The rise in sea level is going to happen over time; it won't be like a flood, where one day everything's fine and the next day you're wiped out. If we make no environmental changes, the ice pack on Greenland will probably melt down over the course of several hundred years, which could raise the global ocean by 18 to 20 feet. For the first few feet, we'll probably spend a lot of money trying to protect buildings near the water. But eventually, we'll have to make some hard choices, like giving up pieces of land.

It sounds like a doomsday future, but there are things we can do now to change that scenario—drive less, choose smaller cars, turn down the thermostat, buy energy-efficient lightbulbs and appliances. Another tip: Pay attention to where your food comes from. We can now get anything from anywhere in the world, but the amount of energy it takes to transport it is unbelievable, so eat local foods, in season.

Unfortunately, even with all those changes, the best we can say is that things won't get worse. So when people ask, "Why bother?" I say because we can benefit our children, our grandchildren, and their children. I think that's pretty good motivation to save the planet. — Susi Moser, PHD

(Moser is a scientist with the Institute for the Study of Society and Environment/National Center for Atmospheric Research.)