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.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Do the greenhouse inventories monitor changes in **human-induced** GHGs? If so, to include plant methane you’d need evidence that land use changes or other human activities are actually altering plant methane emissions (the researchers state they did not demonstrate such a link). You’d also need the ability to measure it. There is a link between land use practices and CO2 sequestration and emissions.
If a link is subsequently demonstrated between land use change and plant methane emissions then it could be included in the inventory. This would also require more understanding of which plants, under what conditions, and how much methane is emitted. These details are still mighty sketchy.
There is a more reliable GHG accounting basis (including entries on both sides of the balance sheet) on which CO2 is included in the greenhouse inventories. Now that we’ve made a new discovery of natural sources of methane, does this indicate that we’re missing information on its sinks?
Jen – I’m not an expert on the LUC&F (Land Use Change & Forestry) sector but I think for tree planting to count for Kyoto purposes, it had to be outside normal rotational forestry practices. A new investment.
Similarly the bit of woodland thickening that would count towards Kyoto would be any increase in the rate of current thickening. In other words it has to be emissions above “business as normal”.
A fun quiz for the family, makes you think..?
Q: I’m extra smart. Shouldn’t I pass on my genes?
Well, could you pass a minimal intelligence test if one were required for a “license to breed”?
To find out, simply answer this question:
In light of the 40,000 children dying of malnutrition each day, and considering the number of species going extinct as a result of our excessive reproduction, do you think it would be a good idea to create another of yourself?
YES
NO
Thank you for playing.
http://www.vhemt.org/biobreed.htm#intelltest
rog
That’s a classic!
I’d offer the following postulates about methane, for falsification (homage to David’s remarks earlier)
Note this is not an opinion, but an hypothesis- don’t shoot me please! doesn’t mean I believe it!)
1. The methane effects on temperature scenarios from plants are relative minor and do not affect IPCC model credibility significantly, and the fact that atmospheric methane has a short half-life and an active sink might mean it will deplete rapidly.
2. Albedo uncertainties (global dimming, dust effects, so on), about two fold in magnitude (I understand), are a much more significant falsifying issue regards IPCCC model validity
(Again- freedom to speculate seditious is integral to the scientific method – so don’t shoot me!)
From the little I’ve read detribe, I think you’re about right on the relatively minor contribution made by the methane. The ex-CSIRO Ensis people estimated that the methane emitted by a forest in effect reduced the effectiveness of the carbon sequested by the forest by all of 5%. On top of that, some form of vegetation occupies the site and consequently the important factor is, does the conversion of pasture/annual crops land use to forest land use cause any net increase in methane production? An interesting discovery, but in the end, just another small factor that needs to go into the equation.
Boxer, I gather contributions will depend very much on where the forest grows? Ensis have based their calculations on a forest in Southern Australia? Keppler et al suggest tropical forest emit much more methane?
the researchers stated that plant methane is a relatively minor factor:
“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.”
We need to plant MORE trees then, to counter the small reduction in the marginal GHG sequestration benefit of each tree.
I am really uncomfortable with promoting the use of the word falsification as a synonym for rebuttal. It is clearly a usage first made by some sort of semi-literate, probably american, who did his work experience with that dreadful Reagan era language terrorist whose name, mercifully, escapes me.
A few points about methane;
The IPCC methodology is so arbitrary that it, too, is likely to go the way of it’s grossly deformed progeny, Kyoto.
And in any case, any positive GHG outcome that may be a result of land use change by farmers will disappear up the same orfice that their carbon credits did.
It is interesting that Keppler felt the need to ensure that he was not seen to be too far outside the euro-ghg party line.
Thinksy,
When you write ‘researchers’, do you mean Keppler or Ensis or your internet ‘think’ group at Monash University?
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 ;-).
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?
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).
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.
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.
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.
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.
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)
Popper, Hayek for beginners;
http://www.the-rathouse.com/
Prof. Hendrik Tennekes reflects on climate models and Popper (tks Louis)
http://meteo.lcd.lu/globalwarming/Tenneke/reflections_sceptic.html
….I protest against overwhelming pressure to adhere to the climate change dogma promoted by the adherents of IPCC.
….From this perspective, those that advocate the idea that the response of the real climate to radiative forcing is adequately represented in climate models have an obligation to prove that they have not overlooked a single nonlinear, possibly chaotic feedback mechanism that Nature itself employs.
NOAA support Tennekes and Popper
http://www.nssl.noaa.gov/users/brooks/public_html/sref/srefarticle.html
….We echo the alarm of Tennekes (1988) about the lack of vision concerning the role of humans in forecasting. Beyond that, however, we are alarmed about an equivalent lack of vision about the role of technology in forecasting. We have the opportunity to rethink fundamentally our approach to NWP. The time it will take to have models ready to take advantage of petaflop machines may well be of the same order as the time before the machines are available, perhaps a decade. If we do not start now to explore alternative uses of NWP models, we may miss or, at the very least, delay by years, the possibility of a true revolution and improvement in weather forecasting. Taking less than full advantage of both the human and machine side of the forecasting problem would be a crucial mistake.
The fact that Popper has done some great work and has numerous devoted fans does not excuse the bastardisation of the English language to a point where the one word, and a verb, has two almost directly contradictory meanings. It is sloppy work and his editor is obviously to blame.
BTW, if IPCC use an adjustable variable for albedo (dimming effects) the model is not falsifiable, and unscientific.
PS U Christchurch is a falsity, U Canterbury is valid, methinks.
Last paper – 1988 is a tad old given developments.
There’s something very wrong though with his logic – you can predict some things very well – like seasons and spatial patterns of polar and tropical climate. And they can predict the temperature growth of the last century with multiple forcings. – You will notice that there is a fair bit of noise around the mean – but nevertheless the mean trend is reproduced.
And he is mixing all sorts of differnet scales from weather to seasonal to climate change. You require different things from the models at different scales. With weather you ARE trying to predict the weather on Jan 30, 2006 – but with climate change you are NOT trying to predict the weather of Jan 30, 2030. But you are trying to predict the climatology of 2030.
And of course it also goes both ways – “overlooking a non-linear chaotic mechanism” might mean a very nasty sudden climate shift starts next week or started 10 years ago.
Perhaps Popper is not to blame for bastardisation Ian: he did write Conjectures and Refutations, and moreover the more bloke was linguistically challenged by having to get out of Vienna ahead of Herr Hitler, who wasnt very tolerant of new ideas.
If Trees emit methane they are part of the problem
Do all species of trees emit methane?
Are some better or worse?
Surely this is someting we should know before we plant.
What about other plants?
Does the CO2 plants lock up compensate?
After all CO2 lasts for 100 years methane for only 10
If methane comes from wetlands; would it come from my local lake where piles of sea grass our now washing up on shore and rotting? ( due to nutrient increases in lake water)
Thanks
If trees emit methane, that means if we want to save the world, we need to cut a tree.
But that means the fact that trees provide oxygene that we breath is wrong.
Canberra does have many trees but does that also means that if we want to decrease the amount of methane produced in Canberra, we need to cut the trees in Canberra?
thanks