5,411 research outputs found

    A persistent and dynamic East Greenland Ice Sheet over the past 7.5 million years

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    Climate models show that ice-sheet melt will dominate sea-level rise over the coming centuries, but our understanding of ice-sheet variations before the last interglacial 125,000 years ago remains fragmentary. This is because terrestrial deposits of ancient glacial and interglacial periods1,2,3 are overrun and eroded by more recent glacial advances, and are therefore usually rare, isolated and poorly dated4. In contrast, material shed almost continuously from continents is preserved as marine sediment that can be analysed to infer the time-varying state of major ice sheets. Here we show that the East Greenland Ice Sheet existed over the past 7.5 million years, as indicated by beryllium and aluminium isotopes (10Be and 26Al) in quartz sand removed by deep, ongoing glacial erosion on land and deposited offshore in the marine sedimentary record5,6. During the early Pleistocene epoch, ice cover in East Greenland was dynamic; in contrast, East Greenland was mostly ice-covered during the mid-to-late Pleistocene. The isotope record we present is consistent with distinct signatures of changes in ice sheet behaviour coincident with major climate transitions. Although our data are continuous, they are from low-deposition-rate sites and sourced only from East Greenland. Consequently, the signal of extensive deglaciation during short, intense interglacials could be missed or blurred, and we cannot distinguish between a remnant ice sheet in the East Greenland highlands and a diminished continent-wide ice sheet. A clearer constraint on the behaviour of the ice sheet during past and, ultimately, future interglacial warmth could be produced by 10Be and 26Al records from a coring site with a higher deposition rate. Nonetheless, our analysis challenges the possibility of complete and extended deglaciation over the past several million years

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    From the Editors

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    The oxygenation of extraction and future global ecological democracy: the City of London, the alternative investment market and oil in frontiers in Africa

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    This article explores how the governance of the City of London Corporation perpetuates the oxygenation of extraction, with a focus on oil frontiers and ecological impacts in Africa. It shows how this extractive system limits environmental justice through a spider’s web of tax havens linked to the notoriously under-regulated Alternative Investment Market. The contemporary success of the City of London Corporation is supported by an archaic membership system drawn from financial services. This has also allowed it to support the establishment of the most successful network of secrecy jurisdictions of ‘tax havens’ on the planet, supporting flows for illicit business in commodity frontiers. As extractive operations are given life by the financial flows that circulate through the City and its offshore empire, and take control of land, the potential for local communities to utilise their local ecological knowledge is asphyxiated, limiting the protection of food systems and endangered species. The article explains how this system functions, and why it needs to be reformed to limit Earth’s sixth mass extinction. It does so through case studies of the City of London, the Niger Delta and Turkana Kenya, using ethnography and semi structured interviews. A new system of ecological direct democracy is proposed, limiting global corruption flows into the City’s tax havens, allowing instead for a flourishing globalisation of ecological democracy

    Testing use of mitochondrial COI sequences for the identification and phylogenetic analysis of New Zealand caddisflies (Trichoptera)

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    We tested the hypothesis that cytochrome c oxidase subunit 1 (COI) sequences would successfully discriminate recognised species of New Zealand caddisflies. We further examined whether phylogenetic analyses, based on the COI locus, could recover currently recognised superfamilies and suborders. COI sequences were obtained from 105 individuals representing 61 species and all 16 families of Trichoptera known from New Zealand. No sequence sharing was observed between members of different species, and congeneric species showed from 2.3 to 19.5% divergence. Sequence divergence among members of a species was typically low (mean = 0.7%; range 0.0–8.5%), but two species showed intraspecific divergences in excess of 2%. Phylogenetic reconstructions based on COI were largely congruent with previous conclusions based on morphology, although the sequence data did not support placement of the purse-cased caddisflies (Hydroptilidae) within the uncased caddisflies, and, in particular, the Rhyacophiloidea. We conclude that sequence variation in the COI gene locus is an effective tool for the identification of New Zealand caddisfly species, and can provide preliminary phylogenetic inferences. Further research is needed to ascertain the significance of the few instances of high intra-specific divergence and to determine if any instances of sequence sharing will be detected with larger sample sizes

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