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Tropical cyclones are characterized by a low pressure center with accompanying thunderstorms. They produce extremely powerful winds, torrential rain, high waves, storm surge and tornadoes. They develop over large bodies of warm water, but weaken over land. This explains why they cause significant coastal damages while inland regions are relatively spared from strong winds. However, heavy rains and storm surges may also bring extensive flooding inland.
Atlantic tropical cyclone activity has increased since 1970, and will continue to increase in the 21st century, according to IPCC report. Countries in the Pacific, especially the northwestern region of Japan and China, have experienced a record-breaking season of typhoons. In 1933, 21 Atlantic tropical storms prevailed, record only to be exceeded in 2005 with an all time high of 28 storms. Statistics show that in the Atlantics, hurricanes are becoming more frequent and intense. The number of named storms is nearly 50% higher in the last decade than in the previous four decades. On August 29th, 2005, Hurricane Katrina hit the Gulf of Mexico Coast and New Orleans with devastating effect. Hurricane Katrina was the costliest hurricane, as well as one of the five deadliest, in the history of the United States. It was reported that more then 1,800 people lost there lives, and more then $81 billion dollars in damages occurred. Breton National Wildlife Refuge lost half its area in the storm
Katrina has profound environmental impacts. The storm surge devastated substantial coast lines, together with tidal waves obliterated the Chandeleur Islands. The US Geological Survey estimated an area of 217 square miles completely submerged in water by the hurricanes Katrina and Rita. The damage forced the closure of 16 National Wildlife Refuges. This loss of lands has disrupted numerous marine and migratory habitats.
From late July to mid-September 2008, 6 consecutive severe storms and hurricanes have battered the United States causing damages amounting to billions of dollars. Four of these tropical cyclones swamped Haiti, killing hundreds of people. Hurricanes Gustav and Ike smashed into Cuba before veering off to the US Gulf Coast, where they took their toll on oil and gas fields.
Was Katrina a Sign of the Gathering Storm? One year after Hurricane Katrina devastated the U.S. Gulf Coast, a new survey reveals a majority of U.S. citizens now believe global warming is responsible for extreme weather events in recent years. Many scientists believe that human-induced climate change causes rise in sea surface temperatures in the hurricane formation regions, responsible too for the for the increased frequency and intensity of tropical cyclones in the Atlantic. Hurricane/typhoon wind speeds and core rainfall rates and storm surge levels are projected to increase.
But
there is also a group of scientists having different
school of thoughts, who argue that a natural
cycle called Atlantic Multidecadal Oscillation is
associated with the recent increase in the frequency
of intense hurricanes.
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