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Dinosaur Age Coal and Global Warming
Paleobotany gets political. Studies of fossil plant stomata and coal
deposits yield information on past climate changes and beg the question: is
there a down side to burning all of these fossil fuels so rapidly? Jennifer
McElwain, Steve Hesselbo, and Jessica Wade Murphy issue their report in
_Nature_ this week.
The following text comes from www.spacedaily.com/news/climate-05zzi.html
Burnt Coal From Dinosaur Age Sheds Light On Today's Global Warming
Studying climate change is incredibly complex, yet retracing climate change
and the causes behind those changes is the only way to understand the
effects of burning massive amounts of fossil fuels today.
Over the course of geological time, the amount of carbon trapped in land and
the oceans has waxed and waned. So has the amount of carbon dioxide in the
These fluctuations correlate closely with changes in global temperatures.
Therefore, studying the flow of carbon between land, water and atmosphere
through geological ages can shed light on issues surrounding today's global
New research described in the May 26 issue of Nature provides some missing
pieces in the puzzle depicting the global carbon cycle over geological time.
During what geologists call "oceanic anoxic events," it has long been
suggested that a large amount of the greenhouse gas carbon dioxide is
removed from the atmosphere by millions of microscopic organisms that dwell
in the oceans.
They do this by trapping carbon in their bodies. When they die, their bodies
rain down to the ocean depths and are buried by sediment, locking away the
trapped carbon from the atmosphere for million of years.
Scientists believe that during oceanic anoxic events the biological activity
or "productivity" of these oceanic organisms is for some reason enhanced. On
the other hand, perhaps the number of these oceanic organisms is somehow
much greater during OAEs than during normal times.
Oceanic anoxic events are extremely unusual in other ways, too. They are
often associated with mass extinction among many marine organisms and
coincide with periods of intense global warming.
Scientists have long debated what causes OAEs. The prevailing theory is that
a release of massive amounts of methane into the ocean is the root cause.
The methane, in turn, oxidizes creating colossal amounts of carbon dioxide
in the ocean and atmosphere, which depletes the oceans of oxygen, warms the
planet, and kills off plants and animal species.
Now, a new theory holds that OAEs - in particular the Toarcian OAE, which
occurred about 183 million years ago during the age of dinosaurs - are
triggered by the burning of vast underground coalfields. These coalfields
were set ablaze by the intrusion of molten rock from the Earth's crust.
"The burnt coalfields are hundreds of feet thick and cover vast areas of the
Transantarctic Mountains of Antarctica, as well as South Africa," said
Jennifer McElwain, PhD, Associate Curator of Paleobotany at Chicago's Field
Museum and lead author of the research.
"Huge quantities of methane and carbon dioxide would have been released from
these coals as they were heated to high temperatures by the molten rock."
Although OAEs are not universally accepted as models upon which an
understanding of modern climate change can be based, this new research sheds
light on the possible consequences of the current level of consumption of
"If the incredibly high global temperatures that occurred during the
Toarcian oceanic anoxic event were caused by burning a significant amount of
the Earth's coal deposits within one hundred thousand years, it doesn't take
much imagination to realize what will happen if we burn most of the Earth's
remaining fossil fuels over the coming century, which is what we are in the
process of doing," McElwain said.
The scientists, who worked on this research for more than four years, also
turned up a totally unexpected result: they identified a 200,000-year
interval when atmospheric carbon dioxide dropped to surprisingly low levels
at the start of the Toarcian Oceanic Anoxic Event.
This was probably due to the great number and activity of marine organisms
at this time that effectively sucked carbon dioxide out of the atmosphere
like a sponge. This drop cooled the Earth, maybe even enough to have enabled
ice sheets to form and grow in the polar regions of the Arctic and
The idea of ice sheets during the age of dinosaurs has always been a
Nevertheless, McElwain and coauthors Steve Hesselbo, from the Department of
Earth Sciences at the University of Oxford in England, and Jessica Wade
Murphy, who was an undergraduate student in the Department of Ecology and
Evolution at the University of Chicago at the time of this study, believe
they have tantalizing evidence that the global temperatures were not as
uniformly warm and ice free during the age of dinosaurs, as once assumed.
In this study, which was funded by the Comer Foundation of Science and
Education, atmospheric carbon dioxide levels were determined by counting the
stomata in small fossil leaves collected from Baga Formation, Denmark, of
which 126 specimens were used.
Stomata are minute pores in the surface of leaves through which water vapor
and gases, including carbon dioxide, pass. The fewer the stomata, the more
carbon dioxide in the atmosphere, and vice versa.
"We were certainly surprised to find that our tiny fossil leaves from
Denmark led us half way across the world to coalfields of the Transantarctic
Mountains in Antarctica to form a new theory on how natural geological
processes in the past have caused extreme global warming," McElwain said.
"It's very sobering to realize that humans are currently causing global
warming by similar processes, that is, by burning fossil fuels like coal and
oil. The difference today is that we are causing the atmosphere and climate
to change at a greatly faster rate than has ever been observed in the
"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology
Hopefully our leaders will take this report to heart.