There is quite a bit of buzz surrounding a talk and pending paper from Prof. Murry Salby the Chair of Climate, of Macquarie University. Aussie Jo Nova has excellent commentary, as has Andrew Bolt in his blog. I’m sure others will weigh in soon.
In a nutshell, the issue is rather simple, yet powerful. Salby is arguing that atmospheric CO2 increase that we observe is a product of temperature increase, and not the other way around, meaning it is a product of natural variation. This goes back to the 800 year lead/lag issue related to the paleo temperature and CO2 graphs Al Gore presented in his movie an An Inconvenient Truth, Jo Nova writes:
Over the last two years he has been looking at C12 and C13 ratios and CO2 levels around the world, and has come to the conclusion that man-made emissions have only a small effect on global CO2 levels. It’s not just that man-made emissions don’t control the climate, they don’t even control global CO2 levels.
Salby is no climatic lightweight, which makes this all the more powerful. He has a strong list of publications here. The abstract for his talk is here and also reprinted below.
PROFESSOR MURRY SALBY
Chair of Climate, Macquarie University
Atmospheric Science, Climate Change and Carbon – Some Facts
Carbon dioxide is emitted by human activities as well as a host of natural processes. The satellite record, in concert with instrumental observations, is now long enough to have collected a population of climate perturbations, wherein the Earth-atmosphere system was disturbed from equilibrium. Introduced naturally, those perturbations reveal that net global emission of CO2 (combined from all sources, human and natural) is controlled by properties of the general circulation – properties internal to the climate system that regulate emission from natural sources. The strong dependence on internal properties indicates that emission of CO2 from natural sources, which accounts for 96 per cent of its overall emission, plays a major role in observed changes of CO2. Independent of human emission, this contribution to atmospheric carbon dioxide is only marginally predictable and not controllable.
Professor Murry Salby holds the Climate Chair at Macquarie University and has had a lengthy career as a world-recognised researcher and academic in the field of Atmospheric Physics. He has held positions at leading research institutions, including the US National Center for Atmospheric Research, Princeton University, and the University of Colorado, with invited professorships at universities in Europe and Asia. At Macquarie University, Professor Salby uses satellite data and supercomputing to explore issues surrounding changes of global climate and climate variability over Australia. Professor Salby is the author of Fundamentals of Atmospheric Physics, and Physics of the Atmosphere and Climate due out in 2011. Professor Salby’s latest research makes a timely and highly-relevant contribution to the current discourse on climate.
Salby’s talk was given in June at the International Union of Geodesy and Geophysic meeting in Melbourne Australia. He indicates that a journal paper is in press, with an expectation of publication a few months out. He also hints that some of the results will be in his book Physics of the Atmosphere and Climate which is supposed to be available Sept 30th.
The podcast for his talk“Global Emission of Carbon Dioxide: The Contribution from Natural Sources” is here (MP3 audio format). The podcast length is an hour, split between his formal presentation ~ 30 minutes, and Q&A for the remaining time.
Andrew Bolt says in his Herald Sun blog:
Salby’s argument is that the usual evidence given for the rise in CO2 being man-made is mistaken. It’s usually taken to be the fact that as carbon dioxide concentrations in the atmosphere increase, the 1 per cent of CO2 that’s the heavier carbon isotope ratio c13 declines in proportion. Plants, which produced our coal and oil, prefer the lighter c12 isotope. Hence, it must be our gasses that caused this relative decline.
But that conclusion holds true only if there are no other sources of c12 increases which are not human caused. Salby says there are – the huge increases in carbon dioxide concentrations caused by such things as spells of warming and El Ninos, which cause concentration levels to increase independently of human emissions. He suggests that its warmth which tends to produce more CO2, rather than vice versa – which, incidentally is the story of the past recoveries from ice ages.
Dr. Judith Curry has some strong words of support, and of caution:
I just finished listening to Murry Salby’s podcast on Climate Change and Carbon. Wow.
If Salby’s analysis holds up, this could revolutionize AGW science. Salby and I were both at the University of Colorado-Boulder in the 1990′s, but I don’t know him well personally. He is the author of a popular introductory graduate text Fundamentals of Atmospheric Physics. He is an excellent lecturer and teacher, which comes across in his podcast. He has the reputation of a thorough and careful researcher. While all this is frustratingly preliminary without publication, slides, etc., it is sufficiently important that we should start talking about these issues. I’ll close with this text from Bolt’s article:
He said he had an “involuntary gag reflex” whenever someone said the “science was settled”.
“Anyone who thinks the science of this complex thing is settled is in Fantasia.”
Dr Roy Spencer has suspected something similar, See Atmospheric CO2 Increases: Could the Ocean, Rather Than Mankind, Be the Reason? plus part 2 Spencer Part2: More CO2 Peculiarities – The C13/C12 Isotope Ratio both guest posts at WUWT in 2008. Both of these are well worth your time to re-read as a primer for what will surely be a (ahem) hotly contested issue.
I’m pretty sure Australian bloggers John Cook at Skeptical Science and Tim Lambert at Deltoid are having conniption fits right about now. And, I’m betting that soon, the usual smears of “denier” will be applied to Dr. Salby by those two clowns, followed by the other usual suspects.
Smears of denial and catcalls aside, if it holds up, it may be the Emily Litella moment for climate science and CO2 – “Never mind…”
Tim Ball says:
August 5, 2011 at 7:43 am
God bless you, Tim. You were among the first to really, seriously question the nonsense that was coming out of the warmist camp, and you lead us to the river to drink in the truth. That kind of courage will someday be rewarded.
1. dmmcmah says:
August 5, 2011 at 3:36 pm
John Finn,
One of the things Salby talked about was the huge increase in CO2 from the 1998 El Nino event. Looking at http://www.esrl.noaa.gov/psd/enso/mei/ there were several El Nino’s the past decade. While none of the El Nino’s since 1998 were as large, El Nino was dominant in the first half of the decade and that could explain the increase in CO2 concentration.
For crying out loud. I know that atmospheric CO2 increases faster during El Nino. I said as much at least twice on this blog. During warm El Nino years atmospheric CO2 increases more than during La Nina years – but the point is it continues to go UP – it NEVER comes down.
You say Salby talks “about was the huge increase in CO2 from the 1998 El Nino event.” This implies Salby thinks the ~3 ppm increase was due to the warm ocean surface during that year. Ok so –
Why didn’t atmospheric CO2 levels drop back to 1997 levels in 1999 and 2000?
1999 and 2000 were La Nina years when sea surface temperatures were well down n 1997. CO2 concentrations went up in both 1999 (~1 ppm) and 2000 (~1.8 ppm).
According to UAH, the temperatures during 1998 and 2010 were pretty similar.
Why was atmospheric CO2 concentration ~24 ppm higher in 2010 than in 1998?
What’s caused the increase? Both years were warm and there were no warmer years in between. Salby can’t simply attribute the 1998 CO2 increase to the El Nino of that year. If atmospheric CO2 was ‘equilibriating’ with the higher sea surface temperatures in 1998 then why didn’t it ‘equilibriate’ at a lower level in 1999, 2000 etc. Why was it 24 ppm higher in 2010 than in 1998?
If we get CO2 rises during El Nino years – when do we get falls? You (and Salby) seem to be arguing that it’s a one-way process, i.e. it goes up but doesn’t come down.
In 1958 CO2 concentrations were ~315 ppm; In 1975 they were ~331 ppm. Why? If it takes an anomalously warm El Nino (1998) to raise CO2 levels by 3 ppm, what caused the 16 ppm rise when the world wasn’t warming.
Even in a generally warming world there will be temperature falls. We’ve seen this over the past 30-odd years. But his neven happens with CO2. Between 1958 and 1975 global temperatures were essentially flat. Given these conditins you woulsd expect CO2 levels to remain more or less flat. There would, of course, be some fluctuation due to ENSO (up one year; down the next). But that never happened. Every year, without fail, CO2 concentrations were higher than they were in the previous year.
Given the flat cooling temperatures, What do you think the probability of that happening 17 years in a row is?
ZERO. The year-on -year increase is clearly due to the fact that there is now an additional source of atmospheric CO2.
I’m getting seriously concerned for the credibility of CAGW scepticism. Thank gooodness for the likes of Willis, Hans Erren, Jack Barrett , Ferdinand Engelbeen et al.
Stephen Wilde says:
August 5, 2011 at 5:54 am
John Finn said:
“We know atmospheric CO2 concentration responds to temperature. When it’s warmer CO2 concentration increases – BUT WHEN IT’S COOLER IT SHOULD DECREASE. Not once in the past 50 years has there been a year on year fall. ”
But it is the ocean temperature that counts and not the air temperature and we’ve seen that the oceans vary internally over time as regards the rate at which energy is released at the surface via warmer or cooler surface temperatures.
Quite – but it still doesn’t fit. Annual CO2 levels have risen regarldless of any change in SST.
As for your 800 year lag argument I’ve already explained why this is irrelevant in the context of the last 150 years. The 800 year lag is seen in the ice core records following (and prior to) each glacial maximum. This is when the earth is going through a warming process lasting several thousand years. As ocean circulation ‘digs’ out more CO2 from the deep, more CO2 can be released due to the warmer SST.
The key point here is that atmospheric and sea surface temperatures are warmer than they were 800 years earlier. This is a continuing process. Each 800 year period is warmer than the previous one. Eventually temperatures increased by about 6 degrees C and atmospheric CO2 by ~100ppm
225 responses in a few days, of which only a few with some scepticism. I thought that this was a blog for sceptics, but it seems that most here are only one-way sceptics… Thus please, even if Prof. Salby says something that you like to hear, use some dose of scepticism, and check if what he says is plausible. Unfortunately several of his points are not.
That humans are the cause is quite sure:
– The mass balance: It is impossible that nature was a net contibutor to the increase, because the measured increase is less than the emissions. Thus nature was a net sink for CO2 over the past at least 50 years. As long as the Law of conservation of mass holds. Have a good look at following graph:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em.jpg
In every year, the emissions were larger than what remains in the atmosphere, the difference must go somewhere (and it’s not escaping to space!), it is absorbed by oceans and vegetation. Thus there were (near) always more natural sinks than sources. Thus all natural emissions were completely absorbed (in mass, not in origin of the molecules) by natural sinks and the natural emissions were just part of a turnover of CO2, not contributing to the total mass in the atmosphere. It doesn’t matter if human emissions were 3% or 0.3% or 0.03% of the turnover, because the human emissions were additional, the natural emissions were not.
– The 13C/12C ratio: Indeed there are two main sources of low 13C: fossil fuels and the decay of vegetation. But the earth is greening, thus there is more CO2 absorbed by vegetation than that organic matter decays. That is confirmed by the oxygen balance: less oxygen is used than calculated from fossil fuel burning, thus the biosphere was a net source of oxygen, thus a net absorber of CO2 and preferentially 12CO2, leaving relative more 13CO2 in the atmosphere. But we see a decline of 13CO2 in the atmosphere…
– The process charasteristics: The increase in the atmosphere follows the emissions with an incredible fixed ratio. There is no natural process which is able to follow human emissions in such a way, Natural processes are far more variable. See:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/acc_co2_1900_2004.jpg
and
http://www.ferdinand-engelbeen.be/klimaat/klim_img/temp_co2_1900_2004.jpg
A few other problems:
– While there is an extremely good correlation between accumulated emissions and accumulation in the atmosphere, the correlation is less when one looks at the year by year increase, simply because temperature changes have a short term influence (about 4 ppmv/degr.C) on the increase rate, but hardly visible in the trend itself! Here Salby, as good as Dr. Spencer and others make the error to draw conclusions about the cause of a trend, based on the year by year changes (thus the derivative), where the trend is completely removed!
The long term influence of temperature on CO2 levels, as seen in ice cores, is about 8 ppmv/degr.C. Even an increase of 1 degr.C since the depth of the LIA would not give more than 8 ppmv increase, not the 100+ ppmv as measured. BTW the pCO2 of seawater increases with not more than 16 ppmv/degr.C. And while a temperature increase should decrease the total amount of carbon in the upper layer of the oceans, we measure an increase in carbon (and a decrease in 13C/12C ratio).
– Ice cores, tree carbon and coralline sponges all give small 13C/12C variations over the Holocene, but all show a steady and ever faster decline since about 1850. See:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/sponges.jpg
Fred H. Haynie says:
August 5, 2011 at 2:57 pm
John Finn,
“How come a temperature rise of less than 1 deg C produces the same increase in CO2 as a 6 deg C rise – and in just a tiny fraction of the time?”
Because the ice core data does not have the resolution to accurately reflect actual atmospheric concentrations of CO2.
There are 8 or 9 major ice core records – each with a considerable sample size. The consistency between each record is pretty impressive considering they are taken form such diverse regions. Your argument appears to raly on the fact that the sampling has, with incredible bad luck, failed to pick up the high CO2 level signal.
I believe that 10,000 years ago the atmospheric level of CO2 exceeded 400ppm not 280ppm.
I don’t believe that.
John Finn:
All your supposed questions have been answered by previous posts in this thread. For example you ask this:
“Why was atmospheric CO2 concentration ~24 ppm higher in 2010 than in 1998?
What’s caused the increase? Both years were warm and there were no warmer years in between.”
Please read e.g. my posts above. The rise was induced by the temperature rise that preceded it, and the delay is a function of the rate constants.
I know trolls often repeat nonsense late in threads in hope that late-comers will only read the later posts. But this is a technical thread and your tactic is wasting space.
Richard
Dale I hope your right for australia sake god help us because we don,t want the far left fabien party running us
Richard S Courtney says:
August 6, 2011 at 3:33 am
Please read e.g. my posts above. The rise was induced by the temperature rise that preceded it, and the delay is a function of the rate constants.
That doesn’t fit anymore: the late Ernst Beck predicted a drop of CO2, 5 years after a temperature drop, but we didn’t see any CO2 drop 5 years after the 1998 El Nino. Neither a leveling of CO2 now that there is little or no temperature increase over the past decade. Further back in time, the 1945-1975 temperature drop had no influence on steady increasing CO2 levels in any following period, no matter what lag is used.
John Finn,
“I don’t believe it”
I have analyzed the proxie CO2 and temperature data from around two dozen ice cores from Greenland to Antarctica. Click on my name and study the presentation objectively and not as a “true believer” in IPPC “scripture”. If you really have questions, you can find my e-mail address at http://www.kidswincom.net.
Ferdinand:
You have ‘come late to the party’. So, I will cross-post what I wrote in response to your similar late entry on the blog of Judith Curry.
Richard
Ferdinand,
as you know – but others here may not – I respect your work but disagree with it.
As you say, we have disagreed about this for years (much more than 3 years on the record). And we each think the failure to resolve the matter is the other’s intransigence.
So, before stating our disagreement, I point out that I commend those who are interested in the subject to use your blog as a good, collated information source.
Our disagreement stems from fundamentally different views of the carbon cycle.
You model the system as a set of fixed reservoirs with flows in and out. Importantly, you assume the natural system does not vary and then calculate where the anthropogenic emission ‘goes’. I say your model is a circular argument based on a false assumption. If you assume nature does not change then it follows that any observed change is the anthropogenic emission. I do not “throw out” anything. I point out that an assumption cannot prove itself.
I model the system as being a complex mixture of interconnected parts with a myriad of different time constants affecting their interactions. All the observations which you cite can be explained as merely being effects of the time constants. And I observe facts that my model explains and yours cannot.
Such facts include, for example, the following.
There is no direct correlation between the anthropogenic emission and the increase of CO2 in the air. The best that can be said is that both have increased in recent decades.
But the global temperature is followed with a ~30 year lag by a smoothed version of the CO2 in the air: cf.
http://www.cru.uea.ac.uk/cru/data/temperature/
and
http://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2_data_mlo_anngr.png
At present the yearly increase of the anthropogenic emissions is approximately 0.1 GtC/year. The natural fluctuation of the excess consumption is at least 6 ppmv (which corresponds to 12 GtC) in 4 months. This is more than 100 times the yearly increase of human emission, which strongly suggests that the dynamics of the short-term (i.e. operative in months) natural sequestration processes can cope easily with the human emission of CO2.
The available data strongly suggest that the anthropogenic emissions of CO2 will have no significant long term effect on atmospheric CO2 concentration. The main reason is that the rate of increase of the anthropogenic production of CO2 is very much smaller that the observed maximum rate of increase of the natural consumption of CO2.
As you know, there is more, but I think this is sufficient to explain to others how our views differ.
Richard
Ferdinand Engelbeen says: August 6, 2011 at 3:16 am
Ferdinand, if you agree that the long-term sensitivity of CO2 to polar-temperature is 8 ppmv/degree-C, you can’t make a model that back-casts the temperature-CO2 record if that model has any significant sensitivity of temperature to CO2..
“Sample size” has no impact on resolution.
Resolution is dictated by sample rate; which, in ice cores, is equivalent to accumulation rate. The
Sample Rate vs CO2
The amplitude of the CO2 signal is being attenuated in proportion to the accumulation rate of the ice. This relationship is consistent with the findings of van Hoof et al., 2005, which demonstrated that the ice core CO2 data essentially represent a low-frequency, century to multi-century moving average of past atmospheric CO2 levels.
van Hoof
Ferdinand: Sorry, that last phrase should have been “any significant sensitivity of temperature to CO2.”
—————-
Ferdinand Engelbeen,
We have had an appetizer of Salby’s forthcoming paper.
You say be skeptical of Salby. You must understand that some are also somewhat skeptical of someone like you whose past views will apparently be directly contradicted by Salby . . . Salby being the person you push us to be skeptical about.
I have always found your posts to be sincere. Please continue to be sincere by not suggesting you have a scientifically defensive attitude.
John
John Finn says:
August 6, 2011 at 2:29 am
“Even in a generally warming world there will be temperature falls. We’ve seen this over the past 30-odd years. But his neven happens with CO2. Between 1958 and 1975 global temperatures were essentially flat. Given these conditins you woulsd expect CO2 levels to remain more or less flat. There would, of course, be some fluctuation due to ENSO (up one year; down the next). But that never happened. Every year, without fail, CO2 concentrations were higher than they were in the previous year.
Given the flat cooling temperatures, What do you think the probability of that happening 17 years in a row is?
ZERO. The year-on -year increase is clearly due to the fact that there is now an additional source of atmospheric CO2……”
————————————————————————————————————————-
“But his neven happens [sic], “Given these conditins you woulsd expect [sic]”, “Zero probability”, “Clearly due”…..
Now really….. Surely, you would think that a person who considers himself somewhat intelligent would not be as myopic and close minded? No need to answer that, you already have…….
And get a spell checker – they’re free you know :).
Best,
J.
@Sexton
“So if we were to cut our emissions in half, atmospheric CO2 would be come quasi static?”
That is a prediction of my hypothesis. That wikipedia graph you posted shows atmospheric CO2 smoothed to what appears to be a 5 year average. A graph without the smoothing such as this one from a paper published in Geophysical Research is apt:
http://radioviceonline.com/wp-content/uploads/2009/11/knorr2009_co2_sequestration.pdf
The dips in anthropogenic CO2 align pretty well but as one can see there are natural factors in play which cause greater short term variation than anthropogenic variations. That is to be expected given 97% of emissions are natural. The trend however is pretty clear and my hypothetical natural interglacial equilibrium point of 280ppm is not at all contradicted by the record. It is supported by the record.
There isn’t anything technical I can say here that hasn’t already been said. So….
Somewhere, between the leaked CRU emails, the continuing failure of the models to predict…pretty much anything, the insistence by IPCC that “observation is overrated”, and wonderful gems like this fascinating paper by Professor Salby, the news media and the rest of the world will finally wake up and realize the emperor has no clothes.
What will happen then?
J.Hansford says:
August 5, 2011 at 8:09 am
“Because then, if his view of the C12/13 ration is correct, then the natural CO2′s sinks, emissions and natural variation is unknown, meaning human influences are very minimal…… One just cannot say what portion of anthropogenic CO2 remains in the atmosphere, or for how long, because it is impossible to tell…..
That is also my position. It may not be impossible to tell but it has not yet been told. We are then left with the fact that atmospheric CO2 has been consistently increasing for the past 50 years half as much as anthropogenic emissions. Correlation is not causation of course so we are left with a compelling (IMO) correlelation and no credible evidence to either confirm or deny a causative link.
richard verney says:
August 5, 2011 at 8:53 am
“It is an instrinsic part of the AGW theory that if man was not emitting CO2, CO2 levels measured in the atmosphere would not be increasing.”
No, it is not intrinsic. Atmospheric CO2 increases and decreases considerably more over the short term than anthropogenic emissions can account for. What is intrinsic is that there would be less long term increase if anthropogenic emissions were absent.
Consider you have an open top 55 gallon drum where there’s a leak on the bottom letting out 1 gallon per day and rainfall refills the drum at an average of 1 gallon per day. Over the long term the water level in the barrel will not change. Now say some person comes along and adds an extra ounce per day to the barrel over and above the rainfall. Over a longer period of time the water level in the barrel will rise. Morever as the level rises the water pressure at the bottom rises with it and the leak rate will increase. Thus in order to keep the long term average rise at one ounce per day the person adding the water will have to add more than one ounce.
The above perfectly illustrates my CO2 equilibrium hypothesis.
Richard S Courtney says:
August 5, 2011 at 1:12 pm
“And you are attempting the same reversal of the null hypothesis that Dave Springer tried to foist on us at August 5, 2011 at 6:52 am and I refuted at August 5, 2011 at 8:19 am.: ”
You didn’t refute anything. Unilateral declarations to the contrary notwithstanding.
Ferdinand Engelbeen says:
August 6, 2011 at 5:37 am
That doesn’t fit anymore: the late Ernst Beck predicted a drop of CO2, 5 years after a temperature drop, but we didn’t see any CO2 drop 5 years after the 1998 El Nino. Neither a leveling of CO2 now that there is little or no temperature increase over the past decade. Further back in time, the 1945-1975 temperature drop had no influence on steady increasing CO2 levels in any following period, no matter what lag is used.
Alternatively, wouldn’t the rate of rise be expected to be much higher now than in 1975 with a much higher proportion of the world burning fossil fuels? It only seems to follow that burning more fuels would cause a faster increase. That is not what I see on the Mauna Loa graphs. I see a steady, monotonic, rise that appears to be oblivious to how much fossil fuel use has increased in the world below.
http://www.esrl.noaa.gov/gmd/ccgg/trends/#mlo_full
Not that you need the graph, but for others.
R Taylor says:
August 6, 2011 at 7:07 am
Ferdinand, if you agree that the long-term sensitivity of CO2 to polar-temperature is 8 ppmv/degree-C, you can’t make a model that back-casts the temperature-CO2 record if that model has any significant sensitivity of temperature to CO2..
The sensitivity of CO2 for temperature includes any feedback the opposite way. I doubt that it is significant, but I don’t see the problem. I have made a plot with an arbitrary temperature and CO2 as one-way dependent, with a lag and a two-way feedback:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/feedback.jpg
If the feedback is not too high (10% if I remember well in this example), there is no problem to back-cast both variables.
John Finn says:
August 6, 2011 at 2:29 am
“Even in a generally warming world there will be temperature falls. We’ve seen this over the past 30-odd years. But his neven happens with CO2.”
Technically so but the annual rate of increase in CO2 varied by a factor of 4 during the 1990s from a minimum of 1ppm to a maximum of 4ppm. Clearly these large swings are related to ocean surface temperature. The biggest spike upward and downward in rate of increase in the past 50 years was centered around the 1998 El Nino. As the El Nino gained steam and ocean temperature rose the rate of increase in atmospheric CO2 doubled and when it cooled back down the rate halved again.
See Knorr 2009 figure 2.
http://radioviceonline.com/wp-content/uploads/2009/11/knorr2009_co2_sequestration.pdf
Dave Springer says:
August 6, 2011 at 8:30 am
No, it is not intrinsic. Atmospheric CO2 increases and decreases considerably more over the short term than anthropogenic emissions can account for.
Please have a good look at the emissions and the variablity of the increase in the atmosphere: human emissions are about 200% of the increase in the atmosphere and 200% of the variability around the trend over the past 50 years:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em.jpg
There is assumed in most of the discussions that measured co2 and temperature are tightly coupled, which ever is considered causative. Comparing Mauna Loa co2 records and Hadcrut data at WoodforTrees we find that they are well correlated for 25 years starting around 1975. Unfortunately the data starts in 1958 and that would seem to have little or negative correlation. In addition the correlation again fails after 2000. So of the 52 years of co2 data less than half of it tracks the world temperature. http://www.woodfortrees.org/plot/hadcrut3vgl/from:1940/normalise/plot/esrl-co2/normalise