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...frequently admit, and even when researchers uncover a new piece of data, it isn't always clear what it means. That's very much the case with a new paper about methane emissions, published Thursday in Science. Based on a series of expeditions to the margins of the Arctic Ocean by ship and helicopter, University of Alaska researcher Natalia Shakhova and her colleagues report that methane, a greenhouse gas that is 30 times more effective in trapping heat in the atmosphere than carbon dioxide, is bubbling up from the continental shelf and leaking into the atmosphere. The estimated total...
...Louis Majesty wasn't hit by a sudden storm or any of the other expected dangers of maritime travel. Rather, it may have been the victim of rogue waves. For centuries mariners have told stories about sudden waves that would emerge out of the open ocean without warning, strong enough to topple even large ships. The S.S. Waratah, which vanished on a journey to Cape Town; the M.S. München, lost en route to Savannah, Ga.; even the S.S. Edmund Fitzgerald, "the good ship and true" of the Gordon Lightfoot song, which disappeared on Lake Superior - all were rumored...
Scientists still don't know exactly how rogue waves occur, nor do they know how to predict them. Open ocean waves, possibly including rogue waves, form when wind produces distortion over the surface of the sea - the stronger the wind, the higher the wave, which is why hurricanes can create such destructive walls of water. Tsunamis, on the other hand, like the one produced by the 8.8-magnitude earthquake in coastal Chile on Feb. 27, don't create rogue waves; tsunamis barely make a ripple on the open ocean and gather in size only when they reach shallow land near...
Rogue waves generally occur out in the open ocean. They may be the result of a number of factors coming together - strong winds and fast currents coinciding, for instance - or of a focusing effect, in which several smaller waves join together to form one big wave. There may even be a nonlinear effect at work, in which just a small change in wind speed multiplies to form a big wave. And certain areas of the ocean, like the strong waters off Africa's coast, may be more vulnerable to rogue waves than others...
...than water waves, to get a better sense of how rogues might arise. They created a metal platform in a lab measuring 26 cm by 36 cm (about 10 in. by 14 in.) and randomly placed 60 small brass cones on the platform to mimic the effect of unexpected ocean eddies in the current. When they beamed microwaves at the platform, the scientists found that "hot spots" - the microwave equivalent of rogue waves - appeared up to 100 times more often than standard wave theory would predict. Those results indicate that rogue waves might be a lot more common than scientists...