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.