Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ancient Greenland methane study good news for planet

24.04.2009
An analysis of ancient Greenland ice suggests a spike in the greenhouse gas methane about 11,600 years ago originated from wetlands rather than the ocean floor or from permafrost, a finding that is good news according to the University of Colorado at Boulder scientist who led the study.

Methane bound up in ocean sediments and permafrost, called methane clathrate, has been a concern to scientists because of its huge volume, greenhouse gas potency and potential for release during periods of warming, said Vasilii Petrenko, a CU-Boulder postdoctoral fellow and lead study author.

If just 10 percent of methane from clathrates -- an ice-like substance composed of methane and water -- were suddenly released into Earth's atmosphere, the resulting increase in the greenhouse effect would be equivalent to a 10-fold increase in atmospheric carbon dioxide, he said.

Using carbon 14 as a "tracer" to date and distinguish wetland methane from methane clathrates, an international team determined the methane jump 11,600 years ago likely emanated primarily from Earth's wetlands. "From a global warming standpoint, this appears to be good news," said Petrenko of CU-Boulder's Institute of Arctic and Alpine Research, lead author on a paper that was published in Science on April 24.

Methane is the third most powerful greenhouse gas behind water vapor and CO2 and accounts for roughly 20 percent of the human-caused increase in the greenhouse effect.

As Earth emerged from the last ice age, temperatures in some places in the Northern Hemisphere shot up about 18 degrees Fahrenheit in just 20 years, said Petrenko. Scientists have been concerned that such abrupt warming events could trigger huge oceanic methane "burps" caused by the dissociation of seafloor clathrates, providing a positive climate feedback mechanism that could drive up Earth's temperatures still further.

"If we found that clathrates release a lot of methane to the atmosphere during abrupt episodes of warming, that could signal big trouble for the planet, " said Petrenko. "But even though wetlands appear be the primary source, it's still something to be concerned about."

Methane emitted from human activities like rice cultivation, livestock, the burning of grasslands, forests and wood fuels, gas leaks from fossil fuel production and waste management activities have nearly tripled methane concentrations in Earth's atmosphere in the past 250 years, Petrenko said. The amount of carbon held in methane clathrate deposits on Earth may equal the amount of carbon in all oil, coal and gas reserves on the planet, he said.

Study co-authors were from the Scripps Institution of Oceanography, Oregon State University, the Australian Nuclear Science and Technology Organisation, the National Institute of Water and Atmospheric Research in New Zealand, Danish Technical University and the Commonwealth Scientific and Industrial Research Organisation in Australia. Petrenko conducted most of the research as part of his doctoral thesis at the Scripps Institution of Oceanography under Professor Jeffrey Severinghaus.

The research team extracted several tons of ancient ice from the western margin of the Greenland ice sheet at a site called Pakitsoq, the largest ice samples ever recovered for a climate change study. The researchers cut the ice into blocks with electric chain saws, dumped 17 cubic feet at a time into a vacuum melting tank heated by powerful propane torches, and transferred ancient air released from bubbles in the ice into cylinders for subsequent laboratory analysis, Petrenko said.

The effort, which lasted five field-seasons, was "an undertaking of epic proportions," said Petrenko. "This was the first measurement of its kind, and we really pushed the envelope," he said. "It represents a major advance in analytical methods for studying ancient ice."

Methane clathrates are only stable in conditions that combine cold temperatures and high pressures. Some scientists suspect that a swift and massive warming in the early Cenozoic era about 56 million years ago may have been triggered by huge methane releases from clathrates into the atmosphere, Petrenko said.

Methane levels in Earth's atmosphere increased about 2 percent from about A.D. 1 to 1000 and decreased by 2 percent from 1000 to 1700, which may have been due in part to decreased landscape burning by indigenous people in the Americas devastated by introduced diseases, according to a 2005 CU-Boulder study. About 60 percent of atmospheric methane is now generated from human-related activities, according to the International Panel on Climate Change.

The 2009 Greenland ice study was funded by the National Science Foundation, the American Chemical Society and several other agencies. Petrenko's postdoctoral fellowship at CU-Boulder is funded by The University Corporation for Atmospheric Research.

Contact: Vasilii Petrenko, 303-492-7132 Vasilii.petrenko@colorado.edu
Jim Scott, 303-492-3114

Vasilii Petrenko | EurekAlert!
Further information:
http://www.colorado.edu

More articles from Earth Sciences:

nachricht Geophysicists and atmospheric scientists partner to track typhoons' seismic footprints
16.02.2018 | Princeton University

nachricht NASA finds strongest storms in weakening Tropical Cyclone Sanba
15.02.2018 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>