Excerpted from _Science News_, Vol. 156 no. 17 (p. 260).  Due to
the limitations of ASCII, the German vowel o-umlaut has been
replaced by "oe" throughout this transcription.
 
        Global Burp Gassed Ancient Earth
 
   Some 55 million years ago, the planet belched up billions oftons of
carbon-rich gas, sending an already warm climate into a feverish state.
A study of ocean sediments laid down at this time, during the Paleocene
epoch, is now helping track the source of this gas attack.
 
  Researchers discovered the first signs of this ancient carbon surge
nearly a decade ago, but they have had difficulty determining the timing
of the event.  The sediment study reveals that the upheaval developed
extremely rapidly by geological standards making it almost as fast-paced
as modern emissions of greenhouse gases.
 
  "We now can say we have a better estimate of the event -- when it
happened and how long it took before everything returned to so-called
normal conditions," says Ursula Roehl of Bremen University in Germany.
She and Richard D. Norris of the Woods Hole (Mass.) Oceanographic
Institution report their findings in the Oct. 21 _Nature_.
 
[...]
 
  They calculate that gas rich in carbon-12 flooded the ocean during a
few thousand years or less.  Then, it took 120,000 years for the
chemistry of the ocean to restabilize itself.
 
  This timing matches well with a hypothesis proposed by Gerald R.
Dickens of James Cook University in Townsville, Australia.  In 1995, he
suggested that the carbon surge came from deposits of a frozen substance
called methane hydrate sitting on the continental shelves.
 
  According to the theory, the hydrate suddenly became unstable, causing
methane gas to bubble up into the ocean and then into the air, where it
acted as a powerful greenhouse gas.  By warming Earth, this gas would
have triggered even more hydrate melting.  Dickens has calculated that
such an event would begin rapidly and only after 140,000 years would the
carbon balance return to normal.
 
[...]
 
  Paleobiologists are interested in the event because it caused a
massive oceanic extinction and fostered a grand migration of land
species between continents, says Scott Wing of the Smithsonian
Institution in Washington, D.C.  Dating of the events on land had
disagreed with evidence from the ocean, but the times reported by Norris
and Roehl match up perfectly....

14 responses total.

Fall item 138 is linked to Science item 56.

Very interesting, thanks for entering this item.

Interesting article.  I'm not quite sure what it has to do with our
current debate and concern about Global Warming except to show a trend
of behaviour in which man had no direct participation.  

It is quite possible that the event being documented facilitated the change 
in environment that produced the human species.  Any other path may have
caused some other development chain that did not include mans' appearance.

In any case, we see that the earth did heal.  It did so in a timetable
that was just a mere blink in cosmos significant time.  I stand by my
assertion that not only is the globe resilient, it will also barely
notice man's existance.

Or non-existence? 

There is a lot of methane hydrate now, which could be released by a warming
of the ocean.

The earth "healing" included the extinction of many species. Do we want
to induce another such event, even if the earth will "heal" (maybe without
us)?

Where is the methane hydrate?  If we're doing all this to earth, won't 
it be better off without us?

        *sigh* If the possibility of species-extinction is found to be
        worrisome, then I suggest you get the species out & about.

        Q: how do you defend the _species_ from every possibility?

The methane hydrate is in the seafloor. There is lots in the Gulf of
Mexico (where they drill for gas). Gas diffuses/seeps upward spontaneously
and on contact with water at a low temperature it forms a "slush", which
stays in place in the seafloor sediments. 

Well yes, the rest of the species on earth would be better off without us.
They don't manipulate the earth's ecosystems on scales any way approaching
how man does.

Extinction paranoia?  I don't recall the exact number, but it is said that
a reasonbly large number of specific genetic lifeforms disappear every 
year from our planet.  I don't consider it my personal responsibility
to seek them out and somehow preserve them.  Just the act of interference
must alter the lifepath of a species, regardless of intent.  

It's certainly the case that man has *greatly* accelerated species
extinction.

has there been any indication that anywhere near the amount of methane hydrate
that was released 55 milion yrs ago has collected again, or that such an
amount could even collect again within the next 55 million years?

http://www.aist.go.jp/GSJ/dMG/hydrate/hydrate.resources.html

The most recent estimate is ca. 15-75 E15 kg of carbon in oceanic
methane hydrate. E15 is a big number. How much C has been extracted
to-date from fossil fuels?

This may be a bit of a 'trick' on the part of russ.  The 'sudden event'
that #0 proposes I seem to recall from my reading of newswires happened
over many many hundreds of years(couple thousand?) (sudden indeed if you
are looking at epochs that last millions of years) and is suggested to
have actually caused the evolution of we humans. (One would propose that
being a 'good deal'.)

A good deal for we humans.  Not necessarily a good deal for the
well-established species of the time.  But we're one of those well-established
species this time around, so who knows?

Re #3:  The unlikelihood of the entire chain of events is a given,
but to describe any change as "the" change is logically faulty.
The impact of the Chixulub meteorite leading to the extinction of
the dinosaurs would also have to be "the" change, the evolution of
the proto-mammal species must also be "the" change, etc.  None alone
is sufficient, and perhaps only a few are actually necessary.
 
Re #5:  To correct #7 a bit, the methane hydrates are on the sea
floor and in the sediments thereon.  There are also substantial
amounts of methane hydrate in permafrost on land, if I recall
correctly.  Methane hydrates may come from decomposition of organic
matter in the sediment itself, rather than leakage of gas from
below; we don't know yet.  They form spontaneously when methane
and water are mixed at low temperature and sea-floor pressures.
 
The risk we are taking on is the amplification of warming already
underway.  If the heating of the atmosphere from the addition of
CO2 and various other greenhouse gases (N2O, CFCl3, etc.) causes
the seafloor to warm appreciably, it could lead to the release of
lots of methane (yet another greenhouse gas) into the atmosphere
and a runaway increase of the warming trend.  This could happen so
quickly we would have little time to adapt.  Getting back to the
subject of item #53, it would be far, far worse than even a large
number of Chernobyls.
 
Re #7:  "They don't manipulate the earth's ecosystems on scales any
way approaching how man does."  Arguable.  Cyanobacteria appear to
have created earth's oxygen atmosphere, and their descendants
(chloroplasts) have improved on the work.  This is global alteration
on a scale man can only dream of as yet.  Man currently holds the
title for speed, however.

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