Man-Made Mistakes Increase Devastation Of 'Natural' Disasters

WSJ.com - Science Journal :: SHARON BEGLEY : "While storms such as Hurricane Katrina are sometimes called an act of God or a natural disaster, the devastation they leave behind is not. Some scientists believe even the storms themselves could be at least partly man-made.

As Theodore Steinberg argues, God is getting a bum rap. "This is an unnatural disaster if ever there was one, not an act of God," says Prof. Steinberg, an environmental historian at Case Western Reserve University, Cleveland. "If the potential for mass death and destruction from extreme weather existed anywhere in the U.S., it existed in New Orleans."

In his 2000 book "Acts of God: The Unnatural History of Natural Disaster in America," Prof. Steinberg documented how much of the toll from "natural" disasters, from the 1886 Charleston earthquake to 1990s hurricanes, has been exacerbated by human actions.

The temporary lull in hurricane activity in Florida, from 1969 to 1989, spurred a reckless building boom, for example, putting billions of dollars worth of condos and hotels within reach of storm surges, notes Roger Pielke Jr., of the University of Colorado, Boulder. The Great Miami Hurricane of 1926 would have caused an estimated $90 billion damage had it occurred in 2000, he calculated. It caused just over $1 billion, in today's dollars.

It isn't only hurricanes whose destructiveness has been increased by human actions. Tornadoes turn mobile homes into matchsticks (one of Prof. Steinberg's first jobs was at a New York brokerage firm, where he followed the trailer-home industry). From 1981 to 1997, he found, more than one-third of all deaths from tornadoes occurred among people living in mobile homes; federal regulations didn't require them to withstand high winds, and a 1974 statute actually pre-empted stricter state standards with more lax federal ones.

Throughout the South and Midwest, mobile-home communities and poor neighborhoods are also much more likely to be sited in flood plains.

In New Orleans, the worst-hit parishes were the lower-income ones. But the city also ignored the power of nature. More than one million acres of Louisiana's coastal wetlands, or 1,900 square miles, have been lost since 1930, due to development and the construction of levees and canals. Barrier islands and stands of tupelo and cypress also vanished. All of them absorb some of the energy and water from storm surges, which, more than the rain falling from the sky, caused the current calamity. "If these had been in place, at least some of the energy in the storm surge would have been dissipated," says geologist Jeffret Mount of the University of California, Davis. "This is a self-inflicted wound."

Studies estimate that for every square mile of wetlands lost, storm surges rise by one foot.

Leaving aside whether the levees that broke in New Orleans could have been better constructed, their very existence contributed to the disaster. Built to keep the city from being flooded by the Mississippi, they also keep the Big Muddy from depositing silt to replenish marshes and the river's delta, as do projects that direct the river's water and sediment out to sea to create a deep shipping channel.

The result is that much of New Orleans fell below sea level. Combined with the dredging to build canals, "the Gulf of Mexico is a lot closer to New Orleans than it was when Hurricane Betsy ripped through in 1965," says Prof. Steinberg. Now the gulf is in the city.

The ultimate question is whether Katrina's power reflects human-caused global warming, or is at minimum a harbinger of the kinds of storms we can expect in a warmer world.

No single freak storm can be attributed to global climate trends. But for hurricanes to form, the surface temperature in the tropical Atlantic must exceed about 80° Fahrenheit. That is more likely in a warmer world.

The best science to date suggests the frequency of hurricanes doesn't reflect global warming. Straightforward physics, however, says their intensity might. As the seas and air warm, there is more evaporation, which fuels storms, and more energy available to pump them up. A new analysis by atmospheric physicist Kerry Emanuel of MIT suggests the net power of tropical cyclones (hurricanes and Pacific typhoons), a combination of the energy they pack and how long they last, "has increased markedly since 1970."

The power of storms in the North Atlantic has tripled, while the power of those in the western North Pacific has more than doubled.

Similarly, a 2004 study from the Geophysical Fluid Dynamics Laboratory in Princeton, N.J., part of the National Oceanic and Atmospheric Administration, found that a warmer world is likely to deepen hurricanes' central pressure (a measure of their power) and intensify the rainfall they bring. Today's storms, the scientists write, "may be upstaged by even more intense hurricanes over the next century as the earth's climate is warmed by increasing levels of greenhouse gases in the atmosphere."

By continuing to blame weather extremes on random events, the "stuff happens" attitude, officials and city planners are ignoring their contributions to the disasters that have pummeled the planet and promise to become only worse."