Chemical and isotopic evidence for the nature of the fluid in CH4-containing sediments of the Håkon Mosby Mud Volcano

The pore waters of CH₄-containing sediments of the Håkon Mosby Mud Volcano were rich in NH⁺ ₄, Br^-, and I^-; exhibited a high total alkalinity; but were poor in Cl^-and SO^2- ₄. The geological evidence and our data suggest that organic matter decomposition in preglacial or early interglacial sediments took place during early diagenesis (bacterial processes) and during metamorphism (thermogenic processes under the 3100-m-thick layer of glacial sediments), accompanied by mud volcano fluid generation. It is argued that the CH₄of the mud volcano sediments has a mixed, biogenic and thermogenic, origin.     

SW Barents Sea continental margin heat flow and Håkon Mosby Mud Volcano

The high thermal gradient and heat flow >1000?mW?m^-2 on Håkon Mosby Mud Volcano are ascribed to rapid transport of pore water, mud, and gas in a narrow, deep conduit within a 3.1-km-thick glacial sediment unit. The instability is caused by rapid loading of dense glacial sediments on less dense oozes. Changes in pressure–temperature conditions by sudden, large-scale downslope mass movement may induce structural deformation, opening transient pathways from the base of the glacial sediments to the sea floor. This model may also explain slope maxima elsewhere on the margin.     

Constraining and enabling factors to using long-term climate information in decision-making

We carry out a structured review of the peer-reviewed literature to assess the factors that constrain and enable the uptake of long-term climate information in a wide range of sectoral investment and planning decisions. Common applications of long-term climate information are shown to relate to urban planning and infrastructure, as well as flood and coastal management. Analysis of the identified literature highlights five categories of constraints: disconnection between users and producers of climate information, limitations of climate information, financial and technical constraints, political economy and institutional constraints and finally psycho-social constraints. Five categories of enablers to the uptake of long-term climate information in decision-making are also identified: collaboration and bridge work, increased accessibility of climate information, improvement in the underlying science, institutional reform and windows of opportunity for building trust.

Policy relevance

Our review suggests that stand-alone interventions aimed at promoting the uptake of climate information into decision-making are unlikely to succeed without genuine and sustained relationships between producers and users. We also highlight that not every decision requires consideration of long-term climate information for successful outcomes to be achieved. This is particularly the case in the context of developing countries, where the immediacy of development challenges means that decision makers often prioritize short-term interventions. Care should therefore be taken to ensure that information is targeted towards investments and planning decisions that are relevant to longer-term timescales.     

Interrogating empirical-statistical downscaling

The delivery of downscaled climate information is increasingly seen as a vehicle of climate services, a driver for impacts studies and adaptation decisions, and for informing policy development. Empirical-statistical downscaling (ESD) is widely used; however, the accompanying responsibility is significant, and predicated on effective understanding of the limitations and capabilities of ESD methods. There remain substantial contradictions, uncertainties, and sensitivity to assumptions between the different methods commonly used. Yet providing decision-relevant downscaled climate projections to help support national and local adaptation is core to the growing global momentum seeking to operationalize what is, in effect, still foundational research. We argue that any downscaled climate information must address the criteria of being plausible, defensible and actionable. Climate scientists cannot absolve themselves of their ethical responsibility when informing adaptation and must, therefore, be diligent in ensuring any information provided adequately addresses these three criteria. Frameworks for supporting such assessment are not well developed. We interrogate the conceptual foundations of statistical downscaling methodologies and their assumptions, and articulate a framework for evaluating and integrating downscaling output into the wider landscape of climate information. For ESD there are key criteria that need to be satisfied to underpin the credibility of the derived product. Assessing these criteria requires the use of appropriate metrics to test the comprehensive treatment of local climate response to large-scale forcing, and to compare across methods. We illustrate the potential consequences of methodological choices on the interpretation of downscaling results and explore the purposes, benefits and limitations of using statistical downscaling.     

The chemistry of hydrothermal mounds near the Galapagos Rift

Samples dredged from the sediment mounds have a unique chemistry and mineralogy which reveals details of the hydrothermal processes that produce these deposits. The mounds form primarily by deposition of Fe, Mn and Si from hydrothermal fluids which circulate through the basalt crust and the overlying sediments. The Mn, Fe and Si are strongly fractionated in the process; the Fe and Si precipitate within the mounds under slightly reducing conditions as nontronite, while the Mn is deposited as Mn oxyhydroxides at the seawater-sediment interface. The nontronite is exceptionally well crystallized, and contains less than 200 ppm Al. The Mn minerals, todorokite and birnessite, also have exceptional crystallinity and the distribution of trace elements Cu, Ni, Zn, Co, Ca and Ba in these phases agrees with predictions made on the basis of models of their crystal structure. The environment of deposition which produces this suite of minerals — slow percolation of hydrothermal fluids through pelagic sediments — may not be unique to the Galapagos Rift, as the same suite of minerals has been found in similar setting in the Gulf of Aden and on the Mid-Atlantic Ridge.     

Biodiversity conservation and land rights in South Africa: Whither the farm dwellers?

South Africa is unique in that its globally significant biodiversity, which is under significant threat, coexists with an apartheid history of dispossession that produced a starkly unequal land ownership pattern and widespread rural poverty. It is in this context that the post-apartheid government must fulfil constitutional and international obligations to safeguard environmental assets as well as undertake land reform benefiting the previously dispossessed. Consequently, there is a continuous challenge of reconciling complex and often conflicting relationships between poverty, inequitable access to resources, and the protection of biodiversity. Current efforts to conserve the Cape Floral Kingdom emphasize partnerships between private landowners and existing nature reserves to promote sustainable utilisation of biodiversity. This paper presents a case study exploring how this approach might be reconciled with land rights and opportunities for land-based livelihoods among farm dwellers in the Baviaanskloof area of the Eastern Cape. The paper identifies systemic and structural tensions in current attempts to reconcile biodiversity conservation and farm dwellers’ interests, and documents issues of process and principle that could become important in the future. In doing so, it highlights the influence of on-farm power relations and overly complex institutional arrangements in determining the real extent of participation by affected farm dwellers and the efficacy of social safeguard policies. Findings also caution against an over-reliance on ecotourism as the major occupation and the paper argues instead for support for multiple livelihood strategies.     

Large-scale mass wasting on the north Spitsbergen continental margin, Arctic Ocean

 Closely spaced, single-beam bathymetric and side-scan sonar investigations on the northern slope of the western Svalbard insular platform have revealed the presence of a Late Quaternary slump complex forming a hanging-wall slump canyon near the head of the Malene Bukta (Malene Bay) bathymetric embayment in the northern continental margin. Repeated slump erosion may be responsible for development of this young feature and the Malene Bukta Embayment. Focusing of the slumping may be due to the trapping of gas at shallow sea-floor depths by gas hydrate, with the consequent formation of subjacent gas-rich, low shear-strength decollement zones. Faults have likely controlled the upward migration of gas into the younger sedimentary prism.     

Gas hydrate accumulation at the Håkon Mosby Mud Volcano

Gas hydrate (GH) accumulation is characterized and modeled for the Håkon Mosby mud volcano, ca. 1.5?km across, located on the Norway–Barents–Svalbard margin. Pore water chemical and isotopic results based on shallow sediment cores as well as geothermal and geomorphological data suggest that the GH accumulation is of a concentric pattern controlled by and formed essentially from the ascending mud volcano fluid. The gas hydrate content of sediment peaks at 25% by volume, averaging about 1.2% throughout the accumulation. The amount of hydrate methane is estimated at ca. 10⁸?m³ STP, which could account for about 1–10% of the gas that has escaped from the volcano since its origin.     

Comparison of the MSL synoptic pressure patterns of the Arctic as observed and simulated by the GISS General Circulation Model

Summary The observed daily pressure fields over the Arctic are compared with those obtained from a control run of the Goddard Institute for Space Studies (GISS) General Circulation Model using a classification typing procedure developed by Kirchhofer (1973) and a rotated principal components analysis for both data sets. The simulated patterns appear quite realistic in both frequency and geographical characteristics, although the model data show greater extremes and more closed cells. The procedure described provides a potentially useful method for evaluating the synoptic representativeness of GCM simulations.With 9 Figures