To better understand the potential for catastrophic damage from future hurricanes, scientists are looking to the past.

And the future looks very expensive, the scientists said this week at a meeting of the American Geophysical Union. With wealth and property values increasing, and more people moving to vulnerable coasts, by the year 2020 a single storm could cause losses of $500 billion - several times the damage inflicted by Hurricane Katrina.

Roger A. Pielke Jr., director of the Center for Science and Technology Policy Research at the University of Colorado, presented preliminary results of a study that retraced the path of hurricanes from the past 105 years and calculated the havoc they would wreak on the present-day United States landscape.

Dr. Pielke said the traditional way of looking at the damage inflicted by past hurricanes - calculating the value of property destroyed and adjusting for inflation - was misleading. "Something else is going on," he said. "That something else is society is changing underneath."

Using a database of information about property and people in 168 counties along the Gulf of Mexico and the Eastern Seaboard, Dr. Pielke and his collaborators, Christopher Landsea of the National Oceanic and Atmospheric Administration and Joel Gratz of the University of Colorado, calculated the damage that would occur today from the winds and storm surges of past hurricanes. Their numbers, all adjusted for inflation to 2004 dollars, generally do not include damage from inland flooding.

No. 1 is a storm that received little attention in the historical comparisons that followed Hurricane Katrina: the Great Miami Hurricane of 1926. Similar to Hurricane Katrina in size and ferocity, it caused about $760 million in damage, in 2004 dollars. But if a hurricane of that magnitude followed the same track today, it would leave behind $130 billion of devastation across a Miami area that is far more crowded than it was in 1926, the scientists said.

Similarly, the hurricane that hit Galveston, Tex., in 1900 would cause $53 billion in damage today, and Hurricane Andrew, which caused a record $25.5 billion in damage when it hit Florida in 1992, would cause $51 billion in damage if it hit today.