2010-10-21 09:18:07Basic Rebuttal 100: Mauna Loa is a volcano
Andy S


The observatory near the summit of the Mauna Loa volcano in Hawaii has been recording the amount of carbon dioxide in the air since 1958. This is the longest continuous record of direct measurements of CO2 and it shows a steadily increasing trend from year to year; combined with a saw-tooth effect that is caused by changes in the rate of plant growth through the seasons. This curve is commonly known as the Keeling Curve, named after Charles Keeling, the American scientist who started the project.

Why Mauna Loa? Early attempts to measure CO2 in the USA and Scandinavia found that the readings varied a lot due to the influence of growing plants and the exhaust from motors. Mauna Loa is ideal because it is so remote from big population centres. Also, on tropical islands at night, the prevailing winds are offshore breezes, which bring clean air from high in the atmosphere down to the observatory. This removes any interference coming from the vegetation lower down on the island.

But how about gas from the volcano? It is true that volcanoes blow out CO2 from time to time and that this can interfere with the readings. Most of the time, though, the prevailing winds blow the volcanic gasses away from the observatory. But when the winds do sometimes blow from active vents towards the observatory, the influence from the volcano is obvious on the normally consistent records and any dubious readings can be easily spotted and edited out (Ryan, 1995).




Importantly, Mauna Loa is not the only atmospheric measuring station in the world. As the graph from NOAA shows, other stations show the same year-after-year increasing trend. The seasonal saw-tooth varies from place to place, of course, but the background trend remains steadily upwards. The Keeling Curve is one of the best-defined results in climatology and there really are no valid scientific reasons for doubting it.


Further reading: Spencer Weart's The Discovery of Global Warming describes Charles Keeling's research efforts in more detail. Weart also has a separate article on Keeling's struggle to fund his research. 

2010-10-21 09:20:39
Andy S


As before, I have probably over-egged this particular pudding and I would appreciate anyone highlighting any passage that they consider irrelevant and pointing out any wording that I uses that would not be clear to a "basic" reader.


I should add that I deliberately did not read Riccardo's Advanced draft on the same subject, currently under review here. This means that there will probably be some duplications and, possibly, although I hope not, some contradictions. 

2010-10-22 02:41:40


Always an interesting test regarding contradictions between argument levels, heh!

This is a nice writeup Andy but I think your instincts concerning complication are correct. This is one of those cases where a picture does tell a thousand words or more; the graph by itself stands as a KO punch against  the silly objection.

Spinning 180 degrees, even more complication could be added by noting how Mauna Loa is the subject of intense scrutiny by vulcanologists presenting an entirely separate collection of observations suggesting the volcano argument is bunkum. Their work shows absolutely no hint of any form of activity likely to produce a trend of the kind seen at the observatory. It's not really necessary to add this because again the graph is open-and-shut.

On a trivia note, what's remarkable about the Mauna Loa observatory is that because it's so remote, instruments there (not the CO2 sampling stuff) are simply left lying about on the ground. Nobody's likely to mess w/ 'em because not only is the access route obscure, the observatory is at the end of a punishing drive that literally leaves a driver's arms shaking from continuously spinning the steering wheel at the road threads its way through a moonscape of a'a flows. I won't embed the photo here, but the link below shows the scene nicely.


The little arms scan backwards and forwards; some sort of optical sensor is at the very bottom of the tubes.

Also there are complete mysteries (980k w/atmospheric audio):


What is it?? An awful lot of trouble for a windchime nobody hears...




2010-10-22 07:43:50
Rob Painting

Although Willis gives a good treatment of the topic, Is it wise attaching links to the "dark side"?, directing traffic their way?. Willis sure is nutty about most other things climate related anyway.

I like it, however:  - amplitude & respiration of plants - might not be obvious at the basic rebuttal reader level.

-"noise" & sources of the noise -"Signals & noise" are clear to the technically minded, but maybe contamination or similar wording might be better?. Just a thought.

- The annual sawtooth reflects the draw-down of CO2 as plants grow during the Northern Hemisphere summer.  This requires a better explanation I think. The "sawtooth" aspect in the graphs does need to be addressed, because it won't be clear to the uninformed.

Most rebuttals and posts here tend to finish by summing up and/or emphasizing the main point/s to reinforce the message. I think your rebuttal would be better for following those examples.







2010-10-23 10:48:35
Andy S


Thanks for the comments.

After putting this down for a couple of days it's obvious, even to me, that I need to rewrite it for the basic level. Riccardo made some suggestions on the Advanced version comments that I'll adopt. Also. since Riccardo has covered some of the more difficult points already, I can cut those from my Basic version. (My problem with writing these things is that I always imagine a hostile audience ready to pick away at any weaknesses or sloppy terminology, which leads me to overly complicate explanations and use more difficult vocabulary than is really needed.)

Riccardo pointed out that the article that Willis Eschenbach wrote at WUWT (and that I pointed to) has some inaccuracies. While I don't dispute that, I would still like to include it because it shows that a) the smarter skeptics don't consider Mauna Loa to be a hill to die on and; b) some of the, er, less smart skeptics who commented on Willis's piece refuse even to consider any mainstream climate science, even when explained by one of their own. (There was a similar episode where Roy Spencer tried to argue that the GH Effect did not violate the second law of thermodynamics.) 

Still, if Dappledwater and others still object to me saying anything nice about WUWT on SkSc, let me know and I'll consider removing  the reference.  

Update: I have now completely rewritten it and I hope that it is now more suitable for a Basic Version. Comments, please!

2010-10-23 13:06:13


Great! Nice that you provided a tip of the hat to Keeling, too. 

"...known as theKeeling Curve... " --> "...known as the_Keeling Curve..."

"...observatory; but when they don’t..." Might read better as two separate sentences.

Linking WUWT makes me squirm; every article there must be fact-checked as carefully as if one were handling unexploded ordnance. I'd preface the remark with words to the effect that Eschenbach's piece is a very unusual exception before sending anybody in that direction.  


2010-10-23 13:06:42

Oops, forgot thumb. I'm always the easy one it seems...
2010-10-23 17:19:00
Rob Painting
Still don't like the link to the WUWT, but other than that it's good. I can just imagine the skeptic response - when they find out we're directing people their way for climate related information.
2010-10-23 19:04:27

You may more generically say that even most of the (more educated?) skeptics accept it.
2010-10-24 03:52:08
Bruce Worden

Nicely done, Andy. I tend to agree with Doug that some kind of caveat is in order when sending people to an anti-science site like WUWT. Why not just send them to Wikipedia and leave it at that?

Either way, though, thumbs up from me.

2010-10-24 06:06:12
Andy S


Thanks everybody. I have made the corrections that Doug suggested.

I also removed the reference to WUWT, since nobody agreed with me on that. That site contains a lot of toxic dross and who knows how they might spin the fact that SkSc endorses, even grudgingly, one of their articles. Maybe I'll mention it if it comes up in the comments. Perhaps a new article would be worth writing on what happens when prominent skeptics say sensible things on their blogs. The hostile reactions of the mob to the "apostasy" of Willis and Roy Spencer allows us to draw a line between skeptics who accept at least some of the basic science and those people who really deserve to be called deniers. Perhaps that's too much sociology for this blog and we should stick to our physical science knitting. 

But I digress, I'll perhaps start a thread on this in the "Communicating Science" section of the Forum. 

2010-10-25 07:18:29Comment
Robert Way

Good Job
2010-10-25 15:47:45Published
John Cook

Will publish the advanced version in the not too distant future.
2010-11-27 09:31:56video link?
George Morrison

Tyler Volk, has a decent video that walks the viewer through the well-mixed nature of atmospheric CO2 that is reflected in your chart and 3rd paragraph. It's at a pretty basic level, but for interested readers viewers, it might help drive home the point.