution ice sheet modelling was combined with new terrestrial geological constraints ( in situ 14 C and 10 Be analysis) to reconstruct the evolution of two major ice streams entering the Weddell Sea over 20 000 years. The results demonstrate how marked differences in ice flux at the marine margin of the expanded Antarctic ice sheet led to a major reorganization of ice streams in the Weddell Sea during the last deglaciation, resulting in the eastward migration of the Institute Ice Stream, triggering a significant regional change in ice sheet mass balance during the early to mid Holocene. The findings highlight how spatial variability in ice flow can cause marked changes in the pattern, flux and flow direction of ice streams on millennial timescales in this marine ice sheet setting. Given that this sector of the WAIS is assumed to be sensitive to ocean-forced instability and may be influenced by predicted twenty-first century ocean warming, our ability to model and predict abrupt and extensive ice stream ersions is key to a realistic assessment of future ice sheet sensitivity.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 08-2012
End Date: 08-2016
Amount: $672,342.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 12-2024
Amount: $590,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 08-2016
Amount: $270,000.00
Funder: Australian Research Council
View Funded Activity