Much of the debate after Hurricane Katrina focused on the race and class disparities exposed by the flooding. Unfortunately, efforts to plan for future disasters suffer because of too little public attention to the most underreported fact about Hurricane Katrina: People died in greater numbers the greater their age.

More than 1,400 people in Louisiana perished because of Katrina. In November, the Louisiana Department of Health and Hospitals reported that 78 percent of the identified dead were over 51. Thirty-nine percent of the total were over 75.

Fifty percent of New Orleanians over 65 had disabilities, according to Elizabeth Fussell of the Social Science Research Council. That so many were poor, female, African-American, or ill only added to their vulnerability.

These were residents who couldn't crawl out on roofs or set off on the highways with their backpacks, as so many others managed to do.

The infamous deaths at nursing homes in New Orleans and its suburbs tell only a fraction of the story. Many deaths were preventable. Some people were abandoned. One sobbing young woman told National Public Radio how her family had driven away, leaving both her mother and grandmother behind.

But even rescuers paid too little attention to the most vulnerable. ``The elderly and critically ill plummeted to the bottom of priority lists as calamity engulfed New Orleans," The New York Times reported in September. Older people, reported The Sacramento Bee, ``had special needs neglected by disaster workers." Even they may not know that dehydration occurs faster in the elderly, and is harder to reverse. Fussell found that others died of chronic illnesses that could be managed under normal conditions but became lethal without medicine or treatment.

Ageism, the bias against midlife and older people, comes in many forms, from indifference to aversion to hostility to gerontophobia. Inattention and ignorance -- simple failures to recognize the particular risks to senior citizens -- can compound the potential harm during a crisis. Ageism contributed to those terrible deaths in imaginable and unknown ways.

With global warming producing more frequent hurricanes and heat waves that are especially deadly to the elderly, we must learn the lessons of Katrina. Unfortunately, New Orleans Mayor Ray Nagin seems serene about his plans for a future evacuation. ``People are pretty attuned to leaving [now] if I say you have to leave," he told USA Today. As if the only reason people had failed to leave was that they didn't want to listen to their mayor. Nagin, the media, and many others aren't dealing with the real problem: a tragic, widespread story of age and disability.

Mayors, police, civil groups, academics, journalists -- we all need to focus on the most vulnerable. And we need to focus on ageism just as we do race, class, and gender bias. As part of their disaster preparations, city agencies need to compile lists by neighborhood of the frail elderly and the disabled, and figure out how to help them if needed. We also need lists of neighbors willing to make themselves responsible for others if civic institutions fail again. At many points in our lives -- when we are young, hospitalized, injured, convalescent -- most of us who consider ourselves independent rely on others. Katrina should have taught us that we all live and die by interdependence.

Will the fortunate -- those of us who are, for the moment, unimpaired -- prize the lives of older people and invite them in as our car heads toward safety? Or will the next Katrina also be a disaster foretold?

Margaret Morganroth Gullette is a resident scholar at the Women's Studies Research Center at Brandeis University and a contributor to the book ``There Is No Such Thing as a Natural Disaster: Race, Class, and Hurricane Katrina."