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The six species of mountain frogs (Philoria: Limnodynastidae: Anura) are endemic to south-eastern Australia. Five species occur in headwater systems in mountainous north-eastern New South Wales (NSW) and south-eastern Queensland (Qld), centred on the Gondwana Rainforests of Australia World Heritage Area. A previous molecular genetic analysis identified divergent genetic lineages in the central and western McPherson Ranges region of Qld and NSW, but sampling was inadequate to test the species status of these lineages. With more comprehensive geographic sampling and examination of the nuclear genome using SNP analysis, we show that an undescribed species, P. knowlesi sp. nov., occurs in the central and western McPherson Ranges (Levers Plateau and Mount Barney complex). The new species is not phylogenetically closely related to P. loveridgei in the nuclear data but is related to one of two divergent lineages within P. loveridgei in the mtDNA data. We postulate that the discordance between the nuclear and mtDNA outcomes is due to ancient introgression of the mtDNA genome from P. loveridgei into the new species. Male advertisement calls and multivariate morphological analyses do not reliably distinguish P. knowlesi sp. nov. from any of the Philoria species in northeast NSW and southeast Qld. The genetic comparisons also enable us to define further the distributions of P. loveridgei and P. kundagungan. Samples from the Lamington Plateau, Springbrook Plateau, Wollumbin (Mt Warning National Park), and the Nightcap Range, are all P. loveridgei, and its distribution is now defined as the eastern McPherson Ranges and Tweed caldera. Philoria kundagungan is distributed from the Mistake Mountains in south-eastern Qld to the Tooloom Scrub on the Koreelah Range, southwest of Woodenbong, in NSW, with two subpopulations identified by SNP analysis. We therefore assessed the IUCN threat category of P. loveridgei and P. kundagungan and undertook new assessments for each of its two subpopulations and for the new taxon P. knowlesi sp. nov., using IUCN Red List criteria. Philoria loveridgei, P. kundagungan (entire range and northern subpopulation separately) and P. knowlesi sp. nov. each meet criteria for Endangered (EN B2(a)(b)[i, iii]). The southern subpopulation of P. kundagungan, in the Koreelah Range, meets criteria for Critically Endangered (CE B2(a)(b)[i, iii]). These taxa are all highly threatened due to the small number of known locations, the restricted nature of their breeding habitat, and direct and indirect threats from climate change, and the potential impact of the amphibian disease chytridiomycosis. Feral pigs are an emerging threat, with significant impacts now observed in Philoria breeding habitat in the Mistake Mountains.

Rationale: In recent years, the primary reference material (RM) for the VPDB scale, NBS19, has become unavailable, and the RM used for low-end scale-anchoring, LSVEC, was found unsuitable due a drift in the δ 13 C value. Given these problems, new RMs aimed at realising the VPDB δ 13 C scale with low uncertainty were produced. Establishing the consistency of the new RMs with the "old" RMs prompted our revision of the underlying principles of RM value assignments, and the VPDB δ 13 C scale realisation and its long-term sustainability., Methods: Analysis of major developments of the VPDB scale, a review of the contemporary requirements for RMs, and comparison with well-established measurement scales have been performed, with the aim of revising the VPDB δ 13 C scale, principles of RM value assignments, and calibrator hierarchy. Requirements for scale-anchoring RMs with low uncertainty and measures to establish the scale sustainability have been formulated., Results: The revised scale realisation is based on multiple reference points, well-defined calibration hierarchy and the use of well-understood methods for value assignment. The realisation scheme includes the new primary RM IAEA-603 and scale-anchoring RMs IAEA-610, IAEA-611 and IAEA-612, covering δ 13 C from +2.46 to -36.7 ‰ VPDB, with uncertainties, including inhomogeneity and stability assessment, of less than 0.015 ‰. The values of these four RMs were assigned in a mutually consistent way; agreement between measurements made using this realisation with those made using the VPDB scale of 2006 has been demonstrated on NIST CO 2 RMs 8562-8564., Conclusions: Multipoint-anchoring of the VPDB δ 13 C scale provides several distinct "points" on the scale as means for cross-measurements to check the stability and viability of RMs and detect drift of values, if any. This ensures that the δ 13 C scale is suitable for the most demanding applications, and provides options for developing further RMs with high accuracy inside a robust scale realisation scheme., (© 2020 John Wiley & Sons Ltd.)

The severe drought of the 1930s Dust Bowl decade coincided with record-breaking summer heatwaves that contributed to the socio-economic and ecological disaster over North America's Great Plains. It remains unresolved to what extent these exceptional heatwaves, hotter than in historically forced coupled climate model simulations, were forced by sea surface temperatures (SSTs) and exacerbated through human-induced deterioration of land cover. Here we show, using an atmospheric-only model, that anomalously warm North Atlantic SSTs enhance heatwave activity through an association with drier spring conditions resulting from weaker moisture transport. Model devegetation simulations, that represent the wide-spread exposure of bare soil in the 1930s, suggest human activity fueled stronger and more frequent heatwaves through greater evaporative drying in the warmer months. This study highlights the potential for the amplification of naturally occurring extreme events like droughts by vegetation feedbacks to create more extreme heatwaves in a warmer world.

The Indian Ocean Dipole (IOD) is the dominant mode of interannual variability over the tropical Indian Ocean (IO) and its future changes are projected to impact the climate and weather of Australia, East Africa, and Indonesia. Understanding the response of the IOD to a warmer climate has been largely limited to studies of individual coupled general circulation models or multi-model ensembles. This has provided valuable insight into the IOD's projected response to increasing greenhouse gases but has limitations in accounting for the role of internal climate variability. Using the Community Earth System Model Large Ensemble (CESM-LE), the IOD is examined in thirty-five present-day and future simulations to determine how internal variability influences properties of the IOD and their response to a warmer climate. Despite small perturbations in the initial conditions as the only difference between ensemble members, significant relationships between the mean state of the IO and the IOD arise, leading to a spread in the projected IOD responses to increasing greenhouse gases. This is driven by the positive Bjerknes feedback, where small differences in mean thermocline depth, which are caused by internal climate variability, generate significant variations in IOD amplitude, skewness, and the climatological zonal sea surface temperature gradient.

Reconstructing the dynamic response of the Antarctic ice sheets to warming during the Last Glacial Termination (LGT; 18,000-11,650 yrs ago) allows us to disentangle ice-climate feedbacks that are key to improving future projections. Whilst the sequence of events during this period is reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records, making it difficult to assess relationships between Antarctic ice-sheet (AIS) dynamics, climate change and sea level. Here we present results from a highly-resolved 'horizontal ice core' from the Weddell Sea Embayment, which records millennial-scale AIS dynamics across this extensive region. Counterintuitively, we find AIS mass-loss across the full duration of the Antarctic Cold Reversal (ACR; 14,600-12,700 yrs ago), with stabilisation during the subsequent millennia of atmospheric warming. Earth-system and ice-sheet modelling suggests these contrasting trends were likely Antarctic-wide, sustained by feedbacks amplified by the delivery of Circumpolar Deep Water onto the continental shelf. Given the anti-phase relationship between inter-hemispheric climate trends across the LGT our findings demonstrate that Southern Ocean-AIS feedbacks were controlled by global atmospheric teleconnections. With increasing stratification of the Southern Ocean and intensification of mid-latitude westerly winds today, such teleconnections could amplify AIS mass loss and accelerate global sea-level rise.