Are gassy plants a climate culprit?
12 January 2006
Thought plants were fighting climate change by guzzling greenhouse gases? Scientists are shocked to discover that our leafy friends are actually producing the climate-changing gas methane. Are our forests making things worse?
Antenna investigates...This story was published in Nature on 12 January 2006.
Image: Frank Keppler
Plants produce methane - that's the latest announcement from German climate scientists.
The team behind the research say it'll turn current understanding upside down. 'These findings will have an extraordinary impact on both past and future climate.'
Frank Keppler, atmosphere scientist, Max-Plank-Institut fuer Kernphysik, Heidelberg, Germany
Frank Keppler, atmosphere scientist, Max-Plank-Institut fuer Kernphysik, Heidelberg, Germany
Frank Keppler, atmosphere scientist, Institut fuer Kernphysik, Heidelberg, Germany
Image: Frank Keppler
Image: Frank Keppler
The team made their groundbreaking discovery by putting plants in glass chambers and measuring how the gases in their environment changed. The remarkable results show plants are a major methane source, which no-one knew before. |
How much methane are plants putting into the atmosphere?
'Our estimates suggest that 10 to 30% of the atmosphere's present methane content is produced by plants, mostly from tropical regions. Before now biological methane formation was only thought to occur under strictly anaerobic conditions (without oxygen), in environments such as wetlands.'
Frank Keppler
Frank Keppler
Image: Frank Keppler
Why did no-one realise that plants produce methane until now?
'There is only one logical explanation. Textbook knowledge is that methane is only produced under conditions without oxygen. For that simple reason, nobody looked closely at this before.'
Thomas Roeckmann, atmosphere scientist, Institute for Marine and Atmospheric Research, Utrecht, The Netherlands
Thomas Roeckmann, atmosphere scientist, Institute for Marine and Atmospheric Research, Utrecht, The Netherlands
Thomas Roeckmann, atmosphere scientist, Institute for Marine and Atmospheric Research, Utrecht, The Netherlands
Image: Thomas Roeckmann
Is this extra methane bad news for climate change?
'Yes, methane is a greenhouse gas that affects climate by absorbing the radiation emitted by the Earth's surface and reflecting it back to the Earth, thus adding to the greenhouse effect.
'Yes, methane is a greenhouse gas that affects climate by absorbing the radiation emitted by the Earth's surface and reflecting it back to the Earth, thus adding to the greenhouse effect.
'But we are not talking about extra methane, this methane has always been there. The bad news is that this source may increase with climate change.'
Thomas Roeckmann
Thomas Roeckmann
Burning fossil fuels produces carbon dioxide, which is a greenhouse gas. Now it looks like plants producing methane are causing trouble too. See how greenhouse gases affect our climate at:
What does all this mean for the planet?
'I think there are both scientific and political implications for this research. Scientists will need to find out how living plants can produce a gas like methane and secondly how this huge new source will fit into the global methane budget.'Dave Lowe, atmosphere scientist, National Institute of Water and Atmospheric Research, New Zealand.
Dave Lowe, atmosphere scientist, National Institute of Water and Atmospheric Research, New Zealand
If I plant a tree to help combat climate change, am I wasting my time?
'Methane emissions will lessen the greenhouse benefit of a tree grown in a reforestation programme, but we don't have enough data to answer this question at the moment.'
Thomas Roeckmann
Thomas Roeckmann
'We now have the spectre that new forests might increase greenhouse warming through methane emissions rather than decrease it. It will be very important to find out whether trees are reducing or increasing the overall greenhouse gases in the atmosphere. Nobody knows the answer to this yet.'Dave Lowe