OT what is going with these hurricanes?
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Caseloads
Posts: 27725 Alba Posts: 0 Joined: 7/29/2001 Member: #41 |
9/21/2005 6:30 PM
yeah, this whole thing makes me worry about global warming.
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Rich
Posts: 27410 Alba Posts: 6 Joined: 12/30/2003 Member: #511 USA |
9/21/2005 7:26 PM
It's either global warming or Bush is cursed.
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MinsHeartsReezy
Posts: 20766 Alba Posts: 0 Joined: 2/12/2005 Member: #872 USA |
9/21/2005 7:59 PM
http://news.nationalgeographic.com/news/2005/08/0804_050804_hurricanewarming_2.html
Is Global Warming Making Hurricanes Worse? John Roach for National Geographic News August 4, 2005 Hurricanes bring winds and slashing rains that flood streets, flatten homes, and leave survivors struggling to pick up the pieces. But has global warming given the storms an added punch, making the aftereffects more dreadful? According to hurricane historian Jay Barnes of Pine Knoll Shores, North Carolina, ocean heat is the key ingredient for hurricane formation. More heat could "generate more storms and more intense hurricanes," he said. Numerous studies in recent years have found no evidence that the number of hurricanes and their northwest Pacific Ocean cousins, typhoons, is increasing because of the rise in global temperatures. But a new study in the journal Nature found that hurricanes and typhoons have become stronger and longer-lasting over the past 30 years. These upswings correlate with a rise in sea surface temperatures. The duration and strength of hurricanes have increased by about 50 percent over the last three decades, according to study author Kerry Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology in Cambridge. Emanuel's finding defies existing models for measuring storm strength. Current models suggest that the intensity of hurricanes and typhoons should increase by 5 percent for every 1ºC (1.8ºF) rise in sea surface temperature. "We've had half a degree [Celsius] of warming, so that should have led to a 2.5 percent increase [in intensity], which is probably not detectable," Emanuel said. "What we've seen is somewhat bigger than that, and we don't really know why." One possibility, Emanuel said, is that ocean temperatures may be increasing more quickly than atmospheric temperatures. "When that happens we've shown theoretically you get an increase in the intensity of hurricanes," he said. Anatomy of a Hurricane According to Barnes, who has authored several books on U.S. hurricane history, the physics of hurricanes are complex and full of variables. "But the sun beating down on Earth is the primary thing that gets it going," he said. Barnes explains in his book North Carolina's Hurricane History that the summer heat warms the ocean's surface and spurs evaporation. As heat and moisture rise into the atmosphere, billowing clouds, scattered showers, and thunderstorms form. As the thunderstorms multiply, they can get picked up by low-pressure systems drifting through equatorial waters, forming a tropical depression. The spin of the Earth causes the winds within the storm to whirl around the center of the low pressure. This spinning can form an eye of a storm. The strongest part of a hurricane is the eye wall, on the edge of the calm center. "The size of the eye wall can vary, and the intensity of the storm can vary depending on how much heat is available" and other factors such as high altitude winds, Barnes said. According to Emanuel, if global temperatures continue to rise, it is reasonable to assume that hurricane activity will increase, as there is more heat to drive the storms. Global Observation Previous studies have tried to measure whether typhoons and hurricanes were becoming more frequent. Emanuel's research, however, focused on the total energy generated by the storms over their duration. "They can have the same frequency, but if they get stronger or last longer this metric will show an increase," he said. When Emanuel looked at the hurricane record in the North Atlantic, where the storms of most interest to U.S. residents form, he found that intensity fluctuated from decade to decade. This fluctuation roughly corresponded with factors such as the El Niño weather phenomenon, which has been shown to influence hurricane formation. However, North Atlantic hurricanes account for only 12 percent of the total number of hurricanes and typhoons that form globally each year, Emanuel said. "If you look at a more global measure of this metric, you don't see these strong interdecadal swings. They cancel each other out between one ocean and the other," he said. "You see instead a large upward trend." According to Emanuel, on a global scale, the strength of storms corresponds with ocean temperatures: It goes up when temperatures go up, down when temperatures goes down. Most scientists say the rise in sea surface temperature in the last 30 to 50 years is a signal of global warming. "That's their conclusion, not mine," Emanuel said. "[But] it would follow reasonably well from this metric that the upswing [in intensity] … is a result of global warming." |
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MinsHeartsReezy
Posts: 20766 Alba Posts: 0 Joined: 2/12/2005 Member: #872 USA |
9/21/2005 8:03 PM
http://www.livescience.com/forcesofnature/ap_050731_hurricanes_stronger.html
Study: Global Warming Making Hurricanes Stronger By Associated Press posted: 31 July 2005 06:29 pm ET Is global warming making hurricanes more ferocious? New research suggests the answer is yes. Scientists call the findings both surprising and "alarming'' because they suggest global warming is influencing storms now -- rather than in the distant future. However, the research doesn't suggest global warming is generating more hurricanes and typhoons. The analysis by climatologist Kerry Emanuel of the Massachusetts Institute of Technology shows for the first time that major storms spinning in both the Atlantic and the Pacific since the 1970s have increased in duration and intensity by about 50 percent. These trends are closely linked to increases in the average temperatures of the ocean surface and also correspond to increases in global average atmospheric temperatures during the same period. "When I look at these results at face value, they are rather alarming,'' said research meteorologist Tom Knutson. "These are very big changes.'' Knutson, who wasn't involved in the study, works in the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, N.J. Emanuel reached his conclusions by analyzing data collected from actual storms rather than using computer models to predict future storm behavior. Before this study, most researchers believed global warming's contribution to powerful hurricanes was too slight to accurately measure. Most forecasts don't have climate change making a real difference in tropical storms until 2050 or later. But some scientists questioned Emanuel's methods. For example, the MIT researcher did not consider wind speed information from some powerful storms in the 1950s and 1960s because the details of those storms are inconsistent. Researchers are using new methods to analyze those storms and others going back as far as 1851. If early storms turn out to be more powerful than originally thought, Emmanuel's findings on global warming's influence on recent tropical storms might not hold up, they said. "I'm not convinced that it's happening,'' said Christopher W. Landsea, another research meteorologist with NOAA, who works at a different lab, the Atlantic Oceanographic & Meteorological Laboratory in Miami. Landsea is a director of the historical hurricane reanalysis. "His conclusions are contingent on a very large bias removal that is large or larger than the global warming signal itself,'' Landsea said. Details of Emanuel's study appear Sunday in the online version of the journal Nature. Theories and computer simulations indicate that global warming should generate an increase in storm intensity, in part because warmer temperatures would heat up the surface of the oceans. Especially in the Atlantic and Caribbean basins, pools of warming seawater provide energy for storms as they swirl and grow over the open oceans. Emanuel analyzed records of storm measurements made by aircraft and satellites since the 1950s. He found the amount of energy released in these storms in both the North Atlantic and the North Pacific oceans has increased, especially since the mid-1970s. In the Atlantic, the sea surface temperatures show a pronounced upward trend. The same is true in the North Pacific, though the data there is more variable, he said. "This is the first time I have been convinced we are seeing a signal in the actual hurricane data,'' Emanuel said in an e-mail exchange. "The total energy dissipated by hurricanes turns out to be well correlated with tropical sea surface temperatures,'' he said. "The large upswing in the past decade is unprecedented and probably reflects the effects of global warming.'' This year marked the first time on record that the Atlantic spawned four named storms by early July, as well as the earliest category 4 storm on record. Hurricanes are ranked on an intensity scale of 1 to 5. In the past decade, the southeastern United States and the Caribbean basin have been pummeled by the most active hurricane cycle on record. Forecasters expect the stormy trend to continue for another 20 years or more. Even without global warming, hurricane cycles tend to be a consequence of natural salinity and temperature changes in the Atlantic's deep current circulation that shift back and forth every 40 to 60 years. Since the 1970s, hurricanes have caused more property damage and casualties. Researchers disagree over whether this destructiveness is a consequence of the storms' growing intensity or the population boom along vulnerable coastlines. "The damage and casualties produced by more intense storms could increase considerably in the future,'' Emanuel said. |
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Nalod
Posts: 70750 Alba Posts: 155 Joined: 12/24/2003 Member: #508 USA |
9/21/2005 9:28 PM
Layden.
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OT what is going with these hurricanes?