Bishop Hill Emissions
Feb 3, 2011 After the Paul Nurse programme the other day, eyebrows were raised over one of the claims in the show, namely that emissions from fossil fuel burning dwarfed natural emissions. Here's an excerpt from the transcript:
Bob Bindschadler: We know how much fossil fuel we take out of the ground. We know how much we sell. We know how much we burn. And that is a huge amount of carbon dioxide. It's about seven gigatons per year right now.
Paul Nurse: And is that enough to explain...?
Bob Bindschadler: Natural causes only can produce - yes, there are volcanoes popping off and things like that, and coming out of the ocean, only about one gigaton per year. So there's just no question that human activity is producing a massively large proportion of the carbon dioxide.
Paul Nurse: So seven times more.
Bob Bindschadler: That's right.
Aynsley Kellow, writing in the comments said that this was wrong, and so I thought I would try to clarify things by writing to Dr Bindschadler and finding out his source. This is it.
The source is the Arctic Impact Climate Assessment apparently, although I haven't actually looked for the graph in its original location yet. You can see the 7:1 ratio in the front graph, and you will also see that the graph is comparing two anthropogenic sources of carbon dioxide, namely fossil fuels and land-use changes. Dr Bindschadler has agreed that this the graph therefore doesn't support the claim he made in the Horizon programme.
Dr Bindschadler suggests that the 7:1 figure is actually not that far out from the correct figure for net anthropogenic:natural carbon dioxide emissions, so the effect of the mistake is limited. We should note, however, that he was originally speaking about emissions rather than net emissions. But even if you look at the net figures I still don't think the numbers are correct. Prof Kellow has pointed me to this page at Skeptical Science, which puts the net figures at 29 GtCO2 emissions for anthropogenic and a net 17 GtCO2 (450-439+338-332) absorbtion from natural sources. For what Prof Nurse and Dr Bindschadler were actually talking about in the Horizon show, gross emissions, the 7:1 ratio for anthropogenic to natural becomes, by my reckoning 1:27 (i.e. with natural emissions completely dwarfing anthropogenic).*
So in terms of what is interesting us here, the figures in the Horizon show were clearly completely wrong, which I guess we knew. It's good to have confirmation of this though. The question is, what does this mean for Prof Nurse and the reputation of the BBC?
*Note that the Skeptical Science page is talking in terms of GtCO2 while Dr Bindshadler was talking Gt carbon, but it's the ratios we are interested in.
Reader Comments (108)
Hengist
It is well established that >3% of atmospheric CO2 is anthropogenic in origin. So 97% or slightly more is the natural action of the carbon cycle.
Carelessly or intentionally, this was grossly misrepresented in the exchange between Bindschadler and Nurse.
Are you really, seriously trying to waste more time in comments on this blog arguing about that?
Obviously the above gives a ratio of 32:1, so presumably 27:1 is derived from a higher estimate of the anthropogenic contribution. There's your range and derivation.
Happy now?
Perhaps you should learn to count.
Mr Montford you are the one saying "Even the scientist interviewed by the programme has admitted that he got the figures wrong." Let us see the admission. I suggest if it is appropriate to publish your synopsis it would be appropriate to publish the supporting correspondence . Last weekend we had Gavingate and it was appropriate to publish a private email and it was deemed appropriate to pick over what that meant. Why have the standards changed?
I haven't commented on this aspect of Gavingate.
You can see the graph he sent me - it doesn't support his case. As I note in the head post he has suggested that the figures are close to the position for net emissions, but that isn't what he was discussing in the programme.
If you want the correspondence, go and ask Bindschadler. He doesn't bite.
Carelessly or intentionally, this was grossly misrepresented in the exchange between Bindschadler and Nurse.">
Write the figures down this way to do the book keeping:
Account Source Sink
----------------------+---------
Human 29 0
Volcanoes 7 0
Vegetation etc 439 450
Oceans 332 338
-----------------------------
Sum 807 788
Balance: 19
</table>
(Note - I've changed the numbers to GTons CO2 and not GTons Carbon equivalent for the sake of consistency).
(Note 2 - it doesn't seem possible to put neat tables into this website, my apologies if difficult to read).
Bishop Hill appears to be comparing the human 29GTons on the Source side with the 807 total on the Source side. Of course, what is really relevant is the Balance, which is the net increase in atmospheric CO2.
The INCREASE in the total amount of CO2, namely 40%, can be accounted for entirely by human activity. The only effect of the natural carbon cycle on this figure is to mitigate the increase by some 50%. The fact that individual "man-made" molecules of CO2 then get replaced by "natural" ones over the course of time has no effect on the total increase of CO2. Bindschadler and Nurse do not misrepresent anything.
Tom P
I don’t disagree with your figures or the accumulation of anthropogenic CO2 in the atmosphere.
But the dispute here is with what was said. The Bindschadler/Nurse exchange misrepresented the annual contribution of anthropogenic CO2 to the annual turnover of the carbon cycle:
I know Bindschadler swaps from GT CO2 to GT C without a blink:
And this has caused confusion. As has the entire exchange, because the President of the Royal Society and a NASA scientist couldn’t discuss scientific facts in a coherent manner.
Relative annual contributions to global emissions are as stated: >3% anthropogenic to <97% natural.
Nurse and Bindschadler misrepresented the facts, either through carelessness or intent.
But is that what was being discussed? You quote the exchange out of context. Unless you can show that they were discussing the carbon cycle of the planet as a whole, it is quite clear that they were discussing the reason for the increasing CO2 levels in the atmosphere. In that case they were not "misrepresenting the contribution to the annual turnover" because they were not talking about it.