Could it happen again?

This is the fourth Mardi Gras since Hurricane Katrina struck the city of New Orleans and the U.S. gulf coast. Rebuilding projects continue, and some wonder if new levees will hold.

Scientists believe that hurricanes have become more frequent during the last century, and global warming is the likely culprit.

Even the most conservative scientific statements agree that human activity is significantly contributing to weather shifts, and we'll experience more extreme weather from now on. The American Meteorological Society predicts more intense precipitation and significant regional shifts in the patterns of rainfall. All of this may lead to persistent droughts and floods.

The Union of Concerned Scientists points out that increased rain plus melting glaciers will lead to rising sea levels. With so many people living on the coasts, more cities are threatened by storm swells and flooding ... just like Katrina.

California's capital of Sacramento currently lives with the greatest risk of flooding of any major American city. River levees were begun over 100 years ago, and not all of them have been upgraded.

The Army Corps of Engineers and the Federal Emergency Management Agency recently declared that there's a 60% chance of a levee breach in some areas around the city. The Sacramento Area Flood Control Agency (PDF) estimates that at least 230,000 residents would be displaced in such a disaster, and the flood damages could cost $11.2 billion.

That's just one place where a Katrina-like disaster could be on the horizon. Some towns have already seen unusual flooding, like parts of Ohio in 2007. If you live in a river plain, expect the unexpected from now on.

It's not only folks with a beach view who have to worry, thanks to global climate change. Just another reason we all need to do our part and reduce carbon emissions in our everyday lives.

As a precautionary measure, homeowners should look into buying flood insurance. If you live in a recognized flood-prone area, you may be required to get it by your mortgage lender.

Everyone should assemble an emergency preparedness kit. The Red Cross has a good list of supplies for adults and children. Gather canned food, bottled water, first-aid supplies, flashlights, batteries, and other basics in a central place in your home. Make sure each family member knows where it is, and check on the contents at least once a year to replace stale food and expired batteries. Don't forget about your pets either!

All this gear is handy to have no matter where you live -- natural disasters, blackouts, and other emergencies can happen any time. One of the lessons Hurricane Katrina unfortunately taught us is that we have to look out for ourselves and our neighbors.