Australasian Temperature Reconstructions Spanning the Last Millennium

Gergis, Joëlle; Neukom, Raphael; Gallant, Ailie J. E.; Karoly, David J.

doi:10.1175/jcli-d-13-00781.1

Cited by 38 publications

(63 citation statements)

References 144 publications

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“…For completeness, we have in Table S1 (in the supporting information) summarized available regional/continental scale reconstructions, extending back to at least A.D. 1000 and published prior to November 2016 [ Cook et al , ; Gergis et al , ; Guangliang et al , ; Guiot et al , ; Kaufman et al , ; Luterbacher et al , ; McKay and Kaufman , ; Shi et al , , , ; Wang et al , ; Yang et al , ; Neukom et al , ; Ge et al , ; Hanhijärvi et al , ; Trouet et al , ; PAGES 2k Consortium , ]. Such reconstructions are hampered by essentially the same problems as hemispheric or global scale reconstructions.…”

Section: Reconstructions Of the Last Millennium: Proxies And Methodsmentioning

confidence: 99%

Challenges and perspectives for large‐scale temperature reconstructions of the past two millennia

Christiansen

Ljungqvist

2017

Reviews of Geophysics

124

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Knowledge of the temperature variability during the last one to two millennia is important for providing a perspective to present‐day climate excursions, for assessing the sensitivity of the climate to different forcings, and for providing a test bed for climate models. Since systematic instrumental temperature records only extend back to the nineteenth century, such knowledge mainly relies on climate‐sensitive proxy data. Here we critically assess some of the many challenges related to large‐scale multiproxy temperature reconstructions. We begin with a review of available large‐scale temperature reconstructions, focusing on the differences in low‐frequency variability and the response to natural forcings such as major volcanic eruptions and changes in total solar irradiance. Then, we discuss different proxy selection strategies, review previously used reconstruction methods, and discuss their ability to reconstruct the amplitude of the low‐frequency variability. To shed additional light on the challenges of large‐scale reconstructions, we investigate the spatial and temporal correlation structures in the observed temperature field and discuss the implications of these correlation structures regarding the required number and positions of proxies. We demonstrate how the unavoidable uncertainty related to noisy proxies will show up as bias and variance in the reconstruction and that the partition between these forms of errors depends on the reconstruction method. Pseudo‐proxy experiments are conducted to further discuss the influence of noise and the requirements regarding the geographical location and number of proxies necessary for reliably reconstructing the low‐frequency variability. We conclude with recommendations for future large‐scale temperature reconstructions.

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Section: Reconstructions Of the Last Millennium: Proxies And Methodsmentioning

confidence: 99%

Challenges and perspectives for large‐scale temperature reconstructions of the past two millennia

Christiansen

Ljungqvist

2017

Reviews of Geophysics

124

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“…Multiple approaches for integrating Australasian palaeoclimate data have recognised the importance of teleconnection stability and how varying teleconnection strength through time may impact reconstruction interpretations Goodwin et al, , 2014Lorrey et al, 2014;Gergis et al, 2016). All of the approaches are potentially limited by the short length and quality of calibration timescales, uncertainties in proxy archive dating, regional biases from uneven spatial coverage, seasonal sensitivity, and in some cases multiple influences on proxy archive interpretation (i.e.…”

Section: Climate Teleconnectionsmentioning

confidence: 99%

“…The utilisation of high-quality sites near to, but outside, the location of interest may lead to regional reconstructions with higher statistical skill, as they may preserve sig-nals of large-scale circulation patterns rather than local climate features (Gallant and Gergis, 2011;Gergis et al, , 2016Ho et al, 2013). In Australia, sites along the southern coast of South Australia and Victoria are impacted by a similar atmospheric circulation features and remote climate drivers as major cities and agricultural centres of southern Australia (Murphy and Timbal, 2008), lending the potential to use palaeoclimate records from near the coast to infer patterns of change inland (Ho et al, 2013).…”

Section: Climate Teleconnectionsmentioning

confidence: 99%

“…A recent highresolution reconstruction of Australian temperature over the last millennium demonstrates the regionally specific timing and magnitude of temperature fluctuations that can be directly compared to climate model simulations to determine dynamical influences (see studies listed in Sect. 4a of Gergis et al, 2016). Overall, understanding of regional climate variability is important for using palaeoclimate data to evaluate possible responses to future climate change.…”

Section: Climate Teleconnectionsmentioning

confidence: 99%

“…High-resolution archives, such as tree rings, corals, varved sediments, and some ice cores, have been used to reconstruct regional and global temperature trends over the Common Era (PAGES2k Consortium, 2013;Gergis et al, 2016;Mann, 2007;Mann and Jones, 2003). In addition to several advantages of using annually resolved data, such as chronological precision and temporal resolution, annually resolved data possess some limitations when examining the past 2 millennia.…”

Section: Introductionmentioning

confidence: 99%

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Low-resolution Australasian palaeoclimate records of the last 2000 years

et al. 2017

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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 14 C dates and the use of estimated autocorrelation between sampled 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 coretop dating, inclusion of tephra layers where possible, and increased date density during the Common Era.

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Disruption of cultural burning promotes shrub encroachment and unprecedented wildfires

Mariani

Connor

Theuerkauf

et al. 2022

Frontiers in Ecol & Environ

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Recent catastrophic fires in Australia and North America have raised broad‐scale questions about how the cessation of Indigenous burning practices has impacted fuel accumulation and structure. For sustainable coexistence with fire, a better understanding of the ancient nexus between humans and flammable landscapes is needed. We used novel palaeoecological modeling and charcoal compilations to reassess evidence for changes in land cover and fire activity, focusing on southeast Australia before and after British colonization. Here, we provide what we believe is the first quantitative evidence that the region’s forests and woodlands contained fewer shrubs and more grass before colonization. Changes in vegetation, fuel structures, and connectivity followed different trajectories in different vegetation types. The pattern is best explained by the disruption of Indigenous vegetation management caused by European settlement. Combined with climate‐change impacts on fire weather and drought, the widespread absence of Indigenous fire management practices likely preconditioned fire‐prone regions for wildfires of unprecedented extent.

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Australasian Temperature Reconstructions Spanning the Last Millennium

Cited by 38 publications

References 144 publications

Challenges and perspectives for large‐scale temperature reconstructions of the past two millennia

Challenges and perspectives for large‐scale temperature reconstructions of the past two millennia

Low-resolution Australasian palaeoclimate records of the last 2000 years

Disruption of cultural burning promotes shrub encroachment and unprecedented wildfires

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