Methane Release Could Cause Abrupt, Far-Reaching Climate Change

———————————————————————-
“When the ice sheets became unstable, they collapsed, releasing
pressure on the clathrates. The clathrates then began to de-gas.”

“‘… an abrupt and catastrophic global warming …”

“Uncovering the methane reservoir could potentially warm the Earth
tens of degrees, he said, and the mechanism could be very rapid.”

“The scientists found the broadest range of oxygen isotopic variation
ever reported from marine sediments, which they attribute to melting
waters in ice sheets as well as destabilization of clathrates by
glacial meltwater.”
——————————————————————–

National Science Foundation
Press Release 08-087
<http://www.nsf.gov/news/news_summ.jsp?cntn_id=111554&org=NSF>

Methane Release Could Cause Abrupt, Far-Reaching Climate Change
May 28, 2008

An abrupt release of methane, a powerful greenhouse gas, from ice
sheets that extended to Earth’s low latitudes some 635 million years
ago caused a dramatic shift in climate, scientists funded by the
National Science Foundation (NSF) report in this week’s issue of the
journal Nature.

The shift triggered events that resulted in global warming and an
ending of the last “snowball” ice age.

The researchers believe that the methane was released gradually at
first and then very quickly from clathrates–methane ice that forms
and stabilizes beneath ice sheets.

When the ice sheets became unstable, they collapsed, releasing
pressure on the clathrates. The clathrates then began to de-gas.

“Our findings document an abrupt and catastrophic global warming that
led from a very cold, seemingly stable climate state to a very warm,
also stable, climate state–with no pause in between,” said geologist
Martin Kennedy of the University of California at Riverside (UCR),
who led the research team.

“What we now need to know is the sensitivity of the trigger,” he
said. “How much forcing does it take to move from one stable state to
the other–and are we approaching something like that today with
current carbon dioxide warming?”

This transition “from ‘snowball Earth’ into a warmer period shows the
compelling need for research on abrupt climate change in Earth’s
history,” said H. Richard Lane, program director in NSF’s Division of
Earth Sciences. “These changes have much to tell us about the modern
human-induced threat of rapid climate change.”

According to Kennedy and colleagues, methane clathrate
destabilization acted as a runaway feedback to increased global
warming, and was the tipping point that ended the last snowball
Earth. (The snowball Earth hypothesis posits that the Earth was
covered from pole to pole in a thick sheet of ice for millions of
years at a time.)

“Once methane was released at low latitudes from destabilization in
front of the ice sheets, warming caused other clathrates to
destabilize,” Kennedy said. “Clathrates are held in a
temperature-pressure balance of only a few degrees.”

Not all of Earth’s methane was released millions of years ago.
Methane clathrates are present today in Arctic permafrost and beneath
the oceans at continental margins; they will remain dormant, it’s
thought, unless triggered by warming.

This trigger is a major concern, Kennedy said, because it’s possible
that very little warming could unleash this trapped methane.

Uncovering the methane reservoir could potentially warm the Earth
tens of degrees, he said, and the mechanism could be very rapid.

Such a fast uncovering of clathrates could have triggered a
catastrophic climate and biogeochemical reorganization of the ocean
and atmosphere around 635 million years ago, Kennedy believes.

The abruptness of the glacial termination, along with changes in
ancient ocean chemistry and chemical deposits in the oceans, have
been a challenge to climate scientists.

“The geologic deposits of this period are quite different from what
we find in subsequent deglaciation,” Kennedy said. “They immediately
precede the first appearance of animals on Earth, suggesting some
kind of environmental link.”

Also called marsh gas, methane is a colorless, odorless gas. As a
greenhouse gas, it is about 30 times more potent than carbon dioxide.

“Today we’re conducting a global-scale experiment with Earth’s
climate system,” Kennedy said, “and witnessing an unprecedented rate
of warming, all with little or no knowledge of what instabilities
lurk in the climate system and how they can influence life on Earth.

“Much the same experiment was done 635 million years ago, and the
outcome is preserved in the geologic record. We see that strong
forcing on the climate, not unlike the current carbon dioxide
forcing, results in the activation of latent controls in the climate
system that, once initiated, change climate to a completely different
state.”

Kennedy and colleagues collected hundreds of marine sediment samples
in South Australia for stable isotope analysis, an important tool
used in climate reconstruction.

The scientists found the broadest range of oxygen isotopic variation
ever reported from marine sediments, which they attribute to melting
waters in ice sheets as well as destabilization of clathrates by
glacial meltwater.

Kennedy was joined in the study by David Mrofka of UCR and Chris von
der Borch of Flinders University, Australia.

The study also was supported by grants from NASA’s Exobiology Program.

-NSF-

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Iqbal Pittalwala, UCR (951) 827-6050 iqbal@ucr.edu

The National Science Foundation (NSF) is an independent federal
agency that supports fundamental research and education across all
fields of science and engineering, with an annual budget of $5.92
billion. NSF funds reach all 50 states through grants to over 1,700
universities and institutions. Each year, NSF receives about 42,000
competitive requests for funding, and makes over 10,000 new funding
awards. The NSF also awards over $400 million in professional and
service contracts yearly.

Receive official NSF news electronically through the e-mail delivery
and notification system, MyNSF (formerly the Custom News Service). To
subscribe, visit www.nsf.gov/mynsf/ and fill in the information under
“new users”.

Useful NSF Web Sites:
NSF Home Page: http://www.nsf.gov
NSF News: http://www.nsf.gov/news/
For the News Media: http://www.nsf.gov/news/newsroom.jsp
Science and Engineering Statistics: http://www.nsf.gov/statistics/
Awards Searches: http://www.nsf.gov/awardsearch/
National Science Foundation
The National Science Foundation, 4201 Wilson Boulevard, Arlington,
Virginia 22230, USA
Tel: (703) 292-5111, FIRS: (800) 877-8339 | TDD: (800) 281-8749
Last Updated:
May 28, 2008
Text Only
Last Updated: May 28, 2008

————————————————————————————-

Bookmark the permalink.

Comments are closed