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.
- Grundell, Rosie, Gell, Peter, Mills, Keely, Zawadzki, Atun
- Authors: Grundell, Rosie , Gell, Peter , Mills, Keely , Zawadzki, Atun
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Paleolimnology Vol. 47, no. 2 (2012), p. 205-219
- Full Text: false
- Reviewed:
- Description: Sinclair Flat is small wetland, located within the gorge section of the Murray River floodplain. situated near Blanchetown, South Australia, the wetland is closely linked to the River and, since regulation, has become permanently inundated. High summer evaporation rates deplete the volume of water within the wetland. However, this is compensated by perennial inflow via a permanent inlet from the River. This site provides an opportunity to explore the relative contribution of river and wetland diatom flora to the sediment record, and the fluvial and aerial contribution of radiometric isotopes to the system. The geochronological and biostratigraphic data provide an insight into the history of the water quality of Sinclair Flat. Evidence exists for the River being a source of sediments and isotopes and of diatom species typical of the main river channel. Prior to 1950, Sinclair Flat was an oligotrophic, oligosaline, clear-water wetland. The wetland shifted gradually to an environment that favoured clear-water benthic species, most likely as a consequence of changes following river regulation in the 1920s, although the capacity to date these sediments is limited. During the 1950s, the wetland became plankton dominated. Peaks in epiphytic diatoms during the 1960s suggest increased emergent macrophyte cover. The contemporary condition is of a connected, turbid, eutrophic and mesosaline lagoon. The ecological condition of Sinclair Flat has diverged considerably from its historical range of condition. This record supports evidence from upstream of widespread state switches in the Murray-Darling Basin floodplain wetlands. This record also lends considerable weight to modern studies attesting to the degraded state of the waterways of the Murray-Darling Basin and the impact of river regulation practices on the water quality of these ecosystems. © 2011 Springer Science+Business Media B.V.
- 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.
- Pearson, Stuart, Lynch, Jasmyn, Plant, Roel, Cork, Steve, Taffs, Kathryn, Dodson, John, Maynard, Simone, Gergis, Joelle, Gell, Peter, Thackway, Richard, Sealie, Lynne, Donaldson, Jim
- Authors: Pearson, Stuart , Lynch, Jasmyn , Plant, Roel , Cork, Steve , Taffs, Kathryn , Dodson, John , Maynard, Simone , Gergis, Joelle , Gell, Peter , Thackway, Richard , Sealie, Lynne , Donaldson, Jim
- Date: 2015
- Type: Text , Journal article
- Relation: Holocene Vol. 25, no. 2 (2015), p. 366-378
- Full Text: false
- Reviewed:
- Description: Despite the great potential of palaeo-environmental information to strengthen natural resource policy, science and practical outcomes naturally occurring archives of palaeo-environmental and ecosystem service information have not been fully recognised or utilised to inform the development of environmental policy. In this paper, we describe how Australian palaeo-environmental science is improving environmental understanding through local studies and regional syntheses that inform us about past conditions, extreme conditions and altered ecosystem states. Australian innovations in ecosystem services research and palaeo-environmental science contribute in five important contexts: discussions about environmental understanding and management objectives, improving access to information, improved knowledge about the dynamics of ecosystem services, increasing understanding of environmental processes and resource availability, and engaging interdisciplinary approaches to manage ecosystem services. Knowledge of the past is an important starting point for setting present and future resource management objectives, anticipating consequences of trade-offs, sharing risk and evaluating and monitoring the ongoing availability of ecosystem services. Palaeo-environmental information helps reframe discussions about desirable futures and collaborative efforts between scientists, planners, managers and communities. However, further steps are needed to translate the ecosystem services concept into ecosystem services policy and tangible management objectives and actions that are useful, feasible and encompass the range of benefits to people from ecosystems. We argue that increased incorporation of palaeo-environmental information into policy and decision-making is needed for evidence-based adaptive management to enhance sustainability of ecosystem functions and reduce long-term risks.
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
Ecological shift and resilience in China's lake systems during the last two centuries
- Zhang, Ke, Dong, Xuhui, Yang, Xiangdong, Kattel, Giri, Zhao, Yanjie, Wang, Rong
- Authors: Zhang, Ke , Dong, Xuhui , Yang, Xiangdong , Kattel, Giri , Zhao, Yanjie , Wang, Rong
- Date: 2018
- Type: Text , Journal article , Review
- Relation: Global and Planetary Change Vol. 165, no. (2018), p. 147-159
- Full Text: false
- Reviewed:
- Description: The worldwide decline of wetland ecosystems calls for an urgent reassessment of their current status from a resilience perspective. Understanding the trajectories of changes that have produced the current situation is fundamental for assessing system resilience. Here, we examine long-term dynamics of wetland ecosystem change by reviewing paleoecological records from 11 representative lakes in China. We identify unprecedented change in alga communities in the context of last two centuries. Striking ecological shifts have occurred in all lakes, yet with spatial and temporal differences. The long-term trajectories of change in diatom species composition and structure indicate gradually eroded system resilience. These ecological shifts were shaped by socio-economic activities as China transformed from a rural agricultural to an industrialized society within the last several decades, during which multiple drivers have accumulated and acted synergistically. The balance between ecosystem and society, which appeared to exist for thousands of years, was broken by increasing population, new technology, and urbanization since the 1980s. The consequences are the emergence of new positive feedbacks with the potential to drive the coupled systems into undesirable states. By linking long-term social and ecological change at a regional scale, our study provides a novel contribution to the understanding of lake ecosystems resilience in present-day China. We argue that sustaining wetland ecosystems requires integrated approaches that incorporate a deeper understanding of social-ecological dynamics over decadal-centennial timescales to address the complex underlying mechanisms leading to the current degradation.
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