Fire & ice.

Ice on fire?! Is this some sort of magic trick? No, it's a different kind of ice called methane hydrate. It's made of single molecules of flammable natural gas trapped in cages of frozen water. And it could be a new, plentiful fuel source.

Scientists first discovered methane hydrates in 1970, while drilling into the seafloor. For two decades, they avoided drilling near suspected hydrate deposits, fearing the trapped gas could blast apart their equipment.

But scientists looking for alternative fuel sources would like to tap into the methane. Packed with carbon, the essential component of all fossil fuels, the seafloor methane probably comes from the gassy wastes of bacteria. By some estimates, the hydrates contain more carbon than coal or oil.

The catch: Methane hydrates are extremely hard to study. "It's like trying to study ice cream in the Sahara Desert," says Charles Paull, a marine geologist at the University of North Carolina at Chapel Hill. "The samples melt as you observe them."

In nature, they lie buried beneath the seafloor. There, high pressure and low temperatures squeeze water and methane into solid form. Researchers haul samples to the surface in pressurized containers to keep them intact. Otherwise, the hydrates' icy shells melt and the gas inside escapes. Result: No more fuel.

Also, some scientists worry that releasing methane -- a greenhouse gas -- into Earth's atmosphere could increase global temperatures. In fact, Paull says, methane escaping from hydrates may have helped warm Earth at the end of the last Ice Age (about 10,000 years ago).

Back then, Paull explains, a lot of ocean water was frozen. So there was less liquid water in the seasand and less pressure on the seafloor. The low pressure allowed hydrates to melt and belch up methane.

To learn more about the rare ice, scientists are trying to make samples in labs. Talk about trial by fire.