Discussion > So where are Salby and Darwall wrong .... precisely?
Sandy S - I was simply copying and pasting part of a transcript of Salby's talk.
Raff - be patient.
Martin A
There's an interesting document here which is relevant to this discussion.
SandyS
No contradiction, I am afraid, just lack of clarity – the ice age to which I referred is that of about 10,000 years ago, when CO2 levels were in the region of 4,000ppm; the ice age to which you read it as is the “little ice age” (aka LIA) of just 200 years ago, when CO2 levels were around 250ppm, and crop failure and famine were endemic in Europe.
Radical Rodent
Martin A
I wasn't sure if that was the case. I'll search tomorrow unless someone comes up with the data while I'm sleeping!
SandyS
Yeah, I screwed up that post, didn't I? Of course CO2 is going up at half the rate we are emitting. From which it is self evident that it is us wot dunnit. Tell me how your "valid arguments that they are recovering" can be "valid" in the face of that.
Er, where do your 4000/250 numbers come from?
Raff
Patience? It is hard to be patient when you are "intensely scared". Then again, it is hard to be intensely scared of Salby when the very mention of him makes you giggle.
Raff
What happened to all the CO2 released when humans burnt the fossil fuels?
Louise
And Then There's Physics
".. this is getting silly now...."
Yes, I have to agree, but no worries, as we know you are the common denominator, it makes ignoring the ignorant so very easy. Many thanks for your contributions. They are truly invaluable!
Green Sand
Raff [10:58pm]
'Er, where do your 4000/250 numbers come from?'
Google's your friend Raff, but I think Rodent's time scales might be a bit off. I found a chart at http://www.geocraft.com/WVFossils/Carboniferous_climate.html that shows CO2 and global Temp from 600 mya or so, according to which CO2 at 4000 ppm was last reached around 390 mya in the Devonian period, and has been comfortably below 1000ppm since around 70mya. Citation is C.R. Scotese after RA Berner 2001 (GEOCARB III). Another popular chart from the Vostok Ice Core record shows CO2 below 300 ppm since at the least 400 kya.
Probably best to be careful coz any estimate before 1950 or so is from proxy data and since the time scales are vast probably subject to some averaging, which will invariably smooth away high values, particularly if they lasted for a short period of time, say 200 years or so.
russep3
Radical,
To get to 4000, you need to go back 100s of millions of years. During the last ice age, it was more like 180ppm. Also, bear in mind that when CO2 concentrations were in the thousands, the Sun was fainter.
Raff,
Then again, it is hard to be intensely scared of Salby when the very mention of him makes you giggle.
I see you have the same problem I have.
Louise,
What happened to all the CO2 released when humans burnt the fossil fuels?
Indeed, if the rise in atmospheric CO2 isn't due to our burning of fossil fuels, where has the CO2 from that gone?
And Then There's Physics
Martin A
I can't find any information on measurement of Carbon isotopic mix in the various releases into the atmosphere. There are various papers about measuring in air bubbles in ice and in ancient wood to give historic data.
SandyS
A couple of years ago I did a bit of reading on the Faint Young Sun. From what I remember, it was considered to be faint for the first 2 billion years of life so up to about 2 billion years ago. The obvious solution for those who think CO2 is the main (only) climatic control knob is to assign the warming to the higher CO2 content then. But there are other theories to account for what is known as the Faint Sun Paradox. So personally I think that this statement is a bit misleading
Also, bear in mind that when CO2 concentrations were in the thousands, the Sun was fainter.
From memory again I think thak CO2 in the atmosphere was higher than 2000ppm about 150 million years ago including a cool period climatically. The Faint Yong Sun can be discounted as a factor in that time scale as it can in the previous 4000ppm 400-650 million years ago time frame.
SandyS
"Then again, it is hard to be intensely scared of Salby when the very mention of him makes you giggle."
a.k.a. nervous laughter. A natural human response to fear.
splitpin
The correlation between the growth rate of atmospheric CO2 and temperature (more specifically the SOI) was first noticed by Bacastow back in the 1970s.
R. B. BACASTOW, "Modulation of atmospheric carbon dioxide by the Southern Oscillation", Nature 261, 116 - 118 (13 May 1976); doi:10.1038/261116a0
Abstract: ATMOSPHERIC CO2 records for the South Pole and Mauna Loa Observatory, Hawaii, show a seasonal variation, presumably arising from the uptake and release of CO2 by vegetation, and a long term increase, almost certainly caused by combustion of fossil fuel. The increase is much greater in some years than in others1,2. Changes in the rate of fossil fuel combustion are not likely to be the cause of the variation in yearly increase, as combustion has increased very steadily3. I present here evidence that the variation is connected to the Southern Oscillation, a large scale atmospheric and hydrospheric fluctuation with an irregular period of 1–5 yr (ref. 4). The connection, if present, indicates that a principal cause of the variation may be a change in the rate of removal of CO2 by the oceans.
Salby never mentions the work of Bacastow, which is a shame as if he did, he would know that later work based on it had already identified the cause of the correlation, e.g. Jones et al (2001)
Chris D. Jones, Matthew Collins, Peter M. Cox, and Steven A. Spall, 2001: The Carbon Cycle Response to ENSO: A Coupled Climate–Carbon Cycle Model Study. J. Climate, 14, 4113–4129. doi: http://dx.doi.org/10.1175/1520-0442(2001)014<4113:TCCRTE>2.0.CO;2
which gives us:
"Climatic changes over land during El Nino events lead to decreased gross primary productivity and increased plant and soil respiration, and hence the terrestrial biosphere becomes a source of CO2 to the atmosphere. Conversely, during El Nino events, the ocean becomes a sink of CO2 because of reduction of equatorial Pacific outgassing as a result of decreased upwelling of carbon-rich deep water. During La Nina events the opposite occurs; the land becomes a sink and the ocean a source of CO2."
Salby also claims (in his Sydney institute talk) that the IPCC were unaware of this, which is incorrect, it is discussed section 7.3.2.4 of the IPCC AR4 WG1 report.
So my first point is that the phenomenon Salby discusses is nothing new, there is already a know explanation for what we see, but Salby (who is not an expert on the carbon cycle) is unaware of the work that has already been done on this.
The mathematical flaw in Salby's argument is pretty easy to see, for anyone with a good grasp of calculus and statistics. Salby notes there is a correlation between temperature and the growth rate of atmospheric CO2. However, correlations are completely insensitive to constant offsets in the signals on which they are computed. The long term rise in atmospheric CO2 is due to the mean value of the growth rate, which is a constant offset. This means that the correlation he has observed is mathematically incapable of explaining any of the long term rise in atmospheric CO2.
A full explanation of this error can be found here: http://www.skepticalscience.com/salby_correlation_conundrum.html
There is also a very simple way that we can know that the rise in atmospheric CO2 cannot be caused by ocean degassing, which is that the oceans are becoming more acidic (or less alkaline for the pedantic). If the oceans were loosing CO2 to the atmosphere, they would be beoming more alkaline.
There are multiple lines of evidence that show that the rise in atmospheric CO2 is anthropogenic, which are summarised here http://www.skepticalscience.com/anthrocarbon-brief.html.
If you want a peer reviewed paper that explains the basics, you can find mine here: http://pubs.acs.org/doi/abs/10.1021/ef200914u, which deals with a previous incorrect argument making similar claims, but starts by explaining how we know the rise is anthropogenic.
Gavin C. Cawley, "On the Atmospheric Residence Time of Anthropogenically Sourced Carbon Dioxide", Energy Fuels, 2011, 25 (11), pp 5503–5513 DOI: 10.1021/ef200914u
Note I haven't vilified Salby here, I have just explained how we can know that he is incorrect, I have pointed out that he was unaware of the existing work on this topic and pointed out where his mathematical error lies. Clinging on to climate skeptic arguments that are clearly wrong does neither side of the debate any good, all it does is waste time and make the skeptic side of the debate appear to be ill-informed. I would suggest you follow Fred Singers advice and drop this one, it is one of the canards he mentions in his American Thinker article Climate Deniers Are Giving Us Skeptics a Bad Name (his choice of words, not mine).
I'd be happy to discuss this at the appropriate threads on SkS (links given above) where the relevant equations etc. are set out.
Gavin Cawley
Sandy, CO2 is clearly not the only influence on planetary temperature. Atmospheric composition apart from CO2, Earth's distance from the sun, sun cycles, age of the sun, albedo and volcanic activity to name the obvious influences on temperature. You wont find anyone who disputes this or claims that CO2 is the only "control knob" (apart from some in the skeptic camp who one might expect to know better). If you feel you can quantify these influences accurately over the last millennia or even back to the start of complex lifeforms, go ahead. It might be interesting to see which proxy sources you have such confidence in. But talk of possible higher or lower levels ages ago has no influence over the simple observation that rising atmospheric levels are trailing rising human caused emissions.
Raff
Typical
You go off for a night's sleep and a morning's shopping and then come back to find everyone's gone all technical while you weren't looking!
Seriously, thanks to everyone for contributing and especially Graham Cawley's post, because it does address the direct question of proving Salby wrong, though I fear he is a little naive to think that any contribution from anyone associated with this site would last more than a nanosecond on Cook's blog or that anyone from here would want to add to his hit rate.
Possibly when he releases all the data associated with his rather dubious "research" into the question of scientific consensus we may think differently.
Sorry, Graham, but there it is!
I'll need to look to someone else to analyse the actual claims in that post since it's way above my scientific pay grade but thanks for posting it.
Raff
Are you ever going to provide us with a posting that is anything other than content-free and which just might move the debate along in any sort of positive way?
Just asking.
Mike Jackson
Just for reference, my name is Gavin, rather than Graham. Your posts at SkS won't be moderated if you stick to the comments policy there, essentially if you stick to discussing the science in a polite, scientific manner, there will be no problem. I have made an attempt to build bridges by posting here, a more constructive response would be to give it a try yourself by posting at SkS (who cares about "hit rates"?).
Gavin Cawley
My own understanding is that the CO2 levels in the atmosphere have varied widely throughout the lifespan of the planet, and, during the last ice age (about 22,000 years ago, not 10,000, as I did state earlier) it was around 4,000ppm (0.4%). This can be found on many sites, and if you don’t know that, then you have done very poor research.
If the oceans were loosing CO2 to the atmosphere, they would be beoming more alkaline. [sic]This is assuming that CO2 is the only cause of ocean acidity. Bearing in mind that the quantities of CO2 we are talking about is actually not very much (400ppm is 0.04%), then you are suggesting that carbonic acid is a very, very strong acid, which… erm… it isn’t. No, there are certainly other sources of acid in the oceans, not least the deep sea vents, around which the acidity levels are extraordinarily high (or pH extraordinarily low, if you prefer), yet life still thrives. As for the “outgassing” that Mike Jackson referred to, this is mooted as warmer water can contain less dissolved gas than cooler water, thus any contained in water will be released as it warms.
(Good morning, Mike. I, too, balk at visiting the site recommended having had some very nasty responses there in the past; as for the other person, do what I do and ignore – how can anyone who has a name such as that admit to sniggering at the name “Salby” and expect to be taken seriously?)
Radical Rodent
Radical,
My own understanding is that the CO2 levels in the atmosphere have varied widely throughout the lifespan of the planet, and, during the last ice age (about 22,000 years ago, not 10,000, as I did state earlier) it was around 4,000ppm. This can be found on many sites, and if you don’t know that, then you have done very poor research.
I haven't found any sites that suggest this. Everything I've found suggest that atmospheric CO2 has not exceeded (until the 20th century) 300ppm for at lest 1 million years and 22000 years ago it was below 200ppm.
I, too, balk at visiting the site recommended having had some very nasty responses there in the past
Yes, it can be quite horrible when the responses are nasty. Having said that, I haven't actually experienced that or seen much of that on SkS, so it might be worth a try.
And Then There's Physics
Raff
good to see that you agree with me for a change as regards CO2; you'll also notice that rising CO2 is trailing the recovery from the LIA and human industrialisation is trailing that also. I don't think it is up to me or any skeptic to quantify these influences accurately all we have to do is to point out to people, such as yourself, who think that CO2 is a problem that they should be included in models and to ask for data on how they are modelled (if at all).
As you now agree there are more inputs to be considered do you actually know how well they are modelled? From your previous posting I think I know the answer but would like you to confirm it.
SandyS
Aug 21, 2014 at 11:33 AM | Gavin Cawley
Does stick to the comments policy apply to all comments from whatever facet of the discussion they come?
SandyS
RadicalRodent wrote "This is assuming that CO2 is the only cause of ocean acidity."
O.K., "all things being otherwise equal, If the oceans were losing CO2 to the atmosphere, they would be beoming more alkaline."
"Bearing in mind that the quantities of CO2 we are talking about is actually not very much (400ppm is 0.04%), then you are suggesting that carbonic acid is a very, very strong acid, which… erm… it isn’t."
no, this is all quite standard, see the series of SkS posts by Doug Mackie that explain ocean acitification, starting here. Those researching the carbon cycle and ocean acidification are well aware of the strength of carbonic acid.
"No, there are certainly other sources of acid in the oceans, not least the deep sea vents, around which the acidity levels are extraordinarily high (or pH extraordinarily low, if you prefer)"
Yes, but the amount of CO2 they release is not very big, even compared to anthropogenic fossil fuel use.
"yet life still thrives."
irrelevant to the discussion of the cause of the rise in atmospheric CO2.
"As for the “outgassing” that Mike Jackson referred to, this is mooted as warmer water can contain less dissolved gas than cooler water, thus any contained in water will be released as it warms."
Yes, this is half of Henry's law. The other half says that the solubility of CO2 in the oceans is proportional to the difference in the partial pressure of CO2 in the atmosphere and the concentration in the surface oceans, the constant of proportionality depends on temperature. This means that as atmospheric CO2 rises, the solibility increases and the oceans start to take up CO2. Which effect is winning out? The fact that the annual rise in atmospheric CO2 is less than anthropogenic emissions shows pretty clearly that the increased solubility is currently the stronger factor (as is ocean acidification).
Note the change in atmospheric CO2 from glacial to interglacial conditions is about 100ppm, resulting from a global temperature change of about 8 degrees C. Temperatures have changed by only about 1 degree over the last century, so this temperature driven outgassing can only explain about 12ppm of the observed rise of over 100ppm. Unless of course you can explain why the oceans are nearly an order of magnitude more sensitive to temperature now than they were during the last interglacial (and why there is no longer a lag of 800 years).
Gavin Cawley
Gavin:
Having said that, I haven't actually experienced that or seen much of that on SkS…Play Devil’s advocate, and challenge the arguments being put over; try questioning all the points being raised, and see how long it is before someone turns on you. Many years ago, I was as alarmed as many still are about the “threat” of AGW; however, I wanted to know quite how CO2 could be such a greenhouse gas as claimed, it being such a tiny proportion of the atmosphere, a question I raised on many sites, included SkS. Nobody has yet managed to answer it (other than, “Because it does! D’uh…”), but the responses I got from many sites such as and including SkS were very unpleasant, many resorting to recommending self-harm and suicide. While sites such as BH have also not answered the question, the responses have generally been a lot more civilised, which helped drop the scales from my eyes.
Radical Rodent
Radical,
Play Devil’s advocate, and challenge the arguments being put over; try questioning all the points being raised, and see how long it is before someone turns on you.
Here's the bit that you may be missing (and I say this as someone who runs and tries to moderate a blog). It's fine to question the points. However, if someone responds with a clear explanation of why the point is correct and why your question of the point is wrong, it gets a little frustrating if the person doing the questioning doesn't acknowledge that or simply moves on to something else. It's not the questioning, itself that is the issue, it's how the discussion goes from there on.
For example, you've stated more than once that CO2 levels were around 4000 ppm during the last ice (20000 years ago or so). You've been somewhat dismissive of those who can't find this out easily. However, you are very clearly wrong. Have you acknowledge this error yet?
And Then There's Physics
And, I did not say that that they are “recovering”, I said that I have seen valid arguments that they are recovering (yes, upwards, as they were at levels that were getting close to being too low for effective photosynthesis). Please do not misquote.