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Public Radio's Environmental News Magazine (follow us on Google News)

The Discovery of Global Warming

Air Date: Week of

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Global warming may be a well-known phrase today, but when scientists first started talking about it, they were usually talking to themselves. Host Steve Curwood and Spencer Weart discuss the historian’s new book, “The Discovery of Global Warming.”


CURWOOD: Long before global warming became a rallying cry for environmental groups and political fodder on Capitol Hill, it was a fragmented and obscure field of science. Few researchers thought to connect the many dots that would eventually outline the global evidence of human-induced climate change. Those who did met with resistance and a certain unyielding psychology among scientists, politicians and the public.

Historian Spencer Weart documents the twists and turns as climate change slowly emerged as a science. His new book is called “The Discovery of Global Warming.” And he says that it wasn’t one branch of science that made it all come together.

WEART: It took many different kinds of scientists to work on it, and for a long time many of them didn’t even know of one another’s existence. And even today it’s very difficult to get them all on the same page, so to speak. Climate change has also involved new social mechanisms, quite unprecedented in the history of science, for getting hundreds of scientists from different field all together to understand one another.

CURWOOD: Okay, so what are those different fields?

WEART: Well, besides volcanology, and solar physics, and oceanography, and biology, we obviously have to consider meteorology. And, perhaps quite crucially, computer science, in order to do the big computer models that we need. Then there’s also the ice caps which play a crucial role. And one can even dig down into what seem like obscure fields like soil mechanics, because the rate of runoff depends on how the climate changes. All sorts of things like that.

CURWOOD: Spencer, there are dozens of scientists mentioned in your book, but there’s one person, Guy Stewart Callendar, who seems to take a pretty big role in the story that you tell here. Could you tell us that story please?

WEART: He seemed to be one of these people who were common in the past century, who liked to sit around and do amateur science of one kind or another. And what he had done was to compile weather statistics. Other people had done this, and there was some indication in the 1930s that the world was getting warmer. And Callendar put together statistics better than anybody else had done so far to show that this was a truly global effect. But then, unlike everybody else, he thought that this wasn’t just some random thing, that it was something that we were causing. And he went back to old theories that had come out in the late 19th century that by putting carbon dioxide into the air we might be able to warm the Earth. This was something that most scientists paid little attention to, but Callendar went back and burrowed around in old statistics and found that, by George, the carbon dioxide level of the atmosphere actually was warming. And he said, see, we’re the ones who are responsible for this warmer weather that we’ve been having recently. And he stood up before the Royal Meteorological Society in 1938, and told them that global warming was something that might indeed happen and could perhaps even be seen at that time.

CURWOOD: Now, when Guy Stewart Callendar comes to this meeting, and says, hey, things seem to be warming up, did he suggest what might happen as a function of that?

WEART: Well, like most people at the time, he was mainly interested in it just as a scientific phenomenon, and thought “well, if it really does turn out that over the next few centuries we get a couple of degrees warmer that would be nice, because it will prove that carbon dioxide might have something to do with the ice ages,” which was the scientific problem that really interested people. At that time, people saw global warming as something that, if it did happen, would come only over centuries and be maybe a degree or so. Because people didn’t really picture how the world population and industrialization were increasing exponentially. And so people thought it would come very slowly, and also they thought anything that happened that slowly would probably be benign and it would make for better crops and that sort of a thing.

CURWOOD: Give me a sense of history as to when science began to understand that certain chemicals, that certain compounds, could change the balance of the Earth’s climate.

WEART: Well, people actually realized in the mid 19th century that the Earth’s atmosphere plays a major role in regulating the climate. The question that became interesting was “so what?” What difference does this make? It was probably because of the atomic bomb that people changed their minds about that. People began to think, well, maybe we are able to do things of global significance. And then, of course, along came ideas like chemical pollution, with Rachel Carson’s “Silent Spring,” the idea that the whole Earth might indeed be affected somehow by chemical pollution. So began to think, well, maybe the carbon dioxide that we’re putting into the air is actually enough to affect the whole global system.

CURWOOD: When does the scientific community begin to think pretty seriously that humans are promoting global warming, and why?

WEART: It was a very step-wise change. The first thing was the recognition that there might be a remote risk of global warming a couple of centuries ahead. And that came in the late 1950s and early 60s as a result of two developments. One was calculations that carbon dioxide level in the atmosphere really could rise, that it wouldn’t all just be absorbed in the oceans or in the rocks or whatever. And the second was a measurement by Charles Keeling which showed that the level was, in fact, rising. With the idea that, well, let’s go measure the carbon dioxide level in the atmosphere now, and then we’ll come back and measure it 20 years from now and see if it’s increased, and that will give us some idea whether we need to worry about global warming in the 21st or maybe 22nd century.

CURWOOD: Now, this is what, 1958?

WEART: This is 1957, ‘58. But Keeling, through enormous effort and ingenuity, managed to measure the level so precisely that in only two years he was able to show that the level of carbon dioxide in the atmosphere was being raised. That was certainly one of the main things that got people to thinking seriously about it, the visible demonstration that carbon dioxide has been rising year by year.

CURWOOD: When do the folks who make their living from carbon dioxide, with fossil fuels and the such, when do they start to pay attention to this?

WEART: Corporations can be very far-sighted about something that they think might concern their economic interests. And as soon as global warming was mentioned, back in the 1950s even, there were some corporate interests that were concerned about the bad image that it might give carbon emissions. And on the other hand, some people in the nuclear energy industry, already in the 1960s, began to say, well, if there ever is global warming, maybe nuclear energy will be the solution. And people in the coal industry began to say, no, no, you guys have it all wrong, there’s nothing wrong with carbon dioxide. This was already in the 1960s they were starting to do that. And the people in the energy industries, particularly coal, oil, and automotive industries, began to take steps, and by the 1970s, and particularly by the 1980s, they were spending a considerable amount of money in attempts to sidetrack the issue, and attempts to convince people that it was not a problem that needed to concern them.

CURWOOD: So, how did the scientists handle this? Here you have very deep-pocketed industry taking on the work that they’re doing.

WEART: Well, different scientists handled it in different ways. Some scientists, to be very blunt, took the money and found reasons to explain scientifically, as they thought it, why global warming did not need to be a problem. Other scientists took to the airwaves, so to speak, and began to give interviews to reporters so that they could mount their own educational efforts, as they would say. Most scientists didn’t trust any of this, and they had the viewpoint, well, we’ll sit here and do the studies, and they’ll be so definitive and convincing that surely the politicians will have to be convinced by the pure logic of our thoughts.

CURWOOD: Recently, 43 senators voted on a bill to reduce emissions that promote global warming. From a historian’s point of view, what do you think this recent action will mean in the greater history of global warming?

WEART: When I look at the way that this has been approached politically – and in the larger sense of the forces that are arrayed on both sides – I can’t help being reminded of the controversy over chemical pesticides, over ozone depletion, and one could name many other things including lead in gasoline, and tobacco, and so forth. Many cases in which initially it seemed ridiculous, in which powerful economic forces said there was no reason to worry. This just smells like that. It’s a case where sooner or later people will be convinced. But it takes a long time for the economic forces to be convinced that perhaps the issue can be attacked without seriously damaging their economic interests.

CURWOOD: Spencer Weart is director of the Center for History of Physics at the American Institute of Physics in Maryland, and author of “The Discovery of Global Warming.” Thanks for taking this time with me today.

WEART: Thank you. My pleasure.



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