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Warming and Melting Mass loss from the ice sheets of Greenland and Antarctica account for a large fraction of global sea-level rise. Part of this loss is because of the effects of warmer air temperatures, and another because of the rising ocean temperatures to which they are being exposed. Joughin et al. (p. 1172) review how ocean-ice interactions are impacting ice sheets and discuss the possible ways that exposure of floating ice shelves and grounded ice margins are subject to the influences of warming ocean currents. Estimates of the mass balance of the ice sheets of Greenland and Antarctica have differed greatly-in some cases, not even agreeing about whether there is a net loss or a net gain-making it more difficult to project accurately future sea-level change. Shepherd et al. (p. 1183) combined data sets produced by satellite altimetry, interferometry, and gravimetry to construct a more robust ice-sheet mass balance for the period between 1992 and 2011. All major regions of the two ice sheets appear to be losing mass, except for East Antarctica. All told, mass loss from the polar ice sheets is contributing about 0.6 millimeters per year (roughly 20% of the total) to the current rate of global sea-level rise.

As the U.S. Food and Drug Administration (FDA) considers approving a genetically modified (GM) Atlantic salmon (Salmo salar), it faces fundamental questions of risk analysis and impact assessment. The GM salmon-whose genome contains an inserted growth gene from Pacific chinook salmon (Oncorhynchus tshawytscha) and a switch-on gene from ocean pout (Zoarces americanus)-would be the first transgenic animal approved for human consumption in the United States (1, 2). But the mechanism for its approval, FDA's new animal drug application (NADA) process (2), narrowly examines only the risks of each GM salmon compared with a non-GM salmon (2, 3). This approach fails to acknowledge that the new product's attributes may affect total production and consumption of salmon. This potentially excludes major human health and environmental impacts, both benefits and risks. Regulators need to consider the full scope of such impacts in risk analyses to avoid unintended consequences (4), yet FDA does not consider ancillary benefits and risks from salmon market expansion (2, 3), a result of what may be an overly narrow interpretation of statutes.

1 The carbon dioxide system in seawater: equilibrium chemistry and measurements 1.1 Introduction 1.2 Basic chemistry of carbon dioxide in seawater 1.3 The definition and measurement of pH in seawater 1.4 Implications of other acid-base equilibria in seawater on seawater alkalinity 1.5 Choosing the appropriate measurement techniques 1.6 Conclusions and recommendations 2 Approaches and tools to manipulate the carbonate chemistry 3 Atmospheric CO2 targets for ocean acidification perturbation experiments 4 Designing ocean acidification experiments to maximise inference 5 Bioassays, batch culture and chemostat experimentation 6 Pelagic mesocosms 7 Laboratory experiments and benthic mesocosm studies 8 In situ perturbation experiments: natural venting sites, spatial/temporal gradients in ocean pH, manipulative in situ p(CO2) perturbations 9 Studies of acid-base status and regulation 9.1 Introduction 9.2 Fundamentals of acid-base regulation 9.3 Measurement of pH, total CO2 and non-bicarbonate buffer values 9.4 Compartmental measurements: towards a quantitative picture 9.5 Overall suggestions for improvements 10 Studies of metabolic rate and other characters across life stages 10.1 Introduction 10.2 Definition of a frame of reference: studying specific characters across life stages 10.3 Approaches and methodologies: metabolic studies 10.4 Study of early life stages 10.5 Techniques for oxygen analyses 10.6 Overall suggestions for improvements 10.7 Data reporting 10.8 Recommendations for standards and guidelines 11 Production and export of organic matter 12 Direct measurements of calcification rates in planktonic organisms 13 Measurements of calcification and dissolution of benthic organisms and communities 14 Modelling considerations 15 Safeguarding and sharing ocean acidification data 15.1 Introduction 15.2 Sharing ocean acidification data 15.3 Safeguarding ocean acidification data 15.4 Harmonising ocean acidification data and metadata 15.5 Disseminating ocean

Three Historic Blowouts 1. Lauren Schenkman Figure Mexico 1979 "CREDIT: NOAA" The decade from 1969 to 1979 witnessed three massive spills from offshore oil wells around the world. Here is how they compare in size and impact. IXTOC 1 The biggest well-related spill was triggered on 3 June 1979, when a lack of drilling mud allowed oil and gas to shoot up through the 3.6-km-deep IXTOC 1 exploratory well, about 80 km offshore in the southern Gulf of Mexico. The initial daily outflow of 30,000 barrels of oil was eventually reduced to 10,000 barrels. The well was finally capped more than 9 months later. Mexico's state-owned oil company, PEMEX, treated the approximately 3.5-million-barrel spill with dispersants. U.S. officials had a 2-month head start to reduce impacts to the Texas coastline. Figure North Sea 1977 "CREDIT: WALLY FONG/AP PHOTO" Ekofisk The first major spill in the North Sea resulted in the release of 202,000 barrels of oil about 250 km off the coast of Norway. The 22 April 1977 blowout caused oil to gush from an open pipe 20 m above the sea surface. The well was capped after a week. Between 30% and 40% of the spill evaporated almost immediately. Rough waters broke up the slick before it reached shore. Figure Santa Barbara 1969 "CREDIT: BETTMANN/CORBIS" Santa Barbara A blown well 1 km below the sea floor and 9 km off the coast of Santa Barbara, California, spewed out a total of 100,000 barrels of oil. The initial eruption occurred on 28 January 1969, and the well was capped by mud and cement on 7 February, but the pressure forced oil through sea floor fissures until December. The oil contaminated 65 km of coastline. At least 3700 birds are known to have died, and commercial fishing in the area was closed until April.

Isles of Abundance Britain has taken another step toward designating the world's largest marine reserve around the Chagos Islands, a group of 55 coral protrusions in the Indian Ocean. The government announced the end of a 4-month public comment period on 5 March and is expected to reach a final decision by May. The Chagos contain half of the Indian Ocean's remaining healthy reefs. The waters are said to be among the cleanest on Earth, allowing corals to grow in deep water less vulnerable to global warming. The islands are located in the equatorial "tuna belt," which hosts what a Royal Zoological Society of London report called one of the "most exploited, badly enforced fisheries in the world." A total ban on fishing in the 544,000-square-kilometer zone, an area the size of France, would make it an even larger protected area than the current record-holder, the 360,000-km2 Papahanaumokuakea Marine National Monument in the northwestern Hawaiian Islands. The Pew Environment Group has spearheaded a 3-year campaign for creation of a Chagos reserve. It would be "literally an island of abundance in a sea of depletion," says Pew's Jay Nelson. The islands are uninhabited except for the U.S. Navy base on Diego Garcia. Some 1500 Chagossians were deported to Mauritius in the 1970s for military security.