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[Data: 23/06/2011] [Categorie: Video;Ecologia ] [Fonte: Oggi Scienza] |
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OggiScienza TV – The state of the ocean Siamo sull’orlo di un’estinzione di massa, come quelle che nella preistoria hanno cancellato dalla faccia delle Terra molte delle specie allora viventi: è il monito di un panel di 27 scienziati chiamati a raccolta lo scorso aprile a Oxford dall’Internatonal Programme on the State of the Ocean (IPSO) e dall’International Union for the Conservation of Nature. Gli scienziati dopo aver analizzato la letteratura scientifica recente hanno concluso che il degrado del mare sta procedendo in maniera ben più veloce del previsto.
A high-level international workshop convened by IPSO met at the University of Oxford earlier this year. It was the first inter-disciplinary international meeting of marine scientists of its kind and was designed to consider the cumulative impact of multiple stressors on the ocean, including warming, acidification, and overfishing. The 3 day workshop, co-sponsored by the International Union for Conservation of Nature (IUCN), looked at the latest science across different disciplines. The 27 participants from 18 organisations in 6 countries produced a grave assessment of current threats — and a stark conclusion about future risks to marine and human life if the current trajectory of damage continues: that the world's ocean is at high risk of entering a phase of extinction of marine species unprecedented in human history. Delegates called for urgent and unequivocal action to halt further declines in ocean health. (click for press release) The report summary (released 21 June 2011) outlines the main findings and recommendations. The full report will be released at a later date. Title: Rogers, A.D. & Laffoley, D.d'A. 2011. International Earth system expert workshop on ocean stresses and impacts. Summary report. IPSO Oxford, 18 pp. For a full list of participants, please see table at the end of the long version. Report Summary: long version / shorter version. The report is also accompanied by four case studies, which look in more detail at some of the workshop's main findings. Case Study 1: The potentially deadly trio of factors — warming, acidification and anoxia — affecting today's oceans, by Professor Jelle Bijma, Marine Biogeosciences, Alfred Wegener Institute for Polar and Marine Research. Watch his explanation, beginning with the growing problem of anoxia, or dead zones, in the ocean. In Brief: Most, if not all, of the five global mass extinctions in Earth's history carry the fingerprints of the main symptoms of global carbon perturbations (global warming, ocean acidification and anoxia or lack of oxygen; e.g. Veron, 2008). It is these three factors — the 'deadly trio' — which are present in the ocean today. In fact, the current carbon perturbation is unprecedented in the Earth's history because of the high rate and speed of change. Acidification is occurring faster than in the past 55 million years, and with the added man-made stressors of overfishing and pollution, undermining ocean resilience. Case Study 2: End of paradise: Coral reefs facing multiple attacks, by Ove Hoegh-Guldberg , Director, Global Change Institute, University of Queensland In Brief: What the multi-disciplinary approach of the IPSO workshop made clear for the first time was the multiple threats reefs are facing, that are now acting together to have a greater impact than if they were occurring on their own. This suggests that existing scientific projections of how coral reefs will respond to global warming have been highly conservative and must now be modified. Case Study 3: Pollution and Marine Species: new challenges of an old problem by Professor Tom Hutchinson, Centre for Environment, Fisheries & Aquaculture Science (CEFAS) In Brief: Continued releases and slow breakdown rates mean that legacy chemical pollution ( such as from DDT) remains a major concern. However, concerns have been raised recently over a wide range of novel chemicals now being found in marine ecosystems or suspected to be harmful to marine life. High-profile examples include brominated flame retardants, fluorinated compounds, pharmaceuticals and synthetic musks used in detergents and personal care products. Some of these chemicals have been located recently in the Canadian Arctic seas, and some are known to be endocrine disrupters or can damage immune systems. Marine litter and plastics are also of major concern, and there is evidence that certain plastics can transport other harmful chemicals in the marine environment. Case Study 4: Vanishing Resource: The Tale of the Chinese Bahaba by Dr William Cheung, Lecturer in Marine Ecosystem Services, School of Environmental Sciences at the University of East Anglia In Brief: Scientists at the IPSO meeting agreed that overfishing is exerting an intolerable pressure on ecosystems already under attack by the effects of acidification and warming, and other largely man-made ocean problems. A recent study showed that 63% of the assessed fish stocks worldwide are over-exploited or depleted and over half of them require further reduction of fishing, in order to recover. The near extinction of a fish called Chinese bahaba (Bahaba taipingensis) is one of the many examples that highlight how overfishing threatens marine biodiversity. It has taken less than seventy years for this giant fish to become critically endangered after it was first described by scientists in the 1930s. Other contributors to the IPSO/IUCN workshop: Professor Dan Laffoley, Senior Advisor at the International Union for the Conservation of Nature emphasises the vital role of the ocean for humans and the deadly combination of stressors at play. Professor Charles Sheppard, Warwick University gives further perspective to the extinction threat facing coral reefs — and stresses that the knock-on effects are already being felt on land. Professor Chris Reid, Marine Institute, University of Plymouth and Sir Alister Hardy Foundation for Ocean Science highlights the speed of change which has been greater than most scientists prediced even in worst case scenarios. Dr. Alex Rogers, Scientific Director of IPSO and Professor of Conservation Biology at the Department of Zoology, University of Oxford, gives the overview of the main problems affecting the ocean — and some suggested solutions. |
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