The Sustainability Review Interview with Dr. Wallace Broecker

We at The Sustainability Review had the privilege to sit down with the oracular grandfather of climate science, Dr. Wallace (Wally) Broecker, Newberry Professor of Geology in the Department of Earth and Environmental Sciences at Columbia University. We consulted him for his thoughts on his work and on the past and future paths of sustainability science. What follows is an edited transcript of our conversation. The Sustainability Review (TSR): What started you looking into atmospheric carbon dioxide accumulation?

Dr. Broecker (WB): The first thing I worked on was carbon 14 measurements. The emphasis was on two things: dating of late quaternary events, and using it to get the rate of ocean circulation by measuring the age of the carbon in deep water. The latter lead me to be interested in the carbon cycle. Right now 25 or 30 percent of the CO2 we produce is going into the ocean; eventually that will increase to 80 percent or so, but only over hundreds of years. The way we know this is by measuring the radiocarbon distribution in the ocean. That got me hooked.

While I was doing my thesis, there wasn’t much talk about CO2. Then several papers came out in the late 1950s and Charles David Keeling started his measurement series establishing how rapidly CO2 was going up. This made it more interesting. Could we explain what was happening? We knew the amount of fuels burned and we knew the increase in the atmosphere. Interestingly enough if you put a curve through the measurements assuming that 57 percent of the amount of fossil fuels burned remained airborne, excepting a few fluctuations, it fits Keeling’s curve beautifully. So where was the other 43 percent?

TSR: Where did these efforts take you? Can you touch on having to testify before congress?

WB: The frustrating thing was that in those days, congressmen would want something in the congressional record…initially, you’d be told you had five minutes…which meant they would jibber-jabber around and you’d be cut down to one minute.

I was asked to testify in the 1980s and I learned enough to know that writing down something to present was useless because you probably wouldn’t be able to use it at all, so I decided I’d write something to be published in Nature (1981). It was published and it was the first warning about abrupt climatic changes.

TSR: You once discussed how you find something sacred about science and that you don't like to see findings "monkeyed with." Once knowledge is in the open, however, scientists lose control of the conclusions people make. How do scientists deal with that?

WB: I think that scientists have to be very honest. I’ve always been very honest; people respect me for that. When you start exaggerating to get attention—and a lot of environmental claims have been exaggerated—that just destroys your credibility. I’m guilty of that now and then, but I try not to be.

TSR: How do you approach your work?

WB: I’m considered an idea person. Probably the best feeling you get is when you discover something new. If I had to base my reputation on measurements, I’d be run-of-the-mill. But I’m clever at putting apples and oranges together and coming up with something interesting. That is my strength. I often wondered why I could do that. I’m dyslexic, so maybe that has something to do with it; my mind works differently. People at times have said they’re afraid to show me data because I have such a quick mind that I spot what it means. That’s my talent.

TSR: Taking a step back, we found a profile of you in The New York Times from 1998. It shared some of your thoughts about computers ‘short circuiting’ a researcher’s thinking about the workings of earth’s ocean/atmosphere systems and that a pencil, on plain white paper are your investigative allies of choice. Who are your sleuthing companions these days?

WB: I started all this way before computer simulations. We used what we called box models where you transfer materials from one box to another. We learned enough about how the ocean works to build a simple model. Then we would get to the point where this allowed us to shortcut—we’d been through a number of steps and so we could add new ones more much more quickly.

TSR: In conceiving of this interview, we had an analogy in mind: sustainability science today may parallel where climate science was 50 years ago.

WB: Well, they’re very different. What I was doing was hard science, and in a sense, that’s much easier because you’re trying to do something tangible. A lot of sustainability science is less well-defined, and here [at ASU] specifically it’s more like social science than hard science. Where I am at Columbia it’s more hard science than social science just because Lamont Observatory is so big it tends to dominate the research direction of our Earth Institute. We started a sustainability concentration for undergraduates four years ago, and now there’s a sustainability major. It took a while to get the committees at the university to agree, because there is always the suspicion that it’s too diffuse. But of course, it has to be.

TSR: How do you see climate science informing sustainability science and sustainability science informing climate science? Do you see those interactions happening?

WB: There has to be interaction. If somebody has a scenario about switching to a new energy [we need to know], how much will it cost? What I do could be called reverse engineering. Engineers design systems. We try to figure out the design of God’s machine, the earth’s systems. It’s complicated. Just to make a model of the atmosphere that includes cloud droplets is a tough chore. So we’re working to understand how this system operates and therefore, what will happen if we perturb it. We’re good at what’s called "back of the envelope" calculations. It’s very important to eliminate the easy things right away. We quantify. You have to have that, because everything we do is going to cost money, and everything we do is going to have environmental consequences.

What I see now is that the concern about environmental consequences is stalling many things that could be done about CO2. We must get away from that mentality because everything we do has environmental consequences. Also I get discouraged when I see people competing. I was asking Klaus Lackner, my hero, why people are so antagonistic toward his idea that you can take CO2 out of the air. He said there are lots of reasons, and one is that there’s a large group of people who want to re-fit power plants and of course that would take huge profits. So they don’t want air capture. That’s insane; we must do both. One will prove to be cheaper and environmentally less objectionable and that one will win out. That’s the way the world runs.

TSR: You once noted, "No one lives on their past successes…It isn't very satisfying. You live on what you're doing this year, this month. My great joy in life comes in figuring something out. I figure something out about every six months or so, and I write about it and encourage research on it, and that's the joy of life" (1). What are you working on now?

WB: One is what I call the Mystery Interval. Twenty-five thousand years ago the carbon 14 content of the carbon in the atmosphere and upper ocean was 40 percent higher than now. That stunned us. By dating corals using uranium series isotopes, the radiocarbon signature content can be turned, making it possible to calculate back to what it was initially. In many different kinds of samples, it was shown to be 40 percent higher. Now we’re trying to figure out why that was. The only way we can explain it is that during glacial time the ocean was stratified—instead of mixing the radiocarbon through the whole ocean, it was mixed only through the upper part, while in the lower half radiocarbon was decaying away. Because of this the upper half in the atmosphere would have more radiocarbon and the lower half would have less, and then at the end of the glacial period these two reservoir were mixed together.

The other thing I’m working on is paleohydrology—using stalagmites and closed basin lakes—to say something about moisture history. Fifteen thousand years ago, during part of the deglaciation, the water cover in the great basin—Oregon, Utah, Nevada—was ten times more than today. That means there had to have been somewhat less evaporation, but also seven or eight times more water coming down rivers. That’s amazing. And there was probably only two times more rainfall. This wet period lasted hundreds of years, and then there was a millennial duration drought that cut the water availability to less than today’s.

We found that these changes are globally orchestrated. The thing that interests me is that what happened 15,000 years ago had to do with a shift caused by a southward shift in the location of the thermal equator. When the northern hemisphere was cooled by extra sea ice this shift made huge and abrupt hydrologic changes.

Climate change models say that as CO2 rises the northern hemisphere will heat twice as fast as the southern hemisphere. The reason is that there’s more ocean in the southern hemisphere—it will hold back the heating. This is going to shift the thermal equator. So the question is, will that produce similar effects to the shifts we see in closed-basin lake records? If so you Westerners are in bad trouble. However, what’s happening today is not the same as the previous shifts. One was induced by sea ice and the other was induced by differential CO2 warming. There are differences. Maybe the differences will cause what happens to be very different.


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