Paleontologists and geologists are looking to the ancient past for clues about whether global warming will result in mass extinctions. What they're finding is not encouraging.

The world's greatest lake, holding 20 percent of the planet's surface fresh water, has long remained one of the most pristine places on earth. Now, as Russia's economy booms and its climate warms, the Siberian lake faces new threats.

The burgeoning amount of carbon dioxide in oceans is affecting a lot more than coral reefs. It is also damaging marine life and, most ominously, threatening the future survival of marine populations.

By taking bits of a single gene, scientists are using DNA barcoding to identify new species. If a portable hand-held scanning device can be developed, one ecologist says, it could “do for biodiversity what the printing press did for literacy.”