'Climate findings used for political purposes'

A number of climate scientists have accused the Delta Commission of misinterpreting their findings on rising sea levels for political purposes. The commission was set up last year by the Dutch government to report on how the Netherlands can best prepare for global warming.

Climate scientists have been fiercely debating whether the results of the Delta Commission are accurate or whether some findings have been exaggerated. International scientists who worked on the commission’s recommendations feel their work has been high-jacked for political purposes.

“We were asked about the worst possible prognosis for the Netherlands over the coming two centuries. We were asked which scenarios could not be ruled out because of a lack of information. The commission then presented our findings as probabilities. That's not fair,” says Hans von Storch, director of the institute of coastal research in Germany.

Roderik van de Wal, a glacier expert at Utrecht University, shares this opinion. He too took part in the study of the 'worst possible' scenarios relating to rising sea levels. “We concluded that the highest level of increase for the Netherlands would be somewhere between 55 and 110 centimetres by the year 2100, with a margin of error of around 30 centimetres. Not only did the commission emphasise the maximum limit, but also the maximum possible margin of error. This gives the wrong impression. It frightens people unnecessarily.”

Plausible maximum

The chairman of the Delta Commission, by former Dutch agriculture minister Cees Veerman, presented his conclusions on September 3.

Members of the commission strongly deny the accusations. They say they did not predict probabilities but possibilities. Pavel Kabat, climate scientist at Wageningen University and a member of the Delta Commission, also defends the report's conclusions. “Our advice referred to the plausible maximum, so that this could be taken into consideration when deciding what measures to take. It’s like building a bridge - the design must take into account the heaviest load that will use it.”

The dissenting scientists have the impression that their research has been used to put politicians and the public under pressure. “Of course, what they actually wanted was a billion euros,” says Hans von Storch referring to the fact that the commission concluded that between 1.2 billion and 1.6 billion euros a year is needed to protect the country against rising sea levels. And his Dutch colleague Roderik van de Wal says: “A political choice was made on the basis of our findings. The conclusions could just as well have been different ones.

“Take the melting of the glaciers in Greenland and the Antarctic. In recent years they have been melting more quickly than we thought. But we don't know why, nor how long it will continue. This does not mean that because of this you can already predict that the sea levels will rise more in another hundred or two hundred years. You could also decide to review the situation in another ten years.”

No regrets in the future

Von Storch: “Why are we already deciding what measures to take? The commission is behaving as if the worse case scenario is already a certainty. Whereas there’s still so much we don't know. It is quite possible that in another year we will know if this scenario [in the report] is less or more probable.”

But Kabat defends the commission’s conclusions: “We are proposing measures intended to guarantee that we will have no regrets in the future. For instance, by shoring up the coast with extra sand you are taking into account the possibility that sea levels could rise faster than expected.”

Kabat says he regrets the commission did not invite all the scientists from the international community to the presentation. “Then they would have had a better understanding of how we went about our work.”

Last week, the Delta Commission published a number of studies which had served as a basis for its findings. The report on the worse case scenarios was not among them “because it is currently being subjected to a peer review for a scientific publication [Nature].”