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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.

"The Orangeburg Scarp, a band of hard, crusty sediment teeming with tiny plankton fossils that runs from Florida to Virginia, marks an ancient shoreline where waves eroded bedrock 3 million years ago. That period, the middle Pliocene, saw carbon dioxide levels and temperatures that many scientists say could recur by 2100. The question is: Could those conditions also result in Pliocene-epoch sea levels within the next 10 to 20 centuries, sea levels that may have been as much as 35 meters higher than they are today? The answer, say climate scientists, may lie 17,000 kilometers away in East Antarctica. The East Antarctic Ice Sheet is the world's largest, a formation up to 4 km thick and 11 million km2 in area that covers three-quarters of the southernmost continent. Its glaciers were thought to sit mostly above sea level, protecting them from the type of ocean-induced losses that are affecting the West Antarctic Ice Sheet. But studies of ancient sea levels that focus on the Orangeburg Scarp and other sites challenge that long-held assumption. Not everybody believes the records from Orangeburg. But combined with several other new lines of evidence, they support the idea that parts of East Antarctica could indeed be more prone to melting than expected. "

Winds of Change Jane Qiu Antarctica does not respond to global warming uniformly like a giant ice cube. Changing wind patterns are an unsung force shaping Antarctica's future. Retreating sea ice and stronger winds have caused seawater to mix more deeply, a process that churns sunlight-dependent phytoplankton into the ocean's depths. As a result, phytoplankton biomass has declined by 12% over the past 30 years. Higher on the food chain, that means fewer krill and fish larvae. These creatures are also getting hammered by the loss of sea ice, which hides them from predators. The complex interplay between air, sea, and ice has emerged as a central theme underlying climate change in Antarctica. Shifting wind patterns and corresponding ocean changes can explain climate responses across the continent.

December 18, 2012 The Ten Best Ocean Stories of 2012 | | | Share on redditReddit | Share on diggDigg | Share on stumbleuponStumble | Share on emailEmail | More Sharing ServicesMore Two market squids mating 2012 was a big year for squid science. Photo Credit: © Brian Skerry, www.brianskerry.com Despite covering 70 percent of the earth's surface, the ocean doesn't often make it into the news. But when it does, it makes quite a splash (so to speak). Here are the top ten ocean stories we couldn't stop talking about this year, in no particular order. Add your own in the comments! 2012: The Year of the Squid From the giant squid's giant eyes (the better to see predatory sperm whales, my dear), to the vampire squid's eerie diet of remains and feces, the strange adaptations and behavior of these cephalopods amazed us all year. Scientists found a deep-sea squid that dismembers its own glowing arm to distract predators and make a daring escape. But fascinating findings weren't relegated to the deep: at the surface, some squids will rocket themselves above the waves to fly long distances at top speeds. James Cameron Explores the Deep Sea Filmmaker James Cameron has never shied away from marine movie plots (See: Titanic, The Abyss), but this year he showed he was truly fearless, becoming the first person to hit the deepest point on the seafloor (35,804 feet) in a solo submarine. While he only managed to bring up a single mud sample from the deepest region, he found thriving biodiversity in the other deep-sea areas his expedition explored, including giant versions of organisms found in shallow water. Schooling sardines form a "bait ball." Small fish, such as these schooling sardines, received well-deserved attention for being an important part of the food chain in 2012. Photo Credit: © Erwin Poliakoff, Flickr Small Fish Make a Big Impact Forage fish-small, schooling fish that are gulped down by predators-should be left in the ocean for larger fish, marin

Experts Agree Global Warming Is Melting the World Rapidly Richard A. Kerr Forty-seven glaciologists have arrived at a community consensus over all the data on what the past century's warming has done to the great ice sheets: a current annual loss of 344 billion tons of glacial ice, accounting for 20% of current sea level rise. Greenland's share-about 263 billion tons-is roughly what most researchers expected, but Antarctica's represents the first agreement on a rate that had ranged from a far larger loss to an actual gain. The new analysis, published on page 1183 of this week's issue of Science, also makes it clear that losses from Greenland and West Antarctica have been accelerating, showing that some ice sheets are disconcertingly sensitive to warming.

"Welcome to the Penguin Science Education Page! Here you will find fun and educational activities to help students learn about many interesting aspects of Adelie penguin life, history and their relationship to climate change. Students can also send questions to the researchers who study penguins, check the nests of penguins as they look today, and (if the season is right) even receive a postcard from Antarctica! Adelie Penguin's existence in the far south region of our planet is a fascinating subject. The average day in the life of a penguin is filled with adventure and drama, as they struggle to live and thrive in a challenging environment and changing climate. "

"We present a reference, comprehensive, high-resolution, digital mosaic of ice motion in Antarctica assembled from multiple satellite interferometric synthetic-aperture radar data acquired during the International Polar Year 2007 to 2009. The data reveal widespread, patterned, enhanced flow with tributary glaciers reaching hundreds to thousands of kilometers inland over the entire continent. This view of ice sheet motion emphasizes the importance of basal-slip-dominated tributary flow over deformation-dominated ice sheet flow, redefines our understanding of ice sheet dynamics, and has far-reaching implications for the reconstruction and prediction of ice sheet evolution. "