Environment / Global Warming

Most leading climate experts don’t agree with Henrik Svensmark, the 49-year-old director of the Center for Sun-Climate Research at the Danish National Space Center in Copenhagen. In fact, he has taken a lot of blows for proposing that solar activity and cosmic rays are instrumental in determining the warming (and cooling) of Earth. His studies show that cosmic rays trigger cloud formation, suggesting that a high level of solar activity—which suppresses the flow of cosmic rays striking the atmosphere—could result in fewer clouds and a warmer planet. This, Svensmark contends, could account for most of the warming during the last century. Does this mean that carbon dioxide is less important than we’ve been led to believe? Yes, he says, but how much less is impossible to know because climate models are so limited.

There is probably no greater scientific heresy today than questioning the warming role of CO2, especially in the wake of the report issued by the United Nations Intergovernmental Panel on Climate Change (IPCC). That report warned that nations must cut back on greenhouse gas emissions, and insisted that “unless drastic action is taken . . . millions of poor people will suffer from hunger, thirst, floods, and disease.” As astrophysicist ?Eugene Parker, the discoverer of solar wind, writes in the foreword to Svensmark’s new book, The Chilling Stars: A New Theory of Climate Change, “Global warming has become a political issue both in government and in the scientific community. The scientific lines have been drawn by ‘eminent’ scientists, and an important new idea is an unwelcome intruder. It upsets the established orthodoxy.”

We talked with the unexpectedly modest and soft-spoken Henrik Svensmark about his work, the criticism it has received, and truth versus hype in climate science.

Was there something in the Danish weather when you were growing up that inspired you to study clouds and climate?

I remember being fascinated by clouds when I was young, but I never suspected that I would one day be working on these problems, trying to solve the puzzle of how clouds are actually formed. My background is in physics, not in atmospheric science. At the time when I left school and began working, it was almost impossible to get any permanent work whatsoever in science. That was why, after doing a lot of physics on short-term things at various places, I took a job at the Meteorological Society. And once I was there I thought, “Well, I had better start doing something.” So I started thinking about problems that were relevant in that field, and that was how I started thinking about the sun and how it might affect Earth.

It was a purely scientific impulse. With my background in theoretical physics, I had no—well, certainly not very much—knowledge about global warming. I simply thought that if there is a connection to the sun, that would be very interesting, and I certainly had no idea it would be viewed as so controversial.

In 1996, when you reported that changes in the sun’s activity could explain most or all of the recent rise in Earth’s temperature, the chairman of the United Nations Intergovernmental Panel called your announcement “extremely naive and irresponsible.” How did you react?

I was just stunned. I remember being shocked by how many thought what I was doing was terrible. I couldn’t understand it because when you are a physicist, you are trained that when you find something that cannot be explained, something that doesn’t fit, that is what you are excited about. If there is a possibility that you might have an explanation, that is something that everybody thinks is what you should pursue. Here was exactly the opposite reaction. It was as though people were saying to me, “This is something that you should not have done.” That was very strange for me, and it has been more or less like that ever since.

So it’s difficult to do climate research without being suspected of having a hidden agenda?

Yes, it is frustrating. People can use this however they want, and I can’t stop them. Some are accusing me of doing it for political reasons; some are saying I’m doing it for the oil companies. This is just ridiculous. I think there’s a huge interest in discrediting what I’m doing, but I’ve sort of gotten used to this. I’ve convinced myself the only thing I can do is just to continue doing good science. And I think time will show that we are on the right track.