In mid-August 2005, a small tropical disturbance (a migratory cluster of powerful thunderstorms) formed over the Atlantic Ocean east of the Lesser Antilles. At the start, there was nothing much to distinguish it from three other such disturbances then hovering over the south Atlantic and Gulf of Mexico. Even after it strengthened over the Bahamas and was christened Hurricane Katrina, it remained an unremarkable storm, a Category 1 on the Saffir-Simpson hurricane scale, with sustained winds of only 129 kilometers per hour (kph). Katrina struck the Florida coast between Miami and Fort Lauderdale on Thursday, August 25, causing 11 deaths but relatively minor damage.
But after traversing the Florida peninsula and entering the Gulf, Hurricane Katrina underwent a startling transformation. Over land, the storm had weakened to tropical storm strength. But Katrina soon moved over the Gulf loop current, a flow of warm water that acts as a heating element for hurricanes. In the space of a few hours on August 26, Katrina bulked up into a Category 3 hurricane. By Saturday, it had grown into a giant Category 5 storm, with top winds a furious 269 kph. Its clouds covered most of the Gulf of Mexico.
Hurricane Katrina was poised to become one of the biggest natural disasters, and the single costliest one, in American history--and to deliver a profound shock to the nation's sense of security. Katrina's storm surge wave devastated the Mississippi Gulf coast and nearly destroyed an entire city, New Orleans. When it was over, at least 1,836 people were dead and 237,000 homes were wrecked. One estimate put total damage at $150 billion.
But Katrina was much more than a natural event; human hands played a role in the damage and in the storm's equally disastrous aftermath. Katrina exposed deep institutional flaws in the nation's emergency response, supposedly upgraded following the terrorist attacks of September 11, 2001. It easily overwhelmed the federal levee system, built by the U.S. Army Corps of Engineers, that protected New Orleans and its nearby suburbs; investigations showed afterward the system was considerably weaker than the Corps had claimed and that serious engineering errors had been made in its construction. Katrina also dealt a serious blow to the standing of President George W. Bush, who had staked his presidency on his ability to protect the citizenry, yet seemed unable to muster a robust response to the storm.
Category 5 storms are relatively rare. But in the weeks before Katrina's appearance, the 2005 Atlantic hurricane season had turned exceptionally busy and violent--possibly, some atmospheric scientists concluded, because of higher sea surface temperatures linked to global warming (see "Black Water Rising," p. 26). Six weeks earlier, Hurricane Dennis had become the first Category 4 storm in history to appear before August, striking Mexico before making its final landfall on the Florida panhandle on July 10. Dennis was followed quickly by Hurricane Emily, which became a ferocious Category 5 storm and thrashed the Mexican coast in late July. Additional powerful storms followed, and forecasters were forced to revise their predictions for the rest of the season, doubling the number of storms anticipated.
On August 26, as Katrina gained size and strength in the Gulf of Mexico, National Hurricane Center forecasters watched in alarm as their computer models shifted its projected course steadily westward: it started over the Florida panhandle, moved across Alabama and Mississippi, then finally settled, like a bullseye, on New Orleans.
Of all the places a hurricane might strike in the United States, New Orleans was the single most vulnerable spot. The city was built on the Mississippi River delta, where the low-lying topography offered few obstacles to storm surges, the huge hurricane-driven domes of water that can flood vast areas when a storm moves ashore. New Orleans' Corps of Engineers-built system of hurricane levees was complex and extensive, but could only repel storm surges from relatively weak hurricanes--most Category 1 storms and some, but not all, Category 2 and 3 storms. Scientists, emergency managers, and elected officials had known for years that if a Category 4 or 5 storm hit New Orleans head-on, the city could be destroyed as the surge wave overtopped levees and flooded inhabited areas. Perversely, the levees and floodwalls built to protect the city and its suburbs would contain the water that flowed over them, creating giant lakes where neighborhoods once had been.
As Hurricane Katrina tracked toward New Orleans on Saturday, emergency response agencies kicked into high gear. The governors of Louisiana, Mississippi, and Alabama asked President Bush to declare their coastal counties disaster areas even before Katrina struck, an unusual move intended to get federal agencies moving more aggressively to position food, water, and emergency supplies close to potential disaster zones. The Federal Emergency Management Agency (FEMA) began staffing its emergency operations center round the clock and moving medical, search and rescue, and emergency management teams into position.
To all eyes, it appeared the bureaucratic gears were meshed and efficiently whirring away. But all was not well. After the Department of Homeland Security (DHS) was created in the wake of 9/11, FEMA had effectively gotten lost in the shuffle. It was one of 22 agencies incorporated into the giant new department. As the nation's lead responder in a disaster...