Appy Sluijs on the NRC climate blog

Should climate scientists exaggerate?

Scientists are often enraged at the quality of the public debate, Appy Sluijs, climate scientist at Utrecht University, writes. But that debate is about more than just facts.

This blog was published on 29 May 2018 on the climate blog of the NRC.

'A tweet with utter nonsense. Anyone more rubbish to add?' This is how Gerrit Hiemstra responded on Twitter to Thierry Baudet's claims about climate change. A rather fanatical twitter storm followed. The readers' replies were far from mild, with support for both sides expressed in 140-character phrases.

You might know Hiemstra as the NOS public broadcasting company's weatherman. He also owns a company that makes weather forecasts and has ties to Wageningen University. Baudet is a politician and leader of the Forum voor Democratie [Forum for Democracy]. Hiemstra's area of expertise, meteorology, is clearly closer to the theme of climate change than Baudet’s. That is obvious. Yet it is doubtful as to whether Hiemstra has changed anyone's opinion. Has something gone wrong here?

The parties that loom large in the public debate on climate are, on the one hand, the extremist environmental movements and, on the other, so-called climate change deniers, whether or not fed by a professional lobby. The first believe that the Netherlands will be flooded in 20 years' time. The second are convinced that CO2 has a minimal impact on climate change. Both ignore the data collected internationally over decades, the subsequent scientific debate, and the resulting facts about human impact on climate.

The public debate on climate change, including the vast collection of unverified information in the media and on the Internet, is miles away from its scientific counterpart.

Unverified information

The public debate on climate change, including the vast collection of unverified information in the media and on the Internet, is miles away from its scientific counterpart. This applies not only to the topic of climate change, but also to issues such as vaccinations, immigration and genetically modified organisms - all of which directly affect emotion or our way of life.

Scientists are often enraged at what they consider to be the appalling quality of the public debate. Facts that are the result of years of analysis and scientific discussion are constantly being called into question in the public debate - by amateurs, would you believe. Yet, scientists have not been able to control the public debate on the basis of the facts, as shown by the example of Hiemstra and Baudet.
But is that bad?

Of course, we all want climate change to be debated on the basis of the climatic facts. But there is also a range of other issues, standards and interests at play in the public and political debates. Take, for instance, the economist with figures on the costs of climate mitigation, or a climate change denier who represents the (gut) feeling of part of the Dutch population. It is the public debate that determines which facts are relevant.

Different role

The scientist's role in this differs from the environmental movement's or climate change denier's. Firstly, the scientist must always stick to the current state of scientific knowledge - the others may exaggerate, trivialise or even lie. Secondly, the scientist’s opinion or motivation is irrelevant - in the classic model. Whereas some want to save the world and others represent shareholders of a large oil company, the scientist has to present the current state of insights without any bias.

So, journalists must ensure that they do not mangle the scientific and public debates. Do not organise a debate between a scientist and a climate change denier or an environmental extremist. Anyone with some debating skills can dismiss scientific facts that have been collected with great effort as nonsense or irrelevant without overexerting themselves and at the same time file their nails impassively. To the average audience, it feels like the scientist simply presents an opinion.

As scientists we have to realise that in the public debate we cannot settle a discussion with arguments, as we are used to.

As scientists we have to realise that in the public debate we cannot settle a discussion with arguments, as we are used to. Not everyone regards scientific consensus as decisive. If we want to have a greater influence on the public debate, we should not constantly play the unbiased puppet without an opinion. We have to be more creative with the communicative resources that we have.


Adrian Parr visited Utrecht University recently. She is an environmental and cultural philosopher, soon to be at Texas University in Arlington, as well as UNESCO professor of Water Accessibility and Sustainability. In one of her lectures she not only talked about the water problems in the slums of Africa, she also showed parts of the film she had made about them. The film has been awarded fifteen international prizes, also at major festivals. When she lectures or writes articles or books, she seamlessly adapts them to the audience. We, climate scientists, would do well to take so much flexibility as our example.

A great example of another form of communication is the wonderful website for secondary school students we created for the Netherlands Earth System Science Centre, a major national research project on climate. It includes profiles of doctoral students who, at the start of their 4-year research programme, show in a professionally produced film which scientific questions they are going to ask and how they intend to solve them. Updates are posted on a blog. In other words, it is a science website without answers. This is crucial to show that scientific facts are the result of years, sometimes decades, of careful research.

Hiemstra was also flexible; perhaps because he got angry or perhaps he consciously chose to take on a second role as a representative of science, that of debater versus a climate change denier. This discussion in 140-character phrases did not lead to effective communication of current scientific insights, of course. But he did stimulate the public debate, and the entire Netherlands gave the climate a moment’s thought.

Scientists at Utrecht University are regularly reporting on their research on the climate blog of the NRC. They are united around the strategic theme of 'Pathways to Sustainability'.