Earth's Methane Burp Cleared Way for Dinos

Earth's Methane Burp Cleared Way for Dinos - The mass extinction that opened the door for the rise of the dinosaurs about 201 million years ago caused by a spike in carbon were pumped into the atmosphere - probably release of methane from the ocean floor, a new study shows.

This tip is accelerating climate change are already underway, ultimately leading to end-Triassic, the researchers say.

Scientists already suspected that a rapid warming and changes to ocean chemistry at the time killed off the dinosaurs competitors, so to begin their era. And they knew that at the time, pumped eruptions of lava through fissures in the earth's carbon dioxide into the atmosphere.

But this new study shows that slightly more than the 600,000 years of eruptions, massive than anything that threatens the human history, came about half of the species from extinction. [Greatest Mysteries: What Causes Mass Extinctions]

Excavating fossils chemical

About 201 million years old, was the supercontinent Pangaea split apart. During the process, which eventually were to form the Atlantic Ocean and the land masses that resulted now in North America, Europe and Africa split apart, forming deep cracks, which spewed lava and carbon dioxide.

The researchers know that something happened this time because they can look at a kind of chemical fossil - the ratio of carbon atoms of different weights, called isotopes. Volcanic eruptions and fissures spew more of a lighter version of carbon (built into carbon dioxide) into the atmosphere. Methane and carbon, but it favors the lighter form even more.

Study director Micha Ruhl, a postdoctoral researcher at the University of Copenhagen and his colleagues determined the ratios of the molecules in the protective wax produced from plant leaves and preserved in sediment at the bottom of the Tethys Ocean, the precursor to the Mediterranean. (These sediments are now quite high up in the Austrian Alps.)

The researchers found a high point for the lighter isotope of carbon 12, for a stint lasts about 20,000 to 40,000 years ago.

A strong shift in the ratio indicated that no methane, carbon dioxide, was responsible, said Ruhl.

Although it remains in the atmosphere for a shorter time, methane is a stronger greenhouse gas than carbon dioxide. There are several ways large amounts of methane could be released into the atmosphere, but Ruhl believes methane from the ocean floor is probably the main cause.

Under the right conditions, bacteria on the seafloor tuck it away might be caused, but warming by spewing carbon dioxide for the release of methane have requested. In the atmosphere, the methane would be more warming and thus have caused the release of more methane, creating a feedback, he said.

Previous studies examined the ratio of carbon isotopes in the samples from North America and England brought and found evidence that the outbreaks of the future Atlantic damaged dramatic global carbon cycle, probably by pouring carbon dioxide into the atmosphere - and probably create greenhouse conditions - at the time of extinction.

This study does not show up, as much a disorder of the carbon cycle as it appeared in Ruhl's loud Jessica Whiteside, a biopaleontologist at Brown University and lead researcher on this earlier work.

The difference between the two studies' results by a local effect could be explained because the samples came from different locations, said Whiteside.

Past and future consequences

There might be pouring out of the seabed methane explain the degree of change Ruhl study for the carbon ratio is shown as Whiteside.

"I think it is in line with the majority of the papers, not only to the mass extinction, but on the other four major mass extinction," she said.

The other four have also been linked to disturbances in the carbon cycle in combination. Are involved in three cases, massive volcanic eruptions, and the third, the Cretaceous-Tertiary extinction that killed the dinosaurs, volcanoes, and is both an asteroid impact has been implicated in, she said.

As man now much greenhouse gas pumped into the atmosphere, it is conceivable that history could repeat itself, Ruhl said if global warming calls for the release of methane currently stored in the seabed.

"If that happens, accelerate climate change dramatically," he said.

Ruhl, however, pointed out that it is difficult to know what happened in the past to the present extrapolated.

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