Palaeobiological evidence for Southern Hemisphere Younger Dryas and volcanogenic cold periods

Current consensus places a Southern Hemisphere post-glacial cooling episode earlier than the Younger Dryas in the Northern Hemisphere. New Zealand sequences of glacial moraines and speleothem isotopic data are generally interpreted as supporting the absence of a Southern Hemisphere Younger Dryas. Radiocarbon age series of habitat specialist moa (Aves: Dinornithiformes) show, however, that a sudden return to glacial climate in central New Zealand contemporary with the Younger Dryas. The cooling followed significant warming, not cooling, during the period of the Antarctic Cold Reversal. In addition, the moa sequence chronology also shows that the Oruanui (New Zealand) and Mt Takahe (Antarctica) volcanic eruptions were contemporary with abrupt cooling events in New Zealand. The independent high spatial and temporal resolution climate chronology reported here is contrary to an inter-hemispheric post-glacial climate see-saw model.

Late Pleistocene and Early Holocene Microblade-based Industries in Northeastern Asia

This monograph creatively uses Lewis Binford’s macroecological approach developed from his book Constructing Frames of Reference (2001) against both interglacial and glacial climate conditions, to provide an explanation of variation and change among late Pleistocene and early Holocene microblade-based societies in northeastern Asia.

Stalagmites: from Science Application to Museumization

The concept of geoheritage is related to places of geological interest, generally of aesthetic, cultural, socio-economic and/or scientific value. Many geosites are of karstic nature, because of their intrinsic beauty, their singularity and high geodiversity. Caves are among the most visited and economically exploited geological landforms. They constitute geosites as a whole, with their scenic landscapes, hydrogeological importance and the presence of bewildering natural rock and mineral formations including stalactites, stalagmites, flowstones and many other bizarre speleothem shapes. In some cases, a single speleothem, and the palaeoclimate record it contains, can be on its own of extraordinary importance to science. Once studied, these samples are often stored in research institution collections, rarely accessible to the wide public. In this paper, we report on the museumization of a stalagmite that has delivered a unique and exceptionally long glacial climate record from southern Italy, shedding light on the causes that led to the Neanderthal contraction and Modern Human expansion in this mild Mediterranean climate between 45 and 42 thousands years ago. The proposed museumization aims to demonstrate the potential of speleothems, after scientific application, in terms of educational and tourist resources. This approach allows to highlight the scientific importance of karst and cave geosites to the wide public, promoting their conservation and the valorisation of the studied cave-material.

Are Cryosphere-Driven Feedbacks a Requisite for Abrupt Climate Events? (Site U610, DSDP Leg. 94)

<p>Abrupt climate events are important features of glacial climate scales on centennial and millennial timescales. These events' mechanistic trigger is often ascribed to either ice sheet-related feedback mechanisms or large freshwater pulses. In both cases, amplification occurs when these triggers bear upon the Atlantic Meridional Overturning Circulation (AMOC). However, the focus on glacial climate states in abrupt climate change research has led to an underrepresentation of research into interglacial periods. It thus remains unclear whether high-magnitude climate variability requires large cryosphere-driven feedbacks or whether it can also occur under low ice conditions. Using sediment core DSDP U610B (53°13.297N, 18°53.213W) located in the Rockall Trough, we present a high-resolution analysis of surface and deep water components of the AMOC spanning the transition from Marine Isotope Stage (MIS) 19.3 to 19.1 to test if orbital boundary conditions similar to our current Holocene can accommodate abrupt climate events. Above the core site, the dominant oceanographic feature is the North Atlantic Current and at 2417-m water depth, U610 is influenced by Wyville Thomson Overflow Water flowing southwards. We utilise a multiproxy approach including paired grain size analysis, planktic foraminifera assemblage counts, and ice-rafted debris counts within the same samples allowing us to resolve the timing between both surface and bottom components of the AMOC and their response to abrupt climate events during MIS-19 in the eastern subpolar gyre. We also present for the first time a new splice and composite depth scale for Site U610. Based on preliminary results, rapid shifts in both deep overflow and surface climate characterise this period.</p>

The Structure of Millennial Scale Glacial Climate Variability

<p>The Dansgaard-Oeschger (D-O) oscillation recorded in isotopic analyses of Greenland ice cores is a climate oscillation with millennial scale variability alternating between cold stadial climate and warm interstadial climate states. Using a series of long comprehensive climate model integrations of the glacial climate system under different levels of radiative forcing, we formulate a simple heuristic model to emulate the D-O oscillation. We demonstrate that the D-O oscillation has properties that are consistent with an internal unforced oscillation as well as displaying interesting behaviour that is consistent with noise induced transitions. Therefore, the D-O oscillation is more aptly characterized as a stochastic oscillator with stadial and interstadial durations that are more dependent upon a control parameter and internal climate variability rather than an intrinsic characteristic timescale.</p>

Late pleistocene climate changes recorded in the central part of the northern european loess belt, "Современные исследования трансформации криосферы и вопросы геотехнической безопасности сооружений в Арктике"

The northern European loess belt (NELB) was created in cold climate conditions on the foreground of Pleistocene continental glaciations. Loess-paleosol sequences (LPS) in this region were strongly influenced by periglacial processes and environments. Three types of periglacial structures are especially useful to reconstruct the former periglacial environment: cryogenic wedges with primary mineral infilling, cryoturbation and gelifluction structures, and ice-wedge pseudomorphs. These structures often form well-distinguishable marker horizons within LPS. We assume that at least some of these horizons were formed as a result of sudden, short-term cooling followed by equally sudden warming of the climate, when ice wedges and permafrost were decay. Periglacial records in the LPS confirm the general instability of the last glacial climate. The main periglacial stages correlate well with cold events of the marine record. However, their correlation with Greenland ice cores requires further research using modern methods and techniques.

Vegetation over the last glacial maximum at Girraween Lagoon, monsoonal northern Australia

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.