12 research outputs found

    Volcanic glass from the 1.8 ka Taupō eruption (New Zealand) detected in Antarctic ice at ~ 230 CE.

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    Chemical anomalies in polar ice core records are frequently linked to volcanism; however, without the presence of (crypto)tephra particles, links to specific eruptions remain speculative. Correlating tephras yields estimates of eruption timing and potential source volcano, offers refinement of ice core chronologies, and provides insights into volcanic impacts. Here, we report on sparse rhyolitic glass shards detected in the Roosevelt Island Climate Evolution (RICE) ice core (West Antarctica), attributed to the 1.8 ka Taupō eruption (New Zealand)-one of the largest and most energetic Holocene eruptions globally. Six shards of a distinctive geochemical composition, identical within analytical uncertainties to proximal Taupō glass, are accompanied by a single shard indistinguishable from glass of the ~25.5 ka Ōruanui supereruption, also from Taupō volcano. This double fingerprint uniquely identifies the source volcano and helps link the shards to the climactic phase of the Taupō eruption. The englacial Taupō-derived glass shards coincide with a particle spike and conductivity anomaly at 278.84 m core depth, along with trachytic glass from a local Antarctic eruption of Mt. Melbourne. The assessed age of the sampled ice is 230 ± 19 CE (95% confidence), confirming that the published radiocarbon wiggle-match date of 232 ± 10 CE (2 SD) for the Taupō eruption is robust

    Original plant diversity and ecosystems of a small, remote oceanic island (Corvo, Azores): Implications for biodiversity conservation

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    Remote islands harbour many endemic species and unique ecosystems. They are also some of the world's most human-impacted systems. It is essential to understand how island species and ecosystems behaved prior to major anthropogenic disruption as a basis for their conservation. This research aims to reconstruct the original, pre-colonial biodiversity of a remote oceanic island to understand the scale of past extinctions, vegetation changes and biodiversity knowledge gaps. We studied fossil remains from the North Atlantic island of Corvo (Azores), including pollen, charcoal, plant macrofossils, diatoms and geochemistry of wetland sediments from the central crater of the island, Caldeirão. A comprehensive list of current vascular plant species was compiled, along with a translation table comparing fossilized pollen to plant species and a framework for identifying extinctions and misclassifications. Pollen and macrofossils provide evidence for eight local extinctions from the island's flora and show that four species listed as ‘introduced’ are native. Up to 23% of the pollen taxa represent extinct/misclassified species. Corvo's past environment was dynamic, shifting from glacial-era open vegetation to various Holocene forest communities, then almost completely deforested by fires, erosion and grazing following Portuguese colonisation. Historical human impacts explain high ecological turnover, several unrecorded extinctions and the present-day abundance of vegetation types like Sphagnum blanket mire. We use Corvo as a case study on how fossil inventories can address the Wallacean and Hookerian biodiversity knowledge gaps on remote islands. Accurate baselines allow stakeholders to make informed conservation decisions using limited financial and human resources, particularly on islands where profound anthropogenic disruption occurred before comprehensive ecological research

    An international observational study to assess the impact of the Omicron variant emergence on the clinical epidemiology of COVID-19 in hospitalised patients

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    Background: Whilst timely clinical characterisation of infections caused by novel SARS-CoV-2 variants is necessary for evidence-based policy response, individual-level data on infecting variants are typically only available for a minority of patients and settings. Methods: Here, we propose an innovative approach to study changes in COVID-19 hospital presentation and outcomes after the Omicron variant emergence using publicly available population-level data on variant relative frequency to infer SARS-CoV-2 variants likely responsible for clinical cases. We apply this method to data collected by a large international clinical consortium before and after the emergence of the Omicron variant in different countries. Results: Our analysis, that includes more than 100,000 patients from 28 countries, suggests that in many settings patients hospitalised with Omicron variant infection less often presented with commonly reported symptoms compared to patients infected with pre-Omicron variants. Patients with COVID-19 admitted to hospital after Omicron variant emergence had lower mortality compared to patients admitted during the period when Omicron variant was responsible for only a minority of infections (odds ratio in a mixed-effects logistic regression adjusted for likely confounders, 0.67 [95% confidence interval 0.61-0.75]). Qualitatively similar findings were observed in sensitivity analyses with different assumptions on population-level Omicron variant relative frequencies, and in analyses using available individual-level data on infecting variant for a subset of the study population. Conclusions: Although clinical studies with matching viral genomic information should remain a priority, our approach combining publicly available data on variant frequency and a multi-country clinical characterisation dataset with more than 100,000 records allowed analysis of data from a wide range of settings and novel insights on real-world heterogeneity of COVID-19 presentation and clinical outcome

    The value of open-source clinical science in pandemic response: lessons from ISARIC

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