It is very hard to claim that mostly natural forces caused the warming from 1910 to 1945 and mostly man-made forces caused the similar warming from 1975 to 2009. The simplest explanation, given the data before us, is that the natural forces were the same in the two periods. That being said and accepting that man does have some influence on climate today with his CO2 and methane emissions, it seems more likely that our influence is in the 22% to 25% range. “More than half” is not credible to this observer.No, it's not hard to claim that at all.
Andy's committed a logical fallacy of personal incredulity. The temperature goes up when there's a positive forcing or when a negative forcing disappears. The forcings can be different yet still have the same effect. In the early 20th century the negative forcing from volcanic activity disappeared, and the solar forcing got a bit stronger. In the second half of the twentieth century it was virtually all human forcing, primarily CO2.
Andy's article was almost too dumb to comment on. What I will write about is a comment by Don Easterbrook. He wrote:
August 23, 2016 at 1:35 pm
As I (and a number of others) pointed out years ago, the 1915-1945 warming is almost identical to the 1979-2000+ warming, clearing showing that you don’t need any CO2 increase at all to get that kind of warming. And it is no coincidence that both periods correspond to warm PDO periods. A nearly identical situation occurred in the preceding century–a warm period from about 1850 to 1880, followed by a cool period from 1880 to 1915, similar to the 1945 to 1977 cool period (before it was erased by NASA and NOAA).
So the question became, how long have these 25-30 years alternating warm/cool periods been going on? I plotted up the GISP2 oxygen isotope measurements of Stuiver and Grootes for the past 500 years and found a pattern of regularly alternating warm/cool periods with an average duration of 27 years (you can find this curve in several of my publications–just google my name to find them).
This regularly repeating pattern of warm/cool periods of 25-30 years, long before CO2 entered the picture, shows that these climate changes have nothing at all to do with CO2 . And because the past is the key to the future–we can extrapolate this ongoing pattern into the future (which I did in 1999 when I predicted global cooling for the first two decades of this century). The so-called ‘pause’ in recent global warming is not a pause at all, it’s just a continuation of the same pattern that has been going on for 500 years.
I don't know about GISP2, however globally there's not been any 25-30 years of alternating warm/cool periods lately. Look at the chart below. You can shift the slider across if it helps - it's around 30 years wide. So that's why Don's extrapolations into the future turned out to be woefully wrong.
The period 1940-1945 is such an odd feature. Does anybody know what work has been done on trying to assess the impact of WW2 on genuine climate variation and also on any artefacts it has introduced into the temperature record?
ReplyDeleteI'll see what I can find when I get a minute (traveling atm). As I understand it, the spike has something to do with the sea surface temperatures relying too heavily on measurements taken on wartime vessels, and they were different to the ships that sailed before and after the war (and there weren't as many of them).
DeleteFixing this is probably on somebody's "to do" list - if it can be easily fixed. I'm assuming that period is not as accurate as the other years. That assumption could be wrong.
The quantity of particulates released into the atmosphere *should* cause a drop in global temperatures. Running a Google search shows that the usual suspects ('Steven Goddard', Judith Curry, WUWT, Bob Tisdale, etc) have a bit of an obsession with the 1940s 'blip' although I can't for the life of me figure out why (heavy sarcasm).
DeleteI think it's entirely explained by El-Nino, AMO, and PDO on top of the secular warming from CO2.
DeleteIt's a little crude still but you can use this tool to play with some of these factors: http://phosphorus.github.io/app.html?id=17364672&full-screen=true
Set CO2 to 2.25, NINO to 0.03, and PDO to 0.07. The blue line is the result of your selections and shows a similar spike at 1940.
This will be a bit long. I apologize for that. I think i need to turn this into an article.
DeleteI'm frequently amused by the denier arguments involving natural variation. The simplest form of the argument is, "It's been warm before, therefore CO2 can't be causing the warming now."
Any one of an infinite number of analogies can be used to show why this is a silly argument. Sou, I know you have used the image of a body with a knife stuck into it; people have died before of natural causes, therefore this person couldn't have been murdered. I've used the idea that flat tires can happen from running over a nail, therefore a tire can't go flat by being slashed.
Lately, I've been using The 9/11 Analogy: buildings have been destroyed by natural disasters like earthquakes or hurricanes, therefore the World Trade Towers were not brought down by airlines crashing into them.
Half of the response to idiot positions like that of Easterbrook or Andy May is to show the ridiculousness of the basic argument. The other have is evidence-based, something which is implicit in the analogies. In order to argue that two superficially similar results were brought about by the same causes, one has to provide evidence that the same causes were present both times. Further, correlation is not causation; one has to describe the mechanism by which those causes operate, and prove that mechanism was in force in both instances.
The simplest version of the denialist argument is mere pattern recognition. We look at a graph and think we see similar bulges both here and there, and then merely assert the two must had had the same cause. That's not science. That's haruspicy. It's the equivalent of reading tea leaves or watching the flight of migratory birds to predict the fluctuations of the stock market. It has no explanatory power and doesn't even attempt to understand causes.
The reason climate scientists say the current upward temperature trend is caused by CO2 isn't simply because the temperature is going up and so is CO2 production. It's because the causes of previous climate changes are mostly understood, and the forces that drive them are not in place today; and further, we know the impact that rising levels of atmospheric CO2 would be expected to have, and we are seeing precisely that.
I do recall someone was discussing once that the drop may have been caused by WW2 aerosols. Maybe an internet search will turn up something.
DeleteJust eyeballing it it looks like a warm peak that regressed back to the mean afterwards, so if it is real and not just an artifact I would say it was just a burst of natural warming.
D.C.Petterson
DeleteI prefer the forest fire analogy ('forest fires occurred before there were humans, therefore humans can't be the cause of forest fires').
Your 9/11 analogy, whilst apt, might trigger a whole new set of conspiracy theories in the mind of the average climate 'sceptic'!
imv the best response to the "happened before" meme, is Forest Fires
Deletethat they occurred exclusively by natural phenomena over the last million or so years, does not stop the fact, in the present they are overwhelmingly caused by human factors
(quickly googles "biggest cause forest fires")
lol
DeleteI suspect the pre-1940 spike and subsequent brief drop will eventually come down to a combination of factors:
Delete1) The period from 1850 to 1940 saw rapid increase in the use of coal in both home heating and industrial processes; the greenhouse emissions from that could have contributed to the rise of temps pre-1940.
2) An artifact of differences in measurement during the war, which significantly impacted how temperature data was collected.
3) Cooling influences after the war: aerosols caused by the war, and reduction in world industry due to destruction of many European and Japanese factories.
4) Natural variations that coincided with the war, leading to mutually reinforcing forcings (warming before, cooling after).
5) Maybe some other more minor factors we haven't thought of (seems unlikely though).
It's significant that most denialist arguments about the 1930s-1940s spike don't bother with "causes", and simply assert that today's increases can't be human-caused because (another assertion) the 30s-40s spike wasn't human-caused.
DavidR,
Delete"Your 9/11 analogy, whilst apt, might trigger a whole new set of conspiracy theories in the mind of the average climate 'sceptic'!"
It's sort of an experiment to see how hard it is to start rumors :)
>>Sou, I know you have used the image of a body with a knife stuck into it
DeleteThat would have been SkS rather than me, I think. I might have done, but I generally shy away from that sort of imagery.
Victor Venema's most recent blog post touches on some of the issues in the 1940-45 data set: http://variable-variability.blogspot.com/2016/08/naive-empiricism-and-what-theory.html
DeleteExcellent - thanks, Mark.
DeleteI've also fixed the link:
http://variable-variability.blogspot.com/2016/08/naive-empiricism-and-what-theory.html
Sou, sorry for confusing you with SkS. Both great though.
DeleteDC - it's flattering :)
DeleteDC, I suspect that you're probably right about most of that, with one exception. It seems to me that 'reduction in world industry due to destruction of many European and Japanese factories' would reduce aerosol emissions and thus be a post-war warming factor rather than a post-war cooling factor.
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DeleteI have a snigger when I see the deniers come up with all these fantastic theories based on circumstantial evidence (anything but CO2 oh my!). We should send them to Senator Malcolm Roberts so he can challenge them in parliament for not having any evidence :-)
ReplyDelete"... warming from 1910 to 1945 ... similar warming from 1975 to 2009..."
ReplyDeleteOkay, this is a rhetorical question. Why stop the second period at 2009? Warming has continued unabated (in fact, has accelerated) in the subsequent years from 2009 to 2016.
The answer is obvious: because that would make the second period 46 years long (at least--it's still ongoing) as contrasted with the 35 years of the first period, thus blowing the idea of repeating cycles of roughly equal lengths.
Notably, May and Easterbrook didn't mention any "pause" as a significant part of the second period. What's up with that? Are the WUWTism Cultists coming after them with pitchforks for ignoring such a basic tenet of denialist dogma?
It the same problem when they bring the 1860 - 1880 warming period as part of the 60 year cycle. That's only a 20 year period compared with the past 46 years.
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ReplyDeleteRe. the "there always been forest fires" meme, I once asked some skeptic who had put it in strong terms (something like: since the earth formed 4 billion years ago there have always been floods, hurricanes, forest fires, etc.) if that had been the case before the oxygenation of the atmosphere could support combustion or before the evolution of land plants.
ReplyDeleteNo reply, and I doubt I convinced him of anything except to be more careful with his talking points.
Don E:
ReplyDelete"I plotted up the GISP2 oxygen isotope measurements of Stuiver and Grootes for the past 500 years and found a pattern of regularly alternating warm/cool periods with an average duration of 27 years (you can find this curve in several of my publications–just google my name to find them).
This regularly repeating pattern of warm/cool periods of 25-30 years, long before CO2 entered the picture, shows that these climate changes have nothing at all to do with CO2 . And because the past is the key to the future–we can extrapolate this ongoing pattern into the future (which I did in 1999 when I predicted global cooling for the first two decades of this century)"
Don Easterbunny 'finds' a 'pattern' in GISP2: circa 30 year warming cooling periods at one site, which he then blithely extrapolates to a global scale signal....he uses his 'discovery' to predict, in 1999, cooling in the first two decades of this century..
His 'prediction' fails his first test...but the Easterbunny does not notice.
What is going on in his head?
"Your Honour, ladies and gentlemen of the jury, forest conflagrations and scrub fires have blazed across this nation - indeed, they have shaped the continent as we know it - for countless millenia, well before Homo sapiens ever trod upon its shores or traversed its (highly flammable!) interior, and certainly well before the invention of the puny, insubstantial Zippo lighter you have been presented as supposed 'evidence', and yet the prosecution has the temerity to make a claim that my client is guilty of some putative crime it refers to as 'arson'..."
ReplyDelete(Lord Monckton at the Antipodean bar?)
More likely the Antediluvian bar...
DeleteR
Don Easterbrook brings up an interesting argument. If this PDO alternates every so often proving that temperature rise is natural than sea level rise must be natural because of the tides.
ReplyDeleteTherefore we can't do anything about it and we don't need to worry about it. Just as we do not worry about or bother to fight plagues and cancer.