Geologists pinpoint source of major global warming event more than 55 million years ago

November 18, 1999

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 partners.

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," Katz believes.
-end-


National Science Foundation

Related Global Warming Articles from Brightsurf:

The ocean has become more stratified with global warming
A new study found that the global ocean has become more layered and resistant to vertical mixing as warming from the surface creates increasing stratification.

Containing methane and its contribution to global warming
Methane is a gas that deserves more attention in the climate debate as it contributes to almost half of human-made global warming in the short-term.

Global warming and extinction risk
How can fossils predict the consequences of climate change? A German research team from Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), the Museum of Natural History Berlin and the Alfred Wegener Institute compared data from fossil and marine organisms living today to predict which groups of animals are most at risk from climate change.

Intensified global monsoon extreme rainfall signals global warming -- A study
A new study reveals significant associations between global warming and the observed intensification of extreme rainfall over the global monsoon region and its several subregions, including the southern part of South Africa, India, North America and the eastern part of the South America.

Global warming's impact on undernourishment
Global warming may increase undernutrition through the effects of heat exposure on people, according to a new study published this week in PLOS Medicine by Yuming Guo of Monash University, Australia, and colleagues.

Global warming will accelerate water cycle over global land monsoon regions
A new study provides a broader understanding on the redistribution of freshwater resources across the globe induced by future changes in the monsoon system.

Comparison of global climatologies confirms warming of the global ocean
A report describes the main features of the recently published World Ocean Experiment-Argo Global Hydrographic Climatology.

Six feet under, a new approach to global warming
A Washington State University researcher has found that one-fourth of the carbon held by soil is bound to minerals as far as six feet below the surface.

Can we limit global warming to 1.5 °C?
Efforts to combat climate change tend to focus on supply-side changes, such as shifting to renewable or cleaner energy.

Global warming: Worrying lessons from the past
56 million years ago, the Earth experienced an exceptional episode of global warming.

Read More: Global Warming News and Global Warming Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.