Turtle fossil shows how 'super-greenhouse effect' created tropical Arctic
The discovery of a fossilised ancient turtle reveals the North Pole was once "extremely" warm and tropical, scientists said.
The North Pole: "extremely" warm and tropical millions of years ago Photo: GETTY IMAGES
Animals migrated from Asia to North America directly across the formerly frost-free Arctic Ocean, new evidence shows.
Geologists made the breakthrough after discovering the fossil of a freshwater Asian turtle - dating back millions of years - in Canada.
John Tarduno, a US-based professor of geophysics at the University of Rochester, said: "We've known there's been an interchange of animals between Asia and North America in the late cretaceous period, but 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."
Numerous rivers from the adjacent continents would have poured fresh water into the ancient Arctic sea, he said.
Fresh water, which is lighter than marine water, may have rested on top of the salty ocean water allowing animals such as the turtle to migrate with relative ease.
The professor, who published his findings in the journal Geology, added: "We found this turtle right on top of the last flood basalts - a large stretch of lava from a series of giant volcanic eruptions.
"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 is 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."
The research team plans to return to the Arctic to look for more fossils.
No comments:
Post a Comment