. Earth Science News .
Global Warming - The Blame Is Not With The Plants

by Staff Writers
Utrecht, Netherlands (SPX) Jan 19, 2006
In a recent study (Nature, 12 January 2006), scientists from the Max Planck Institute for Nuclear Physics, Utrecht University, Netherlands, and the Department of Agriculture and Rural Development for Northern Ireland, UK, revealed that plants produce the greenhouse gas methane.

First estimates indicated that this could account for a significant proportion of methane in the atmosphere. There has been extended media coverage of this work with unfortunately, in many instances, a misinterpretation of the findings.

Furthermore, the discovery led to intense speculations on the potential relevance of the findings for reforestation programs in the framework of the Kyoto protocol. These issues need to be put in the right perspective.

The most frequent misinterpretation we find in the media is that emissions of methane from plants are responsible for global warming. As those emissions from plants are a natural source, they have existed long before man's influence started to impact upon the composition of the atmosphere.

It is the anthropogenic emissions which are responsible for the well-documented increasing atmospheric concentrations of methane since pre-industrial times. Emissions from plants thus contribute to the natural greenhouse effect and not to the recent temperature increase known as `global warming'. Even if land use practices have altered plant methane emissions, which we did not demonstrate, this would also count as an anthropogenic source, and the plants themselves cannot be deemed responsible.

Furthermore, our discovery led to intense speculation that methane emissions by plants could diminish or even outweigh the carbon storage effect of reforestation programs with important implications for the Kyoto protocol, where such programs are to be used in national carbon dioxide (CO2) reduction strategies.

We first stress that our findings are preliminary with regard to the methane emission strength. Emissions most certainly depend on plant type and environmental conditions and more experiments are certainly necessary to quantify the process under natural conditions. As a first rough estimate of the order of magnitude we have taken the global average methane emissions as representative to provide a rough estimate of its potential effect on climate.

These estimates (for details, see below) show that methane emissions by plants may slightly diminish the effect of reforestation programs. However, the climatic benefits gained through carbon sequestration by reforestation far exceed the relatively small negative effect, which may reduce the carbon uptake effect by up to 4 per cent. Thus, the potential for reduction of global warming by planting trees is most definitely positive. The fundamental problem still remaining is the global large-scale anthropogenic burning of fossil fuels.

Details of calculations used

In our study, we have linked global methane emission estimates to plant growth, which is generally quantified as net primary productivity (NPP). On a global basis NPP amounts to ~62 x 1015 g of carbon/yr, which corresponds to an uptake of 227 x 1015 g of CO2/yr. On the emission side, our study suggests annual global methane emissions by plants of 62-236 x 1012 g/yr CH4. Thus, for each kg of CO2 assimilated by a plant roughly 0.25 to 1 to 4 g of CH4 is released.

During growth of a new forest, up to 50% of plant tissue is lost again in the short term through decomposition of plant litter of leaves and roots [1]. This then doubles the estimate to 0.5 to 2 g methane emitted per kg of CO2 assimilated and stored in plants for longer periods. Over a 100-year horizon, the global warming potential of methane is ~20 times higher than that of carbon dioxide. Thus, for climate, the benefits gained by reforestation programs would be lessened by between 1 and 4 per cent due to methane emissions from the plants themselves.

Thomas Rockmann1,2, Jack Hamilton3, Frank Keppler2 and Marc Brass1,2

1 Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands; 2 Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany; 3 Department of Agriculture and Rural Development, Agriculture, Food and Environmental Science Division, Newforge Lane, Belfast BT9 5PX, UK

Original work: Frank Keppler, John T. G. Hamilton, Marc Brass and Thomas Rockmann Methane emissions from terrestrial.

Related Links

Asteroid Breakup 8 Million Years Ago Cooled Climate
Paris (AFP) Jan 18, 2006
The explosion of a large asteroid some 8.3 million years ago showered the Earth with so much dust that the planet's climate system may have cooled, a study published on Thursday says.







  • Record-Smashing Hurricane Season Cost 50Bn Dollars
  • E African Drought Threatens Millions More With Famine
  • Drought Forces Suspension Of Kenyan Elephant Relocation
  • Japan To Remind Indonesia Of Tsunami With Wave-High Poles

  • Global Warming - The Blame Is Not With The Plants
  • Asteroid Breakup 8 Million Years Ago Cooled Climate
  • Mobile Climate Monitoring Facility To Sample Skies In Africa
  • Aussie Climatologists Contend With A New Trend

  • TIGER Innovators Enhance North-South Collaboration
  • EPA Obtains Agencywide Access To GlobeXplorer Online Earth Imagery Services
  • New Legislation Initiated To Support Commercial Remote Sensing Industry
  • Space Imaging Awarded Additional $24 Mln From Pentagon's NGA

  • Iran, Nigeria Lead To Oil Spike
  • Lithium-Ion Batteries Could Replace Standard Batteries In Hybrid Vehicles
  • Couple To Drive Round The World With Only 50 Fill-Ups
  • China's Developing World Energy Strategy

  • U.S. Makes Big Pledge Against Bird Flu
  • Woman Is 6th Fatal Victim Of Bird Flu In China
  • Concern Over China's Surveillance Methods After 6th Death
  • Measles Outbreaks Kill 34 In Ethiopia

  • Intelligent Design Again Stopped By Court
  • Opposition Renewed To Kenya Sending 'Threatened' Species To Thailand
  • Landslides An Overlooked Killer That Can Be Tamed
  • British Police Seize TV Transvestite's 'Gorilla Coat'

  • Campaigners Urge Chirac To Visit Indian 'Asbestos' Scrapyard
  • Radioactive Produce On Sale In Moscow 20 Years After Chernobyl
  • India Orders Pollution Watchdogs To Check French 'Asbestos' Ship
  • Haze Dynasty

  • Study Suggests Why Neanderthals Vanished
  • New Technique Puts Brain-Imaging Research On Its Head
  • New Maps Reveal True Extent Of Human Footprint On Earth
  • Distinct Brain Regions Specialized For Faces And Bodies

  • 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