"Global Warming: The Culprit? Evidence mounts that human activity is helping fuel these monster hurricanes"

Magazine article

By: Jeffery Kluger

Date: October 3, 2005

Source: Kluger, Jeffery. "Global Warming: The Culprit? Evidence mounts that human activity is helping fuel these monster hurricanes." Time 166, no. 14 (October 3, 2005): 42.

About the Author: Jeffery Kluger is a senior writer for Time magazine, having started with the publication in 1996 as a contributor. Following the cover story on global warming, Kluger and two other writers were given the Whitman Bassow Award from the Overseas Press Club of America for best reporting on international environmental issues. Kluger has also written for Discover, New York Times Business World, Family Circle, and Science Digest magazines.

INTRODUCTION

There was a record number of tropical storms and hurricanes during the 2005 Atlantic hurricane season. This included one of the most damaging hurricanes of all time, Hurricane Katrina, which displaced thousands of people and caused billions of dollars of damage to the city of New Orleans. Scientists are questioning whether the intense hurricane season is just a randomly occurring phenomenon, or whether it is a sign that global climate change is beginning to take hold.

The Atlantic hurricane season runs from June 1^st until the end of November. Twenty-one names are set aside for the potential hurricanes in a given season. The names are generated from lists originally created by the US National Hurricane Center, and are now managed by the World Meteorological Organization. If there are more than twenty-one tropical storms or hurricanes in a year, Greeks letters are assigned to the storms in alphabetical order. 2005 is the first year when there were enough storms to require the use of Greek letters.

Scientists claim there is evidence that hurricanes have increased in intensity over the last thirty to thirty-five years, concluding that there has been a decrease in category one and two storms, and an increase in the proportion of category three, four, and five storms. Category five is the highest ranking a hurricane can be given, based on the Saffir-Simpson scale, with this ranking given to a storm with winds greater than 155 miles per hour, and storm surge that exceeds eighteen feet. It is believed that warmer sea-surface temperatures cause the increase in hurricane intensity. Scientists say increases in wind speeds and rainfall associated with the storms are evidence of an intensification of the natural global hydrological cycle. The cycle begins with heat provided by the sun. As the sea and atmosphere warm, the water begins to evaporate, absorbing the heat energy. The evaporated moisture then makes its way to the the upper atmosphere, where it comes in contact with much cooler temperatures. Once it begins to cool, the evaporated moisture releases the stored energy, and condenses. Global warming has increased the surface temperature of the ocean, providing added fuel to growing storms and hurricanes, making them more intense.

Despite the records set in 2005, some scientists say there is little evidence of an increasing trend in the annual number of storms. They argue that such a trend would require a more consistent increase in the number of storms over several years, or decades. There are arguments that climate change has little to do with the intensity of storms in the Atlantic. Some argue that Hurricane Katrina gained intensity over a patch of deep warm water in the Gulf of Mexico, which was not representative of an overall change in temperature of the sea. This is supported by saying that global warming only impacts the surface waters, something that hurricanes likely displace. If only the surface is warm, hurricanes would decrease in intensity by coming in contact with cool deeper waters. These scientists suggest Katrina found deeper warm water by chance.

PRIMARY SOURCE

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SIGNIFICANCE

There is evidence that natural, cyclic occurrences of weather related systems, such as the El Niño Southern Oscillation in the Pacific Ocean, can impact hurricane intensity. It has been documented that during El Niño years, when there are warmer waters in the Eastern Pacific, hurricanes in the Atlantic are less frequent. Scientists create models to monitor the interaction between the Earth's complex climate systems as they respond to global warming. Continued work on designing models that incorporate new knowledge on the understanding of climate systems are necessary to further understand how climate change impacts such things as hurricane intensity. As satellite imagery and other mapping techniques improve, the accuracy of climate change modeling is likely to improve. The variables in the models can then be augmented with actual data to improve the predictions the models provide.

The growing interest in the frequency and intensity of hurricanes is also driven by socio-economic concerns. Hurricanes have damaged billions of dollars worth of property in recent years. Some people say that it is these high monetary impacts that are driving the argument that hurricanes have increased in strength. More people live in coastal areas than ever before, increasing the odds that a hurricane making landfall will destroy homes and businesses in its path. Prior to such population densities on the coast, hurricanes were damaging forests and other uninhabited lands. Experts also say that such development has removed natural barriers, decreasing the natural hurricane buffers that forests and swamps provide.

FURTHER RESOURCES

Books

Houghton, John. Global Warming: The Complete Briefing. Cambridge, UK; New York: Cambridge University Press, 2004.

Michaels, Patricia. Meltdown: The Predictable Distortion of Global Warming by Scientists, Politicians, and the Media. Washington, D.C.: Cato Institute, 2004.

Periodicals

McDonald, R.E., D.G. Bleaken, D.R. Cresswell, V.D. Pope, and C.A. Senior. "Tropical storms: Representation and Diagnosis in Climate Models and the Impacts of Climate Change." Climate Dynamics 25, no. 1 (July 2005): 19-36. Available online at 〈http://www.springerlink.com/openurl.asp?genre=article&issn=0930-7575&volume=25&issue=1&spage=19〉 (accessed March 17, 2006).

Moreira, Naila. "The Wind and the Fury: Has climate Change Made Hurricanes Fiercer, or Are Such Claims Hot Air?" Science News 168, no. 12 (September 17, 2005): 12. Available online at 〈http://www.sciencenews.org/articles/20050917/bob8.asp〉 (accessed March 17, 2006).

Websites

"Global Warming and Hurricanes: Computer Model Simulations." National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory, August 2001. 〈http://www.gfdl.noaa.gov/∼kd/OnePagers/OnePageF01.pdf〉 (accessed March 17, 2006).

"Interaction with El Niño: How Hurricane Frequency May Be Affected." WW 2010: University of Illinois. 〈http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/enso.rxml〉 (accessed March 17, 2006).