Low-resolution Australasian palaeoclimate records of the last 2000 years

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 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.

Comparison of published palaeoclimate records suitable for reconstructing annual to sub-decadal hydroclimatic variability in eastern Australia: implications for water resource management and planning

“…As documented in previous studies (e.g. Tozer et al, 2016Tozer et al, , 2018Dixon et al, 2017Dixon et al, , 2019Zhang et al, 2018), and as evident from Section S1 in the Supplementary Material, there are numerous sources of uncertainty associated with palaeoclimate records and lack of agreement across different sources of palaeoclimate https://doi.org/10.5194/hess-2020-314 Preprint. Discussion started: 30 June 2020 c Author(s) 2020.…”

“… Australia (e.g. Gallant and Gergis, 2011;Ho et al, 2014;Allen et al, 2015aAllen et al, , 2015bHo et al, 2015aHo et al, , 2015bVance et al, 2015;Tozer et al, 2016Tozer et al, , 2018Dixon et al, 2017Dixon et al, , 2019Kiem et al, 2020);  Asia (e.g. Davi et al, 2013;Feng et al, 2013;Pederson et al, 2014;Nguyen and Galelli, 2018;Rao, 2018;Wang et al, 2019);…”

Late Quaternary Climate Variability and Change from Aotearoa New Zealand Speleothems: Progress in Age Modelling, Oxygen Isotope Master Record Construction and Proxy-Model Comparisons

“…New Zealand provides critical Southern Hemisphere palaeoclimate data and perspectives about Late Quaternary environmental change [1,2]. Atmospheric circulation regimes that influence this region produce strong, heterogeneous regional hydroclimate impacts from key modes of variability like the El Niño-Southern Oscillation, Madden-Julian Oscillation, the Interdecadal Pacific Oscillation, and the Southern Annular Mode [3][4][5][6][7].…”

Introduction to the special issue “Climate of the past 2000 years: regional and trans-regional syntheses”

“…Alongside these efforts, lower-resolution (interannual to multi-decadal resolution) archives offer the opportunity to develop longer records of past climate and environmental change. In this special issue, several new reconstructions are presented that highlight the complementary value of lowerresolution records for deriving millennial-length reconstructions from Australia (Dixon et al, 2017), the North Atlantic (Franke et al, 2017), North America (Shuman et al, 2018), the sub-Arctic (Nicolle et al, 2018), and the Arctic (Linderholm et al, 2018). These studies provide insights into multi-decadal to centennial forcing mechanisms, and provide a long-term context for late twentieth century regional change.…”