Many climate scientists say they see a "fingerprint" in recent temperature increases that they claim is distinctive and makes current temperature increases different from past "natural" temperature increases.
So, to see if we are all as smart as the climate scientists, here are two 51-year periods from the 20th century global temperature record as provided by the Hadley CRUT3. Both are scaled the same (each line on the y-axis is 0.2C, each x-axis division is 5 years) — in fact, both are clips from the exact same image. So, which is the anthropogenic warming and which is the natural?
One clip is from 1895 to 1946 (the"natural" period) and one is from 1957 to present (the supposedly anthropogenic period).
If you have stared at these charts long enough, the el Nino year of 1998 has a distinctive shape that I recognize, but otherwise these graphs look surprisingly similar. If you are still not sure, you can find out which is which here.
You’ve gotta give the A G WARMongers their due. 1998 jumped out at me too. OBVIOUSLY a fingerprint. I’m now a believer. Where do I sign up?
Obviously it is the fascist-capitalist one that is anthropogenic.
When I hear of AGW’s fingerprint, I think of the stratosphere cooling and the troposphere warming. It appears that there is quite a bit of controversy whether this stratosphere/troposphere dichotomy exists. I do not really see the troposphere warming in the data, but I do see the stratosphere cooling. However, the cooling does not appear to be a consistent trend, rather it seems to be a step funciton, often correlated to major volcanic eruptions.
What would make you think that the warming from 1895 to 1946 had no anthropogenic cause?
An Inquirer – how do you not see the troposphere warming? How do you not see a consistent trend in the stratosphere cooling? In what possible sense is there any controversy at all about the warming of the troposphere being accompanied by a cooling of the stratosphere?
The warming of the troposphere shown is within the bounds of the noise and statistically indistinguishable from zero. The cooling of the stratosphere is not a consistent trend, but appears to occur in two discrete steps, being constant in between. The controversy is between those amateurs who try to draw conclusions from applying spurious linear regression models assuming additive iid Gaussian errors, and those knowledgeable statisticians who understand the issues surrounding long term persistence and its effect on trend estimation. Hope that helps.
Random Lurker:
Perhaps an expansion on what Stevo has said: Tropospheric temperatures are no higher now than they were 28 years ago — no net gain over a period during which the AGW movement has emphasized that we are experiencing global warming. RATPAC and HadAT radiosonde datasets show decreasing tropospheric temperatures from the 1950s to the late 1970s.* Meanwhile, stratospheric temperatures have been flat for over 13 years. If the AGW movement claims that a 13-year phase of temperature increases from the 1980s to the 1990s is significant, then they also need to concede that 13 years of flat stratospheric temperatures are significant.
*(Readers of this blog are familiar with the movement’s explanation that aerosols caused cooling in the 60s and 70s. After reading dozens of the aerosol studies, I am not convinced of either the legitimacy of their use in GCM — too much like dummy variables — or that they can explain away downward trends in past tropospheric temperatures.)
Oops, one point which I do not think is clear in the earlier posts: I understand that part of the fingerprint is that tropospheric temperatures are supposed rise faster than surface temperatures. (AGW anticipates not only rising tropospheric termperatures, but also this trend should be faster that surface temperature trends.) Such a relationship is particularly hard to see.
FYI: the Random Lurker above is not the same one who enquired about Amundsen’s navigation of the North West Passage.
“What would make you think that the warming from 1895 to 1946 had no anthropogenic cause?”
For one thing, the IPCC report.
Have a look at this graph, which comes from the IPCC report:
http://www.coyoteblog.com/global_warming_climate_graphs/image039.jpg
The blue area represents what the IPCC models say would have happened (in terms of temperature) without anthropogenic effects. The pink area represents what the same models backcast with anthropogenic effects included. Before 1960 or so, the pink and blue areas pretty much coincide.
What this means is that, according to the IPCC, anthropogenic effects did not have a significant effect on global temperatures before 1960.
Let’s put it another way: Your question is essentially an attempt to shift the goalposts.
Why have you removed the scales from these diagrams? When I click through your link, it is obvious that the first of your graphs is on a higher scale than the second. If the CRUT3 data is valid, then it would seem that your post validates a theory of worsening global warming, and if it is not valid this post seems to have no point at all. What is going on?
Stevo – to back up your claim about statistical significance, please tell us what you believe the error is on the quoted trend of +0.170K/decade, and how you calculated it. Also please explain in what statistically significant sense the stratospheric trend cannot be described as consistent. You also didn’t demonstrate what controversy there is about the stratosphere cooling while the troposphere warms. Maybe you know of a paper about it. A link would help.
An Inquirer – Tropospheric temperatures are no higher now than they were 28 years ago – I looked up temperatures in July 1980 from GISS, HadCrut, RSS and UAH. The numbers were 0.18, 0.055, 0.002 and 0.08. Then I looked up the temperatures for July 2008. They were 0.51, 0.403, 0.147 and 0.06. So tropospheric temperatures are higher now than they were 28 years ago, unless you place your trust exclusively in UAH measurements. There would seem to be no possible justification for doing that.
If the AGW movement claims that a 13-year phase of temperature increases from the 1980s to the 1990s is significant, then they also need to concede that 13 years of flat stratospheric temperatures are significant. – not really. It depends on the characteristics of the data. There is no mathematical rule that says that a 13 year trend is statistically significant regardless of what you are looking at. In any case, who has claimed statistical significance in a 13 year trend? What is this ‘AGW movement’ of which you speak?
dreamin – your graphs shows that temperatures rose more steeply in the early 20th century than they would have in the absence of anthropogenic effects.
The point of the post is that the change in temperature is essentially the same. The word “warming” expresses a change. The point of the post is to demonstrate that the amount and speed of warming is not unusual. The height to which it reaches is a different matter – we don’t have a long enough record to tell if it is unusual.
And apart from the judgemental word “worsening”, I think we would all agree that assuming CRUT3 is valid, the graph confirms global warming. Nobody here disagrees that there has been global warming. The question is, is it anthropogenic, or could it be natural?
Stevo – do you read? You said Nobody here disagrees that there has been global warming. On this very page someone claims that Tropospheric temperatures are no higher now than they were 28 years ago — no net gain over a period during which the AGW movement has emphasized that we are experiencing global warming
What makes you think we do not have a long enough record to tell if current temperatures are unusual? Antarctic ice cores can tell us temperatures over the last several hundred thousands years. Other techniques can be used to estimate temperatures over the last several hundred billion years. How long a record do you want?
About that stratosphere record (from random lurker), it starts out in 1979. Is that all there is?
The point I am getting at there was a time in the not so dim past when we were unaware of the existence of such a thing as a stratosphere.
Over the 79 – 07 chart, there are two major temperature jumps. Those are volcano events (I believe) where ash and gas pierced the stratosphere.
If such an event were artificially created by, say for instance, over a thousand atmospheric test detonations of Atomic and Hydrogen bombs, spread out at regular intervals, over two decades prior to the beginning of that stratospheric temperature record, wouldn’t that tend to artificially elevate the start point.
We might be witnessing a stratosphere in recovery, moving back to it’s normal, pre Atomic weapon age, state.
“Other techniques can be used to estimate temperatures over the last several hundred billion years. How long a record do you want?”
Wow, if you know of such a method or methods, I betcha there are some physicists that would love to talk to you. Measuring pre-Big Bang temperatures should certainly be worth a Nobel Prize.
Dearime: “What makes you think we do not have a long enough record to tell if current temperatures are unusual? Antarctic ice cores can tell us temperatures over the last several hundred thousands years. Other techniques can be used to estimate temperatures over the last several hundred billion years. How long a record do you want?”
A point of clarification: Antarctic ice cores tell us about the temperature record of the Antarctic — that is, a localised temperature record. I think the discussion here is about global temperature trends. If you want to look at global temperature trends, then one would probably want to consult other proxies, and most are not very accurate beyond 400 years as per the assessment from the National Academy of Sciences: “Large-Scale Multiproxy Reconstruction Techniques”. Which is generally accepted to be a gold standard study.
Typical Denialist trick–cherry-picking dates and then sliding and eyballing.
You’ve very conveniently omitted the period 1947 – 1956 (precisely the period when the great ‘bucket/inlet’ switch took place!). So of course they LOOK the same, but if you really knew anything about climate change you’d know that this is how you tell that they’re not.
Sorry, but you’ve fallen for the old ‘up-down’ fallacy.
“Og,”
Perhaps you are proving the point that the fingerprint of AGW is missing. You provided GISS, HadCrut, UAH and RSS data. Typically, GISS and HadCrut are regarded as surface temperatures and the last two are associated with the troposhere. Your surface temperatures are rising faster than the troposphere — not a fingerprint of AGW. (For my comment on 28 years, I was referring to the troposphere graph provided by “Random Lurker” @ August 26, 2008 at 12:43 PM. That graph shows basically no increase from 1980 to 2008. It is possible that his graph is a different subset of tropospheric temperatures than the data you provided.) We all realize the potential of cherry picking data, but time and time again, we see data that does not support the fingerprint of AGW. For all that I can predict, it is very possible that 2008 will be a short term aberration in temperature, but it is noteworthy that whatever noise is causing the aberration is stronger than long-term AGW influences.
“DEARIME”:
Typically, when references are made to global warming, the speaker is thinking of surface temperatures. Again, my comment that Tropospheric temperatures are no higher now than they were 28 years ago is referencing the troposphere graph provided by “Random Lurker” @ August 26, 2008 at 12:43 PM, not surface temperatures.
…more often referred to as “the excluded middle fallacy”, Peter. I completely agree. Seems that the blogger had nothing better to do.
DB – two crucial points elude you. First, faster tropospheric warming is not something which only anthropogenic effects would produce. And second, it is observed. Read this for more information. As for the troposphere graph which you claim shows ‘basically no increase‘, what do you think the line and the text about “Trend = 0.170K/decade” mean?
Which is higher even than Giss…
Hmm, lots of new names with a very similar writing style to a well-known troll. Someone’s discovered sock-puppetry!
Peter Gallagher, I think you’ll find name-calling a not very effective rhetorical trick. Also, did you even read the text before looking at the graphs? Including the bit you want in would make one continuous graph.
To all the regular posters. I don’t have time personally to dig in depth into much of the science and I generally appreciate the insight that most of you add to the discussion. Unfortunately someone has decided to try to confuse the discussions on this blog by randomly posting using the screen names of many of the regulars here. This “person” has obviously corrupted this particular thread and at least a few others. This is quite unfortunate.
To anyone new to this blog. Please give little or no credence to this particular thread.
Warren,
I have been reading this blog for several months now and have found many of the discussions to be quite insightful and informative. However, until or unless you can come up with a way for a person to register a particular screen name, this blog is susceptible to this type of attack, which could lead to a distinct loss of credibility.
This is the REAL og, and I did not post the previous comment. SOmeone needs to keep better tabs on the damned sockpuppets here.
Another nice post Warren!
The absurdity of the IPCC/AGW argument is that one of these graphs can be explained by natural variation, volcanoes and solar variation. The other can only be explained by anthropogenic GHGs!
Don’t know about that, Vince. I’ve yet to be hijacked. Are you referring to “Scientist”? I can clearly see his handwriting at the first “og’s” post, but I can’t see more of that in other comments. Still, it’s soon to dismiss this thread as not having credence at all. I see a healthy discussion (at least it didn’t fall to flame-baiting and insults and stuff… yet)
Luis? Is that you? heh
The French fleet used to pull that trick back in colonial times – flying the British flag in order to get within gun range of the English.
It’s an admission of inferiority.
Sharpen your battle axes my hearty fellows.
Join the battle.
Let your face assume a fierce aspect.
Let the halls run deep with vulcan blood and let the greens dispair.
Samuel Pickwick – you seem amazed at the concept that what can explain one set of observations is not necessarily the explanation of all observations that look similar. The sky is blue. The walls of my living room are also blue. I claim that one can be explained by natural variation, the other can only be explained by anthropogenic effects. And yet they’re both blue! So the claim must be absurd, by your logic.
Well, Papertiger, tell that they were inferior to the sunk ships!
I stand by my reasoning that this post is a straw-man of gigantic proportions. Stephen’s comment, whoever he might reallybe (I couldn’t care less about that), has a point there. To say that both climbs are equal in slope and scope tells us nothing more than just that. It’s perfectly possible that the IPCC’s stance of GHG’s affecting one more than the other be true. So this post in particular is nonsensical (pointless). I’m looking forward for those videos Warren promised us, and I hope he doesn’t have this kind of rethorics backing him up. It wouldn’t be good.
This thread has no credence.
I am also a moron.
Is this a healthy discussion?
I’m Scientist, and so’s my wife.
@ Luis, @ Stephen,
I apologize: this was an effort at humor. Never safe on climate weblogs. Of course this clever post is NOT ‘cherrypicking’ in any meaningful sense since no statistical conclusions are drawn. My accusation that the graphs omit the great ‘bucket/inlet’ period is only sarcasm (about that particularly pointless controversy).
I thought the ‘up-down’ fallacy would have given it away. There is no such fallacy although (although there IS an ‘excluded middle’ here, as Luis points out…). Up is ‘up’ and Down is ‘down’: I can’t believe that even semioticists, warmists or the the anti-fat diet police would hold otherwise.
Best wishes to you.
@Peter Gallagher: (this is the real Stephen btw): Sorry, missed your irony completely. It’s sometimes hard to spot online, although you are right, the “up/down” reference should have been a bit obvious!
A solar cycle record, superimposed on the two temperature graphs, would be interesting.
We know that there was an unusually strong set of sun cycles from 21 to 23.
What were cycles 17-19 like?
papertiger – suggest you read this paper.
Oops. This is the correct link.
Well you got me there, Peter. Because english is not my first language, I have a lack of knowledge of many expressions that seem non-sensical but may have some sense to the knowers. So I always get caught at that kind of things.
BTW, if the post tries not to do any point, then again, it may not be cherry picking (thought I think that the subliminal message is of that nature), but by rigorous definition and ignoring any subtleties, it is pointless.
From the page the article linked to: “These script-generated graphs are auto-scaled by default.”
So any similarities between the two graphs gets thrown out the window until they are both scaled by the correct amount.