Jonathan Tyler

A diatom‐inferred record of lake variability during the last 900 years in Lützow–Holm Bay, East Antarctica

Publisher: Wiley

Date: 02-2016

DOI: 10.1002/JQS.2845

Identifying coherent patterns of environmental change between multiple, multivariate records: an application to four 1000-year diatom records from Victoria, Australia

Publisher: Elsevier BV

Date: 07-2015

DOI: 10.1016/J.QUASCIREV.2015.04.010

Persistent influence of obliquity on ice age terminations since the Middle Pleistocene transition

Publisher: American Association for the Advancement of Science (AAAS)

Date: 13-03-2020

DOI: 10.1126/SCIENCE.AAW1114

Abstract: Understanding more exactly how the timing of deglaciations depends on changes in insolation, or the energy received by Earth from the Sun, requires precise and independent records of both environmental change and solar energy input. Bajo et al . strengthened the weak link of that two-member chain, the environmental record, by developing a precise, radiometrically dated chronology of the 11 deglaciations of the past million years derived from speleothems. This allowed them to show more clearly how the initiation and duration of glacial terminations over that period depended on solar obliquity and precession. Science , this issue p. 1235

Carbon isotope discrimination in leaves of the broad‐leaved paperbark tree, Melaleuca quinquenervia, as a tool for quantifying past tropical and subtropical rainfall

Publisher: Wiley

Date: 19-04-2016

DOI: 10.1111/GCB.13277

Abstract: Quantitative reconstructions of terrestrial climate are highly sought after but rare, particularly in Australia. Carbon isotope discrimination in plant leaves (Δleaf ) is an established indicator of past hydroclimate because the fractionation of carbon isotopes during photosynthesis is strongly influenced by water stress. Leaves of the evergreen tree Melaleuca quinquenervia have been recovered from the sediments of some perched lakes on North Stradbroke and Fraser Islands, south-east Queensland, eastern Australia. Here, we examine the potential for using M. quinquenervia ∆leaf as a tracer of past rainfall by analysing carbon isotope ratios (δ(13) C) of modern leaves. We firstly assess Δleaf variation at the leaf and stand scale and find no systematic pattern within leaves or between leaves due to their position on the tree. We then examine the relationships between climate and Δleaf for a 11-year time series of leaves collected in a litter tray. M. quinquenervia retains its leaves for 1-4 years thus, cumulative average climate data are used. There is a significant relationship between annual mean ∆leaf and mean annual rainfall of the hydrological year for 1-4 years (i.e. 365-1460 days) prior to leaf fall (r(2) = 0.64, P = 0.003, n = 11). This relationship is marginally improved by accounting for the effect of pCO2 on discrimination (r(2) = 0.67, P = 0.002, n = 11). The correlation between rainfall and Δleaf , and the natural distribution of Melaleuca quinquenervia around wetlands of eastern Australia, Papua New Guinea and New Caledonia offers significant potential to infer past rainfall on a wide range of spatial and temporal scales.

Holocene El Niño–Southern Oscillation variability reflected in subtropical Australian precipitation

Publisher: Springer Science and Business Media LLC

Date: 07-02-2019

DOI: 10.1038/S41598-019-38626-3

Abstract: The La Niña and El Niño phases of the El Niño-Southern Oscillation (ENSO) have major impacts on regional rainfall patterns around the globe, with substantial environmental, societal and economic implications. Long-term perspectives on ENSO behaviour, under changing background conditions, are essential to anticipating how ENSO phases may respond under future climate scenarios. Here, we derive a 7700-year, quantitative precipitation record using carbon isotope ratios from a single species of leaf preserved in lake sediments from subtropical eastern Australia. We find a generally wet (more La Niña-like) mid-Holocene that shifted towards drier and more variable climates after 3200 cal. yr BP, primarily driven by increasing frequency and strength of the El Niño phase. Climate model simulations implicate a progressive orbitally-driven weakening of the Pacific Walker Circulation as contributing to this change. At centennial scales, high rainfall characterised the Little Ice Age (~1450–1850 CE) in subtropical eastern Australia, contrasting with oceanic proxies that suggest El Niño-like conditions prevail during this period. Our data provide a new western Pacific perspective on Holocene ENSO variability and highlight the need to address ENSO reconstruction with a geographically erse network of sites to characterise how both ENSO, and its impacts, vary in a changing climate.

Pliocene reversal of late Neogene aridification

Publisher: Proceedings of the National Academy of Sciences

Date: 08-02-2016

DOI: 10.1073/PNAS.1520188113

Abstract: The warm climates of the Pliocene epoch are considered our best analog for a future anthropogenic greenhouse world. However, understanding of the nature of Pliocene climate variability and change on land is currently limited by the poor age control of most existing terrestrial climate archives. We present a radiometrically dated history of the evolution of Southern Hemisphere vegetation and hydroclimate from the latest Miocene to the middle Pliocene. These data reveal a sharp increase in precipitation in the Early Pliocene, which drove complete vegetation turnover. The development of warm, wet early Pliocene climates clearly reversed a long-term Southern Hemisphere trend of late Neogene cooling and aridification, highlighting the question of what initiated this sustained, ∼1.5-My-long interval of warmth.

Post little ice age drying of eastern Australia conflates understanding of early settlement impacts

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.QUASCIREV.2018.10.033

Calcium and strontium isotope systematics in the lagoon-estuarine environments of South Australia: Implications for water source mixing, carbonate fluxes and fish migration

Publisher: Elsevier BV

Date: 10-2018

DOI: 10.1016/J.GCA.2018.07.036

Coherent patterns of environmental change at multiple organic spring sites in northwest Australia: Evidence of Indonesian-Australian summer monsoon variability over the last 14,500 years

Publisher: Elsevier BV

Date: 09-2018

DOI: 10.1016/J.QUASCIREV.2018.07.018

Investigating the palaeoenvironmental context of Late Pleistocene human dispersals into Southeast Asia: a review of stable isotope applications

Publisher: Springer Science and Business Media LLC

Date: 13-04-2022

DOI: 10.1007/S12520-022-01540-3

Abstract: We review palaeoenvironmental applications of stable isotope analysis to Late Pleistocene archaeological sites across Southeast Asia (SEA), a region critical to understanding the evolution of Homo sapiens and other co-existing Late Pleistocene (124–11.7 ka) hominins. Stable isotope techniques applied to archaeological deposits offer the potential to develop robust palaeoenvironmental reconstructions, to contextualise the occupational and non-occupational history of a site. By evaluating the published research in this field, we show that sediments, guano, tooth enamel, speleothem and biomolecular material such as leaf waxes have great potential to provide site-specific palaeoenvironmental records and local and catchment-scale landscape context to hominin dispersal in the region. However, stable isotope techniques used in these contexts are in their infancy in SEA, and the diagenetic controls associated with hot and humid environments that typify the region are not yet fully understood. Additionally, availability of sources of stable isotopes varies between sites. Nonetheless, even the limited research currently available shows that stable isotope analyses can aid in developing a better understanding of the role of the environment on the nature and timing of dispersals of our species eastwards into SEA and beyond.

Low-resolution Australasian palaeoclimate records of the last 2000 years

Publisher: Copernicus GmbH

Date: 26-10-2017

DOI: 10.5194/CP-13-1403-2017

Abstract: Abstract. Non-annually resolved palaeoclimate records in the Australasian region were compiled to facilitate investigations of decadal to centennial climate variability over the past 2000 years. A total of 675 lake and wetland, geomorphic, marine, and speleothem records were identified. The majority of records are located near population centres in southeast Australia, in New Zealand, and across the maritime continent, and there are few records from the arid regions of central and western Australia. Each record was assessed against a set of a priori criteria based on temporal resolution, record length, dating methods, and confidence in the proxy–climate relationship over the Common Era. A subset of 22 records met the criteria and were endorsed for subsequent analyses. Chronological uncertainty was the primary reason why records did not meet the selection criteria. New chronologies based on Bayesian techniques were constructed for the high-quality subset to ensure a consistent approach to age modelling and quantification of age uncertainties. The primary reasons for differences between published and reconstructed age–depth models were the consideration of the non-singular distribution of ages in calibrated 14C dates and the use of estimated autocorrelation between s led depths as a constraint for changes in accumulation rate. Existing proxies and reconstruction techniques that successfully capture climate variability in the region show potential to address spatial gaps and expand the range of climate variables covering the last 2000 years in the Australasian region. Future palaeoclimate research and records in Australasia could be greatly improved through three main actions: (i) greater data availability through the public archiving of published records (ii) thorough characterisation of proxy–climate relationships through site monitoring and climate sensitivity tests and (iii) improvement of chronologies through core-top dating, inclusion of tephra layers where possible, and increased date density during the Common Era.

Natural hazards in Australia: droughts

Publisher: Springer Science and Business Media LLC

Date: 19-09-2016

DOI: 10.1007/S10584-016-1798-7

Development of a southern hemisphere subtropical wetland (Welsby Lagoon, south-east Queensland, Australia) through the last glacial cycle

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.QUASCIREV.2018.09.010

Climate variability in south-eastern Australia over the last 1500 years inferred from the high-resolution diatom records of two crater lakes

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.QUASCIREV.2014.05.001

Development of an autonomous, monthly and daily, rainfall sampler for isotope research

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.JHYDROL.2019.04.074

Hydrogen Peroxide Treatment of Natural Lake Sediment Prior to Carbon and Oxygen Stable Isotope Analysis of Calcium Carbonate

Publisher: American Geophysical Union (AGU)

Date: 09-2018

DOI: 10.1029/2018GC007575

Abstract: The carbon and oxygen stable isotope ratios (δ 13 C and δ 18 O) of authigenic and biogenic lacustrine carbonates are commonly used as past climate proxies, and these carbonates are often preserved within organic‐rich bulk sediment. We measured the δ 13 C and δ 18 O of carbon dioxide evolved from fine‐grained crystalline calcite and biogenic aragonite, mixed with natural organic‐rich lake sediment. We found that if the ratio of total inorganic carbon (TIC) to total organic carbon (TOC) in lacustrine bulk sediment is low, then organic compounds evolve detectable CO 2 during phosphoric acid digestion, leading to an “organic bias” in the measured δ 13 C and δ 18 O. We tested the effect of oxidative pretreatment of the bulk sediment with acidic or alkaline hydrogen peroxide (H 2 O 2 ), at a range of temperatures. Pretreatment with acidic H 2 O 2 not only had a negligible effect on the TIC/TOC but also resulted in dissolution and reprecipitation of carbonate, and a consequent “treatment bias” that was particularly strong for δ 18 O. Oxidation with alkaline H 2 O 2 removed a greater proportion of organic material, with no evidence for carbonate dissolution at temperatures of ≤50 °C. The δ 13 C and δ 18 O values obtained from sediment treated with alkaline H 2 O 2 at 50 °C were both accurate and precise, even for sediment with very low initial TIC/TOC. Our results show that it is possible to obtain accurate δ 13 C and δ 18 O values from carbonates preserved within organic‐rich lacustrine sediment, suitable for use in paleoclimate reconstructions.

Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the Indo-Pacific, Australasian and Southern Ocean regions

Publisher: Copernicus GmbH

Date: 24-11-2017

DOI: 10.5194/CP-13-1661-2017

Abstract: Abstract. 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.

Millennial-scale variability in south-east Australian hydroclimate between 30,000 and 10,000 years ago

Publisher: Elsevier BV

Date: 07-2018

DOI: 10.1016/J.QUASCIREV.2018.05.031

A global multiproxy database for temperature reconstructions of the Common Era

Publisher: Springer Science and Business Media LLC

Date: 11-07-2017

DOI: 10.1038/SDATA.2017.88

Abstract: Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850–2014. Global temperature composites show a remarkable degree of coherence between high- and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.

Discovery Projects - Grant ID: DP190102782

Start Date: 02-2019

End Date: 12-2023

Amount: $465,534.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP200101768

Start Date: 06-2020

End Date: 12-2024

Amount: $464,000.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT230100648

Start Date: 07-2023

End Date: 06-2027

Amount: $971,296.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE230100044

Start Date: 2023

End Date: 12-2024

Amount: $4,378,196.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140104093

Start Date: 07-2014

End Date: 06-2017

Amount: $450,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE180100185

Start Date: 2018

End Date: 12-2019

Amount: $464,531.00

Funder: Australian Research Council