A week or so ago I explained how researchers had discovered that plants are a source of methane: that a new study led by Frank Keppler of the Max Planck Institute in Germany calculates that all the world's living vegetation (forests included) emit between 62 and 236 million tonnes of methane per year. This is apparently equivalent to between 10 and 30 per cent of annual global methane emissions.
Now the same researchers are claiming that their findings have been misinterpreted:
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.
I guess this approach is consistent with the United Nations Framework Convention on Climate Change which defines 'climate change' as that which is attributable directly or indirectly to human activity, click here.
So according to Keppler et al. plants are not responsible for what they emit. I guess this means that they are not responsible either for sequesting carbon dioxide. However, we do count carbon sequestration (post 1990) in national greenhouse inventories, so shouldn't we also count methane emitted from the same plants in the inventory?
Interestingly, in the Nature paper, Keppler et al. state:
In pre-industrial times, that is, without anthropogenic emissions, the relative contribution of methane to the atmosphere by direct plant emissions may have been even larger than today. This could have far reaching implications for the interpretation of atmospheric methane levels and climate signals in the past.
Popper, Hayek for beginners;
http://www.the-rathouse.com/
For Polly and Ian
I must admit to a vice. I buy every book of Karl Popper's and of Vladimir Nabokov's I see. VN can wait, for now, but I urge Ian to read The Open Society and its Enemies to test if willingness to falsify is a virtue, and read Witgenstein's Poker to see if Popper was perfect.
The Popper Web URL
http://www.eeng.dcu.ie/~tkpw/
is a good place to start on falsification as good science. Indeed,falsifiability is perhaps a good one word definition of the Scientific Method.
When I was in NZ, last I searched for Poppermemorabilia in Christchurch with a fellow Popper addict. The tourist staff at the old U Canterbury campus though we were odd, for some reason.
;0)
Bill my quote above is from Jennifer's same source http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2006/pressRelease200601131/
I'm not a member of any monash group, hence Jennifer has now deleted that entry
Graham Young where they say "Emissions from plants thus contribute to the natural greenhouse effect"
To consider counting everything as Jennifer says, we'd need a much greater budget, more time and much more research and understanding of the cycles. Take these preliminary results on plant methane - we don't understand it well enough to count its anthropogenic let alone its wider natural sources and sinks. Accurately counting all natural GHG sources and sinks is not yet within our practical reach. This is not an excuse to stop counting the net contribution that human activities make towards the GHG balance, which is what we're presently monitoring.
The reason that Kyoto had the definitions of anthropogenic was to not give credits to existing activities or things that would have happened anyway. So you had to undertaking a new activity over what have occurred regardless i.e planting a new forest, or reducing land clearing, or "any increase in the current rate of woodland thickening". Existing forestry was regarded as part of the background landscape. I'm not defending necessarily just "explaining". Of course the atmosphere reacts to all of the GHGs regardless of origin - natural or anthropogenic.
From the perspective of the earth's atmosphere it would be better to count everything... the forces that impact on climate do not distinguish, for example, between a forest planted before 1990 and one planted after 1990.
He's not saying it doesn't count towards warming. He's saying it's part of the "natural" background on carbon , methane and NOx GHG processes and not anthropogenic.
Of course in Kyoto type debates - the USA apparently wanted to not worry about attribution so much and count everything - so called "wall to wall" accounting.
That quote from Keppler is extraordinary. While the second point - that there is still a significant net benefit from planting trees - is quite valid. The first point - that methane emitted by trees does not contribute to global warming because it is not man-made - is garbage. One wonders how an institute with such an illustrious lineage could have sunk to a stage where spin doctors were allowed to put those words into an academic's mouth (I'm being generous to Keppler here, it's much worse if they are actually his words).
The quote is from the Ensis group. Interestingly they use Radiata pine which is a southern plantation species as the basis for their calculations and media release - while Keppler's group indicated that methane emissions where more significant from tropical forests?
Hi Ian,
The use of falsification to describe scientific methodology comes from Karl Popper - there's a good bio at http://en.wikipedia.org/wiki/Karl_Popper. Well worth a read if you haven't encountered him before. He certainly wasn't a semi-literate american from the Reagan era ;-).
Thinksy,
When you write 'researchers', do you mean Keppler or Ensis or your internet 'think' group at Monash University?