‘How wonderful to be able to model complex environmental problems!’

He was at a meeting with international colleagues in Montpellier at the end of May when Detlef van Vuuren (53) received a phone call from NWO chairman Marcel Levi. “Of course, I was very surprised and also a bit overwhelmed.”

Although Levi urged him to keep the news as secret as possible, he had no choice but to share his joy with a colleague who was standing next to him. Laughing: “After that, I also called my wife.” Van Vuuren’s wife is Petra de Jongh, professor of Chemistry at Utrecht University.

Climate scenarios
Van Vuuren is particularly praised by the jury of the Spinoza Prize for perfecting the Image model, an abbreviated name of the Integrated Model to Assess the Global Environment. The model is used by the Netherlands Environmental Assessment Agency (PBL), where Van Vuuren works four days a week as a senior researcher. The model analyzes the complex relationships between the environment, economy, behavior and technology. As a result, it offers scientists and politicians insight into the effects of possible policy measures on the climate or the environment, among other things. 

The model played an important role in the reports of the Intergovernmental Panel on Climate Change (IPCC), the United Nations climate panel. Van Vuuren has been one of the authors and coordinators for many years. 

The maximum temperature increases in the Paris Agreement of 1.5 degrees and 2 degrees Celsius have also been supported by scenarios from Van Vuuren’s team. According to the jury, the Image model is ‘the crowning glory of a scientific career’.

Applied scientist
The fact that Van Vuuren, the professor of Integrated Assessment of Global Environmental Change at Utrecht University, has helped numerous scientists from all kinds of different disciplines with his easy-to-use models is evident from the fact that he is one of the most cited climate scientists worldwide. Reuters’ news agency put him in fourth place in a global ranking in 2021 for that reason. 

Van Vuuren says he is perhaps most proud of the fact that his work doesn’t just have scientific influence, but also social influence. He says it’s “really special” that “as a more applied scientist” he has now been awarded the Spinoza Prize. 

The combination of working at PBL and the university is ideal for Van Vuuren. He can freely conduct research together with PhD students, and at the same time, he has easy access to ministries and international organizations. In this way, he can also give Utrecht students an insight into administrative practice.

“But what exactly our influence on political and policy decisions is is always difficult to make explicit,” he says via a Teams connection from the Rocky Mountains. He’s attending the Snowmass workshop at Stanford University, which is well-known in his professional circle. “You can find your input in such a climate agreement, but it’s all very diffuse.”

Greenhouse accountant
The origins of his successful career lie in the 1980s when, as a student of Environmental Science at Utrecht, he was inspired by the Club of Rome’s famous report The Limits to Growth, with which a group of scientists sounded the alarm about the climate as early as 1972. “That was a real eye-opener for me. It’s great that you can use a model to try to understand such complex environmental problems and then create socially relevant scenarios.”

De Volkskrant now calls him ‘the greenhouse accountant of the world’ and Van Vuuren often publicly disseminates his knowledge about climate developments. Recently, he even appeared on stage at Tivoli Vredenburg – accompanied by an orchestra – to explain what humans’ ecological footprint means. 

But he eschews activism. “As a scientist, you have to remain a reliable discussion partner for everyone. Let me put it this way: both Jesse Klaver and Prime Minister Rutte must be able to see that as a scientist you base yourself on facts and not on what you think. At the same time, of course, I can see that not enough is being done. And of course, sometimes that’s difficult.’

‘Paris’ works out well
A question that the Utrecht professor is often asked is whether he is pessimistic or optimistic about the climate. The answer is balanced. Van Vuuren sees that the non-binding nature of the Paris Agreement is one of its biggest successes. Many countries have now made policies to achieve the targets they voluntarily subscribed to. Companies, banks and other sectors of society also seem to understand the importance of this. 

“My conviction is that in the end – despite all the resistance and interests – everyone will realize that climate policy is good for society as a whole. And that it is also cheaper than the alternative of doing nothing. But we will also have to share the burden equally.”

In any case, we will no longer achieve the maximum of one and a half degrees of warming without at least a temporary exceedance, Van Vuuren knows. But the target ‘well below two degrees’ should still be possible, partly thanks to innovations in the field of new energy sources, he thinks. 

“If we continue with the current policy, we will end up with about 2.7 degrees. The gap is still very large, but we have been able to adjust our projections in a positive direction in recent years. Of course, none of this takes away from the fact that we are seeing the consequences of the warming that we are already experiencing everywhere.”

Keep the faith
He is concerned about the election results in Europe and beyond. In the Dutch outline agreement, the Paris objectives are maintained, but the underlying policy is stripped back. 

“But what worries me the most is how we as a society deal with science. If we, as a society, are no longer able to act on the basis of facts but start proclaiming all kinds of alternative truths, then we will really end up in the swamp. What happened before with Covid now threatens to happen to the climate and to nitrogen. Keeping faith in science is super important.”

Planetary limits
Van Vuuren believes that model-based scenario research can contribute even more strongly to the understanding of possible solutions to the climate crisis in the coming years. However, he thinks more attention needs to be paid to “the fairness and feasibility” of those solutions and to the connection with other sustainability problems. 

He says he wants to use the Spinoza Prize to pay attention to this. “An interesting concept here is the so-called planetary limit for climate, nitrogen, biodiversity, water and a few other problems. What is needed to stay within these boundaries? But also: what environmental pressures will we face if we want to give everyone on earth a better level of existence? Shouldn’t we divide our resources a little more fairly?”