. Earth Science News .
Seven-Year Stabilization Of Methane May Slow Global Warming

Methane, the main ingredient of natural gas, warms the atmosphere through the greenhouse effect and helps form ozone, a component of smog.
by Staff Writers
Washington DC (SPX) Nov 21, 2006
Levels of atmospheric methane, an influential greenhouse gas, have stayed nearly flat for the past seven years, following a rise that spanned at least two decades, researchers say. This finding indicates that methane may no longer be as large a global warming threat as previously thought, and it provides evidence that methane levels can be controlled.

Scientists also found that pulses of increased methane were paralleled by increases of ethane, a gas emitted during fires. This is further evidence, they say, that methane is formed during biomass burning and that large-scale fires can be a big source of atmospheric methane.

Professors Sherwood Rowland and Donald Blake of the University of California, Irvine, and researchers Isobel Simpson and Simone Meinardi, say that one reason for the slowdown in the growth of methane concentration may be leak-preventing repairs made to oil and gas pipelines and storage facilities, which can release methane into the atmosphere. Other reasons may include slower growth or actual decrease in methane emissions from coal mining, rice paddies, and natural gas production, they say.

"If one really tightens emissions, the amount of methane in the atmosphere 10 years from now could be less than it is today. We will gain some ground on global warming if methane is not as large a contributor in the future as it has been in the past century," said Rowland, a co-recipient of the 1995 Nobel Prize for discovering that chlorofluorocarbons in such products as aerosol sprays and coolants were damaging the Earth's protective ozone layer. The research will be published 23 November in Geophysical Research Letters.

Methane, the main ingredient of natural gas, warms the atmosphere through the greenhouse effect and helps form ozone, a component of smog. Since the Industrial Revolution in the late 1700s, atmospheric methane has more than doubled. About two-thirds of methane emissions can be traced to human activities, such as fossil-fuel extraction, rice paddies, landfills, and cattle farming.

Scientists in the Rowland-Blake laboratory use canisters to collect sea-level air in locations from northern Alaska to southern New Zealand. They then measure the amount of methane in each canister and calculate a global average.

From 1978 to 1987, the amount of methane in the global troposphere increased by 11 percent, a more than one percent increase each year. In the late 1980s, the growth rate slowed to between 0.3 percent and 0.6 percent per year. It continued to decline into the 1990s, but with a few sharp upward fluctuations, which scientists have linked to non-cyclical events such as the eruption of Mount Pinatubo in 1991 and Indonesian and boreal wildfires in 1997 and 1998. Then, from December 1998 to December 2005, the samples showed a near-zero growth of methane, ranging from an annual 0.2 percent decrease to a 0.3 percent gain.

Along with methane, the scientists also measured levels of other gases, including ethane, a by-product of petroleum refining that also is formed during biomass burning, and perchloroethylene, a chlorinated solvent often used in the dry cleaning process. Ethane levels followed the peaks and valleys of methane over time, but perchloroethylene showed a different pattern. This finding provides evidence that biomass burning can on occasion, as in Indonesia in 1997 and Russia in 1998, be a large source of atmospheric methane, the researchers say.

They say there is no reason to assume that methane levels will remain stable in the future, but the fact that leveling off is occurring now indicates that society can do something about global warming. Methane has an atmospheric lifetime of about eight years. Carbon dioxide, the main greenhouse gas that is produced by burning fossil fuels for power generation and transportation, can last a century and has been accumulating steadily in the atmosphere.

"If carbon dioxide levels were the same today as they were in 2000, the global warming discussion would leave the front page," Rowland said. "But to stabilize this greenhouse gas, we would have to cut way back on emissions. Methane is not as significant a greenhouse gas as carbon dioxide, but its effects are important. The world needs to work hard to reduce emissions of all greenhouse gases."

Title: "Influence of biomass burning during recent fluctuations in the slow growth of global tropospheric methane" Authors: Isobel J. Simpson, F. Sherwood Rowland, Simone Meinardi, and Donald R. Blake: Department of Chemistry, University of California, Irvine, California, USA. Citation: Simpson, I. J., F. S. Rowland, S. Meinardi, and D. R. Blake (2006), Influence of biomass burning during recent fluctuations in the slow growth of global tropospheric methane, Geophys. Res. Lett., 33, L22808, doi:10.1029/2006GL027330.

Related Links
University of California, Irvine
AGU
Learn about Climate Science at TerraDaily.com

Dutch Bask In Warmest Autumn In Three Centuries
The Hague (AFP) Nov 19, 2006
The autumn of 2006 has been the warmest in the Netherlands for over 300 years, 12.5 percent hotter than the previous year which was already a record, meteorologists said Sunday. "Beating the record by more than one degree centigrade, that is exceptional," the Royal Netherlands Meteorological Institute said in a statement.







  • Red Cross Says Preparation Can Mitigate The Toll Of Disasters
  • Bad Weather Hampers Aid To Flood-Hit Western Afghanistan
  • Huge Aid Operation Underway As Floods, Crocs Ravage Kenya, Somalia
  • Computer Software Enables Rapid Response To Time-Critical Emergencies

  • 'Divided' Countries Could Leave Climate Deal In 'Tatters'
  • Seven-Year Stabilization Of Methane May Slow Global Warming
  • Dutch Bask In Warmest Autumn In Three Centuries
  • Central Asian States Launch Program To Reverse Desertification

  • European Space Agency And Google Earth Showcase Our Planet
  • SciSys Wins Software Role For CryoSat-2 Mission
  • Next Generation Imaging Detectors Could Enhance Space Missions
  • SSTL Signs Contract With Federal Republic Of Nigeria For Supply Of EO Satellite

  • Petroleum Targets Unearthed By UH Professor
  • Microorganisms One Part Of The Solution To Energy Problem
  • Carbon Storage Eyed In New US-Australian Climate Change projects
  • Lockheed Martin Awards Lithium Technology With ATLAS V Battery Contract

  • Setting The Stage To Find Drugs Against SARS
  • Pattern Of Human Ebola Outbreaks Linked To Wildlife And Climate
  • UGA Researchers Use Laser, Nanotechnology To Rapidly Detect Viruses
  • 26,000 Russians Contracted HIV Since Start Of Year

  • Looking At Life In Lyon
  • Extraordinary Life Found Around Deep-Sea Gas Seeps
  • Wnt Signaling System Reactivates Dormant Limb Regeneration Program
  • Teeth Tell Ancient Tale

  • Police Fire Teargas To Break Toxic Waste Demo
  • Beijingers Told To Stay Indoors As Smog Hangs Over North China
  • Greens See Red Over A Thousand Hindu Fires In India
  • Mafia Waste Trafficking Threatens The Environment

  • Neanderthal Genome Sequencing Yields Surprising Results
  • Dad Inspired 'Jurassic Park,' Son Inspires 'Jurassic Poop'
  • Buffet for Early Human Relatives Two Million Years Ago
  • Unraveling Where Chimp And Human Brains Diverge

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement