The way we're warming the planet, we can probably expect sea levels to rise at least a meter, on average, by the end of the century. That's what most scientific projections suggest, anyway. One kink, though, is that that's just an average—the seas won't go up uniformly by one meter all across the globe. Some places will see much higher rises than that, some places much lower. Michael Lemonick has a great Environment360 piece delving into some of the factors that make sea-level rise so odd and unpredictable.