Brussels, 12 Jan 2006
Methane is a known greenhouse gas, with 32 times the global warming potential of carbon dioxide, and it plays a role in atmospheric oxidation chemistry as well as affecting stratospheric ozone. Methane production is well known in areas such as rice paddies and swamps, where bacteria act on vegetation in low-oxygen conditions. Methane levels have increased three-fold in the last 250 years.
However, research led by Frank Keppler of the Max Planck Institute in Heidelberg, Germany, suggests that methane may also be released by a large number of plants in normal conditions. This turns the thinking behind the Kyoto Protocol around, as the protocol assumed that the worlds forests are not producers of methane, and are in fact net consumers of carbon dioxide, and therefore crucial in slowing down the greenhouse effect.
The team demonstrated that '[...] using stable carbon isotopes that methane is readily formed in situ in terrestrial plants under oxic conditions by a hitherto unrecognized process. Significant methane emissions from both intact plants and detached leaves were observed during incubation experiments in the laboratory and in the field.'
The team believes that forests may contribute ten to 30 per cent of the world's methane - a vast quantity. Should their finding prove to be true, then the forestry 'credits' available under the Kyoto Protocol could be reviewed.
'We suggest that this newly identified source may have important implications for the global methane budget and may call for a reconsideration of the role of natural methane sources in past climate change,' reported the team in the journal Nature.
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