Modelling the sensitivity of Mediterranean Outflow to anthropogenically forced climate change

 The possible future impact of anthropogenic forcing upon the circulation of the Mediterranean, and the exchange through the Strait of Gibraltar is investigated using a Cox-type model of the Mediterranean at 0.25° × 0.25° resolution, forced by “control” and “greenhouse” scenarios provided by the HadCM2 coupled climate model. The current structure of the Mediterranean forced by the “control” climate is compared with observations: certain aspects of the present circulation are reproduced, but others are absent or incorrectly represented. Deficiencies are most probably due to weaknesses in the forcing climatology generated by the climate model, so some caution must be exercised in interpreting the enhanced greenhouse simulation. Comparison of the control and greenhouse scenarios suggests that deep-water production in the Mediterranean may be reduced or cease in the relatively near future. The results also suggest that the Mediterranean outflow, may become warmer and more saline, but less dense, and hence shallower. The volume of the exchange at the Strait of Gibraltar seems to be relatively insensitive to future climate change, however. Our results indicate that a parameterisation of Gibraltar exchange and Mediterranean Outflow Water (MOW) production may be able to provide adequate representation of the changes we observe for the purposes of the current generation of climate models. Received: 10 August 1998 / Accepted: 11 October 1999     

Guiding ecological principles for marine spatial planning

The declining health of marine ecosystems around the world is evidence that current piecemeal governance is inadequate to successfully support healthy coastal and ocean ecosystems and sustain human uses of the ocean. One proposed solution to this problem is ecosystem-based marine spatial planning (MSP), which is a process that informs the spatial distribution of activities in the ocean so that existing and emerging uses can be maintained, use conflicts reduced, and ecosystem health and services protected and sustained for future generations. Because a key goal of ecosystem-based MSP is to maintain the delivery of ecosystem services that humans want and need, it must be based on ecological principles that articulate the scientifically recognized attributes of healthy, functioning ecosystems. These principles should be incorporated into a decision-making framework with clearly defined targets for these ecological attributes. This paper identifies ecological principles for MSP based on a synthesis of previously suggested and/or operationalized principles, along with recommendations generated by a group of twenty ecologists and marine scientists with diverse backgrounds and perspectives on MSP. The proposed four main ecological principles to guide MSP—maintaining or restoring: native species diversity, habitat diversity and heterogeneity, key species, and connectivity—and two additional guidelines, the need to account for context and uncertainty, must be explicitly taken into account in the planning process. When applied in concert with social, economic, and governance principles, these ecological principles can inform the designation and siting of ocean uses and the management of activities in the ocean to maintain or restore healthy ecosystems, allow delivery of marine ecosystem services, and ensure sustainable economic and social benefits.     

Confirmation of an interglacial age for the Condat tufa (Dordogne,France) from biostratigraphic and isotopic data

The Condat tufa is a localised deposit, reaching 8.2m in thickness, composed of freshwater carbonates deposited in a complex series of environments which include marsh, spring and stream facies. Five radiocarbon determinations had previously been obtained from different stratigraphic levels within the tufa and had given a consistent series, ranging from 12320 ± 175 BP to 31050 ± 1500BP. Although the youngest two dates, from near the surface of the tufa, had been rejected as being anomalously young, the older dates were regarded as indicating tufa formation during the last cold stage. Biostratigraphic analyses of the molluscan and ostracod faunas, presented here, demonstrate that the tufa formed under fully temperate conditions throughout. The occurrence of certain snails that are either locally extinct (e.g. Belgrandia marginata) or unknown living in western France (e.g. Daudebardia brevipes), together with the geomorphological setting, suggest that the tufa is of interglacial age. New radiocarbon determinations of the Condat tufa all proved to be >33 Ka BP and support this conclusion.     

新发现7个X选 BL Lac天体和1个类星体(英文)

利用ROSAT－VLA方法筛选，从ROSATX射线源中选出了19个新BLLac天体和类星体的候选体．在1994年至1996年1月期间，利用北京天文台2．16m望远镜对其中16个进行光谱证认，发现了7个新的X选BLLac天体及一个类星体，类星体的红移值为：z＝0.331±0．0015．     

Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry

A bimodal volcanic suite with KAr ages of 0.05–1.40 Ma was collected from the Sumisu Rift using alvin. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with arc rifting and back-arc basin initiation. Major element geochemistry of the basalts is most similar to that of basalts found in other, more mature back-arc basins, which indicates that back-arc basins need not begin their magmatic evolution with lavas bearing strong arc signatures.Volatile concentrations distinguish Sumisu Rift basalts from island arc basalts and MORB. H₂O contents, which are at least four times greater than in MORB, suppress plagioclase crystallization. This suppression results in a more mafic fractionating assemblage, which prevents Al₂O₃ depletion and delays the initiation of Fe₂O_3^(tot) and TiO₂ enrichment. However, unlike arc basalts,Fe^3+/ΣFe ratios are only slightly higher than in MORB and are insufficient to cause magnetite saturation early enough to suppress Fe₂O_3^(tot) and TiO₂ enrichment. Thus, major element trends are more similar to those of MORB than arcs.H₂O, CO₂ and S are undersaturated relative to pure phase solubility curves, indicating exsolution of an H₂O-rich mixed gas phase. HighH₂O/S, highδD, and low (MORB-like)δ³⁴S ratios are considered primary and distinctive of the back-arc basin setting.     

Reports from the Smithsonian’s Global Volcanism Network, May 2010

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 35, no. 5, May 2010 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.     

Estimation of maximum seasonal tropical cyclone damage in the Atlantic using climate models

Natural Hazards - There are several different estimates of the observed cyclone damage potential of tropical cyclones based on observations of size, intensity and track. For the analysis of climate...     

Enteric fermentation and ruminant eructation: the role (and control?) of methane in the climate change debate

Anthropogenic processes are responsible for between 55% and 70% of the estimated 600 Tg of methane that is released annually into the atmosphere, with enteric fermentation a major contributor to emissions in a number of countries. This paper therefore reviews current levels of CH₄ discharges by both animal type and country, and shows how the growth or decline in national herds over the last 20 years has significantly altered the global composition of enteric emissions. As developing countries are now responsible for almost three-quarters of such emissions, this has important implications in terms of mitigation strategies—particularly as such countries are presently outside the remit of the Kyoto Protocol.