SPIEGEL ONLINE: But weren't you one of the alarmists 20 years ago? Do you think your position at that time was wrong?
Bengtsson: I have not changed my view on a fundamental level. I have never seen myself as an alarmist but rather as a scientist with a critical viewpoint, and in that sense I have always been a skeptic. I have devoted most of my career to developing models for predicting the weather, and in doing so I have learned the importance of validating forecasts against observed weather. As a result, that's an approach I strongly favor for "climate predictions." It's essential to validate model results, especially when dealing with complex systems such as the climate. It's essential do so properly if such predictions are to be considered credible.
SPIEGEL ONLINE: You think there's a need for climate research to do some catching up in this regard?
Bengtsson: It is frustrating that climate science is not able to validate their simulations correctly. Since the end of the 20th century, the warming of the Earth has been much weaker than what climate models show.
SPIEGEL ONLINE: But the IPCC report discusses these problems in detail.
Bengtsson: Yes, the scientific report does this but, at least in my view, not critically enough. It does not bring up the large difference between observational results and model simulations. I have full respect for the scientific work behind the IPCC reports but I do not appreciate the need for consensus. It is important, and I will say essential, that society and the political community is also made aware of areas where consensus does not exist. To aim for a simplistic course of action in an area that is as complex and as incompletely understood as the climate system does not make sense at all in my opinion.
SPIEGEL ONLINE: In the past, you have complained about what you described as a strong tendency towards politicization in climate research. Why have you now joined an organization that is inherently political in nature?
Bengtsson: Throughout my life, I have been fascinated by predictability and frustrated by our inability to predict. I don't believe it makes sense for our generation to believe or pretend that we can solve the problems of the future because do not understand what these problems will be. Just do this thought experiment: Imagine you're in month of May 1914, and try to work out a plan of action for the next 100 years! Hardly anything will make sense.SPIEGEL ONLINE: So do you suggest we should carry on with business as usual just because forecasts are complicated?
Bengtsson: No. I think the best and perhaps only sensible policy for the future is to prepare society for change and be prepared to adjust. In 25 years, we'll have a world with some 9 to 10 billion people that will require twice as much primary energy as today. We must embrace new science and technology in a more positive way than we presently do in Europe. This includes, for example, nuclear energy and genetic food production to provide the world what it urgently needs.