Jim D,Salby is a powerful intellect. don’t be so quick to dismiss him. I know the extremes do, but you shouldn’t. Let it play out, follow the data. The data speaks for itself.
Comment on The 50-50 argument by Bob
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Comment on The 50-50 argument by curryja
I read ATTP on salby, his response is pretty thin gruel
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Comment on The 50-50 argument by Pekka Pirilä
60 years is 2.4 times 25 years. That makes all the difference, as AGW can be isolated only as a smooth deterministic trend, not quite linear, but smooth anyway.
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Comment on The 50-50 argument by captdallas2 0.8 +/- 0.2
tonyb, It was April 19, 1950. There was a big headline in the papers that CO2 had just taken over. It is known as bicycle day in some academic circles.
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Comment on The 50-50 argument by kim
Likely smooth and likely small.
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Comment on The 50-50 argument by kim
I think I must have written ‘last quarter of the last century’ on lucia’s blackboard at least a hundred times.
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Comment on The 50-50 argument by Jim D
It is common sense that if Man puts x amount of CO2 into the air, and the CO2 amount in the air goes up by x/2 while the ocean acidifies, this is cause and effect in its plainest exposition. What nonsense are these people suggesting happened to the manmade CO2? Someone needs to explain Salby in plain English. He’s kidding you people, and is probably surprised to have a following.
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Comment on The 50-50 argument by Jim D
tonyb, the numbers you suggest of 7 ppm per degree (or I would say 10-15 ppm per degree including the biosphere) are OK and sane, but that is not at all what Salby is saying. He is saying all 120 ppm came out as a result of the warming of less than a degree(!). Do you agree with that? Note that outgassing of 90 ppm occurred as the last Ice Age ended and that was from warming of 6-8 C. These numbers fit with chemical equiibrium arguments.
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Comment on The 50-50 argument by Jim D
A good rule of thumb is: don’t trust anything less than 30 years when it comes to climate change factors, otherwise you are just looking at irrelevant noise.
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Comment on The 50-50 argument by gbaikie
–It is common sense that if Man puts x amount of CO2 into the air, and the CO2 amount in the air goes up by x/2 while the ocean acidifies, this is cause and effect in its plainest exposition. —
And when ocean “naturally” breathes in and out about 100 GT per year, it’s also acidifying and de-acidifying, also?
And when one considers the ocean already contains 50 times more CO2 than atmosphere or say more than 50 trillion tonnes of CO2, what effect would their be if during a brief period of time [say any where within a week or month or even a year] one could add, say .1 trillion tonnes to this existing 50 trillion tonnes CO2 then what in terms acidifying occurs in such a body?
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Comment on The 50-50 argument by Mike Jonas
Agree. But I’m not sure the logic is right either.
Judith talks of considering man’s contribution to global temperature increase in three bands. I don’t think that’s any more helpful than two bands. Surely it is better to work out what man’s and nature’s contributions actually were.
There is an additional complication : You can’t use the linear logic of working out what man’s contribution was, and then subtracting it from the observed temperature increase in order to estimate nature’s contribution. You can’t even try to work them both out as parts of the whole. Because Earth’s system is non-linear, to work out how man has changed it you have to work out what nature would have done in the absence of man’s contribution, and then compare that with the observed. Take atmospheric CO2 for example : over the man-affected period, man has added twice as much CO2 to the atmosphere as the observed CO2 increase of ~40%. Using the linear logic, man’s contribution has been 200% of the increase, and nature’s -100%. But without man’s contribution, atmospheric CO2 would have increased slightly. Man’s contribution was therefore not 200%, but less than 100%. Quite a difference!
But now we have a much bigger problem: As Judith pointed out –
“The IPCC does not have a convincing explanation for:
– warming from 1910-1940
– cooling from 1940-1975
– hiatus from 1998 to present”
Correct, and disturbing. Nor does it have an exlanation for MWP, Roman WP, Minoan WP, Holocene Optimum, or for the LIA and the other cold periods in between. IOW, the IPCC is totally incapable of working out what nature would have done.
So, what percentage of the observed warming was man-made? We haven’t even started to find out, because none of the IPCC’s work has been directed towards finding it..
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Comment on The 50-50 argument by curryja
I don’t regard this as a useful rule of thumb; in fact it is this kind of thinking that has led to the IPCC detection failure. We need to understand the decadal to centennial modes of natural climate variability. there is nothing magical about 30 yrs; in fact 30 yrs is nominally half of an AMO cycle, so that period can be particularly misleading.
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Comment on The 50-50 argument by Jim D
gbaikie, the famous Keeling curve shows the natural annual part, and it is nothing like the background trend that accelerates in what must be a dumbfounding correlation to emission rates for you.
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Comment on The 50-50 argument by Rob Ellison
If, over 60 years, natural variability averages out to zero, it doesn’t matter how strong natural variability is compared to man-made climate change, what’s left over is the man-made part. Thus the IPCC can and should consider it to be extremely likely that human influence dominates the net rise in temperature over the past 60 years.
The warming and cooling regimes in the 20th century have been precisely identified. Cooling from 1944 – warming from 1976 to 1998.
If we assume with John Nielsen-Gammon that ‘natural variability’ averages out to zero since 1944 – then the rate of increase is 0.07 degree C/decade. Or some 0.381 degrees C in total. As most of the CO2 increase in the atmosphere happened after 1944 – we are entitled to infer that the impact of anthropogenic greenhouse gases on surface temperature is not all that significant.
A similar result can be obtained by excluding the noisy bifurcations (dragon-kings) at climate transition periods – 1976/1977 and 1998/2001. As Kyle Swanson did at realclimate.
It begs the question of whether natural variability does average to zero between 1944 and 1998. If we extrapolate the idea of surface warming associated with El Nino and cooling with La Nina – the picture changes with El Nino dominance in the 20th century following centennial La Nina dominance.
It has intriguing echoes of the cosmogenic isotope record and suggests a top down UV/ozone mechanism for multi-decadal – and longer term – changes in the frequency and intensity of ENSO events. The source of these changes must be somewhere – and ‘sloshing’ is utterly unconvincing for these low frequency shifts.
Indeed – with ENSO we can go much further back in the Holocene with high resolution proxies. Moy et al (2002) present the record of sedimentation shown above which is strongly influenced by ENSO variability. It is based on the presence of greater and less red sediment in a lake core. More sedimentation is associated with El Niño. It has continuous high resolution coverage over 12,000 years. It shows periods of high and low ENSO activity alternating with a period of about 2,000 years. There was a shift from La Niña dominance to El Niño dominance some 5,000 years ago that was identified by Tsonis (2009) as a chaotic bifurcation – and is associated with the drying of the Sahel. There is a period around 3,500 years ago of high ENSO activity associated with the demise of the Minoan civilisation (Tsonis et al, 2010). It shows ENSO variability considerably in excess of that seen in the modern period.
In this UV/ozone theory of ENSO – low solar UV activity results in a more negative Southern Annular Mode spinning up the South Pacific gyre and biasing the system to more frequent and intense La Nina. The same effect in the northern hemisphere drives more or less cold upwelling in the north east Pacific. The periodicities are no coincidence.
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Comment on The 50-50 argument by Gareth
“Here, too, the hiatus increases confidence that there’s not some unknown but significant positive forcing agent other than greenhouse gases that’s driving temperature. The smaller the rate of warming, the smaller the possibility that a separate, additional cause of warming is being missed, and that, therefore, greenhouse gases account for most or all of the total amount of warming”.
So, the further the observations diverge from the theory, the more sure you can be that the theory is correct. Nice!
Clearly, someone is in denial. But strangely, it is not the AGW ‘denialists’.
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Comment on The 50-50 argument by willard (@nevaudit)
> That something else he wrote somewhere else was true does not change the fact that the quoted sentence was false.
That changes the relevance of the “quoted by willard” bit quite a lot. I quoted the first tweet of that exchange.
You’re entitled to claim that Bart’s tweet is false without identifying which bit is wrong, without excluding which bit is not, without justification whatsoever, without even considering the timeline, or even the “seems” at the beginning.
If you can remind me of a quantification somewhere, that’d be nice.
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Comment on The 50-50 argument by Rob Ellison
And in case you are wondering – UV intensity seems out of phase with the solar cycle at least in the SORCE record.
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Comment on The 50-50 argument by Mike Jonas
vuk – “not only *not* unprecedented”. Not that I’m not unhappy with a triple negative.
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Comment on Week in review by jim2
The “high energy” paper mentions that public policy brought energy to the masses. In the US, private industry brought energy to the masses. The first step was taken by John Rockefeller who enabled people to replace wood with kerosene. It was only up from there. He got rich in the process, but he produced jobs and benefited society. Viewed in that light, he gave back as he got.
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Comment on The 50-50 argument by thisisnotgoodtogo
It’s fine if you’re all thumbs…eh, Jim D?
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