Arctic: Turtles may be slow, but they're known to migrate long distances.

Recent satellite tracking found a leatherback turtle traveled 12,774 miles from Indonesia to Oregon, one of the longest recorded migrations of any vertebrate animal. But scientists had no idea that freshwater, tropical turtles had traveled to the Arctic --until they discovered a fossil there. It was the last place scientists expected to find a fossil of a freshwater, tropical turtle. But they did. They named it the Aurora Turtle.

The Aurora Turtle discovery suggests animals migrated from Asia to North America not around Alaska, as once thought, but directly across a freshwater sea floating atop the warm, salty Arctic Ocean. The fossil was found atop basalt, a rock associated with lava flows. That offers a clue as to what might have warmed the climate 90,000,000 years ago.

"We found this turtle right on top of the last flood basalts — a large stretch of lava from a series of giant volcanic eruptions," said John Tarduno from the University of Rochester. "That leads us to believe that the warming may have been caused by volcanoes pumping tremendous amounts of carbon dioxide into the Earth's atmosphere. There's evidence that this volcanic activity happened all around the planet — not just the Arctic. If it all happened on a short enough timescale, it could cause a super-greenhouse effect. "...This is the first example we have of a fossil in the High Arctic region showing how this migration may have taken place. We're talking about extremely warm, ice-free conditions in the Arctic region, allowing migrations across the pole."

Similar changes may be occurring in parts of the oceans today. A study in 2005 found that since the late 1960s, much of the North Atlantic Ocean has become less salty, in part due to increases in freshwater runoff induced by global warming, scientists said.