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Chordotonal at 00:46 AM on 8 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
"Extraordinary claims, counter to large collections of existing work, require extraordinary evidence -"
This phrase is from Carl Sagan. (-snip-). Its actually a plea for a handicap. And to make such a plea would indicate that ones hypothesis needs a handicap. (-snip-). (-snip-).
Moderator Response:[DB] Off-topic and sloganeering snipped.
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Chordotonal at 00:42 AM on 8 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Its a thing both odd and very ambitious to be using "Curve fitting" as a pejorative in science. At least this fellow found a curve that fit.
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Dikran Marsupial at 00:18 AM on 8 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
CBDunkerson wrote "How could this Humlum paper have gotten through peer review?"
Peer review can only be expected to be a basic sanity check, and sometimes the reviewers selected may not be sufficiently expert to spot the flaws. The more times a paper is submitted to a journal, the more likely it is that some journal will accept it eventually. Peer review has always been susceptible to the occasional failure, but science has adopted a good way of dealing with bad papers, which is to simply ignore them. The problem comes when papers are written that have impact on the general public that don't have the background to see the errors.
In many fields bad papers draw little attention from anyone, it is the public focus on climatology that means that the bad papers get exposed. If "skeptics" didn't draw so much attention to them in the blogsphere/press, the bad climate papers would be simply ignored as well.
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DSL at 23:57 PM on 7 June 2013It's soot
Beyond that, though, what reality apparently ignores or is ignorant of are the following two realities:
1. Global ice mass loss is in no way fundamental evidence ("trump card") for the theory of anthropogenic global warming. It is evidence for the proposition that ice melts when conditions are physically conducive to melting. If you want physical evidence of a warming planet, look at ocean heat content and the expected and observed shifts in general circulation.2. CMIP3 modelling severely underestimated Arctic sea ice loss (by 60-70 years). If the reason for that underestimation is BC (and I'm not saying it is), then removing the BC signal would probably leave CMIP3 modelers (some of those tens of thousands of "warmist scientists") in a much improved position.
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KR at 23:56 PM on 7 June 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Why is the AMO used in this MLR analysis still detrended linearly?
Please suggest a better way if you know of any. Note that to minimize collinearity in the MLR, the AMO index preferrably should not contain a trend, but you are encouraged to suggest different ways for detrending.
I would strongly suggest theTrenberth Shea 2006 methodology, supported by Anderson et al 2012, as one detrending methodology worth considering.
At the very least, I would suggest repeating your analysis with these and/or with a simple quadratic detrending - and determining the sensitivity of your analysis (and conclusions) to the choice of detrending method. That issue is, I believe, the core of these discussions, and a question well worth answering.
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KR at 23:45 PM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
John000 - I would suggest looking at the Climate Sensitivity thread, where the various uncertainties are discussed.
Estimates for climate sensitivity come from model results, from observations over the instrumental period, from responses to volcanic eruptions/aerosols, and paleo observations over the last few ice age cycles. Not just models! The climate sensitivity values used in such discussions are, in general, the synthesis of many lines of evidence, which is one of the reasons why extrema estimates such as Lu's tend to raise eyebrows.
Extraordinary claims, counter to large collections of existing work, require extraordinary evidence - Lu has not supplied the same, nor answered earlier criticisms of his work.
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John0001 at 23:40 PM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
IanC#40: Thank you, Ian. You made good points.
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gws at 22:09 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
@1 Esop
Some positive: There was a good article/interview in Bergens Tidene last Wednesday (in Norwegian) with Bruno Latour, this year's Holbergsprisen vinner. He also made some excellent points about denying climate change in the print version, which I could not find online.
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CBDunkerson at 22:05 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Mark, while the publication of your analysis is a wonderful response, I have to look at this Humlum paper and others like it with a growing sense of dread. It seems to me as if 'alternative realities' are creeping into science just as they have into politics, journalism, law, economics, and other formerly respectable fields.
How could this Humlum paper have gotten through peer review? Why would Global and Planetary Change publish it? How can the universities that employee the authors not be embarrassed to be associated with this?
I always thought that science was largely resistant to falsification because bad results would inevitably be uncovered and damage the credibility of all involved. Yet we seem to be seeing a lot of clearly wrong analysis getting published and no particular fallout when it is uncovered. Indeed, I doubt the denialsphere will stop praising Humlum in light of your findings... rather they will continue to accept his as valid and reject yours... creating two different views of reality. A situation I view with horror.
Obviously, there has always been fringe 'science' and from time to time it has gotten published... but am I wrong in believing that things have changed in that we are now seeing it actively celebrated and promoted even in the face of proof to the contrary? I fear a future in which publishing bad science can be a path to greater carreer success. Rupert Murdoch's News Corporation routinely puts out false propaganda in the guise of journalims... and is beloved for it. Radical ideologues routinely get appointed to the highest courts despite rulings bearing no resemblance to legal precedent or justice. Raving lunatics frequently get elected to high political office. The whole world is suffering from the guidance of economists who promoted austerity during a massive global recession.
If this kind of madness takes hold in the sciences we are truly doomed.
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Lanfear at 21:39 PM on 7 June 2013It's soot
Reality's writing here got me thinking of what would be the implications if the following claim would be true:
"Arctic melt---and that of glaciers and the permafrost is caused not by CO2, but by black carbon[ soot] from the burning of forests and other biomass in China, India, Indonesia, other Asian countries and Brazil"
My thinking is that the BC needs to be pretty well mixed into the upper layer of the troposphere in order to travel all the way to the arctic, and hence, it should be visible also in the Himalayas, even in the uppermost areas.
So is it legitime to assume that in order for BC to be the dominant effect, and especially considering that the some of the listed countries surround the Himalayas, the effect should also be visible in upper levels of the said region. Ie. the topmost glaciers should also be darker and melting?
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EliRabett at 21:01 PM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Dave@23 UV effets is a handwave at the change in the proportion of UV radiation in the solar spectrum within the solar cycle. The increased UV below 306 nm then does increased photochemistry. Lu does little more than handwave
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MA Rodger at 19:21 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
reality @21.
I would reinforce the message @24 by saying that you must be very careful with your language. You say " ...there is no acceleration in the rate of change of CO2." I don't know if the meaning is what you intended but it is not true. The rate of change of CO2 is not accelerating. Nor is it flat as you assert it is. It is increasing but roughly linearly, ie CO2 levels are accelerating at roughly a constant rate.
A further argument for 100% of the increase being human in origin is the constant ratio between rises in atmospheric CO2 and emitted CO2 . Over the last 50 years that ratio has remained wobbling between 40% & 50% . And this ratio remains totally unaffected by the addition of the emissions from "China's huge growth in coal-fired power stations and cars etc in recent years" which may feature large in press reports but whose impacts are best analysed numerically.
And long may that ratio stay 40-50%. If it starts dropping it will likely be due to feedback CO2 emissions from the melting cryosphere or warming oceans.
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MarkR at 19:02 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
#21 reality
The top graph is just some functions I made up to demonstrate what one part of their approach does. I found the visual impact helpful.
The bottom one shows the components of CO2 rise and you can see that both human emissions and atmospheric CO2 accelerate. Over this time period the rates are extremely similar and if you directly compare atmospheric CO2 with human emissions then the correlation coefficient is about 0.99.
By differentiating it you cut the cooefficient drastically, to around 0.4. This is because the short term variability masks much of it on short timescales, which was the point I tried to make with the top graphs!
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Dikran Marsupial at 18:46 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
reality@21 Humlums argument is based on a (already well known) correlation between the rate of increase in atmospheric CO2 and temperature. The rise in atmospheric CO2 is cause by the average rate of increase being positive. Correllations however are insensitive to the average value of the signals, so the correllation between the rate of increase in atmospheric CO2 and temperature can not explain the increase itself.
We know that the rise is caused by human emissions. Atmospheric concentrations are rising more slowly than cumulative human emissions, so consevation of mass means that the natural environment must be a net carbon sink, taking more CO2 out of the atmosphere each year than it puts in. There is a natural contribution, but it is strongly negative.
The reason that there is little rate of increase while anthropogenic emissions have been rising approximately exponentially, is that rising atmospheric CO2 concentrations mean that the natural net carbon sink has been strengtheneing as well. This gives rise to the constant so called "airborne fraction". If you are happy with differential equations, there is a worked example in the paper I wrote which is referenced in my SkS article here.
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reality at 18:45 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Esop...
What no attention is paid to by many warmist scientists, is the role of black carbon in the melting of the Arctic sea ice.
Scientists, including Drew Shindell of NASA, Jacobson and Ramanthan amongst many others [ non-sceptics], met with Congress to tell them the results of research that showed that ~50% of the Arctic melt---and that of glaciers and the permafrost is caused not by CO2, but by black carbon[ soot] from the burning of forests and other biomass in China, India, Indonesia, other Asian countries and Brazil---and a smaller amount from the burning of diesel fuel.
Warmist scientists cite the Arctic melt as the trump card that 'proves' the earth is warming alarmingly, but they almost never mention the black carbon problem at all.
Yet Drew shindell said that there's no point in only going after CO2 mitigation, since black carbon can be relatively easily mitigated with almost immediate effect.
It would seem that scientists who don't mention BC, and pretend that the only impact on the melting in the Arctic is rising CO2 emissions ,are deceiving the world---not helping at all, when some clamor from them would help politicians to do what's necessary--especially as the Arctic melt has a catastrophic feedback in the lowering of albedo, by the formation of dark water where once there was ice.
Moderator Response:[Dikran Marsupial] Discussion of black carbon is off-topic, this article is concerned with the cause of the increase in atmospheric CO2. If you want to discuss black carbon, please find a more appropriate thread.
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gws at 18:40 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
@21
"What you object to in ..."
Please read the article again. You have just created a strawman.
"If the CO2 in the atmosphere ..."
You are beating the strawman, 1. by ignoring the discussion and information given by others before your entry, 2. by ignoring the overwhelming evidence. Pretty much what Humlum et al. did ...
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reality at 17:46 PM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
What you object to in Humlum's graphs seems to be that the constant nature of the increase in CO2---same gradient---when differentiated produces a flat line, showing that there is no acceleration in the rate of change of CO2.
If the CO2 in the atmosphere was caused by human emissions, with little or no natural contribution, surely the curve would have a changing gradient [no longer linear and constant] depicting the increases in emissions eg with China's huge growth in coal-fired power stations and cars etc in recent years.
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KK Tung at 15:54 PM on 7 June 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
In reply to MA Rodger at post 135: Four of us, Dikran Marsupial, Dumb Scientist, Jiansong Zhou and I, have spent hours making tens of thousands of Monte Carlo simulations trying to answer the question: if the anthropogenic signal is highly nonlinear (quadratic or fifth order polynomial), will the linear detrending of the AMO index used in MLR necessarily leave us with a wrong linear anthropogenic trend? The correct summary of our efforts so far ( I have not gotten to post 134 yet, but will shortly) should be, in my humble opinion, that we have not found such an example (although we should always be on guard for such a possibility). This is despite some of the extreme examples constructed and discussed here, and undoubtedly more such examples have been tried but not shown here ( I know we have tried many). A thank you is in order to the three of you.
I therefore disagree with your summary:
In this thread, it has been demonstrated by Dikran Marsupial & also Dumb Scientist that the MLR analysis is sensitive to an underlying quadratic trend if a sinusoidal signal used in the MLR is linearly detrended when the trend it contains is quadratic.
In all logical and semi-realistic cases, the MLR so far has yielded the right answer within its 95% confidence internal, although in some cases, the "right" answer is useless because the error bars are too large. We think we understand why in some of these hypothetical cases the error bars are so large. Fortunately the error bars are usefully smaller for the real data.
Given this situation, here is the question:-
Why is the AMO used in this MLR analysis still detrended linearly?
Please suggest a better way if you know of any. Note that to minimize collinearity in the MLR, the AMO index preferrably should not contain a trend, but you are encouraged to suggest different ways for detrending.
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Doug8919 at 14:08 PM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Calling the Science Daily piece an 'article' is generous - it's just a reprint of the press release, which is all Science Daily does. Of course, this didn't stop it being cited as supporting the research by The Australian's consistently abysmal Cut & Pate column.
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IanC at 12:27 PM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Hi John,
Indeed there is still a large uncertainty in the equilibrium climate sensitivity (ECS), primarily due to cloud feedback, which dominates the uncertainty: the range of cloud feedback in 12 models is almost as large as the spread in ECS itself; I think this is unlikely to converge until we get to the point where clouds can be modelled somewhat explicitely.
Even though the spread among model is large, the important thing is that even if you pick out the best case scenario for each feedback aong the models in Dufresne and Bony 2008 (i.e. model 1 for surface albedo and water vapour+lapse rate, model 2 for cloud feedback, you will still get a warming that is very close to 2 degrees. In other words, there is very strong evidence that warming will not be less then a degree.
Climate model is really just a way for us to quantify our physical understanding. Skeptics often point to the uncertainty as a problem, but I think the right way to look at the spread is that we can implement our current knowledge in 12 different ways, and under no circumstances is the warming neglible.
Yes, most of the time ECS is used instead of splitting it up to alpha and beta, I think the reason is that you can't in reality increase the temperature without the water vapour feedback, so making the distinction between the two is pointless for most applications.
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MarkR at 11:24 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
#15 chris : thanks for the mention, it appears to have dropped out due to a minor technical problem, I have contacted the publisher about returning the reference to the bibliography.
#6 HJones : Figure 1 is only an example of what happens with a linear trend and cycles. Two more points are 1) The green line is cycles, which would be the 'natural' case. The blue line is what would happen with a constant flux from humans. 2) the real human emissions (and contribution to atmospheric CO2) have accelerated, which was why a correlation was easier to pick out.
#18 Jonas : differentiating a linear function returns the gradient, e.g. dy/dx when y=5x returns 5. That's why my first graph has the blue line as a constant value of 1.
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MA Rodger at 10:21 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
KR @14.
And indeed Tamino was correct in his 'pointing' although the rate of increase in CO2 forcing has been looking somewhat borderline linear in recent years. This is perhaps surprising given the strong rises in CO2 emissions over the last decade. Certainly the slow rise in emissions during the 70s & 90s are now replaced by far faster rates, in ppm the fastest on record by far. Yet that is the thing with exponential growth - it is very difficult to maintain.
And it is mainly because of those 70s & 90s slowdowns that CO2 emissions are not exponential. Indeed the period 1960-2010 (or to date even) can be seen as less-than-exponential since 1969.
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HeisenIceBerg at 09:15 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Well, this is embarrassing. Not only do I currently attend the University of Waterloo, but I’m also physics major. Professor Lu’s main research areas are:
- Biophysics and biochemistry (molecular switches controlling DNA damage and cell death)
- Ultrafast laser spectroscopic techniques
- Nanometer-scale surface science
- Environmental/atmospheric science (ozone depletion science)
I took those directly from his department profile page. The last one seems oddly out of place as compared to the others, though his past study of ozone depletion would explain his predisposition toward CFCs.
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Jonas at 09:10 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Differentiating a linear function yields zero. Differentiating a cyclic function (sine/cosine) yields a shifted cyclic function: removing a linear that way trend proves only one thing: the disinterest in the linear trend.
I wonder how this passed through "peer review". It would be interesting to have a correlation of "journal name" with "disproven paper" (as opposed to refined/enhanced paper) ...
On the other hand, we can interpret that thing in a different(iated?) way: temperature change (even the small detrended/differentiated change) correlates with CO2: QED! Thanks Humulum, you just "proved" the CO2 effect, and when switching back to the real world (non detrended), the result is: lineraly increasing human CO2 emissions cause climate change ...
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John0001 at 08:14 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Hi Ian,
Very good interpretation of the climate sensitivity and good comment on Lu's paper.
But I still have one question. Suppose that the equilibrium climate sensitivity finally to calculate the temperature change due to a radiative force is equal to the value of alpha times beta. You say that alpha =1.1 deg with good certainty. But if beta has a large range of uncertainties, then the equilibrum climate sensitivity still has a large range of uncentainties. And you would probably agree that in the literature, researchers sometimes just use the equilibrium climate senstivity without separating alpha and beta.
Thanks.
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robert way at 07:56 AM on 7 June 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Perhaps those who are discussing these issues should read THIS paper before continuing further:
http://link.springer.com/content/pdf/10.1007%2Fs00382-013-1669-0.pdf -
IanC at 07:51 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
John,
First off, IPCC does not develope climate models, and they only summarize published results; the model themselves are developed by independent research groups all around the world.
One thing that you have to understand about climate sensitivity itself is an idea that helps us understand and characterize the bulk behaviour of climate models, and it is not a parameter that can be set a priori.
The parameter alpha, which I think is the same as the Plack response, describes how the earth will warm/cool according to a change in radiative force, whether due to sun or greenhouse gases, in the absernce of feedback. This is very well constrained, as it is from (relatively) simple physics. All climate models agree on this very well; and you can see it from a graph from Dufresne and Bony 2008: all models gives a planck feedback of 1.1 degrees.
The real uncertainly is on the feedback (beta), and this is entirely responsible for the range of uncertainties: 2.3-4.2 degrees for doubling of CO2. Even this can be broken into its components: surface albedo (ice cover etc.), water vapour, and cloud feedback. You can see that the most of the uncertainty comes from changes to clouds; this is is of course a known limitation to current climate models.
To reiterate, climate sensitivity cannot be set and it simply reflects our understanding of the various aspect of climate physics, and the uncertainty in climate sensitivity reflects uncertainty in our understanding as well as constraints on our ability to quantify this understanding through a climate model.
Whether 2.3-4.2 degrees is large depends on what you are looking at. From a purely scietific point of view it is rather large, but from a broader perspective it is not: what matters is that we are quite certain that it is above 1, and likely above 2, which is more important from a policy point of view.
Also I shold clarify that curve fitting can be very informative if done correctly, and the results are interpreted with care. Unfortunately Lu's paper is not one of them IMO.
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Icarus at 07:43 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
It's sad that we still have to combat such inane nonsense as this Humlum paper. Surely there are better things for intelligent climate scientists to be doing?
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EliRabett at 07:18 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Co2 above the tropopause (e.g. in the stratosphere and thermosphere) is a coolant because it radiates after collisional excitation, but there is little upwelling radiation in spectral regions where it can absorb. Net result is that it pushes more radiative energy out to space than it absorbs from below and acts as a coolant. See, for example
http://www.atmosphere.mpg.de/enid/20c.html
Recently, Eli asked Leif Svagaard about
"Has anyone worked on adjusting pre 1979 solar irradiance reconstructions based on Kopp and Lean (2011)?
http://www.dtic.mil/dtic/tr/fulltext/u2/a535690.pdf
http://rabett.blogspot.com/2013/03/the-blog-of-new-sun.html
which drops the solar constant to 1361 W/m2, decreases the peak to minimum intensity a bit and straightens out time history since 1979 and basically makes anything said about TSI previously, both for before 1979 and after wrong, and got this reply
"yes, almost all the old stuff is obsolete. That does not deter the enthusiasts, of course"
Prof. Lu is very enthusiastic. Not very well informed, but very enthusiastic
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JosHagelaars at 07:15 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Thanks for the post, excellent work!
Humlum's paper is full of extreme statements, one example: "Empirical observations indicate that changes in temperature generally are driving changes in atmospheric CO2, and not the other way around.". Humlum 'forgot' the existence of ENSO and other factors that have a large influence on the annual growth rate of CO2. Scientific omissions, a professor unworthy.
For Dutch readers, we covered the online release of Humlum's paper in September 2012 on Klimaatverandering - Humlum: over emissies en omissies.
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dana1981 at 06:55 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
John001 @33 - equilibrium climate sensitivity is a physical output from a climate model. It's not based on 'curve fitting' at all.
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dana1981 at 06:52 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
John001 @31 - you're missing a key difference. Solanki and Krivova and the part of my blog post you reference weren't trying to determine how much global warming has been caused by the sun. We were looking at correlations and/or trying to figure out the maximum possible solar contribution. What Lu did was assume that the maximum possible solar contribution is reality, without providing any evidence to support that assumption.
The difference with respect to Foster and Rahmstorf is that F&R also accounted for all other known large natural temperature influences in their multiple regression.
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Rob Nicholls at 06:48 AM on 7 June 2013Will Tropical Forests Remain Carbon Sinks?
Matthew L, I agree entirely that nature is wonderful. Unfortunately I'm not optimistic that nature will prevent us causing a mass-extinction if our civilisation continues along the path of increasing fossil fuel burning. There have been mass-extinctions in the past when large changes in temperature have happened in a short time (on a geological time-scale), and we seem to be on track to cause similar abrupt changes in temperature (unless we change course radically). Even if there isn't a mass extinction, I think that global warming is likely to cause food security problems for a sizeable proportion of humanity. I'm not sure how well the world's agricultural systems will cope with the high temperature extremes and changes in rainfall in the coming decades. CO2 fertilisation won't necessarily help in the future in areas where plants are unable to grow due to extreme heat or drought.
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chris at 06:27 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
MarkR, Don't forget to add Humlum et al to the reference list in your comment when you get the proofs to review!
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John0001 at 06:23 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
Ian,
Good point.
Aren't there large uncertainties in the climate sensitivity (alpha) in IPCC climate models?
When one says that there would be 1 or 4 deg C increase in temperature corresponding a doubling of CO2 concentration, how sure for this assumption? Were the results not called CALCULATED results in IPCC climate models? Did we call them curve fitting correlations?
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KR at 05:50 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
MA Rodger - Actually, as Tamino has pointed out, CO2 growth is faster than exponential, meaning forcings are increasing faster than linearly. Faster than exponential growth with a small exponent, mind you, but still faster than exponentially.
Quick test - take annual CO2 values, import to Excel, take the Ln( ) and graph. If growth was linear this would be a straight line, but it has an upward curve, hence faster than linear growth.
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Hans Petter Jacobsen at 05:46 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Hjones@8: Yes, there was a small drop in the yearly carbon emissions in 2009. But the cumulative carbon emissions increased in 2009 almost as much as before. It is therefore as expected that the atmospheric CO2, which is a cumulative value, also increased in 2009.
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IanC at 05:23 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
John,
Regarding your second point, I think you are mistaken.
To arrive at the curves plotted in figure 12, one has to convert concentration to radiative forcing via eq 7, and convert radiative forcing via eq 6.
There are three parameters. The parameter chi in eq 7 is the only one obtained using WMO radiative transfer codes. alpha on the other hand is a parameter, and Lu chose alpha = 0.9 K/Wm-2 because it fitted the observations the best (see figure 6 of his 2010 paper in Journal of Cosmology), not based on any physical model. So it was a curve fitting exercise.
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MA Rodger at 05:02 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
HJones @6/8/10.
Anthropogenic CO2 emissions 1960-2010 aren't what you'd call "exponential".
The annual rise in atmospheric CO2 did dip in 2011 but this is more attributable to the La Nina event of that peaked in 2008 and far less attributable to the small reduction in CO2 emissions that year.
Some time back I created a graph using actual numbers (GISS temperature & MLO CO2) to rebut one of these Humlum type papers (it may have been the Murry Salby lecture) but the equasion being bandied about has been used with real data 1959-2012 and supports the veracity of Figure 1a in the post above, the green and blue of figure 1 being coloured pinkand red.
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Dikran Marsupial at 04:54 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
HJones, I think you need to go and read some of the previous SkS articles on the nature of the carbon cycle. The annual rise in CO2 is about half of anthropogenic emissions, the rest is taken up by the environment (the natural net flux is negative). However that is only what happens on average, sometime the natural environment takes up more than half of anthropogenic emissions, sometimes less. The magnitude of this flux is much bigger than 1.5% of the anthropogenic flux.
Your second paragraph misses the key point, which is that it is the difference between natural emissions and natural uptake that determines the environments effect on atmospheric CO2 levels, not the magnitudes of the fluxes themselves. This difference is (a) negative and (b) on average about half the magnitude of anthropogenic emissions.
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HJones at 04:44 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
I wouldn't expect a very noticable "drop-off" firstly because a 1.4% isn't very much, and secondly because the natural net flux has a fairly high annual variability that is likely to mask changes as small as 1.4%.
That is my point. The natural net flux cannot mask it as the increase is 100% human caused. Not 98%, 100%.
Not to mention the natural fluxes are a whole order of magnitude greater,and yes, the variations in the natural flux is not only bigger than human emmission variations, they are likely bigger than the actual human emmissions period.
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Dikran Marsupial at 04:37 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
HJones, at the bottom of the page you mention, it says:
"CO2 emissions grew 5.9% in 2010 to reach 9.1 GtC (33.5Gt CO2), overcoming a 1.4% decrease in CO2 emissions in 2009"
I wouldn't expect a very noticable "drop-off" firstly because a 1.4% isn't very much, and secondly because the natural net flux has a fairly high annual variability that is likely to mask changes as small as 1.4%. I rather doubt the 5.9% increase in 2010 (assuming that figure is correct) will be very visible either, as it would represent a 5% change in the slope of the plot over the span of a year, which would be a change of the order of a single pixel.
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HJones at 04:13 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
This source shows a drop in CO2 emmissions in 2009. They also show that for the past decade, the avg ppm increase in CO2 was 2.1 ppm/yr, and for the prior decade, the avg was 1.7 ppm/yr.
Looking at their graph, there was NO drop of CO2 concentration in 2009.
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Dikran Marsupial at 03:44 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
HJones@6 Please provide a reference that doccuments the "slowdown" that you expect to see.
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HJones at 03:30 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Dikran Marsupial,
Thanks for the help with the figure. I had a simpler one in mind, but essentially the same data. I realize that it is the variability that Mark is discussing.
MarkR,
They already are both fluxes. Looking at your figure1,the green line- human emmissions - it appears to be continually increasing. Since it is a flux, the flux must be increasing. Human emmissions have not increased by a steady rate. The increase would be best described as exponential, up until the recent world wide recession. There has been decreases in emmissions, and most definately decreases in the rate of the increases (I know poorly worded - the exponential characteristic of the increase in emmissions has flatlined) -
Since your graphs don't encompass this recent "slowdown", I don't know if you studied anything more recent. Looking elsewhere, the CO2 seems to climb fairly steadily (~ 2ppm/yr) - wouldn't there be a corresponding slowdown in the increase in ppm? If it is 100% human - a slow down in emmissions should have a slowdown in resultant ppm, correct?
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John0001 at 03:30 AM on 7 June 2013Lu Blames Global Warming on CFCs (Curve Fitting Correlations)
I just read Solanki and Krivova (2003) and found the following:
"[10] In Figure 2 we have scaled the irradiance such that the magnitudes of the temperature and irradiance variations are similar between 1856 and 1970. To be precise, we minimize the X2 between irradiance and temperature prior to 1970. This implies converting irradiance into temperature using a linear regression."
There is essentially no difference from Fig. 9 in Lu (2013).
And dana1981 (Dana Nuccitelli ?) also used a similar presentation in this post, "IPCC Draft Report Leaked, Shows Global Warming is NOT Due to the Sun", 14 December 2012 by dana1981 (http://www.skepticalscience.com/ipcc-draft-leak-global-warming-not-solar.html ).
Aren't there double standards??
Moreover, the results presented in his Figs. 12 and 13 of Lu (2013) are the temperatures observed and CALCULATED using the IPCC radiative-force equation for CFCs, rather than based on correlations between temperature and CFC concentrations.
Please stop damaging the reputation of IPCC.
Moderator Response:[JH] Please lose the snarky tone.
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MarkR at 02:30 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Hi HJones @ #3
I didn't treat them differently. I converted both of them into fluxes and then compared them like-with-like.
Humlum et al's method took all the data they could find and then did something that would turn a lump sum into a flux. But they didn't realise that the human emissions data they took were already a flux. They converted the flux into the rate-of-change-of-flux.
In my comparison I determine an estimated natural flux in ppm yr-1, the human emissions in ppm yr-1 and total atmospheric change in ppm yr-1. Humlum et al instead turned the human part into ppm yr-2, so it is them who treated the human emissions differently from the others.
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Dikran Marsupial at 02:24 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
@HJones, FIgure 1 in AR4 only shows representative volumes of the annual fluxes, it doesn't tell you anything about their variability, which is what Humlums' argument is based on. Sadly Humlum is making pretty much the same mistake as Salby correlations tell you about the similarity of the "wiggliness" of two datasets, but it tells you nothing about their average values. It is the average values of the fluxes that governs the increase in atmospheric CO2, not the "wiggliness", which is why Humlum's conclusions are incorrect.
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HJones at 01:58 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
First, congrats.
I do have a question, though. As per your Problem 4, the original paper did not treat human emmissions as a "speed", but looking at the quote below from another thread here (how do natural and human CO2 emmissions compare)
As you can see in Figure 1, natural land and ocean carbon remains roughly in balance and have done so for a long time – and we know this because we can measure historic levels of CO2 in the atmosphere both directly (in ice cores) and indirectly (through proxies).
Figure 1: Global carbon cycle. Numbers represent flux of carbon dioxide in gigatons (Source: Figure 7.3, IPCC AR4).
(Moderator - couldn't get the graph to display - a little help?)
My question is this, both the FF emmissions and the natural emmisssions appear to be the same type - both are fluxes.
Why did you find the need to treat the human emmissions differently?
Moderator Response:[Dikran Marsupial] Figure added, hopefuly this is the one you wanted.
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Dikran Marsupial at 01:48 AM on 7 June 2013New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made
Well done Mark, writing comments papers is normally a bit of a thankless task, but I think it is important nevertheless.
It is well worth remembering that getting a paper published is the first step in its acceptance, not the last. Before getting too excited about a paper it is well worth waiting to see if it either results in a comment paper, or if it recieves very few citations. Both of these things are indicators that a paper is flawed or of little value to the scientific community. It is a shame the press releases for "gamechanging" papers happen when the paper is published, later on when it is found to be dull/flawed/wrong and not "gamechanging" afterall, it is no longer newsworthy.
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