Boost to CO2 mass extinction idea
By Helen Briggs
BBC News science reporter



A computer simulation of the Earth's climate 250 million years ago suggests that global warming triggered the so-called "great dying".
A dramatic rise in carbon dioxide caused temperatures to soar to 10 to 30 degrees Celsius higher than today, say US researchers.

The warming had a profound impact on the oceans, cutting off oxygen to the lower depths and extinguishing most lifeforms, they write in the latest issue of Geology.

The research adds to the growing body of evidence that higher temperatures, rather than a giant space rock hitting the planet, led to the greatest mass extinction in history.

Prehistoric extinction

The extinction, at the end of the Permian Period and the beginning of the Triassic, has puzzled scientists for many years.


Some 95% of lifeforms in the oceans became extinct, along with about three-quarters of land species.
Many possible reasons for this catastrophic event have been proposed - including impacts, volcanism, climate change and glaciation. Hard evidence, however, has been difficult to find.

The latest data from scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, supports the view that extensive volcanic activity over the course of hundreds of thousands of years released large amounts of carbon dioxide and sulphur dioxide into the air, gradually warming up the planet.

Deep impact

The NCAR team used a research tool known as the Community Climate System Model (CSSM) which looks at the combined effects of atmospheric temperatures, ocean temperatures and currents.


PERMO-TRIASSIC EXTINCTION
The greatest of all Earth's mass extinctions occurred about 250 million years ago
About 95% of marine species and three-quarters of all families on the Pangean (above) landmass perished
Rocks from the end of the Permian period can be seen today in places such as China, Italy and Pakistan
Chief suspects include sea-level fluctuations, volcanic activity, space impacts and melting methane-ice in sea sediments

Their work indicates that temperatures in higher latitudes rose so much that the oceans warmed to a depth of about 3,000m (10,000ft).
This interfered with the circulation process that takes colder water, carrying oxygen and nutrients, into lower levels. The water became depleted of oxygen and was unable to support marine life.

"The implication of our study is that elevated CO2 is sufficient to lead to inhospitable conditions for marine life and excessively high temperatures over land would contribute to the demise of terrestrial life," Jeffrey Kiehl and colleagues write in Geology.

Until recently, computer models of past climate have been hampered by the difficulty of accounting for complex interactions between the various components of the Earth's climate system

Professor Paul Wignall, of the University of Leeds, UK, who studies the Permian-Triassic boundary, says the models have not been sophisticated enough to recreate such "lethal super-greenhouse climates".

"I suspect many in the modelling community have been sceptical about just how bad conditions were 250 million years ago, even though the evidence is in the rocks; but now the latest climate system modelling is able to replicate climatic conditions that came close to destroying life on Earth," he told the BBC News website.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/4184110.stm

If our global warming is the start of something big, Then uh....I'm speechless in a way, Though I've heard this before.

I've always had bad luck, But being born around this just plain sucks!

They don't tell you how much CO2 had to be pumped out by the Siberian Traps basalt eruptions in order to produce such catastrophic temperatures though

Nor, indeed, just how the eruptions produced so much CO2.

Clathrate (Methane Hydrate) still looks a more likely prime suspect (albeit aided and abetted by CO2)

i remember hearing that the reason it got so hot was because a huge metor struck the earth and caused this all.

A few related articles:-

http://euro.astrobio.net/news/article1552.html

http://www.geolsoc.org.uk/template.cfm?name=fbasalts

http://www.mantleplumes.org/Impacts.html

Sure it didn't hit you in the head?

Thanks for the good reading Talon and Essan.

I would like to see a comparison of where we are at today with ever decreasing oxygen levels due mostly to industrialisation and auto pollution. That coupled with huge amounts of deforestation. Do you two think we are reaching the same crossroads again in the near future...in our lifetime perhaps?