VATICAN CITY — German professor Hans Schellnhuber was one of the most influential scientists advising Pope Francis on his encyclical on the environment Laudato Si (The Care for Our Common Home).

As the founder and director of the Potsdam Institute for Climate Impact Research, the climatologist and self-professed atheist was involved from the beginning to the conclusion of Laudato Si and helped to arrange all four meetings on the encyclical, most recently acting as the spokesman of established climate research, according to the Frankfurter Allgemeine Zeitung.

On Wednesday, the Vatican announced Schellnhuber had been appointed a member of the Pontifical Academy of Sciences.

During his presentation at the Vatican launch of the Pope’s second encyclical on Thursday, Schellnhuber argued that failure to reduce carbon emissions will lead to “our neighbors and children” being exposed to “intolerable risks.” He also said that “contrary to what some have claimed, it is not the mass of poor people that destroys the planet, but the consumption of the rich.”

On a hopeful note, he said that “technologically, the deployment of clean energy for all is feasible: This energy, in fact, is available in abundance. All we have to do is develop the means to properly harvest it and responsibly manage our consumption.”

In the following interview with the Register, given after his presentation on Thursday, Schellnhuber responded to claims made in various reports that he favors population control, primarily by means of contraception and abortion. He rejected comments he allegedly made in 2009, saying the Earth has a capacity for 1 billion people instead of 7 billion, as it currently stands. He also responded to climate-change skeptics, who argue that there is no consensus on climate-change science.


Are you of the opinion that combating climate change will naturally lead to some kind of population control?

No, this is a popular confusion and distortion of the situation. I speak as a scientist of course, and of course there are ethical reasons to say population control is good or bad, or whatever. I’m not entering into that debate, but when it comes to the climate-change debate and one looks at the figures, if you do a sober analysis, you will see it’s not population dynamics that are jeopardizing the climate. Look at per-capita emissions for example … you have people in African countries who contribute next to nothing in terms of global warming.

So if you are able, by behavioral change, and that’s in the encyclical, to change the emissions of rich people by just 10%, it’s much more effective than any population strategy you might put in place.


Why is population control promoted then?

It’s easily said: “Let’s control the population,” but how would you like to do it? The biggest experiment in history is what China did with its one-child policy, and with this they will have a lot of problems to pay for because it will completely ruin their demographic development. So I would say it’s a red herring in the whole debate. It’s brought up, in particular, by those people who simply want to have inaction on climate and always point to something very toxic, namely population control, and they say: “Oh, with the Catholic Church, unless you’ve got your act together on demography and population, on reproductive health and so on, shut up when it comes to climate.”


You’re reported to have said in 2009 that the world’s climate would be stable if it had just 1 billion people instead of 7 billion. What did you mean by that?

Again, it’s a complete lie. You can go back to the original lecture. I gave it in Copenhagen. I know there are some vicious people who try to discredit you. I have never spoken in favor of population-control measures. What I said in Copenhagen in 2009 was about the carrying capacity of the Earth. There have been estimates since the 1700s on how many people the Earth can carry, so to speak. This number goes up and down, and some say 10 billion; others 100 billion; some just 100 million.

All I said was that if we had unlimited global warming of eight degrees warming, maybe the carrying capacity of the Earth would go down to just 1 billion, and then the discussion would be settled. There would be nothing to do. I was just saying that if global warming is not brought under control, we may see a collapse of human population; so it was just about cause and effect, and it had nothing to do with any proposition or suggestion. But these people just turned the wording around and will always find a way to attack you if they don’t like your overall course. So I feel totally innocent in all of that.


What alternative do you favor?

Since 2000, I have started a series of conferences with Nobel laureates on sustainability. We had [German] Chancellor [Angela] Merkel giving the keynote speech, and we’ve just had one in Hong Kong. Actually, some of my colleagues from the U.S. said: “Yes, climate change is good and so on to protect the climate, but what about population dynamics?” This goes back to Paul Ehrlich in the 1960s and The Population Bomb [Ehrlich’s bestselling 1968 book that predicted, among other things, mass starvation of humans in the 1970s and 1980s due to overpopulation).

I’ve always pushed back on that. I’ve said the climate problem is completely independent of the population problem. If you want to reduce human population, there are wonderful means: Improve the education of girls and young women. Then the demographic transition will be a little bit faster, and, as Cardinal Turkson said, you will enhance human capital and have the emancipation of many people on Earth. So I subscribe to a good education, and that’s the only way of population strategy I would support.


What do you say to those who say climate-change science is not proven?

It’s ridiculous. Are the [critics] maybe chemists? I’m a physicist by training, and I’ve worked on fundamental physics for a long time. I’m also a mathematician. The thing is the following: If you ask any scientific question, you’ll never have 100% certainty, not even in mathematics. There’s the famous mathematical theorem by Kurt Gödel, where a given mathematical hypothesis may not be proven true or false.

So when you have such a complicated question like: “Will greenhouse gases enhance global mean temperatures by four degrees,” do you really expect not be able to find one or two climatologists on Earth who will say it’s complete nonsense? If I give you a theory on superconductivity for example, I will find even 30% of people who will disagree with the consensus, so to speak. This is no proof [that it’s untrue]; it simply shows you that in a free country you can have a debate about everything.

Some people still believe the Earth is flat. I cannot disprove them unless they’re willing to go into a plane and go around the Earth, or space station. But if you would expect science to provide 100% certainty, then we would not be in the realm of science anymore, we would be church, and they have a different role than we have. So I do not think one should be fooled by these outliers.

Edward Pentin is the Register’s Rome correspondent.