Rise in CO2 levels 200 mln yrs ago led to sudden collapse in plant biodiversity

June 19th, 2009 - 2:08 pm ICT by ANI  

Washington, June 19 (ANI): In a new study, scientists have found that a rise in carbon dioxide (CO2) levels 200 million years ago led to a sudden ancient collapse in plant biodiversity.

The evidence for the collapse in the plant biodiversity was unearthed by scientists in the form of 200 million-year-old fossil leaves collected in East Greenland.

The researchers were surprised to find that a likely candidate responsible for the loss of plant life was a small rise in the greenhouse gas carbon dioxide, which caused Earth’s temperature to rise.

Global warming has long been considered as the culprit for extinctions, but the surprise, according to this research, is that much less carbon dioxide gas in the atmosphere may be needed to drive an ecosystem beyond its tipping point than previously thought.

Until this research, the pace of the extinctions was thought to have been gradual, taking place over millions of years.

It has been notoriously difficult to tease out details about the pace of extinction using fossils, scientists say, because fossils can provide only snap-shots or glimpses of organisms that once lived.

Using a technique developed by scientist Peter Wagner of the Smithsonian Institution National Museum of Natural History in Washington, D.C., the researchers were able to detect, for the first time, very early signs that these ancient ecosystems were already deteriorating, before plants started going extinct.

The method reveals early warning signs that an ecosystem is in trouble in terms of extinction risk.

“The differences in species abundances for the first 20 meters of the cliffs (in East Greenland) from which the fossils were collected are of the sort you expect,” said Wagner.

“But, the final 10 meters show dramatic loses of diversity that far exceed what we can attribute to sampling error: the ecosystems were supporting fewer and fewer species,” he added.

By the year 2100, it’s expected that the level of CO2 in the modern atmosphere may reach as high as two and a half times today’s level.

“This is of course a ‘worst case scenario,” said Jennifer McElwain of University College Dublin, the research paper’s lead author. “But it’s at exactly this level (900 parts per million) at which we detected the ancient biodiversity crash,” she added.

“We must take heed of the early warning signs of deterioration in modern ecosystems,” she said.

According to the scientists, the majority of modern ecosystems have not yet reached their tipping point in response to climate change, but many have already entered a period of prolonged ecological change. (ANI)

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