- Petherick, Lynda, Bostock, Helen, Cohen, Tim, Fitzsimmons, Kathryn, Tibby, John, Fletcher, M. S., Moss, Patrick, Reeves, Jessica, Mooney, Scott, Barrows, Timothy, Kemp, Justine, Jansen, John, Nanson, Gerald, Dosseto, Anthony
- Authors: Petherick, Lynda , Bostock, Helen , Cohen, Tim , Fitzsimmons, Kathryn , Tibby, John , Fletcher, M. S. , Moss, Patrick , Reeves, Jessica , Mooney, Scott , Barrows, Timothy , Kemp, Justine , Jansen, John , Nanson, Gerald , Dosseto, Anthony
- Date: 2013
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 74, no. (2013), p. 58-77
- Full Text: false
- Reviewed:
- Description: Temperate Australia sits between the heat engine of the tropics and the cold Southern Ocean, encompassing a range of rainfall regimes and falling under the influence of different climatic drivers. Despite this heterogeneity, broad-scale trends in climatic and environmental change are evident over the past 30ka. During the early glacial period (~30-22ka) and the Last Glacial Maximum (~22-18ka), climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important Murray-Darling Basin. The temperate region at this time appears to be dominated by expanded sea ice in the Southern Ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast (including Tasmania) and southwest Australian coasts. The deglacial period (~18-12ka) was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records, while there is some evidence for climatic reversals (e.g. the Antarctic Cold Reversal) in high resolution marine sediment cores through this period. The high spatial density of Holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after ~12ka, presumably in response to increasing temperature, while hydrological records reveal spatially heterogeneous hydro-climatic trends. Patterns after ~6ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the El Niño/Southern Oscillation. © 2013 Elsevier Ltd.
- Description: 2003011211
- Augustinus, Paul, Cochran, Ursula, Kattel, Giri, D'Costa, Donna, Shane, Phil
- Authors: Augustinus, Paul , Cochran, Ursula , Kattel, Giri , D'Costa, Donna , Shane, Phil
- Date: 2012
- Type: Text , Journal article
- Relation: Quaternary International Vol. 253, no. (2012), p. 18-31
- Full Text: false
- Reviewed:
- Description: A high-resolution record of lacustrine environments spanning ca. 30-9calkaBP was obtained from Onepoto maar, northern North Island, New Zealand. The multi-proxy record of environmental change is constrained by tephrochronology and AMS 14C ages and provides evidence for episodes of rapid environmental change during the Last Glacial Coldest Period (LGCP: 28.5-18calkaBP) and Late Glacial-Interglacial Transition (LGIT) from northern New Zealand. The Onepoto pollen record indicates that the LGCP was cold, dry and windy in the Auckland region with vegetation dominated by herbs and grasses in a beech forest mosaic. At the same time the diatom record indicates oligotrophic conditions with low lakes levels and turbulence whilst cladocerans indicate low water temperatures. The inference of cold, dry and windy conditions during the LGCP is supported by geochemical evidence for increased sediment influx, charcoal and CO 2 limiting conditions for terrestrial macrophytes. Rapid climate amelioration and forest expansion after ca. 18calkaBP corresponds with reduced sediment influx, diatom and cladoceran-inferred higher lake levels indicating increasing moisture availability and temperature. Diatom flora indicates that an oligotrophic, circumneutral lake was becoming established during the LGIT but conditions were still variable. Between ca. 13.8 and 12.5calkaBP two brief drier and possibly cooler episodes are apparent (ca. 13.8-13.2 and 13-12.5calkaBP) followed by a warm phase combined with generally stable high lake levels between ca. 12.5 and 10.5calkaBP. Subsequently the lake water chemistry became more alkaline and eutrophic, possibly because sea level had risen high enough by this time to influence ground water chemistry. © 2011 Elsevier Ltd and INQUA.
Expressions of climate perturbations in western ugandan crater lake sediment records during the last 1000 years
- Mills, Keely, Ryves, David, Anderson, Nicholas, Bryant, Charlotte, Tyler, J.J.
- Authors: Mills, Keely , Ryves, David , Anderson, Nicholas , Bryant, Charlotte , Tyler, J.J.
- Date: 2014
- Type: Text , Journal article
- Relation: Climate of the Past Vol. 10, no. 4 (2014), p. 1581-1601
- Full Text:
- Reviewed:
- Description: Equatorial East Africa has a complex regional patchwork of climate regimes, sensitive to climate fluctuations over a variety of temporal and spatial scales during the late Holocene. Understanding how these changes are recorded in and interpreted from biological and geochemical proxies in lake sedimentary records remains a key challenge to answering fundamental questions regarding the nature, spatial extent and synchroneity of climatic changes seen in East African palaeo-records. Using a paired lake approach, where neighbouring lakes share the same geology, climate and landscape, it might be expected that the systems will respond similarly to external climate forcing. Sediment cores from two crater lakes in western Uganda spanning the last ∼1000 years were examined to assess diatom community responses to late Holocene climate and environmental changes, and to test responses to multiple drivers using redundancy analysis (RDA). These archives provide annual to sub-decadal records of environmental change
- Authors: Mills, Keely , Ryves, David , Anderson, Nicholas , Bryant, Charlotte , Tyler, J.J.
- Date: 2014
- Type: Text , Journal article
- Relation: Climate of the Past Vol. 10, no. 4 (2014), p. 1581-1601
- Full Text:
- Reviewed:
- Description: Equatorial East Africa has a complex regional patchwork of climate regimes, sensitive to climate fluctuations over a variety of temporal and spatial scales during the late Holocene. Understanding how these changes are recorded in and interpreted from biological and geochemical proxies in lake sedimentary records remains a key challenge to answering fundamental questions regarding the nature, spatial extent and synchroneity of climatic changes seen in East African palaeo-records. Using a paired lake approach, where neighbouring lakes share the same geology, climate and landscape, it might be expected that the systems will respond similarly to external climate forcing. Sediment cores from two crater lakes in western Uganda spanning the last ∼1000 years were examined to assess diatom community responses to late Holocene climate and environmental changes, and to test responses to multiple drivers using redundancy analysis (RDA). These archives provide annual to sub-decadal records of environmental change
- Reeves, Jessica, Barrows, Timothy, Cohen, Tim, Kiem, Anthony, Bostock, Helen, Fitzsimmons, Kathryn, Jansen, John, Kemp, Justine, Krause, Claire, Petherick, Lynda, Phipps, Steven
- Authors: Reeves, Jessica , Barrows, Timothy , Cohen, Tim , Kiem, Anthony , Bostock, Helen , Fitzsimmons, Kathryn , Jansen, John , Kemp, Justine , Krause, Claire , Petherick, Lynda , Phipps, Steven
- Date: 2013
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 74, no. (2013), p. 21-34
- Full Text: false
- Reviewed:
- Description: The Australian region spans some 60° of latitude and 50° of longitude and displays considerable regional climate variability both today and during the Late Quaternary. A synthesis of marine and terrestrial climate records, combining findings from the Southern Ocean, temperate, tropical and arid zones, identifies a complex response of climate proxies to a background of changing boundary conditions over the last 35,000 years. Climate drivers include the seasonal timing of insolation, greenhouse gas content of the atmosphere, sea level rise and ocean and atmospheric circulation changes. Our compilation finds few climatic events that could be used to construct a climate event stratigraphy for the entire region, limiting the usefulness of this approach. Instead we have taken a spatial approach, looking to discern the patterns of change across the continent.The data identify the clearest and most synchronous climatic response at the time of the Last Glacial Maximum (LGM) (21±3ka), with unambiguous cooling recorded in the ocean, and evidence of glaciation in the highlands of tropical New Guinea, southeast Australia and Tasmania. Many terrestrial records suggest drier conditions, but with the timing of inferred snowmelt, and changes to the rainfall/runoff relationships, driving higher river discharge at the LGM. In contrast, the deglaciation is a time of considerable south-east to north-west variation across the region. Warming was underway in all regions by 17ka. Post-glacial sea level rise and its associated regional impacts have played an important role in determining the magnitude and timing of climate response in the north-west of the continent in contrast to the southern latitudes. No evidence for cooling during the Younger Dryas chronozone is evident in the region, but the Antarctic cold reversal clearly occurs south of Australia. The Holocene period is a time of considerable climate variability associated with an intense monsoon in the tropics early in the Holocene, giving way to a weakened monsoon and an increasingly El Niño-dominated ENSO to the present. The influence of ENSO is evident throughout the southeast of Australia, but not the southwest. This climate history provides a template from which to assess the regionality of climate events across Australia and make comparisons beyond our region. © 2013.
- Description: 4 Earth Sciences
- Description: 21 History And Archaeology
Palaeoenvironmental change in tropical Australasia over the last 30,000 years - a synthesis by the OZ-INTIMATE group
- Reeves, Jessica, Bostock, Helen, Ayliffe, Linda, Barrows, Timothy, De Deckker, Patrick, Devriendt, Laurent, Dunbar, Gavin, Drysdale, Russell, Fitzsimmons, Kathryn, Gagan, Michael, Griffiths, Michael, Haberle, Simon, Jansen, John, Krause, Claire, Lewis, Stephen, McGregor, Helen, Mooney, Scott, Moss, Patrick, Nanson, Gerald, Purcell, Anthony, van der Kaars, Sander
- Authors: Reeves, Jessica , Bostock, Helen , Ayliffe, Linda , Barrows, Timothy , De Deckker, Patrick , Devriendt, Laurent , Dunbar, Gavin , Drysdale, Russell , Fitzsimmons, Kathryn , Gagan, Michael , Griffiths, Michael , Haberle, Simon , Jansen, John , Krause, Claire , Lewis, Stephen , McGregor, Helen , Mooney, Scott , Moss, Patrick , Nanson, Gerald , Purcell, Anthony , van der Kaars, Sander
- Date: 2013
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 74, no. (2013), p. 97-114
- Full Text:
- Reviewed:
- Description: The tropics are the major source of heat and moisture for the Australasian region. Determining the tropics' response over time to changes in climate forcing mechanisms, such as summer insolation, and the effects of relative sea level on exposed continental shelves during the Last Glacial period, is an ongoing process of re-evaluation. We present a synthesis of climate proxy data from tropical Australasia spanning the last 30,000 years that incorporates deep sea core, coral, speleothem, pollen, charcoal and terrestrial sedimentary records.Today, seasonal variability is governed largely by the annual migration of the inter-tropical convergence zone (ITCZ), influencing this region most strongly during the austral summer. However, the position of the ITCZ has varied through time. Towards the end of Marine Isotope Stage (MIS) 3, conditions were far wetter throughout the region, becoming drier first in the south. Universally cooler land and sea-surface temperature (SST) were characteristic of the Last Glacial Maximum, with drier conditions than previously, although episodic wet periods are noted in the fluvial records of northern Australia. The deglacial period saw warming first in the Coral Sea and then the Indonesian seas, with a pause in this trend around the time of the Antarctic Cold Reversal (c. 14.5ka), coincident with the flooding of the Sunda Shelf. Wetter conditions occurred first in Indonesia around 17ka and northern Australia after 14ka. The early Holocene saw a peak in marine SST to the northwest and northeast of Australia. Modern vegetation was first established on Indonesia, then progressively south and eastward to NE Australia. Flores and the Atherton Tablelands show a dry period around 11.6ka, steadily becoming wetter through the early Holocene. The mid-late Holocene was punctuated by millennial-scale variability, associated with the El Niño-Southern Oscillation; this is evident in the marine, coral, speleothem and pollen records of the region. © 2012.
- Description: 4 Earth Sciences
- Description: 21 History And Archaelogy
- Description: 2003011213
- Authors: Reeves, Jessica , Bostock, Helen , Ayliffe, Linda , Barrows, Timothy , De Deckker, Patrick , Devriendt, Laurent , Dunbar, Gavin , Drysdale, Russell , Fitzsimmons, Kathryn , Gagan, Michael , Griffiths, Michael , Haberle, Simon , Jansen, John , Krause, Claire , Lewis, Stephen , McGregor, Helen , Mooney, Scott , Moss, Patrick , Nanson, Gerald , Purcell, Anthony , van der Kaars, Sander
- Date: 2013
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 74, no. (2013), p. 97-114
- Full Text:
- Reviewed:
- Description: The tropics are the major source of heat and moisture for the Australasian region. Determining the tropics' response over time to changes in climate forcing mechanisms, such as summer insolation, and the effects of relative sea level on exposed continental shelves during the Last Glacial period, is an ongoing process of re-evaluation. We present a synthesis of climate proxy data from tropical Australasia spanning the last 30,000 years that incorporates deep sea core, coral, speleothem, pollen, charcoal and terrestrial sedimentary records.Today, seasonal variability is governed largely by the annual migration of the inter-tropical convergence zone (ITCZ), influencing this region most strongly during the austral summer. However, the position of the ITCZ has varied through time. Towards the end of Marine Isotope Stage (MIS) 3, conditions were far wetter throughout the region, becoming drier first in the south. Universally cooler land and sea-surface temperature (SST) were characteristic of the Last Glacial Maximum, with drier conditions than previously, although episodic wet periods are noted in the fluvial records of northern Australia. The deglacial period saw warming first in the Coral Sea and then the Indonesian seas, with a pause in this trend around the time of the Antarctic Cold Reversal (c. 14.5ka), coincident with the flooding of the Sunda Shelf. Wetter conditions occurred first in Indonesia around 17ka and northern Australia after 14ka. The early Holocene saw a peak in marine SST to the northwest and northeast of Australia. Modern vegetation was first established on Indonesia, then progressively south and eastward to NE Australia. Flores and the Atherton Tablelands show a dry period around 11.6ka, steadily becoming wetter through the early Holocene. The mid-late Holocene was punctuated by millennial-scale variability, associated with the El Niño-Southern Oscillation; this is evident in the marine, coral, speleothem and pollen records of the region. © 2012.
- Description: 4 Earth Sciences
- Description: 21 History And Archaelogy
- Description: 2003011213
- Mills, Keely, Gell, Peter, Hesse, Paul, Jones, R., Kershaw, Peter, Drysdale, Russell, McDonald, Janece
- Authors: Mills, Keely , Gell, Peter , Hesse, Paul , Jones, R. , Kershaw, Peter , Drysdale, Russell , McDonald, Janece
- Date: 2013
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 60, no. 5 (2013), p. 547-560
- Full Text: false
- Reviewed:
- Description: This paper provides an incisive review of paleoclimate science and its relevance to natural-resource management within the Murray-Darling Basin (MDB). The drought of 1997-2010 focussed scientific, public and media attention on intrinsic climate variability and the confounding effect of human activity, especially in terms of water-resource management. Many policy and research reviews make statements about future planning with little consideration of climate change and without useful actionable knowledge. In order to understand future climate changes, modellers need, and demand, better paleoclimate data to constrain their model projections. Here, we present an insight into a number of existing long-term paleoclimate studies relevant to the MDB. Past records of climate, in response to orbital forcing (glacial-interglacial cycles) are found within, and immediately outside, the MDB. High-resolution temperature records, spanning the last 105 years, exist from floodplains and cave speleothems, as well as evidence from lakes and their associated lunettes. More recently, historical climate records show major changes in relation to El Niño-Southern Oscillation cycles and decadal shifts in rainfall regimes. A considerable body of research currently exists on the past climates of southeastern Australia but, this has not been collated and validated over large spatial scales. It is clear that a number of knowledge gaps still exist, and there is a pressing need for the establishment of new paleoclimatic research within the MDB catchment and within adjacent, sensitive catchments if past climate science is to fulfil its potential to provide policy-relevant information to natural-resource management into the future. © 2013 Copyright Taylor and Francis Group, LLC.
- Description: C1
- Kattel, Giri, Augustinus, Paul
- Authors: Kattel, Giri , Augustinus, Paul
- Date: 2010
- Type: Text , Journal article
- Relation: New Zealand Journal of Geology and Geophysics Vol. 53, no. 1 (2010), p. 31-42
- Full Text: false
- Reviewed:
- Description: Subfossil cladocerans have rarely been used for paleoenvironmental reconstruction from New Zealand lake sediments, and here we detail the first examination of the response of cladocerans to past environments from an Auckland maar paleolake. Cladoceran remains were examined in the upper 230 cm of the lacustrine sediments spanning c. 9-31 cal. ka BP from Onepoto maar during which time the lake underwent significant changes. Lake level was relatively high during the Last Glacial Coldest Period (c. 28-18 cal. ka BP), with limited forest in the catchment, shoreline vegetation and low water temperature indicated by the presence of a planktonic taxon, Bosmina meridionalis, and a cold tolerant chydorid cladoceran Alona sp. (affinis type). However, the climate during the last glacial termination after c. 17.9 cal. ka BP changed abruptly, perhaps becoming extremely dry and windy, resulting in increased production of cladoceran resting eggs. Between c. 17.6 and 14.1 cal. ka BP, a gradually ameliorating climate with sustained windiness and dryness might have been unfavourable for hatching of chydorid cladoceran eggs and their recolonisation. After c. 14.1 cal. ka BP, continued climatic amelioration was accompanied by reduced lake levels inferred from high cladoceran littoral: planktonic ratios as well as increased cladoceran diversity and abundance of less cold tolerant chydorid taxa: Alona guttata, Alona sp. (intermedia type) and Alonella excisa. At c. 9 cal. ka BP, the maar crater rim was breached by the marine waters commensurate with postglacial sea-level rise, resulting in degraded water quality and production of a large number of cladoceran ephippia in the sediments. © 2010 The Royal Society of New Zealand.
Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the Indo-Pacific, Australasian and Southern Ocean regions
- Ackerley, Duncan, Reeves, Jessica, Barr, Cameron, Bostock, Helen, Fitzsimmons, Kathryn, Fletcher, Michael-Shawn, Gouramanis, Chris, McGregor, Helen, Mooney, Scott, Phipps, Steven, Tibby, John, Tyler, Jonathan
- Authors: Ackerley, Duncan , Reeves, Jessica , Barr, Cameron , Bostock, Helen , Fitzsimmons, Kathryn , Fletcher, Michael-Shawn , Gouramanis, Chris , McGregor, Helen , Mooney, Scott , Phipps, Steven , Tibby, John , Tyler, Jonathan
- Date: 2017
- Type: Text , Journal article
- Relation: Climate of the Past Vol. 13, no. 11 (2017), p. 1661-1684
- Full Text:
- Reviewed:
- Description:
This study uses the
simplified patterns of temperature and effective precipitation
approach from the Australian component of the international palaeoclimate synthesis effort (INTegration of Ice core, MArine and TErrestrial records - OZ-INTIMATE) to compare atmosphere-ocean general circulation model (AOGCM) simulations and proxy reconstructions. The approach is used in order to identify important properties (e.g. circulation and precipitation) of past climatic states from the models and proxies, which is a primary objective of the Southern Hemisphere Assessment of PalaeoEnvironment (SHAPE) initiative. The AOGCM data are taken from the Paleoclimate Modelling Intercomparison Project (PMIP) mid-Holocene (ca. 6000 years before present, 6 ka) and pre-industrial control (ca. 1750 CE, 0 ka) experiments. The synthesis presented here shows that the models and proxies agree on the differences in climate state for 6 ka relative to 0 ka, when they are insolation driven. The largest uncertainty between the models and the proxies occurs over the Indo-Pacific Warm Pool (IPWP). The analysis shows that the lower temperatures in the Pacific at around 6 ka in the models may be the result of an enhancement of an existing systematic error. It is therefore difficult to decipher which one of the proxies and/or the models is correct. This study also shows that a reduction in the Equator-to-pole temperature difference in the Southern Hemisphere causes the mid-latitude westerly wind strength to reduce in the models; however, the simulated rainfall actually increases over the southern temperate zone of Australia as a result of higher convective precipitation. Such a mechanism (increased convection) may be useful for resolving disparities between different regional proxy records and model simulations. Finally, after assessing the available datasets (model and proxy), opportunities for better model-proxy integrated research are discussed. © Author(s) 2017.
- Authors: Ackerley, Duncan , Reeves, Jessica , Barr, Cameron , Bostock, Helen , Fitzsimmons, Kathryn , Fletcher, Michael-Shawn , Gouramanis, Chris , McGregor, Helen , Mooney, Scott , Phipps, Steven , Tibby, John , Tyler, Jonathan
- Date: 2017
- Type: Text , Journal article
- Relation: Climate of the Past Vol. 13, no. 11 (2017), p. 1661-1684
- Full Text:
- Reviewed:
- Description:
This study uses the
simplified patterns of temperature and effective precipitation
approach from the Australian component of the international palaeoclimate synthesis effort (INTegration of Ice core, MArine and TErrestrial records - OZ-INTIMATE) to compare atmosphere-ocean general circulation model (AOGCM) simulations and proxy reconstructions. The approach is used in order to identify important properties (e.g. circulation and precipitation) of past climatic states from the models and proxies, which is a primary objective of the Southern Hemisphere Assessment of PalaeoEnvironment (SHAPE) initiative. The AOGCM data are taken from the Paleoclimate Modelling Intercomparison Project (PMIP) mid-Holocene (ca. 6000 years before present, 6 ka) and pre-industrial control (ca. 1750 CE, 0 ka) experiments. The synthesis presented here shows that the models and proxies agree on the differences in climate state for 6 ka relative to 0 ka, when they are insolation driven. The largest uncertainty between the models and the proxies occurs over the Indo-Pacific Warm Pool (IPWP). The analysis shows that the lower temperatures in the Pacific at around 6 ka in the models may be the result of an enhancement of an existing systematic error. It is therefore difficult to decipher which one of the proxies and/or the models is correct. This study also shows that a reduction in the Equator-to-pole temperature difference in the Southern Hemisphere causes the mid-latitude westerly wind strength to reduce in the models; however, the simulated rainfall actually increases over the southern temperate zone of Australia as a result of higher convective precipitation. Such a mechanism (increased convection) may be useful for resolving disparities between different regional proxy records and model simulations. Finally, after assessing the available datasets (model and proxy), opportunities for better model-proxy integrated research are discussed. © Author(s) 2017.
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