In designating the oil spill the worst, Obama downgrades the Dust Bowl, floods, deforestation and extermination of bison

From the Oval Office the other night, President Obama called the oil leak in the Gulf of Mexico “the worst environmental disaster America has ever faced.” Senior people in the government have echoed that language.

The motive seems clear. The words signal sympathy for the people of the Gulf Coast, an acknowledgment of the magnitude of their struggle. And if this is really the worst environmental disaster, the wording seems to suggest, maybe people need to cut the government some slack for failing to get it under control right away.

But is the description accurate?

Scholars of environmental history, while expressing sympathy for the people of the gulf, say the assertion is debatable. They offer an intimidating list of disasters to consider: floods caused by human negligence, the destruction of forests across the entire continent and the near-extermination of the American bison.

“The White House is ignoring all the shades and complexities here to make a dramatic point,” said Donald E. Worster, an environmental historian at the University of Kansas and a visiting scholar at Yale.

The professors also note the impossibility of ranking such a varied list of catastrophes. Perhaps the worst disaster, they say, is always the one people are living through now.

Still, for sheer disruption to human lives, several of them could think of no environmental problem in American history quite equaling the calamity known as the Dust Bowl.

“The Dust Bowl is arguably one of the worst ecological blunders in world history,” said Ted Steinberg, a historian at Case Western Reserve University.

Across the High Plains, stretching from the Texas Panhandle to the Dakotas, poor farming practices in the early part of the 20th century stripped away the native grasses that held moisture and soil in place. A drought that began in 1930 exposed the folly.

Boiling clouds of dust whipped up by harsh winds buried homes and cars, destroyed crops, choked farm animals to death and sent children to the hospital with pneumonia. At first the crisis was ignored in Washington, but then the apocalyptic clouds began to blow all the way to New York, Buffalo and Chicago. A hearing in Congress on the disaster was interrupted by the arrival of a dust storm.