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Global Extinction: Gradual Doom as Bad as Abrupt

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"Global Extinction: Gradual Doom as Bad as Abrupt"

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In “The Great Dying” 250 million years ago, the devastation came with runaway greenhouse warming

Photo of Griesbach Creek in the Arctic.

The geology of Griesbach Creek in the Arctic tells an ancient tale of slow extinction.  Source NSF.

A reposted National Science Foundation press release.

The deadliest mass extinction of all took a long time to kill 90 percent of Earth’s marine life–and it killed in stages–according to a newly published report.

It shows that mass extinctions need not be sudden events.

Thomas Algeo, a geologist at the University of Cincinnati, and 13 colleagues have produced a high-resolution look at the geology of a Permian-Triassic boundary section on Ellesmere Island in the Canadian Arctic.

Their analysis, published today in the Geological Society of America Bulletin [abstract here], provides strong evidence that Earth’s biggest mass extinction phased in over hundreds of thousands of years.

About 252 million years ago, at the end of the Permian period, Earth almost became a lifeless planet.

Around 90 percent of all living species disappeared then, in what scientists have called “The Great Dying.”

Algeo and colleagues have spent much of the past decade investigating the chemical evidence buried in rocks formed during this major extinction.

The world revealed by their research is a devastated landscape, barren of vegetation and scarred by erosion from showers of acid rain, huge “dead zones” in the oceans, and runaway greenhouse warming leading to sizzling temperatures.

The evidence that Algeo and his colleagues are looking at points to massive volcanism in Siberia as a factor.

“The scientists relate this extinction to Siberian Traps volcanic eruptions, which likely first affected boreal life through toxic gas and ashes,” said H. Richard Lane, program director in the National Science Foundation’s (NSF) Division of Earth Sciences, which funded the research.

The Siberian Traps form a large region of volcanic rock in Siberia. The massive eruptive event which formed the traps, one of the largest known volcanic events of the last 500 million years of Earth’s geologic history, continued for a million years and spanned the Permian-Triassic boundary.

The term “traps” is derived from the Swedish word for stairs–trappa, or trapp–referring to the step-like hills that form the landscape of the region.

A large portion of western Siberia reveals volcanic deposits up to five kilometers (three miles) thick, covering an area equivalent to the continental United States. The lava flowed where life was most endangered, through a large coal deposit.

“The eruption released lots of methane when it burned through the coal,” Algeo said. “Methane is 30 times more effective as a greenhouse gas than carbon dioxide.

“We’re not sure how long the greenhouse effect lasted, but it seems to have been tens or hundreds of thousands of years.”

Much of the evidence was washed into the ocean, and Algeo and his colleagues look for it among fossilized marine deposits.

Previous investigations have focused on deposits created by a now vanished ocean known as Tethys, a precursor to the Indian Ocean. Those deposits, in South China particularly, record a sudden extinction at the end of the Permian.

“In shallow marine deposits, the latest Permian mass extinction was generally abrupt,” Algeo said. “Based on such observations, it has been widely inferred that the extinction was a globally synchronous event.”

Recent studies are starting to challenge that view.

Algeo and co-authors focused on rock layers at West Blind Fiord on Ellesmere Island in the Canadian Arctic.

That location, at the end of the Permian, would have been much closer to the Siberian volcanoes than sites in South China.

The Canadian sedimentary rock layers are 24 meters (almost 80 feet) thick and cross the Permian-Triassic boundary, including the latest Permian mass extinction horizon.

The investigators looked at how the type of rock changed from the bottom to the top. They looked at the chemistry of the rocks and at the fossils contained in the rocks.

They discovered a total die-off of siliceous sponges about 100,000 years earlier than the marine mass extinction event recorded at Tethyan sites.

What appears to have happened, according to Algeo and his colleagues, is that the effects of early Siberian volcanic activity, such as toxic gases and ash, were confined to the northern latitudes.

Only after the eruptions were in full swing did the effects reach the tropical latitudes of the Tethys Ocean.

The research was also supported by the Canadian Natural Sciences and Engineering Research Council and the National Aeronautics and Space Administration Exobiology Program.

In addition to Algeo, co-authors of the paper are: Charles Henderson, University of Calgary; Brooks Ellwood, Louisiana State University; Harry Rowe, University of Texas at Arlington; Erika Elswick, Indiana University, Bloomington; Steven Bates and Timothy Lyons, University of California, Riverside; James Hower, University of Kentucky; Christina Smith and Barry Maynard, University of Cincinnati; Lindsay Hays and Roger Summons, Massachusetts Institute of Technology; James Fulton, Woods Hole Oceanographic Institution; and Katherine Freeman, Pennsylvania State University.

– National Science Foundation press release.

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12 Responses to Global Extinction: Gradual Doom as Bad as Abrupt

  1. prokaryotes says:

    Humans lack sensibility for the uniqueness of our environment. How can we change that?

    • Tom King says:

      After stubbing my toe a few weeks ago I noticed that I was more sensitive to my unique environment. Unfortunately the heightened sense of awareness faded away within a few days.

      I understand that the end of civilization is several orders of magnitude larger than my bruised toe. But the issues are scalable.

  2. Mark says:

    Not to belittle mass extinctions of megafauna, but my microbiologist friends always scoff – loud and hard – when they hear “__x__ percent of ALL species went extinct”. Part of me wants to organize a vanload next time the American Geo Union meets nearby and we can all where T-shirts saying “Bacteria are species too!”

    Darn megafuana-ists…. and in this day and age!

    (sorry…. gotta find humor where you can)

  3. Peter says:

    When I mention the Great Dying/End Permian and the PETM as global warming through natural events- in these two instances through tectonic movement & volcanism I usually receive no reply.

    The vast majority of the goofed up Kool aid high public cannot understand that C02 induced through natural events is no different then humans burning fossil fuels dug up from the ground for energy- the end result are greenhouse gases trapping heat.

  4. Raul M. says:

    Good morning Joe Romm, yesterday I came across a copy of your book Hell and High Water that I could borrow. I asked a woman to read some of it to me and told her it was scary, though, She read the first line of a chapter and then went silent and in a few seconds said it was scary. She then closed the book and quickly went through the training points she had on GW.
    This morning I got my magnifying glass and started to read the introduction. Yep, as people come to know…

  5. Rabid Doomsayer says:

    We have changed the make up of the atmosphere and oceans so much faster than anything previous, well over an order of magnitude faster. So possibly things might change faster.

    If you wish to study earlier work on hypoxic oceans then the term “Canfield State” may be usefull.It would seem 1000 ppm CO2 is a critical level and we could reach that this century.

    There are still many holes in our knowledge, unfortunately each time a gap is filled the picture worsens.

  6. otter17 says:

    We are treading a similar path to these mass extinctions, yet upping the ante by doing it many times faster.

    From what I have read about the PETM extinction, that took somewhere around 20k years to rise roughly six degrees C. We are potentially capable of gaining six degrees over the 1900-2100 time frame. Would it be safe to tell people that we are following the same path as a previous mass extinction event, except at a 100x faster rate?

  7. Tom King says:

    Wikipedia says the Sun gets 10% brighter every billion years. 1 billion years ago the world was too cold to support life on land. 1 billion years from now the world will be too hot to support life anywhere.

    The extinction event in this article occurred 250 million years ago with a Sun that was 2.5% dimmer and still managed to eliminate 90% of marine life. It makes sense to me that a significantly warmer Sun could allow a human induced extinction event to essentially eliminate all life. After all, we’d just be about a billion years early.

    http://en.wikipedia.org/wiki/Sun

  8. M Tucker says:

    The faster we pump GHG into the atmosphere the faster the warming and we humans have managed to exceed anything nature has accomplished in geologic history. We are now warming at a rate that is many orders of magnitude greater than the PETM event. The most recent warming was in the mid-Pliocene and the GSGS has been studying that with great interest. That event resulted in a warming of about 2 to 3 degrees Celsius; sea levels rose about 25 meters, and occurred over a span of about a million years. All with CO2 levels just a bit higher than today; perhaps 400 to 425 ppm. It is called the PRISM study (Pliocene Research, Interpretation and Synoptic Mapping) and their research is used to verify the climate models, map the migration of climate zones, and to help us understand how quickly ice sheets respond to a just a few degrees of warming.

    The speed of the warming spells extinction for many plants and animals. The civilization we have developed cannot survive. We either solve the problem or face disaster.

  9. Rabid Doomsayer says:

    http://www.manpollo.org/forums/showthread.php?p=7703#post7703

    That the last refuge had a slower extinction rate is not comforting. On the other hand doom next week is better than doom today.