Hurricane Floyd bears down on the east coast of Florida
As is customary with science, the experts are loath to jump to conclusions until all the data is in and all the causes and effects are connected. Scientists almost universally agree that the earth has warmed by about one degree Fahrenheit in this century. Some attribute that to the so-called greenhouse effect, caused by man-made gases that trap the sun's heat on the earth's surface, raising water and air temperatures. Some believe that the warming may be linked to the natural hot and cold cycles that have affected the earth since prehistory, causing, for instance, the ice ages that resulted in glaciers covering much of North America and Northern Europe and the subsequent thaws. A growing number of scientists, noting recent, unpredictable climatic changes including colder temperatures in some areas that defy patterns of both natural and greenhouse effects, attribute the current warming trend to the combined contributions of man and nature.
There is more agreement when it comes to the effects of global warming on weather trends. Few would debate that because hurricanes gather their strength from the warm surface waters of the central Atlantic, the rise in temperatures has probably added to the magnitude of recent storms, says Jim Lushine, meteorologist at the National Weather Service in Miami. "It's safe to assume that the higher water temperatures in the Atlantic are contributing to the intensity of this year's storms," he says. The number of storms is not likely to be affected by the temperature changes, says Lushine, but the strength of the hurricanes will grow as long as water temperatures keep rising.
Of course, as TIME science writer Fred Golden points out, hurricanes pounded the U.S. long before global warming was a catchphrase. A group of storms in the early part of the century long before pollution was considered a major problem resulted in the loss of thousands of lives and billions of dollars in property. The infamous 1900 hurricane that destroyed Galveston, Texas, and killed more than 8,000 people is still considered one of the deadliest storms in history, while the 1935 hurricane that ripped across the Florida Keys, killing more than 400, is the most powerful to have made landfall in the United States.
But there's no doubt that 1999 is shaping up to be a record year: Hurricane Bret made August
interesting in Texas, and if Floyd
follows its predicted path, it will be the first time ever than two major
hurricanes have hit the U.S. in one year. And it's far from over: With more
than two months remaining in the hurricane season (June 1 through November
30), the U.S. could be facing one of the worst series of storms in history. Hurricane
Gert is gaining momentum and pushing west from the Atlantic, followed
closely by another tropical storm, which will be called Harvey if it grows in intensity. "We've
already seen the normal number of major hurricanes this year," says
Lushine. "The average is two per year hitting the U.S., and it looks like
we could see two or even three more before the season is out."
What Happens to Whip Up a Hurricane
A hurricane is an enormous weather system made up of rain-bearing clouds and extremely high winds. In order for a hurricane to become as powerful as an Andrew or a Floyd, it must encounter several very specific environmental factors, including water temperatures above 80 degrees and a calm upper atmosphere. An Atlantic storm begins its life when high cumulus clouds gather over warm waters, often off the west coast of Africa. These clouds become a circular mass of thunderstorms, shaped by the curvature of the earth's atmosphere. These strong thunderstorms develop into tropical storms as they suck warm surface water to the top of the storm. This warm water is released upward into the cooler air, creating dense clouds and a concentrated area of low pressure that surrounds a spiraling, eerily calm eye. Powerful, counterclockwise winds pick up speed as they move over and feed of off warm water, and when they reach speeds of 74 mph or more, the storms are reclassified as hurricanes. Unfortunately for residents of the eastern U.S., the Caribbean and Central America, late-summer conditions in the central Atlantic offer a perfect breeding ground for the destructive storms. In fact, the U.S. hurricane season, which extends from June to November, will often see nine to 10 tropical storms, five of which become hurricanes, while two of those will be classified as intense (category 3, 4 or 5, with winds over 110 mph) hurricanes.
Join National Weather Service meteorologist Jim Lushine today at 4 p.m. EST as he answers your questions about hurricanes: Chat with Jim Lushine
More information on hurricanes and their causes is available at:
https://hurricanes.noaa.gov
TIME Magazine: The Case for a Shifting Climate Is Heating Up
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The 15 Most Powerful Hurricanes in U.S. History
|
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| Date | Location | Intensity |
Deaths
|
Cost (In 1996 dollars)
|
| 1935 | Florida (Keys) | Category 5 |
408
|
NA
|
| 1969 | Camille (Mississippi, SE Louisiana, Virginia) | Category 5 |
256
|
$1,420,700,000
|
| 1992 | Andrew (SE Florida, SE Louisiana) | Category 4 |
52
|
$26,500,000,000
|
| 1919 | Florida (Keys), South Texas | Category 4 |
600
|
NA
|
| 1928 | Florida (Lake Okeechobee) | Category 4 |
1836
|
NA
|
| 1960 | Donna (Florida/Eastern U.S.) | Category 4 |
50
|
$387,000,000
|
| 1900 | Texas (Galveston) | Category 4 |
8,000+
|
NA
|
| 1909 | Louisiana (Grand Isle) | Category 4 |
350
|
NA
|
| 1915 | Louisiana (New Orleans) | Category 4 |
275
|
NA
|
| 1961 | Carla (North/Central Texas) | Category 4 |
406
|
$408,000,000
|
| 1989 | Hugo (South Carolina) | Category 4 |
60
|
$7,000,000,000
|
| 1926 | Florida (Miami), Mississippi, Alabama, Pensacola | Category 4 |
243
|
NA
|
| 1954 | Hazel (South Carolina, North Carolina) | Category 4 |
95
|
$281,000,000
|
| 1947 | SE Florida, SE Louisiana, Mississippi | Category 4 |
51
|
NA |