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The timing and duration of the coldest period in the last glacial stage, often referred to as the last glacial maximum (LGM), has been observed to vary spatially and temporally. In Australia, this period is characterised by colder, and in some places more arid, climates than today. We applied Monte-Carlo change point analysis to all available continuous proxy records covering this period, primarily pollen records, from across Australia (n = 37) to assess this change. We find a significant change point occurred (within uncertainty) at 28.6 ± 2.8 ka in 25 records. We interpret this change as a shift to cooler climates, associated with a widespread decline in biological productivity. An additional change point occurred at 17.7 ± 2.2 ka in 24 records. We interpret this change as a shift towards warmer climates, associated with increased biological productivity. We broadly characterise the period between 28.6 (± 2.8) – 17.7 (± 2.2) ka as an extended period of maximum cooling, with low productivity vegetation that may have occurred as a combined response to reduced temperatures, lower moisture availability and atmospheric CO2. These results have implications for how the spatial and temporal coherence of climate change, in this case during the LGM, can be best interrogated and interpreted. [ABSTRACT FROM AUTHOR]

A multiproxy record from Twin Ponds, VT, is used to reconstruct climatic variability during the late Pleistocene to early Holocene transition. Pollen, ostracodes, δ18O, and lithologic records from 13.5 to 9.0 cal ka BP are presented. Pollen- and ostracode-inferred climatic reconstructions are based on individual species' environmental preferences and the modern analog technique. Principal components analysis of all proxies highlights the overall warming trend and centennial-scale climatic variability. During the Younger Dryas cooling event (YD), multiple proxies show evidence for cold winter conditions and increasing seasonality after 12.5 cal ka BP. The early Holocene shows an initial phase of rapid warming with a brief cold interval at 11.5 cal ka BP, followed by a more gradual warming; a cool, wet period from 11.2 to 10.8 cal ka BP; and cool, dry conditions from 10.8 to 10.2 cal ka BP. The record ends with steady warming and increasing moisture. Post-YD climatic variability has been observed at other sites in the northeastern United States and points to continued instability in the North Atlantic during the final phases of deglaciation. [ABSTRACT FROM AUTHOR]

Northern Australia is a region where limited information exists on environments at the last glacial maximum (LGM). Girraween Lagoon is located on the central northern coast of Australia and is a site representative of regional tropical savanna woodlands. Girraween Lagoon remained a perennial waterbody throughout the LGM, and as a result retains a complete proxy record of last-glacial climate, vegetation and fire. This study combines independent palynological and geochemical analyses to demonstrate a dramatic reduction in both tree cover and woody richness, and an expansion of grassland, relative to current vegetation at the site. The process of tree decline was primarily controlled by the cool-dry glacial climate and CO2 effects, though more localised site characteristics restricted wetland-associated vegetation. Fire processes played less of a role in determining vegetation than during the Holocene and modern day, with reduced fire activity consistent with significantly lower biomass available to burn. Girraween Lagoon's unique and detailed palaeoecological record provides the opportunity to explore and assess modelling studies of vegetation distribution during the LGM, particularly where a number of different global vegetation and/or climate simulations are inconsistent for northern Australia, and at a range of resolutions. [ABSTRACT FROM AUTHOR]

Mounting evidence suggests that the Southern Westerly Winds were significantly equatorially displaced and more intense during the last glacial maximum (LGM), prompting deliberate research identifying proxies to reconstruct these changes. This has focused on rainfall seasonality to track changes in major circulation patterns across the southern hemisphere midlatitude regions. Using a common methodology to reconstruct climatic changes aids comparability and makes it easier to draw significant conclusions regarding general circulation movements. We assess the applicability of Coetzee's (1967) Poaceae:Asteraceae pollen ratio, which has been used successfully in South Africa, in the Australian context. The ratio scores from modern samples fail to capture the weak seasonality in the southeast and on Tasmania but is successful for the rest of the continent. The periods of greatest change compared to present day match known periods of distinct climatic events, namely the mid-Holocene (6–7 cal ka BP), the last deglacial period (15–17 cal ka BP), and two periods during the LGM (20–22 and 31–33 cal ka BP), suggesting large parts of Australia experienced a "double peak" of rainfall seasonality change during the LGM. This confirms that the Poaceae:Asteraceae pollen ratio can be used on records outside of South Africa. [ABSTRACT FROM AUTHOR]

Abstract: A series of 18 fossil beetle assemblages are used to reconstruct the paleoenvironment of the northwest West Coast, New Zealand, over the period of the last interstadial–stadial transition (ca. 37,000–21,300 cal yr BP). The samples were recovered from an in-filled hollow within a dune field ca. 9 km south west of Westport (41°47′S, 171°30′E). This fossil beetle reconstruction is compared to an existing palynological reconstruction from the same site. The beetle assemblages indicate an environment of marshy shrubland interspersed with closed canopy coastal vegetation prior to glacial onset, and a mosaic of closed canopy patches and open tussock grassland during full glacial conditions. These interpretations, contrast with the palynologically based interpretation which indicates subalpine shrubland prior to glacial onset and widespread grassland with little woody vegetation during the period of maximum glacial cooling. This study is consistent with other non-pollen studies in New Zealand and indicates that the palynological interpretation of the paleoenvironment of the Westport region downplays the importance of closed canopy vegetation in the area during the transition from interstadial to full glacial (stadial) conditions. It challenges the interpretation of open vegetation at low elevations during glacial periods from pollen studies. [Copyright &y& Elsevier]

The Holocene climatic history of tropical northern Australia is re-examined using the recently published pollen record from Groote Eylandt to corroborate and refine previous climatic inter pretations. We identify a four-stage Holocene comprising: (1) a continuous increase in effective precipitation (EP) from the beginning of the Holocene to about 5000 BP; (2) a mid-Holocene EP maximum from about 5000 to about 4000 BP; (3) a marked decline in EP somewhere between 4000-3500 Bp; and (4) an EP recovery in the last <2000 years. The mid-Holocene EP maximum is 1000 years later than Holocene EP maxima from temperate Southern Australia and suggests that the records are decoupled at this time.We focus on pollen evidence of environmental change at c. 4000 BP, which marks a break between a continuously ameliorating (increasing EP) climate but with small mean variation in the earlier Holocene and a steady (no directional trend) but highly variable later Holocene. We believe that this break represents the first evidence from the monsoonal lowlands of northern Australia for the onset of 'modern' ENSO-dominated ocean-atmosphere interactions in the Holocene. A simple conceptual model of trans-Pacific teleconnections is presented to explain this onset and as an hypothesis for testing. [ABSTRACT FROM PUBLISHER]

A pollen record from a dunefield lake on Groote Eylandt, Northern Australia is presented. This is the first substantially complete Holocene terrestrial record from the seasonally humid lowland tropics of Northern Australia. The lake originated as a seasonal swamp prior to 10 000 BP. A progressive rise in water tables occurred until a permanent lake was established at about 9000 BP. From 9000 to 7500 BP the lake shows evidence of disruption in the surrounding dunefield. Prior to 7500 BP an open grassland covered the dunefield. After 7500 BP the area was rapidly colonized by Eucalyptus open forest and acacias. These types remain dominant to the present. The data suggest that conditions continuously ameliorated from the base of the record to the mid-Holocene and there is evidence of an effective precipitation maximum at about 4000 BP. Effective precipitation declined after 3800 BP but a recovery took place about 1000 BP. [ABSTRACT FROM PUBLISHER]

Abstract: Paleoenvironmental reconstructions from Little Llangothlin Lagoon have been used to argue for early European impact on the eastern Australian landscape. In particular, these studies have argued for European arrival on the New England Tablelands at about 1800 AD, with significant impacts including the clearance of one species of Casuarina before 1820 AD and significant erosion by 1836 AD (; ; , ). We have re-cored the lagoon, dated the cores using 210Pb and radiocarbon, and counted pollen and other proxies. Our 210Pb results indicate that 210Pb background was achieved stratigraphically later than the erosion event and we have three early Holocene radiocarbon ages in the erosion event interval. We conclude that the ‘erosion event’ predates European settlement. The 210Pb results indicate much less erosion in response to European settlement than suggested by these earlier studies. We also find no notable decline in Casuarina in the pollen record spanning the time of initial European impact, and in fact we find very little Casuarina in the record. Instead of a Casuarina dominated vegetation we conclude that the area was dominated by open Eucalypt forest prior to European settlement. Rather than changes in the regional vegetation in the early 19th century, we attribute changes in the palynoflora spanning the ‘erosion event’ to changes within the lake/wetland and in particular to changes in the dominance of different species of Myriophyllum; most likely due to water depth fluctuation. This site has stood out as indicating an earlier European impact than other localities in eastern Australia, beyond the original limits of settlement near Sydney. Our findings suggest that a more traditional interpretation of this site is warranted and that no very early impact is discernable. [Copyright &y& Elsevier]

Montane vegetation belts are sensitive to climate change; however, it is uncertain to what degree their evolution is influenced by changes in mean annual temperature or seasonal climate. In this study, we use pollen assemblages from a high elevation lake (3780 m.a.s.l.) in the Gongga Mountains on the southeast margin of the Qinghai-Tibetan Plateau, China, to study changes in altitudinal vegetation zones during the last 12,000 years. The relationships between vegetation belts and winter and summer climate parameters are analyzed. Results indicate that winter temperature mainly controlled the development of evergreen broadleaved forest (Cyclobalanopsis and Taxodiaceae), deciduous broadleaved forest (Betula), and sub-alpine shrubland (Rosaceae, Cyperaceae and Gramineae dominated). In contrast, the development of temperate coniferous forest (Pinus and Tsuga) and alpine herbfield (Artemisia and Chenopodiaceae) was mainly controlled by summer temperature and precipitation. Results show that winter temperature gradually increased from the Greenlandian to Meghalayan, indicating that the main driving factor was winter solar insolation in the Northern Hemisphere. Meanwhile, changes in summer temperature and precipitation are consistent with the results from Indian monsoon-dominated areas of China, suggesting that the summer climate in this region is mainly driven by the migration of the Intertropical Convergence Zone. Our findings suggest that the influence of seasonal climate changes should be considered on the evolution of montane vegetation belts. • The vegetation dynamics in SW China are reconstructed during the Holocene. • Contrasting effects of seasonal climate on altitudinal vegetation belts evolution. • Winter temperature followed gradual decline with winter insolation in the NH. • Summer climate is mainly driven by migration of the ITCZ under insolation forcing. [ABSTRACT FROM AUTHOR]