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Harmon Craig
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ORAL HISTORIES

Interviewed by
Spencer Weart
Interview date
April 29, 1996
Location
Scripps Institution of Oceanography
See catalog record for this interview.
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Interview of Harmon Craig by Spencer Weart on 1996 April 29,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
www.aip.org/history-programs/niels-bohr-library/oral-histories/32508

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ABSTRACT
Interview with Harmon Craig discusses work with Harold Urey's group at the University of Chicago (1941-1955, PhD 1951, Navy service 1944-1946, postdoctoral research 1951-1955); carbon isotope research, C13 and C14; George Callendar's CO2 research; work at the Scripps Institute (1955-2003) with Hans Suess, Roger Revelle; box models; nuclear waste and ocean turnover; helium 3 and 4 in the ocean; boat trip with Niels Bohr; Charles Keeling's CO2 analyses.

Transcript
Weart:
This is Spencer Weart, and it’s April 29, 1996, and you are?

Craig:
I’m Harmon Craig from Scripps Institution of Oceanography, University of California San Diego.

Weart:
Why don’t we start out [???] group. We don’t have time to talk about everything, but can you tell me just what were you doing in that? What was the general orientation?

Craig:
I was in Harold Urie laboratory. I did my thesis with Harold Urie. I worked on the stabilizer toques at Harvard. He was farming out different elements to different people because he was the one who went to Near and got Near’s newly developed mass spectrometer, which anybody could build and put together rather easily. It was the machine that revolutionized geochemistry in introducing isotope geochemistry. As I wrote somewhere in the thing I wrote for Near and then got presented with the Goshment [?] Medal. It was an instrument anybody with a screwdriver who could make an audio amplifier to hear Mozart in those days could put this machine together, and we did. Put a lot of them together. And that provided Urie —

Weart:
He just wanted to look into everything.

Craig:
Yes. Well, he was mainly working on paleotemperatures with oxygen isotopes. But he realized of course that he could do — he was looking at oxygen isotopes in the Cretaceous because he wanted to find out what killed the dinosaurs. That was one of the main things driving him was to find out why the dinosaurs died off in the Cretaceous. But he was able to get people who were enthusiastic about the biggest thing that came out of his laboratory was doing oxygen isotopes in the Pleistocene, [?] he did, and so for the first time that there were far more than four glaciations at the Milankovich Curve [???] was responsible. Yes, Meliani’s [???] great work. And it was all done on Pleistocene, whereas the Cretaceous work never came to very much because the fossils have all been recrystallized and [???] and so forth and so on. But then he was able to have people work on oxygen isotopes in silicates. Peter Berchi and Sal Silverman did thesis work on that. He gave me carbon isotopes, he gave [???] hydrogen isotopes.

Weart:
[???] carbon turned out [???] temperatures, or —?

Craig:
No, no, just to find out about the geochemistry of carbon. Nothing essentially was known about isotope variations in carbon. There was a little work that had been done by Near and Gulbranson from five or six different samples, but almost nothing was done, so he said we can study carbon, and he gave hydrogen to Irving Freedman, so he just was able to parcel that on.

Weart:
Just working out the geochemistry of isotopes.

Craig:
Yes. I was a petrologist at the time. I was working on rocks, and I was working for the chairman of the geology department as a thesis on rocks in the Encampment in Wyoming in the Snowy Range over there trying to see if there was a correlation between chemical composition and the structured fabric of the rocks. So it was a theory of that time that these rocks had been effected by molecular diffusion to such an extent that the chemistry was controlled by the structure orientation of fabrics. And after two years it was not working out very well; after two summers in the field.

Weart:
Oh, so you went to Wyoming.

Craig:
Well, oh yeah, I went there several summers.

Weart:
What mountains were these, by the way? Snowy mountains?

Craig:
Snowy Mountains, Snowy Range, just west of the Laramie Range. There’s a park-range that comes up and becomes the Snowy Range. A little town of Encampment, Wyoming. But at that point Saul Silverman had gone to Urie. He was in our department; a very good friend of mine. I had been given the oxygen isotopes and silicates and was working on that, so he told me why don’t you go to see what Urie can offer you as a thesis. And I went, and he said right away, "Oh, carbon isotopes." And that’s when I started on working on carbon isotopes. But Bill Libby and Harold Urie shared a secretary with offices on either side, so were very familiar with Libby and saw him very frequently.

Weart:
Was he more concerned with the dating at this time?

Craig:
Yes, he was working on radiocarbon dating. And we were all in the chemistry department building, but then we moved to the Institution for Nuclear Studies, which later became the Fermi Institution. And Libby was under attack by the geologist groups that did not like how young the radiocarbon dates were coming out for the last glacial events in North America. They were finding 11,000 years at two creeks moraine [???] at the last glacial events, and there was a very prominent geologist in those days, Ernst Anthos [???], come from either Holland or Sweden, and in those days the dating of glacial advances in Scandinavia was done by varbs [???], by the annual layers in the lake settings. And Ernst Anthos claimed to be able to correlate these varbs [???] across an ocean [???]America. He claimed he could correlate them. You know how they look at tree rings and line them up; well, that was the same thing. And he claimed 25,000 years for the last advance, and that was an absolutely fixed specific date. So when Libby was getting 11,000 years, they first said well, you couldn’t get this much chemical alteration and weathering of the tills and so forth; that wasn’t true either. But then he said, as you can read in there, that what happens is he read some papers on decomposition of urea, the isotope effect, that showed that carbon-12 was lost more rapidly than carbon 14 when you went into the chemical effects on urea. And so it was much like the creationists in a way that we were just talking about. You could seize on anything and apply it to the specific problem you had. They said that the trees have been altered tremendously by chemical interaction with water surrounding something, and that carbon 12 has been removed, concentrating the radiocarbon preferentially, because the isotope would react faster in the kinetic relations, and therefore the dates of 10,000 years or 11,000 years should really be 25,000 years to match with Anthos. So Libby’s idea, which was a good — I had worked on plants, and my thesis covered carbon in everything. I worked on diamonds and plants and carbonates and grass and trees and coal and methane, hydrothermal varies [?], and every volcanic gases. I simply just covered the whole field because it had never been done before. I had a world to myself. So Libby said, "Well why not look at the plants that Anthos has sent us to look at. Trees, old branches with decay, and old things that have decayed, and see if there’s any validity in what he would say." Because it was the one big argument against radiocarbon dates, which he very readily wanted to establish. Well, the answer was very simple, of course. It was that fractionation effects for 14C have to be twice the effects of 13C — you had one neutronic, you have two now. So the question was what were the 13Cs, and I analyzed the 13C, and you can see that in the paper. Analyze for 13C data, and they were the same as ordinary trees and plants. So you could show very simply that there had been no significant effect on the 14C. But in that paper I discussed the whole business about the exchange in the budget of C2 — let me show you.

Weart:
Actually, the part of this that I saw, the reason I looked up this paper, was not — you know. That’s important work, but I’m only interested in the carbon dioxide question. So this was one of the very first times we found the age of the ocean at roughly 400 years.

Craig:
Right. This is where we showed — well, what I showed in this paper, in this brief discussion, was that the only thing that could give this fact that the radiocarbon in the surface of the ocean looked 400 years old when it should be zero age. You see, the radiocarbon in the surface of the ocean is enriched by 25 per mil, two and a half percent, in 13C because of the chemical equilibrium in carbonate and CO2. Therefore it should be enriched by five percent or 50 per mil as we use in there, and 14C should be twice of 13C, but it isn’t. It has the same activity as the pre-1950 or the 1950 would. 19th century would, rather. So this meant that there’s a five percent disparity, which five percent of 8,000 year mean life is 400 years. The radiocarbon in the ocean looks 400 years old already, just as it’s in the surface ocean layer, exchanging with the atmosphere. And what I show there is that nothing else can do this dilution in the ocean [???] anything else. It has to be the barrier for air-sea exchange. And then I say in there that that’s a separate paper and I was working on that paper, the separate paper, when I moved to Scripps. Roger Ravel. Roger Ravel came to me and Souse at the same time, and [???] this paper, and then at Scripps we did a series of two or three papers on the exchange time of CO2 in the ocean. But that’s where my interest in it came from was this 1954 work.

Weart:
Yes, I want to get that. First let me just ask you a generic question. How was all this supported at the time? Who paid for all this?

Craig:
AEC and ONR, Urie’s lab and Libby’s too.

Weart:
Did you have any connection with getting that funding, or was that all provided?

Craig:
No, it was all provided by Urie, and I was a post-doc. I was first a Ph.D. student, then I was a post-doc. I was there — I got my Ph.D. in ‘51, but I didn’t leave until ‘54. It was the situation in those days that people in Chicago, it’s like Louie Alvarez waiting so long in Chicago before he got tapped to go to Berkeley. They kept you on until you could find a good job, and in those days there were no good jobs because there were no mass spectrometers. You had to go and raise funds to get a mass spectrometer. Well, at the same time I went to Scripps I had an offer from MIT, that was then going heavily into mass spectrometers because of Patrick Hurley , and I had an offer — no, I had an interview with someone, which Frances Burts [???] didn’t make me an offer because they thought I was not respectable enough to my elders. It happened that the most famous geologist at Harvard were people that claimed that all hot springs, and ore deposit waters, but especially hot springs, came from magma deep down in the Earth’s crust, and they were magmatic water [???]. And I was working at that time on hydrogen oxygen isotopes as well as after-carbon, and I was able to show that all these hot spring waters were simple meteoric waters, rain water recycled because of the hydrogen oxygen, meteoric water lines they came to be called. And at Harvard in those days you didn’t give a seminar for the whole department. You had to go to each ranking professor and give a seminar separately through it. And they didn’t like this at all that-

Weart:
It’s still true if you apply for a job for Harvard they want you to go and visit every professor.

Craig:
Is that right? Well, also I knew very well that the residence time of an assistant professor at Harvard was not very long, because they never promoted anybody. I knew that because a good friend of mine was there at the same time. There were a lot of problems, which I could talk about some day. But in any case, at that time Roger Ravel came along —

Weart:
I want to hold you in Chicago for a minute. Just a couple more questions. First of all, do you know why the RNAE [?] received the supporting work? What they wanted to get out of it?

Craig:
First of all, they had to do it if there was going to be any research because there was no NSF, so there would have been a vacuum. The AC was doing it primarily because two people, Libby and before him John Van Neumann, or maybe at the same time, they were both strong supporters of this. John Van Neumann was a big supporter of environmental research using atoms. Everybody wanted to use atoms for environmental research, and in fact he was the one who made it possible for Hans Souse and me to go to Scripps. He developed — Roger Ravel developed with him a plan to fund a large isotope geochemistry laboratory at Scripps, and that’s what Souse and I went there to help build, or to build in fact. There was nothing when we went there. Just a bare ground with some columns for buildings with no ground floors. But that money came from Neumann setting it up with Roger. So AC was conditioned to that from the beginning, and ONR was doing it because Roger Ravel during World War II and at the end had persuaded them that they had to support fundamental research in oceanography, and Urie’s work, he was a famous name for them, a Nobel Prize winner, and they were able to classify it as oceanography, and so it was OK. I remember it very well because I was recalled. I was a Naval officer at the end of the War in the Navy on an LSM, which gave me my first load of going to the ocean was going to sea. And I got recalled for the Korean War, and at that time Urie was away in Greece and Libby was away someplace else, and I had to get some letters. I had to go up there and get registered and go through all the business, and in the meantime people were trying frantically to — I was in the middle of getting my Ph.D. and I had a baby daughter coming, and I didn’t have a degree yet. Well, for various reasons. I never got a bachelor’s degree because when I got back to Chicago after the War and went right into my undergraduate work the Dean said why don’t you jump right into graduate school. You won’t get a BS degree, but at Chicago you never need a BS degree anyway. Then I didn’t want to get a master’s degree, which it’s not worth anything, so I had nothing. So in the meantime I got a notice that I was being sent to San Diego for antisubmarine warfare development. And I went back to Val [???], and he said where in the hell is San Diego? We never knew anything about San Diego, looked it up in the Britannica. Then I ended up of course in San Diego anyway. They managed to get it deferred on the grounds that ONR and AEC were supporting my research and it was fundamental or something like that. They got us through.

Weart:
Was there any input from the [???] the instrumentation for looking [???] ?

Craig:
There was through Libby, yes. Libby developed this Operation Sunshine, which was looking at all strontium in the milk all over the county.

Weart:
Yes, but even before that, back in the early ‘50s they were obviously looking for Soviet bomb tests and so forth.

Craig:
I don’t think so.

Weart:
(Not audible)

Craig:
No, I don’t think so. The main thing was Libby’s development when he got into the AEC. He ran the Sunshine — he didn’t run the Sunshine project; Ed Martel ran it out in Chicago. Just died recently. Bright guy.

Weart:
How did they detect [???] ?

Craig:
They look for cesium and strontium in milk and in plants.

Weart:
Back in the early ‘50s when they got the fallout from the Soviet bomb [???], right off the airplanes.

Craig:
That was with the airplanes, yes.

Weart:
How did they analyze that stuff?

Craig:
Oh, they did it by singulation counting and by gamma counting, all different methods. But they were getting cadavers from Texas sent up. If you want to know all about this ask Carl Drehee [?] because I was kidding him about it. They were being sent to Columbia.

Weart:
This was in the project Sunshine.

Craig:
Yeah, at Lamont Geological Observatory at Columbia they were burning up cadavers and fetuses, especially fetuses. They got fetuses sent from all over the country. They were ashing them and measuring the —

Weart:
I don’t [???] ?

Craig:
[???] . Nobody wanted to talk about it.

Weart:
OK. One other thing in Chicago. When you were in Chicago, Souse gives you credit in one of his papers for doing his wood stamping when he first was looking for the 13C.

Craig:
Yeah, yeah, yeah. He did the 13C, not the 14C. He had to know the 13C to prove that the 14C was giving a 400 year age of the ocean, or he had to correct. First of all, different trees range by about 10 per mil or one percent in 13C, 12C ratio. So that range would be two percent in 14C. So to correct for that you had to know the 13C and normalize everything to average wood, which was two and a half percent, or 25 mil different from the Chicago carbonate standard that we use. We knew what air carbon was and all that, but you had to normalize all the wood to correct for the C13 variations, the natural variation to the photosynthesis and the various reactions. It was kind of interesting, because — it was an interesting Libby story, which was a small part of this, but sheds some light on Libby. And you’ll read about it in that paper because it’s a very nice example of discovering an effect and making a perfectly rational good theory and going out in the field and testing that theory [tape cuts out] elections and measurements in the laboratory and understanding it exactly and having it be completely wrong. And the experiment, the phenomenon was that all trees and grasses and plants, almost all plants that you looked at, fell within a range of 25 per mil or 20 per mil or two percent to 30 per mil or three percent lower in 13C than the carbonate standards. But there are a few samples of grass, such as I’ve collected out in Kansas at my uncle’s cattle ranch, all showed only 10 per mil or one percent lower in 13C than the standard. They were completely different, these grasses, from all the range of other plants that we had sampled. So I thought it must be due to the fact that there were some of the professors that I had worked under in Chicago had shown that this was calichie soil. The carbonate was being drawn up in the ground water column and by the roots of the grasses and carbonate was coming up. And carbonate is enriched in 13C. So the perfectly good idea was that these plants or grasses were able to use bicarbonate ions derived from carbonate, and that was enriched in 13C, and therefore they were enriched in 13C. And we went to a place in Michigan — Val, what’s the name of that place in Michigan we went to test the 14C, 13C? Remember where we spent the summer vacation? Glenn, Michigan. And there was carbonate sediments with grass growing on them, then there was a forest that had an acid soil and all the carbonate had been leached out. And so we could collect the two grasses indeed. This grass was enriched in carbon 13, this grass was depleted and looked like all other plants. And that’s what’s written in there. It looks like a perfectly good theory. Then I thought well, what I should do is have Myra Reuben, who was a good friend of mine, who had taken over Souse’s laboratory in Washington at the USGS to run the radiocarbon lab measure the 14C, because if this stuff is coming from calichie it should be dead for carbon 14, so these plants should show a very old age as grasses. Just like the ocean, they’re getting some of their stuff from carbonate so it would be dead, so they would look as if they were very low in 14C compared to what other plants are. So I collected all these grasses, especially this Kansas grass, and took it to Washington and Myra Reuben analyzed it, and to our great surprise it looked as if it should born 300 or 400 years in the future. It was too young. It was enriched in 14C. And we guessed what that meant. We guessed that nuclear weapons carbon 14 was building up in the atmosphere. This was the first discovery of it that had ever been seen, carbon 14. This must have been just after this paper — no, not necessarily. It was sometime in [???], when Libby was in Washington as the head of the AEC commission during that time. And we guessed that it must be carbon 14 from bombs. And so we went to see Libby to tell him about this. And Libby was furious. He hated the idea, which he hadn’t known yet, that any bombs could produce carbon 14, because a) it would mess up his dating, and b) it would make people angry at atomic weapons because we were polluting the atmosphere with carbon 14. There were all kinds of reasons. So he told us that this was absolutely ridiculous; there was no way in which the thermonuclear weapons could produce 14C in the atmosphere, forget it, and if we tried to publish such a crazy idea he was bury us into the ground. So we didn’t publish it. And of course the paradoxical or curious part of the story is that what ruined Libby’s counters was the carbon 14 in the atmosphere. His dates got worse and worse because he used charcoal; he made charcoal and counted it. And when you add the charcoal in the air, it was picking up all kinds of carbon 14. It’s so highly absorbent, carbon 14 enriched CO2 from the air. His measurements got terrible and he was being attacked all over the world. There was this famous business of the dating of the Gronigin church. He dated a Gronigin church and the date was obviously absurd. It was far too young. Eight laboratories were then using gaseous measuring CO2 or settling, showed much older ages for this Gronigin church. And to his dying day Libby would never admit that these guys were right and he was wrong, the Gronigin church. So it turned on him in the same way because he would never admit this. But it killed that—

Weart:
No I have to ask you something. How much time do we have?

Craig:
We have a meeting at 5:30. Probably until about 5:15. We have about 45 minutes.

Weart:
OK, so far we’ve only gotten this far.

Craig:
All right, we’ll go faster.

Weart:
Getting back to this first paper of Souse that you helped him with.

Craig:
I don’t remember that paper actually. Which one, the Tellus [?] one?

Weart:
Yes, I guess it was the Tellus.

Craig:
The Tellus, there were three papers all together.

Weart:
No, no, no, this was before that. This was the [???] paper.

Craig:
Then I don’t remember it.

Weart:
[???] wood samples, and there was the first one where he gets some idea that he’s detecting the fossil fuels in the atmosphere. But his [???]?

Craig:
Yeah, that was because they were finding two percent effects and they had to normalize for the 13C to do that, and that’s what I did. I just measured the 13C values.

Weart:
He didn’t get it too accurate. He got the value that was still too low and had to go back and correct it a couple of year later. And [???] were worried, I guess you were worried here too, that he didn’t get — that was confused about much radiocarbon [???] there should be in the cells.

Craig:
Yes, it was that 400 year discrepancy that confused everybody. See, what helped confuse that issue was that J. Lawrence Culp at Lamont, who started the 14C lab there, went out and collected a lot of samples and he would concentrate the carbon on I think — if they had molecular sieves — no, maybe it wasn’t. Maybe it was barium hydroxide or molecular sieve. Some kind of thinking would concentrate the CO2 on it. And that’s the [???] blank in it that he never recognized. And so for a couple of years the Culp data was showing much too high 14C values in everything, and it was because they had a blank of atmospheric 14C which was going up because of the bomb. So there was a lot of — and I mentioned some of that Culp data in there. The first good measurements on ocean water were the measurements of Myra Reuben [???]. We went out and got samples down to several hundred meters of ocean water and gave them to Myra Reuben, and he counted them by settling counting and got good numbers on them, and that’s some of the numbers that are [???] in [???] Tellus paper.

Weart:
Now were these ocean cell problems one of the reasons why you wanted to go on and do this work in the Tellus paper?

Craig:
Well yes, because I was interested in this one here. This one here I planned to continue that to find out exactly how this 400 year discrepancy came from. But also it was because of Roger Ravel’s great interest in the CO2 program. He pushed that a great deal, and in fact he brought — I’m sure what attracted him to both me and Souse was that we were working on the CO2 problem, which he was in to very strongly as a result of having known about Calendar’s work and having known Calendar. And he was the one who originated the idea that this was a great geophysical experiment that we were turning loose all the CO2.

Weart:
That’s great. Did you ever meet Calendar, by the way?

Craig:
No, I corresponded with him, and I have some papers of his that he sent me [???]. Yeah, I corresponded with him.

Weart:
Do you know what the G stood for?

Craig:
George.

Weart:
George. I thought so but I wasn’t sure.

Craig:
But it’s a curious thing with Calendar, if you want to talk about that for five minutes. He was a meteorologist in London, and he was working way out in left field all by himself. He was at the Meteorological Survey. And he got this idea —

Weart:
He worked for Meteorological Survey?

Craig:
Yes, he was a — well, Meteorological something or other. I’ve got his address.

Weart:
I think he was a meteorologist for an industrial firm maybe?

Craig:
Yes, but then he was in the government meteorological office, something like that. I’ve got his address on the papers. But he got the idea that the CO2 must be increasing in the atmosphere from the combustion of fossil fuel. And he put together all the data he could find. There were hundreds and hundreds of measurements in those days. People that even measured in the sea and every place. But a lot of it was they were measuring combustion and contamination and so forth, and a lot of them were bad measurements. But he psyched out what the best measurements were, and he showed an increase — I wish I’d brought that slide so I could show it to you — but he showed an increase from 1900 or 1890 up to some value at the present time.

Weart:
[Not audible]

Craig:
Yeah I know, but I want to show you how the curve looked. It went like this, and these were the measurements [drawing], and there were some up here and some down here.

Weart:
Yes I know. Kealing [?] went back later on and looked over them.

Craig:
Well, there’s a group at Norfolk University, there’s a guy at Norfolk University who’s writing sort of a treatise on Calendar’s work. But these people maintained —

Weart:
[Not audible]

Craig:
Yes, on his work. A guy at Norfolk University.

Weart:
I’d be very interested if you could get me his—

Craig:
I’ll give you his name. I don’t have it with me. I know the guy who knows him.

Weart:
Because I’d like to be in touch with him. Calendar is such a mystery [???]. I’d love to know about him.

Craig:
Oh, he was a great man. But I happen to be in Norfolk last year. They set up a new geochemistry group, the first one they’ve ever had, for Great Britain, and they asked me to give the keynote address for the meeting where they set this up, and so I talked about problems, atmospheric, oceanic, and terrestrial problems — ways you could use isotopes in general. And one of the things I focused on was old air and Calendar’s work, because I had this idea that you could find old air in laboratories, and I knew just where to look. You could look in Cavendish’s lab, you could look in Lord Railey’s lab, you could look in Ramsey’s lab, you could look at Gailiesac [???] who went up in a balloon over France and collected stuff over Paris. Pasteur went to the mountains to prove his germination theories, and he had flasks of air. And I knew that many of these — there were a lot more — and I knew that many of these people would collected more samples than they would ever analyze. They were like me, after all. So these must be lying around in labs. And as a result these guys from Norfolk University went down to Cambridge while I was still there and they went into Cavendish’s old lab and they found two sealed off flasks. One said "hydrogen" and one said "air." These must be the oldest samples that are still around so far, but nobody knows what the air is from or what it is. But there is still some interest, because you know people can get oxygen now precisely enough. Ralph Kealing is doing this at our place. So you could look at oxygen and CO2 in these things. So you have to look for samples that started with Henry Cavendish, because everybody before him put their air samples in pig bladders, but he was the first to put them in soft glass and save them. Anyway, Calendar used this. The people at Norfolk showed me a screen on a computer where they had all Calendar’s data base that he worked with, and they were just random like this. They were just everywhere. These numbers — if you put all the numbers that he looked at are like this on the computer screen. Calendar shows you these seven or eight [???] in his last paper, last two papers, with this nice curve to them. So these guys all want to throw Calendar’s stuff out, and they say no, this was nonsense. How could this guy choose just these and match the curve out of these data? Well, the answer was that he was a genius. This is what geniuses do. Geniuses, or at least outstanding scientists, maybe not geniuses but outstanding scientists, have the ability to pick out from a mass of data what the right ones are. If they’re not right, they’re never heard of again. But if they’re right, that’s a big thing. So Calendar picked out these data. Curiously enough, these were biased by a couple of high samples in there, then there were some lower ones. But curiously enough the combustion curve for CO2 measured since the Industrial Revolution, we had the figures from the coal that was burned, happened to precisely match this curve just by chance by the ones that Calendar had taken, and there was some high values by Boukens [?] in there. They just matched. So Calendar had to say, and he stuck by this to the end of his life, that all the CO2 produced by coal was still in the atmosphere by coal burning, all of it. None of it went away. It was all stuck in the atmosphere. So the resonance time in the atmosphere was what people believed to be 5,000 or 10,000 years or something like that before it got taken out to allow that there. And we were saying in our Tellus papers that only half of it was there.

Weart:
Let’s get to that.

Craig:
And that’s what Calendar sent to me correspondence and then the things about, and that’s the interesting part.

Weart:
Let’s get to that now. So you went to Scripps. Actually I believe at the time you [???] and Jim Arnold were all three—

Craig:
No, Arnold came after us. We brought Arnold here. We actually —

Weart:
At the time in 1954, ‘55, you were also [???] brought up by your principal.

Craig:
Um hum (affirmative). From Chicago. We went to Chicago — we went to La Jolla for one reason: that Roger was able to provide bill-ups. There were no bill-ups, no jobs. Roger had started the idea of building a new university there, the University of California at La Jolla, it was going to be UCLJ.

Weart:
I think we got to stick pretty close here now.

Craig:
OK. Well, he brought me and Simpson Elssaser [???] to be the first professors in there, only because his philosophy was to build from the top down. Research, graduate research, and then undergraduate. So that’s what brought us there: the chance to build a new university because his interest in carbon dioxide, and then this kind of thing. And the fact that Souse and I could go together to some place where we could continue to work together like we had in Chicago. So that’s what brought us there. Then we all got started in looking at the CO2 effect. Roger, and dominating this thing.

Weart:
Now he started working cooperatively with Souse. You’re working on a paper separately. How did that happen?

Craig:
Because they worked on the transient process. They were looking at the transient process of generating the CO2 using Souse’s data on the Souse Effect as it came to be called of what the radiocarbon showed how much had stayed in the atmosphere as a function of time, and they could get the exchange rate from that. And what I restricted myself to was the steady state of the problem, and that’s where I invented box models, which have now become sort of the universal way of modeling all this. We had a three box or a four box model.

Weart:
[???] first box model?

Craig:
Yes, it was the first four box model. And it had atmosphere, mixed layer, deep sea, humus, and biosphere. So it had five boxes. And that was the beginning of box models. Which I said later if I’d known how they were going to proliferate I would have never done that.

Weart:
Now Arnold [???].

Craig:
And Arnold was doing this independently of Ernie Anderson, who had also [???]. Ernie Anderson was at Los Alamos and he had set up counters to do radiocarbon, and Jim Arnold was trying to do radiocarbon with scintillation counting, which never really worked that well. But he and Ernie Anderson were interested in exactly the same thing because it was all in the air, and we were all good friends, and so they independently wrote a paper. But that paper didn’t amount to much unfortunately, because they took the amount of carbon, I forget the — organic carbon or something in the ocean was too high by almost a factor of 100 or something. They weren’t in good touch with people who knew about the ocean and knew these things.

Weart:
They came out in the end with answers pretty close to [???] because [???]

Craig:
Yeah, but we all knew what the answer was because we traded stuff back and forth. We all knew what the answer to that would be, and seven was a nice number. But you see at Scripps I had the advantage in the box model things, I didn’t have a clue as to what the thickness of the mixed layer of the ocean over the whole world would be. But there were people there like Warren Wolster [???] who could look at the data and tell me, "Well, it’s 75 meters plus or minus 25." So I took that 75 meter thing as Wolster’s [???] first guess, not based on very good data, but just his general knowledge. And that figure became a sacred figure. All the people that did box models of carbon, there’s always been this 75 meters. But that all came from a rough guess by Warren Wolster. But that was the reason I could do this, because I was at Scripps with people who knew these things. Let me just say one more thing. For the kinetic phase, the transient phase that Souse and Ravel did first, the most important feature of that model was Roger Ravel’s recognition of what we now call the Ravel factor.

Weart:
I want to get into that.

Craig:
There’s not too much to say, except that Roger’s great contribution was the knowledge of that factor, because he knew very much about this calcium carbonate. You know, there’s a paper by him in the GSA on calcium carbonate over geological time. Have you ever seen that? Geological Society of America bulletin. There’s a big paper by Roger Ravel. And that’s worth looking at. Oh, it must be ‘53 or ‘54, sometime around in there.

Weart:
I want to get into this in some detail, so let’s... In the first place, by the way, you agreed to publish those few papers simultaneously by sending letters back and forth with Arnold?

Craig:
Well no, Arnold would come and visit every so often. And Souse and I shared an office. He and Roger would sit on one side. They didn’t have our building yet. He and Roger were on one side and I on the other.

Weart:
Now, Arnold and Anderson, I sent their paper in to Roger to look at in April of 1956.

Craig:
‘55. No, the Tellus paper was ‘57. You’re right.

Weart:
So it was ‘57. I sent it in in April of ‘56 and they both sat on it and didn’t submit it until August. So I suppose it was in that interval that he was discovering this Ravel Effect.

Craig:
I don’t know. Ravel sat on everything. That was the biggest complaint of him as a director. No problem was too trivial for Roger Ravel. And the reason he was not the first Chancellor at UCSD after he had built the whole thing was that he kept a whole group of regents who would come all the way down to see him especially from Sacramento to discuss the new university. He kept them waiting for two hours, the door opened, and one of the seamen off of our ships, one of the most common people you could find at Scripps came out. He had been wanting to ask Roger Ravel, the director of Scripps, whether he should go to college. And Roger kept him in there two hours explaining the virtues of going to college, while the regents were cooling their heels. And they never forgave him for that. And the other reason was one of the regents said Polly wanted it built in his location way over where San Diego state is. So Roger had terrible relations with the regents. So he never — when Roger Ravel went away to sea or some place, he had to personally sign all the paychecks. Nobody got paid when he was away. He had to personally sign the checks. No detail was too trivial for him. Even with that great mind.

Weart:
That’s very relevant to this, because I had the feeling that this was the kind of thing that led him to this reevaluation of the chemistry of the [???] —

Craig:
You have to remember that he was involved with papers with everybody at Scripps. He coauthored papers with Russ Raid [?] on seismology and with Walter Mock [???], and with almost everybody. He was a great attractor, and keeping people all knowing what each other were doing and working on projects together. And when he left and quit being director that ended at Scripps. That was the end of that great scientific flursion [???].

Weart:
One of the things he had been working on since about 1952 was sea water chemistry, the calcium carbonate [???]

Craig:
Yes, that’s what that GSA paper is all about. It’s a great paper.

Weart:
And it looks like he got started on that because there were some measurements done at the time of the Bikini test. [???] Bikini [???] a lot of measurements [???].

Craig:
That was part of it, but mainly it was because he did that work himself when he came down here to do his Ph.D. thesis at Scripps. [?].

Weart:
[???]. It seems that he got interested in it again. Maybe you can check me on this, but [???] got interested in it again because they started doing [???] measurements, the Bikini [???].

Craig:
I didn’t think he was too much involved in that. He edited a book, which is still an interesting book. It was published by the National Science Foundation on radioactive effects in sea water. It was the first volume ever [???] first published, and he got me into it. He went around and drafted people at Scripps. And I did the first calculation, then, of what in a nuclear power regime when we were generating enough power to generate about as much electricity as we had in the United States or something like that and we were discarding all the fission isotopes into the ocean, what the study states fission results would be. And I did a long paper on that.

Weart:
I noticed that in a speech you gave you talked about the problem of [???] nuclear waste [???]

Craig:
Yes, in the ocean. And that’s where — art: Is this one of the reasons that he was interested in the question of the ocean turnover time?

Craig:
Yes, exactly.

Weart:
Were there other —

Craig:
He pointed out to people — Roger was — his main interest was in heat flow from the bottom on the ocean. Or one of his strongest interests. And people all said that the ocean water was very old at the bottom that it didn’t circulate. And Roger was the first to point out that the in-flow into the ocean would circulate the ocean within a thousand years. You couldn’t have it longer than a few thousand years at the most because the heat flow would make the whole thing turn over.

Weart:
So he was interest in that. Then there was the —

Craig:
Yes. He was interested in heat flow because people’s measurements of heat flow at sea, which he participated in and helped develop that first heat flow measurement, the Bullard Maxwell thing, so that the heat flow on the oceans was about the same as under the continents, and that was not understood. And that’s what strongly intrigued him about it. But he was also interested in atomic tests because they showed this beautiful layering. Ted Fulson was the guy at Scripps that measured all the fission products from the Redwing tests, and they showed that the plume rose to a certain height in the ocean, and then it spread laterally. For 1,000 kilometers you could see this thin film spreading out laterally and transporting fission products. And it was the first indication of how the ocean really circulated in those days, that the [???] advection of layers. For that distance and that time it was amazing.

Weart:
Did he also have an interest because of this project Sunshine business to see what happens with [???] ?

Craig:
No, he wasn’t interested in that. That was in good hands. Libby and Marquel [?] were running it.

Weart:
Were you ever involved with any of this AEC business?

Craig:
No.

Weart:
[???][???] radioactive isotopes and so on?

Craig:
No, not with the fission or anything like that, no.

Weart:
So why were you interested in ocean turnover time?

Craig:
I was interested in everything in those days. Well, first of all I wanted to go to sea because I had loved the Navy so much and being on a ship at sea. And I loved being at sea. And secondly, because I wanted to do things in deep water. Well, I just became interested in the problem. In those days at Scripps it was a big thing. Nobody knew how old the deep water was and how it circulated and mixed. And we did various things. We looked at — well, ultimately we came to look at the helium, which was the big thing. It showed this beautiful circulation from the helium 3 generated at Ridgecrest. That was one of the major things that I did with Brian Clark at that time was show that you could see this stuff coming out of the Ridgecrest all the way across the Pacific. The first helium 3-4 measurements we made at sea, that I collected were from ’69, ‘68, ‘67, ‘68. And I collected stuff from in the Kermadeck Trench [?]. And we thought — it was for an entirely wrong reason. It was great serendipity, which was a lot of my career was serendipity. But we thought, according to Roger, helium 4 should be coming out of the bottom of the ocean along with the heat flow. It was all radiogenic heat flow; helium 4 should be coming out. At that time nobody could measure the helium 4 accurately in the oceans. The equipment wasn’t good enough. But secondly nobody knew the solubilities of helium in the ocean so you couldn’t compare it with solubility very well because there was very bad data on that. And thirdly, as it turned out as we found, air bubbles carried down into the sea by breaking waves and wind get carried down into the water and contribute excess helium relative to — excessive gasses relative to the simple solubility, and they get carried down into the deep water. And so there were three problems there. And one way or another Brian Clark and I decided, an ingenious idea of Brian Clark’s, we should look at helium 3, helium 4 ratios, which nobody could measure accurately in those days. And the reason being that we would find a dilution of the helium 3-4 ratio in the deep water by the radiogenic helium 4 coming out of the bottom of the ocean. So we should see lower helium 3-4 ratios there because it was diluted with this radiogenic heat flow of helium.

Weart:
And you were looking at it —?

Craig:
Vertically. And so we should see an excess of helium 4 over solubility and over the air bubbles, because the solubility and the air bubbles would carry atmospheric helium 3-4 ratios in. But the radiogenic helium 4 atom would dilute that ratio. So I went out to the Kermadeck Trench, and we only had an 8 or 10 big steel flask was all we could afford at the time, and we took water way down at depths of — we thought that you would find the biggest effect at the bottom of the trench. It didn’t occur to us then that the bottom water in trenches has oxygen in it, so it can’t be very old because somebody has got to supply that oxygen to the trenches. The water flows down and it flows through, but that didn’t occur to us. So we took samples in the Kermadeck Trench between 6,000 and 10,000 meters, very deep. But being very careful in some ways, for some reason I under-though, I took three bottles in the upper water. And one bottle happened to be at 2,200 meters and the rest were above it. Well what happened was we found a moderate effect, but it was the other way. Helium 3 was increased relative to helium 4 by about six percent in the bottom waters, but at 2,200 meters it was enriched by 20% or more, some 25% I think, in helium 3, the ratio. And because of the Redwing experiment, and because plate tectonics was just beginning then, and people were talking about east-specific [???] rise and the heat flow at east-specific rise and so forth. And because of the Redwing experiment that showed this [???] stuff spreading out for a thousand kilometers, I recognized, just because of these things, right away that this stuff must be generated at the east-specific rise, plus volcanism along the east specific rise was bringing helium 3 out of the Earth. Brian Clark was sure this had to be primordial helium 3; there was no other way. It was like meteorite helium 3. And I recognized it came out of the east-specific rise and it must have been carried all the way across the ocean some 10,000 kilometers, and you must be seeing it over at the Kermadeck Trench. And there was of course a great resistance to the idea. But we later—

Weart:
Going back to 1956, ‘57, were you aware of the Redwing stuff, or was that sort of [???]???

Craig:
Yes, we knew all that. That was released and Roger and — because Fulsome had worked on it on the grounds it would not be classified.

Weart:
So you had several reasons for realizing that there was a —

Craig:
Well the big thing was it was the opposite from what we were looking for, and we were able to use that. And in fact, it was what Harold Urie always said. "If you find an unexpected answer that’s the opposite of what you’re looking for, it’s almost always much more interesting than the original thing you were looking at." And that was true, because we were later able to pinpoint where the hydrothermal vents were on the east specific rise by looking at gradients of helium 3.

Weart:
When you were doing this work, how much of an interest was there at all in what we now understand as the global warming effect and what Calendar was working on?

Craig:
Just Roger Ravel and Hans Souse. They were voices —

Weart:
They were interested in the question of the oceans [???]?

Craig:
Yeah. I was not particularly interested in it because I saw — when I see the general answer to a problem, and I recognized that there was about half as much CO2 in the atmosphere as had been combusted, that’s often for me enough to see the general thing and go on to something else.

Weart:
Was Souse interested in long-term things like this?

Craig:
Oh yes, Souse was very much at that time. I tend to back off and go to something new. I like to discover things. But Roger felt very strongly this was important to humanity, and that’s why he wanted to develop that.

Weart:
Getting to this, you mentioned this one paragraph in the paper where he talks about the ocean actually, where the surface layer contains much less carbon dioxide than you would think. Do remember did he come and talk to you about that?

Craig:
Souse?

Weart:
No, Ravel, when he first realized it.

Craig:
A little bit, but we worked pretty well independently. He worked with Souse on it, I did my stuff, and then we got together and compared. There’s a section in that paper at the end where I discuss our different approaches, which was not very often done in those days. But I did it.

Weart:
Even in Ravel and Souse’s paper it seems to me, except for that paragraph, has more like a steady stated approach. That it, it imagines that the carbon dioxide being generated and going into the surface layer [???] deep water—

Craig:
But the coal burning produces 12C in a transient situation. That’s what they analyzed. They used that very simple differential equation, which actually wasn’t quite correct. But they got out of it, because it was the Souse Effect that was the big thing. But of course the Souse Effect determined depended on knowing the 13C distributions, which I had measured. So I was interested in it from that viewpoint. But it took two isotopes, 13C and 14C. Many people didn’t recognize that. They thought well, you just get it from 14C. But you couldn’t unless you knew the 13C variation, too. The 13C was what shows you that the surface ocean carbonate CO2 was 400 years old. But other than that — No, they were doing different things. They were doing the transient effect primarily, and what they were really bogged down or what took a long time to really work out was the Ravel factor, this business that the CO2 in concentration increases and the partial pressure in the atmosphere increases into a much greater rate.

Weart:
The way it looks to me is they realized there was a seven year residence. And if I were [???] and I were to think well, seven years and then it goes and circulates down through. And at some point Ravel said it goes in, but then it evaporates back out, and what really counts is how much can stay in there. I think nobody before Ravel had thought that, asked that question. Not just how fast does it go in and out, but [not audible].

Craig:
I covered that in my paper by developing a function that’s used in that paper of the effective mass of CO2 that exchanges with the surface, and I used different values of it to derive what the total 14C balance in the ocean would be. And then we knew the production rate pretty well, because people had calculated the production rate of 14C. So you could match that to the 14C rate, and you could see that the deep water had to be about a thousand years old. And I did a later model which was called the out-crop model nowadays. Remember that model? It looked like this with the mixed layer in here and the polar waters mixing in. So that came into that to some extent. We were interested in — I was interested in that because primarily of studying ocean circulations. Also because Roger was a great influence to keep you interested in something. After these papers were done we would discuss it a lot. He was the kind of guy that would come walking through the halls into your lab late at night, and if you weren’t in your lab he would — I lived very close, right across the street from Scripps, so he would always stop at my house if I wasn’t in my lab. He wanted somebody to talk to. He would roam the halls at night. And if he didn’t find him he would go to somebody’s house. He always wanted to talk science. He would come to my house and we’d sit all night and we’d talk about CO2 and things like that. So it was great to have a director like that who was a fantastic influence on you. You can never be totally uninterested in something you’ve been working on with a guy like that. And Roger thought rather slowly about things. He was the guy that had to take it in and digest it and really understand it and chew at it before he really got down to the real understanding of it. He was wonderful that way. So he’d come back and he would say "but this is the something, but that is an effect, and what about this," and he would come back at it over and over again. In a way it reminded me of the Einstein-Bore correspondence where Bore would keep coming back to Einstein with other problems and chewing and chewing and chewing on it. We took Neils Bore to sea once. I went out to sea with him. I took him to sea on one of our ships for a short cruise. And I thought, "My God, I have the chance to talk to this great man at sea and to really find out so many interesting things." And you know, we talked back at the fan tale of that ship, and it was so noisy back there with the engine going and the wind blowing, and Bore [???] you had to put your ear right next to his mouth to hear anything. I heard almost nothing that he said on that whole trip.

Weart:
[???] that nobody could understand what Bore had to say. I had a couple of other questions. These are just sort of little random ones that I ran across. [???] had to do with Kealing. [???][???] start measure —

Craig:
I brought him there. I remember it well. Roger wanted a guy to start setting up CO2 analyses of the air so that he could see for himself how fast it was increasing, and who could be the guy. Charles David Kealing had been at Northwestern working with Malcolm Dole using oxygen [???]. He actually did his thesis on polyethylene. Old Dole was an organic chemist. Dole had worked on oxygen 18-16 ratio of atmospheric oxygen, doing a lot of rather bad work on that.

Weart:
Then he went to Cal Tech.

Craig:
Then he went to Cal Tech, started setting CO2 measuring with Sam Epstein’s mass spectrometers, and I knew him there. We had sort of a local California society called the Epilogical [???] Society, Epipaleological Society, whatever it was. And I knew Kealing real well, and I knew that he was exactly the guy, because he was your classical pedant. He would work on something with the utmost attention to every little bit of detail. I mean, he wrote a banometer [???] description that cost $100,000 before it was done. And so I said I know exactly the man you want. I brought Kealing down, and that was it. [???]

Weart:
One place I ran across the name was if Kealing was there on IGY funds.

Craig:
Yes.

Weart:
And the IGY funds only lasted up to a certain point, and then it began to run out. I found a letter from you to Souse saying that [???] financial [???]. Do you remember that?

Craig:
Oh, is this from Souse’s — you’ve been through Souse’s files? No, at Scripps you [???].You can see all that.

Weart:
[Not audible]

Craig:
Saying what?

Weart:
Saying that Kealing was going to run out of money [???]

Craig:
That’s right. Roger did something. I don’t know how he got money for him.[???]

Weart:
I’ll tell you how. Let me see, Souse said I have enough money, you take some of my AEC’s money. You can pay me back when I get my next grant. That’s what they did.

Craig:
Ultimately they had to get him into the NSF because there was no other way.

Weart:
So that’s [???]

Craig:
There was a lot of criticism about having Kealing there. People said he’s only doing the same thing over and over again. He’s not doing fundamental research; he’s just measuring to more decimal places and measuring the same thing over and over again. Somebody said that was true, but Roger always used to say in later days, after it was well established about the CO2 thing, Roger would always say, "He’s the only scientist in the world who’s data has been seen both by the President of the United States and the Queen of England."

Weart:
One more thing. 1965, the President signs the [???], the Environmental Pollution Act.

Craig:
PSAC, yeah.

Weart:
You were on the Environmental [???]

Craig:
I was?

Weart:
Your name is down there.

Craig:
My gosh, I guess I was. I have a bad memory for the past, you know. I tend to think forward, and I have a very bad memory. Fortunately my wife has a very good memory. She can tell me where we were any time. But I don’t.

Weart:
OK, well then I won’t ask you [???]

Craig:
I guess I was on PSAC. Was that something that Detler Bronker [?] arranged? I bet it was.

Weart:
I don’t know. There was a sub-panel that Ravel chaired, and you and Kealing and some other people were on it, and this was the first place that was recognized at the highest level that the greenhouse effect would be a problem that was serious. You don’t have—

Craig:
Yes. Kealing’s Curve showed that. That was the thing that really showed that. But I don’t remember much else about it.

Weart:
Well, one thing I was going to ask was what was the main thing [???]Kealing’s Curve [?]?

Craig:
Yes, it was Kealing’s Curve that really showed it dramatically.

Weart:
See, the Academy wants to release the papers from that, so I guess 20-15 [???].

Craig:
Why?

Weart:
They have a [???] rule. You can’t see the papers of the — oh wait a minute, that wasn’t an Academy thing; that was [???].

Craig:
They won’t release the papers? My God, it sounds like the Brits with World War II [???].

Weart:
The Academy can’t see papers from their studies for 50 years. I’ve forgotten, that was a [???]. Now, you said that you had some letters, like Calendar’s and so on.

Craig:
I have the letter from Calendar, and a — I only have one that I saved I think. Calendar has correspondence with me. They have that in Calendar’s files.

Weart:
Where are Calendar’s files?

Craig:
At this guys’ place in Norfolk, or at least at the metrological office and he has access to them.

Weart:
I’ll have to get in touch with him.

Craig:
I’ll get his name for you, and I’ll send you his name.

Weart:
I would very much like that. Let me give you my card so you have my—

Craig:
Even your e-mail. I can give Paul Dennis your e-mail address. But Calendar was very concerned because he wanted to believe his data that he had selected, and they matched the total amount that had been put into the atmosphere, and he didn’t want to give that up. He thought the residence time must be very long in the atmosphere, and he really disliked the idea that only half of it remained in the atmosphere; where did the rest of it go, and when [???].

Weart:
Did you meet him?

Craig:
No. I wish I had.

Weart:
Nobody seems to have met him. [???].

Craig:
Ravel met him I think. I’m sure Roger went to see him.

Weart:
It doesn’t seem he’s got anything [???]. Did he publish papers on anything else he did?

Craig:
Yeah, there was something else he did, but I’ve forgotten what it was. He did some other things, but I haven’t looked at them. But they know this at Norfolk. They have everything about him. Even though they believe that he couldn’t have picked out the right data from this random thing. I told him no, that’s not true. That’s the mark of a really exceptional guy.

Weart:
Right. [???]. Do you have other old papers? Do you have letters you exchanged with Souse or other people like that?

Craig:
Probably. I’ve never — they keep begging me to give my correspondence to the archives. Deborah Day does. But first of all there’s a lot of stuff that’s kind of sensitive about people. Well, I guess you can restrict that. But secondly you would have to go back and sort it out. I hate to do that, to go back through my files and go through it and pick out—

Weart:
Well, you don’t necessarily have to do that [???]. She can do that for you. [???].

Craig:
Yeah, but she has to know — I was the Chairman of the Department and the Division of Earth Sciences for a while.

Weart:
Their [???] is pretty good.

Craig:
OK. I was the director, head of the Department. I was Chairman of the Department and the Division, and there are some sensitive things and battles about promotions—

Weart:
She has Ravels papers. Can you imagine the sensitive stuff that’s in there?

Craig:
Oh yeah. But I know the stuff in Ravel’s papers, I’ve never gone through them, but in his papers and Urie’s papers this stuff on promotions and things like that is restricted. So that’s probably a good idea.

Weart:
That’s the thing is they know how to set aside the —

Craig:
Well, I’ll do it one of these days when I’m not so busy, don’t have so much to do.

Weart:
Can I come and look through some of these?

Craig:
Sure, if I can ever get time to sort them out.

Weart:
You don’t have to sort them out.

Craig:
I’ll sort them out for the archives. I’ll give them to the archives one of these days. What’s your time scale?

Weart:
Well —

Craig:
Now, I know. Everybody is now.

Weart:
I’m going to be in California in June.

Craig:
I don’t think I could have it sorted out by June I don’t think.

Weart:
You don’t have to sort anything out of it. Just point me to it.

Craig:
I’ll tell you what the trouble is, though. The trouble is over the last few years everything is on e-mail and it’s in the computer, but most of it’s not printed out.

Weart:
All I want is the correspondence with — I don’t want your sensitive stuff. I don’t want [???]

Craig:
Yeah I know, you want Souse.

Weart:
[Not audible]

Craig:
I don’t think there’s much correspondence with Souse and Ravel because we were right there talking to each other. It would only be with Calendar. I can rig up the Calendar stuff because I think I looked at some of it when they showed me Calendar’s files. In fact the letter I have — I have a copy of the letter. I’ll find that letter. They gave me a copy of it. [Tape cuts out] ...many, many projects with many, many people, so that there were so many things going on and different things that we were working on and different ideas and different things. And I got interested in other things. Well, I was interested in the ocean circulation. Another guy who had a lot to do with that was Fritz Koczy. He was a great scientist, great scientist. He was a Hungarian and he was one of the immigrants from Europe because of Hitler, and he set his laboratory to measure radio nuclides in the ocean at Miami and did the first radium measurements throughout the ocean. And he was the first to invent this model that later became well known when I applied it to carbon of the vertical diffusion advection model for the mixing of CO2, which is now the basis of what’s now called the Esker [?] model which combines the box diffusion — the box model at the surface with vertical diffusion into the deep water. Koczy did it only using diffusion and not vertical advection. But he did the radium, fit the radium concentrations that way and showed that this kind of a model could be used with a variable diffusivity, and he could explain his profiles even though the data were not very good. Ultimately I got into measuring radium and we did a lot of work on radium in sea water to get the profiles because we’re interested in the circulation. But I used the Koczy model, adding vertical advection. Well, Klaus Ruerkie [???] had done something on that and Walter Moock [???] had done something on that, but those models—

Weart:
This was about what period?

Craig:
Oh, ‘60s. But they hadn’t included in their models the biological effects from carbon, which turned out to be very important. And I did a model which was published, it’s called ABC these days, abyssal carbon, in which I used the vertical advection, which we knew roughly from the amount of ice, of water, that’s generated in the Antarctic and in the North Atlantic from the melting of ice and the change in [???], we know roughly what it should be, the vertical advection term. And diffusivity, turbulent diffusion parameter, and added the biological production of CO2 into the deep water, which is very important, because the organic matter sinks and it’s oxidized down in the deep water. And surprisingly it turned out in this model, which we could see at the same time for measurements that were going on of 14C that the 14C constant of deep water in the oceans, the activity of 14C, or the actual concentration of the 14C atom in the deep water is more or less constant throughout the oceans. Most people don’t recognize this, but still. What changes is the 13C and the 12C. The 12C is increased by the fact that that the organic matter sinks as it’s being oxidized. It uses up oxygen, gives the low oxygen to the deep water, but it adds 12C and also of course 13C. And so the 12C dilutes the 14C-12C model. So when people talked about 1,000, 1,500, 2,000 year age of deep Pacific water, they’re talking only about it’s the effect of the addition of 12C and some 14C coming down too. The addition of 14C by organic matter sinking into the deep water just about balances the decay of 14C. The decay of the mean life, radioactive mean life, is 8,200 years, and 12C is added with a characteristic time of about 10,000 years and 14C of just about 8,000 or 9,000 years. So the result is that the 14C atom concentration throughout the deep water remains the same, but the 12C concentration goes up, and this gives you an apparent age for carbon — which is not the age of the water in any way, but the age of the carbon — and it gives about a 1,500 year age, 1,200 year age in deep Pacific carbon.

Weart:
So tell me, if you went back to your Tellus paper, how much would that be changed by what you know now? For example, you really have the 14C [???].

Craig:
Right, I didn’t have the data. It wouldn’t change very much. It sort of would be about the same. You could pick those different values of that function and it wouldn’t change the box model agent very much. But the box model doesn’t tell you anything about what’s happening in actual circulation. We use a two dimensional model these days. I’ve been working on argon 39 —

Weart:
[???] a while back. I want to go back to this early box model, because I’m a little curious now. When you were in Urie’s group you were experiment, instrumental. Then you came up to Scripps and the first thing you’re doing is you’re doing what I would call theoretical [???]

Craig:
But that’s because our lab wasn’t built for two years after we got there. The AEC delayed the money. We just had bare ground with vertical columns and we had to build a lab. But secondly, that ground had been promised to somebody else by either Roger or I’m thinking there was somebody else, so we had a hell of a fight to set up a lab, and it took us a couple of three years. And then after that I had to set up the mass spectrometers. So it took about three or four years before we were organized to be able to reflect data.

Weart:
So you were [not audible]

Craig:
Yeah. It was an interesting project at the time and I was interested in it. Well, I’ve done a few theoretical things since then. I don’t mind — I like to do theoretical. But it was mainly because of that. I suppose if we had a lab already functioning — Well, I was interested in it and I wanted to do that work because it was the outgrowth of this where I first realized that [???]. I wanted to finish that.

Weart:
[???] had to do with [not audible sentence]

Craig:
But I also wanted to get to sea, but I couldn’t justify, I couldn’t get grants to go to sea until I had a working laboratory. I had to be able to say I was going to do something with the samples we collected. So I had to get a laboratory first.

Weart:
Now you were supported at Scripps, we had it on our contract [???]

Craig:
I was AEC at first. It was that contract that John von Neumann gave to Roger Ravel, and that set up our lab and gave us our support. Then AEC began to get leery about [???] environmental stuff like that.

Weart:
And your Tellus paper you said was supported by ONR.

Craig:
That must have been ONR at that time, yes, because Scripps had a lot of ONR support, naturally. And I was supported by ONR, then I started getting NSF money.

Weart:
Were you ever involved in applying to ONR, or was that all done by Ravel?

Craig:
No, I think we had to write our individual proposals and somebody packaged them all together into a package to ONR, then he would go and defend them to ONR. But we had to write individual proposals. I was supported by ONR for quite a while.

Weart:
Do you have a copy of that?

Craig:
The old proposals?

Weart:
Yes.

Craig:
I probably do because I just told Val to throw them all out. But there are still some of them around.

Weart:
Oh don’t throw them out, because you can’t find them in ONR. The ONR directors, either they’re security classified or they point you to a warehouse that’s about a million cubic feet capacity and say it’s somewhere in there. So if you can find your old proposals to ONR —

Craig:
I’ll look for them. And to AEC. All right, I’ll look for them. But I’m just in a state where I’m about ready to throw them all away.

Weart:
Well don’t do it.

Craig:
I won’t do it. I want my fitness reports from the Navy. I want to look back at my old fitness reports and see what happened, see what was said about me. I want to go to the Bureau of Personnel and try to get those from Freedom of Information or something.