NSF PR 99-69 - November 19, 1999
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Geologists Pinpoint Source of Major Global Warming
Event More Than 55 Million Years Ago
For the first time, a team of scientists has identified
the possible methane release site and critical sequence
of events that precipitated Earth’s bout with global
warming, and the extinction of many deep-sea species
and appearance of new mammalian orders, more than
55 million years ago.
The research project is part of the international Ocean
Drilling Program, which is funded by the National
Science Foundation (NSF) and a consortium of international
In an article to be published this week in the journal
Science, geologists Miriam Katz and Kenneth Miller
of Rutgers University in New Brunswick, New Jersey,
provide support for a link between the mass extinction
millions of years ago and the massive release of methane
and carbon dioxide into the earth’s oceans and atmosphere,
which is not unlike the present input of fossil fuels
into the environment. "We haven't studied these major
carbon influxes before because we didn't know about
them," says NSF's Paul Dauphin, associate program
director for ODP.
In what is known as the latest Paleocene thermal maximum
(LPTM), Earth’s climate and oceans warmed significantly
about 55.5 million years ago. Numerous mammalian orders
appeared while many deep-sea species became extinct
as water temperatures soared by 4 to 8 degrees Celsius.
Since the 1980s, scientists have tried to explain
the rapid climate warming apparent in geochemical
records from around the world.
"One approach to unraveling the possibilities of future
climate change is to study analogs from the Earth’s
past," says Katz. "We have examined clues in the geologic
record of an ancient massive release of carbon into
the Earth’s oceans and atmosphere." The clues came
from analyzing certain geochemical and faunal changes
in a group of microfossils known as foraminifera -
essentially amoebas with shells - in order to reconstruct
ancient oceanographic and climatic conditions.
Working as part of an international scientific team
onboard the Ocean Drilling Program’s vessel the JOIDES
(Joint Oceanographic Institutions for Deep-Earth Sampling)
Resolution, the researchers recovered ocean sediments
from the Blake Nose, 400 kilometers (250 miles) east
of Tallahassee, Florida. Katz and her co-authors have
pinpointed this region as the first location to be
identified as a possible LPTM methane release site,
where methane appears to have escaped from a pressure
zone created by an underlying ancient reef.
Katz says "the triggering mechanism for methane release
is still open to debate," making it impossible for
scientists to predict whether a massive release from
today’s 14,000 gigaton marine gas hydrate reservoir
could occur again.
"We know that 55.5 million years ago, carbon dioxide
was added to the atmosphere at a rate comparable to
present-day fossil fuel input, providing the potential
for using past changes in carbon dioxide levels to
shed light on future climate change possibilities,"