Methane a Greenhouse Gas Time Bomb
Methane, Both Natural and Man-made Could Accelerate Global Warming
Oct 4, 2008
Atmospheric methane levels have more than doubled since the Industrial Revolution, but vast quantities of natural methane are trapped in methane sinks in the Arctic ice and permafrost. Increased global warming threatens to release this methane with catastrophic environmental results.
Global Warming Effects on Natural Methane Sinks
- “The Methane Time Bomb”, by Steve Connor, published by The Independent (UK) on Sept 23, 2008 reveals that the preliminary findings of the “International Siberian Shelf Study 2008” shows that “massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.”
- A press release from the Department of Energy and the Lawrence Berkley National Laboratory, dated Sept. 18, 2008, titled “On the Threshold of Abrupt Climate Change” states that huge quantities of carbon exist as frozen methane hydrates trapped beneath the oceans, particularly in the Arctic regions. It further goes on to say, “In the Arctic, methane hydrate deposits exist near the edge of the safe temperature-pressure zone; in these locales, methane release could be abrupt. The resultant rapid warming would trigger yet more releases of methane: permafrost would melt, and the deep sea would become a dead zone.”
- A paper titled “Methane Hydrate Stability and Anthropogenic Climate Change”, published on July 25, 2007, by D. Archer of the Department of the Geophysical Sciences, University of Chicago, and published in Biogeosciences, Volume 4 states that, “The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth’s radiation budget equivalent to a factor of 10 increase in atmospheric CO2.”
Methane as a Greenhouse Gas
Although there is much less methane in the atmosphere than carbon dioxide, it is a much more powerful greenhouse gas. According to the Intergovernmental Panel on Climate Change (IPCC) report Climate Change 2001: The Scientific Basis, published by Cambridge University Press in 2002, the Global Warming Potential (GWP) of a greenhouse gas is measured against that of carbon dioxide which is given a GWP of 1. Methane has a GWP of 62 over a 20-year period. The “Technical Summary” of the report states that the radiative forcing (heat retaining properties) of methane contribute 20% of the total forcing of all greenhouse gases.
Atmospheric Methane Levels
The IPCC, in their Climate Change 2007: The Physical Science Basis, published by Cambridge University Press, explains on page 140, that the pre-Industrial Revolution levels of methane in the atmosphere were in the region of 700 parts per billion. They then go on to state “In 2005, the global average abundance of CH4 measured at the network of 40 surface air flask sampling sites operated by NOAA/GMD in both hemispheres was 1,774.62 ± 1.22 ppb.”
Sources of Methane
Section 4.2.1.1 of Climate Change 2001: Working Group 1: The Scientific Basis lists the main sources of methane.
- Natural Sources such as wetlands, bacterial action on vegetation and oceans produce in the region of 210 Tg/year (teragrams per year).
- Energy production produces 110 Tg/year.
- Livestock is responsible for 115 Tg/year.
- Waste treatment, biomass burning and landfills are responsible for 105 Tg/year.
- Man-made release of methane makes up over 60% of total atmospheric methane.
A sudden release of methane from the Arctic coupled with the continuing rise in carbon dioxide emissions would certainly put Earth in danger of surpassing the carbon tipping point, with disastrous ecological and environmental consequences.
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