RISING WATERS

Scientists tell us that by 2100, sea levels will rise several feet, flooding wetlands, beaches and coastal cities. And higher water levels will worsen any damage from storm surges or extreme high tides.

What's making sea levels rise? There are two main causes. First, when a liquid is heated, it occupies more space. So as our oceans warm due to climate change, they'll begin to expand and sea levels will rise.

Second, glacial ice is melting. When floating sea ice melts, it doesn't add to the volume in the ocean, just as a melting ice cube won't raise the level in your drink. But in places where glacial ice covers the ground, meltwater flows off the land and into the sea. And when water is added to the ocean in this way, sea levels rise.