Poisonous volcanic gas caused world's largest mass extinction, study

December 2, 2005
World's largest mass extinction was caused by poisonous volcanic gas, study

The research, published in the journal Geology, reveals vital clues about the mass extinction at the end of the Permian period, 250 million years ago, when mammal-like reptiles known as synapsids roamed the earth. Many scientists had previously thought that an asteroid hitting the earth or a deep-sea methane release had caused the extinction, which obliterated more than two-thirds of reptile and amphibian families.

However, analysis of a unique set of molecules found in rocks taken from the Dolomites in Italy has enabled scientists to build up a picture of what actually happened. The molecules are the remains of polysaccharides, large sugar-based structures common in plants and soil, and they tell the story of the extinction.

The molecules date from the same time as a major volcanic eruption that caused the greatest ever outpouring of basalt lava over vast swathes of land in present day Siberia.

The researchers believe that the volcanic gases from the eruption, which would have depleted earth's protective ozone layer and acidified the land and sea, killed rooted vegetation. This meant that soil was no longer retained and it washed into the surrounding oceans.

The chemistry of the rocks reveals that although the sugar molecules were found in marine sediments, they derived from land, supporting the theory that massive soil erosion caused them to end up in the sea.

Soil materials in the oceans would have blocked out light and soaked up oxygen. Analysis of rock chemistry suggests that after the soil crisis on land, the marine ecosystem succumbed to the stresses of environmental change and oceanic life faltered, completing a global catastrophe.

Dr Mark Sephton, from Imperial College London's Department of Earth Sciences and Engineering and lead author of the research, said: "The cause of the end Permian extinction has been highly controversial. We show that the terrestrial ecosystem was the first to suffer. The continent-wide nature of the event implies that it was caused by something in the atmosphere. The unique chemical data indicates that something fast and catastrophic happened on land."

Prof Henk Visscher of Utrecht University, also part of the research team, commented: "Similar to the 'Dead Zone' nowadays spreading in the Gulf of Mexico, the soil crisis could have caused a worldwide expanse of uninhabitable low-oxygen conditions in shallow marine waters. So what began on land ended in the sea. It seems there was no place to hide at this time of great dying."

Dr Sephton believes that lessons can be learned in the present day from the damage caused by the end Permian extinction: "Land degradation is a worsening global problem thanks to human activity and soil erosion has caused the loss of a third of arable land over the last forty years. 35% of the Earth's land is now soil-free. Identifying the nature of the end Permian soil crisis may help us understand what is in store for us in the years ahead," he said.

The research was carried out by an international team of scientists from the United Kingdom, the Netherlands and the United States.

Source: Imperial College London

Explore further: Scientists unravel root cause of plant twists and turns

Related Stories

Scientists unravel root cause of plant twists and turns

September 29, 2015

To feed the world's burgeoning population, producers must grow crops in more challenging terrain – where plant roots must cope with barriers. To that end, Cornell University physicists and Boyce Thompson Institute plant ...

Large trees—key climate influencers—die first in drought

September 29, 2015

In forests worldwide, drought consistently has had a more detrimental impact on the growth and survival of larger trees, new research shows. In addition, while the death of small trees may affect the dominance of trees in ...

The moon

September 21, 2015

Look up in the night sky. On a clear night, if you're lucky, you'll catch a glimpse of the moon shining in all it's glory. As Earth's only satellite, the moon has orbited our planet for over three and a half billion years. ...

Researchers find heavy metals along river after mine spill

September 19, 2015

Researchers say they found scattered accumulations of heavy metals along a 60-mile stretch of riverbank in Colorado and New Mexico a month after the Gold King Mine wastewater spill and say that any potential threat to crops ...

Harvesting clues to GMO dilemmas from China's soybean fields

September 18, 2015

China's struggle - mirrored across the globe—to balance public concern over the safety of genetically modified (GM) crops with a swelling demand for affordable food crops has left a disconnect: In China's case, shrinking ...

Recommended for you

Mexican site yields new details of sacrifice of Spaniards

October 9, 2015

Excavations at the site of one of the Spanish conquistadors' worst defeats in Mexico are yielding new evidence about what happened when the two cultures clashed—and a native people, at least temporarily, was in control.

ZomBee Watch helps scientists track honeybee killer

October 9, 2015

While scientists have documented cases of tiny flies infesting honeybees, causing the bees to lurch and stagger around like zombies before they die, researchers don't know the scope of the problem.

Using optical fiber to generate a two-micron laser

October 9, 2015

Lasers with a wavelength of two microns could move the boundaries of surgery and molecule detection. Researchers at EPFL have managed to generate such lasers using a simple and inexpensive method.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (2) Mar 05, 2009
Permian extinction was most likely caused by Siberian flood basalts. There was a nexus of CO2 released, coal bed combustion, and the resulting climate effects.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.