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A terrestrial (lacustrine and fluvial) palaeoclimate record from Hoxne (Suffolk, UK) shows two temperate phases separated by a cold episode, correlated with MIS 11 subdivisions corresponding to isotopic events 11.3 (Hoxnian interglacial period), 11.24 (Stratum C cold interval), and 11.23 (warm interval with evidence of human presence). A robust, reproducible multiproxy consensus approach validates and combines quantitative palaeotemperature reconstructions from three invertebrate groups (beetles, chironomids, and ostracods) and plant indicator taxa with qualitative implications of molluscs and small vertebrates. Compared with the present, interglacial mean monthly air temperatures were similar or up to 4.0°C higher in summer, but similar or as much as 3.0°C lower in winter; the Stratum C cold interval, following prolonged nondeposition or erosion of the lake bed, experienced summers 2.5°C cooler and winters between 5°C and 10°C cooler than at present. Possible reworking of fossils into Stratum C from underlying interglacial assemblages is taken into account. Oxygen and carbon isotopes from ostracod shells indicate evaporatively enriched lake water during Stratum C deposition. Comparative evaluation shows that proxy-based palaeoclimate reconstruction methods are best tested against each other and, if validated, can be used to generate more refined and robust results through multiproxy consensus.

During the Pliocene, atmospheric CO.sub.2 concentrations (pCO.sub.2) were probably sometimes similar to today's, and global average temperature was â¼3 °C higher than preindustrial. However, the relationships and phasing between variability in climate and pCO.sub.2 on orbital timescales are not well understood. Specifically, questions remain about the nature of a lag of pCO.sub.2 relative to benthic foraminiferal [delta].sup.18 O in late Pliocene Marine Isotope Stage (MIS) M2 (3300 ka), which was longer than during the Pleistocene. Here, we present a multiproxy paleoceanographic reconstruction of the late Pliocene subtropical-subantarctic zone. New dinoflagellate cyst assemblage data are combined with previously published sea surface temperature reconstructions to reveal past surface conditions, including latitudinal migrations of the subtropical front (STF) over the late Pliocene at Ocean Drilling Program (ODP) Site 1168, offshore of western Tasmania. We observe strong oceanographic variability at the STF over glacial-interglacial timescales, especially the interval (3320-3260 ka) across MIS M2. By providing tight and independent age constraints from benthic foraminiferal [delta].sup.18 O, we find that, much more than benthic [delta].sup.18 O or local SST, latitudinal migrations of the STF are tightly coupled to global pCO.sub.2 variations across the M2. Specifically, a northerly position of the STF during the MIS M2 deglaciation coincides with generally low pCO.sub.2 . We postulate that the Southern Ocean CO.sub.2 outgassing varied strongly with migrations of the STF and that this in part accounted for the variability in pCO.sub.2 across MIS M2.

Fossils provide invaluable data for evolutionary studies in oceanic islands. The paleontological record of the Macaronesian archipelagos has been the target of many researchers for a long time, with a recent surge in interest in scientific research related to their paleontological heritage. In the Macaronesian Azores archipelago, the marine invertebrate fossil record from the warmest period of the Last Interglacial stage (also known as Marine Isotopic Stage 5e—MIS 5e) represents approximately 95.6% of the total species. In contrast, the MIS 5e marine vertebrate fossil record comprises only four reported species (2.2%), with marine algae accounting for the remaining 2.2% (four species). This study reports on—and adds to the paleobiodiversity of the MIS 5e deposits at Santa Maria Island (Azores Archipelago)—two marine mesopelagic lanternfishes, identified from their otoliths: Diaphus cf. holti Tåning, 1918, and Symbolophorus veranyi (Moreau, 1888). Finally, we offer a plausible explanation for the presence of mesopelagic fishes in the MIS 5e fossiliferous deposits of Santa Maria Island.

The Arctic is currently undergoing dramatic environmental transformations, but it remains largely unknown how these changes compare with long-term natural variability. Here we present a lake sediment sequence from the Canadian Arctic that records warm periods of the past 200,000 years, including the 20th century. This record provides a perspective on recent changes in the Arctic and predates by approximately 80,000 years the oldest stratigraphically intact ice core recovered from the Greenland Ice Sheet. The early Holocene and the warmest part of the Last Interglacial (Marine Isotope Stage or MIS 5e) were the only periods of the past 200,000 years with summer temperatures comparable to or exceeding today's at this site. Paleoecological and geochemical data indicate that the past three interglacial periods were characterized by similar trajectories in temperature, lake biology, and lakewater pH, all of which tracked orbitally-driven solar insolation. In recent decades, however, the study site has deviated from this recurring natural pattern and has entered an environmental regime that is unique within the past 200 millennia.

Background The glacial-interglacial cycles in the Pleistocene caused repeated range expansion and contraction of species in several regions in the world. However, it remains uncertain whether such climate oscillations had similar impact on East Asian biota, despite its widely recognized importance in global biodiversity. Here we use both molecular and ecological niche profiles on 11 East Asian avian species with various elevational ranges to reveal their response to the late Pleistocene climate changes. Results The ecological niche models (ENM) consistently showed that these avian species might substantially contract their ranges to the south during the Last Interglacial period (LIG) and expanded their northern range margins through the Last Glacial Maximum (LGM), leading to the LGM ranges observed for all 11 species. Consistently, coalescent simulations based on 25–30 nuclear genes retrieved signatures of significant population growth through the last glacial period across all species studied. Climate statistics suggested that high climatic variability during the LIG and a relatively mild climate at the LGM potentially explained the historical population dynamics of these birds. Conclusions This is the first study based on multiple species and both lines of ecological niche profiles and genetic data to characterize the unique response of East Asian biota to late Pleistocene climate. The present study highlights regional differences in the evolutionary consequence of climate change during the last glacial cycle and implies that global warming might pose a great risk to species in this region given potentially higher climatic variation in the future analogous to that during the LIG.

Background The distribution of genetic diversity and the underlying processes are important for conservation planning but are unknown for most species and have not been well studied in many regions. In East Asia, the Sichuan Basin and surrounding mountains constitute an understudied region that exhibits a “ring” of high species richness overlapping the eastern edge of the global biodiversity hotspot Mountains of Southwest China. We examine the distributional history and genetic diversification of the Emei mustache toad Leptobrachium boringii, a typical “ring” element characterized by disjunct ranges in the mountains, by integrating time-calibrated gene tree, genetic variability, individual-level clustering, inference of population splitting and mixing from allele frequencies, and paleoclimatic suitability modeling. Results The results reveal extensive range dynamics, including secondary contact after long-term isolation via westward dispersal accompanied by variability loss. They allow the proposal of a model that combines recurrent contractions caused by Quaternary climatic changes and some failed expansions under suitable conditions for explaining the shared disjunct distribution pattern. Providing exceptional low-elevation habitats in the hotspot area, the eastern edge harbors both long-term refugial and young immigrant populations. This finding and a synthesis of evidence from other taxa demonstrate that a certain contributor to biodiversity, one that preserves and receives low-elevation elements of the east in this case, can be significant for only a particular part of a hotspot. By clarifying the low variability of these refugial populations, we show that discordant mitochondrial estimates of diversity can be obtained for populations that experienced admixture, which would have unlikely left proportional immigrant alleles for each locus. Conclusions Dispersal after long-term isolation can explain much of the spatial distribution of genetic diversity in this species, while secondary contact and long-term persistence do not guarantee a large variation. The model for the formation of disjunct ranges may apply to many other taxa isolated in the mountains surrounding the Sichuan Basin. Furthermore, this study provides insights into the heterogeneous nature of hotspots and discordant variability obtained from genome-wide and mitochondrial data.

It has been previously proposed that glacial inception represents a bifurcation transition between interglacial and glacial states and is governed by the nonlinear dynamics of the climate-cryosphere system. To trigger glacial inception, the orbital forcing (defined as the maximum of summer insolation at 65° N and determined by Earth's orbital parameters) must be lower than a critical level, which depends on the atmospheric CO.sub.2 concentration. While paleoclimatic data do not provide a strong constraint on the dependence between CO.sub.2 and critical insolation, its accurate estimation is of fundamental importance for predicting future glaciations and the effect that anthropogenic CO.sub.2 emissions might have on them. In this study, we use the novel Earth system model of intermediate complexity CLIMBER-X with interactive ice sheets to produce a new estimation of the critical insolation-CO.sub.2 relationship for triggering glacial inception. We perform a series of experiments in which different combinations of orbital forcing and atmospheric CO.sub.2 concentration are maintained constant in time. We analyze for which combinations of orbital forcing and CO.sub.2 glacial inception occurs and trace the critical relationship between them, separating conditions under which glacial inception is possible from those where glacial inception is not materialized. We also provide a theoretical foundation for the proposed critical insolation-CO.sub.2 relation. We find that the use of the maximum summer insolation at 65° N as a single metric for orbital forcing is adequate for tracing the glacial inception bifurcation. Moreover, we find that the temporal and spatial patterns of ice sheet growth during glacial inception are not always the same but depend on the critical insolation and CO.sub.2 level. The experiments evidence the fact that during glacial inception, ice sheets grow mostly in North America, and only under low CO.sub.2 conditions are ice sheets also formed over Scandinavia. The latter is associated with a weak Atlantic Meridional Overturning Circulation (AMOC) for low CO.sub.2 . We find that the strength of AMOC also affects the rate of ice sheet growth during glacial inception.

Although uranium series (U-series) ages of growth-position fossil corals are important to Quaternary sea-level history, coral clast reworking from storms can yield ages on a terrace dating to more than one high-sea stand, confounding interpretations of sea-level history. On northern Barbados, U-series ages corals from a thick storm deposit are not always younger with successively higher stratigraphic positions, but all date to the last interglacial period (~127 ka to ~112 ka), Marine Isotope Substage (MIS) 5.5. The storm deposit ages are consistent with the ages of growth-position corals found at the base of the section and at landward localities on this terrace. Thus, in this case, analysis of only a few corals would not have led to an error in interpreting sea-level history. In contrast, a notch cut into older Pleistocene limestone below the MIS 5.5 terrace contains corals that date to both MIS 5.5 (~125 ka) and MIS 5.3 (~108 ka). We infer that the notch formed during MIS 5.3 and the MIS 5.5 corals are reworked. Similar multiple ages of corals on terraces have been reported elsewhere on Barbados. Thus, care must be taken in interpreting U-series ages of corals that are reported without consideration of taphonomy.

The Western Pacific Warm Pool (WPWP) exhibits different glacial-interglacial climate variability compared to high latitudes, and its sea surface temperatures are thought to respond primarily to changes in greenhouse forcing. To better characterize the orbital-scale climate response covering the WPWP, we constructed a planktonic [delta].sup.18 O stack (average) of 10 previously published WPWP records of the last 800 kyr, available at

The Greater Cape Floristic Region (GCFR) of South Africa is a biodiversity hotspot of global significance, and its archeological record has substantially contributed to the understanding of modern human origins. For both reasons, the climate and vegetation history of southwestern South Africa is of interest to numerous fields. Currently known paleoenvironmental records cover the Holocene, the last glacial-interglacial transition and parts of the last glaciation but do not encompass a full glacial-interglacial cycle. To obtain a continuous vegetation record of the last Pleistocene glacial-interglacial cycles, we studied pollen, spores and micro-charcoal of deep-sea sediments from IODP Site U1479 retrieved from SW of Cape Town. We compare our palynological results of the Pleistocene with previously published results of Pliocene material from the same site. We find that the vegetation of the GCFR, in particular fynbos and afrotemperate forest, responds to precessional forcing of climate. The micro-charcoal record confirms the importance of fires in the fynbos vegetation. Ericaceae-rich and Asteraceae-rich types of fynbos could extend on the western part of the Paleo-Agulhas Plain (PAP), which emerged during periods of low sea level of the Pleistocene.