When they met once in Hamburg, Klaus Hasselmann may have acted like a mathematical magician to Angela Merkel.

You, the young environment minister in the Kohl cabinet, and he, the recognized climate researcher, strolled through the campus together.

Two physicists.

Hasselmann was the undisputed expert on what was scientifically called a climate catastrophe at the time.

And at the time, Hasselmann sounded just like Merkel, as we are used to today from striking schoolgirls: activist.

Joachim Müller-Jung

Editor in the features section, responsible for the “Nature and Science” section.

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But Hasselmann had the physical knowledge and the mathematical instruments in his head that Merkel urgently needed for the preparation of the third world climate summit in Kyoto.

The founding director of the Hamburg Max Planck Institute for Meteorology explained to the young minister on a walk what the world might look like in twenty, fifty and a hundred years from now, probably even in the year 3000, because that is how far Hasselmann's model projections went.

And Merkel?

For them it was new territory, fascinating.

Hasselmann was very sure of his cause. His then still young socio-economic models, "dynamic, integrated multi-actor models", were full-blown economic computer models that were used to estimate the impacts of climate change and caused quite a stir in the research community. Because with their relationship to the economy and politics, they had what it takes to make the political class more responsible for a rigid climate policy. What the models spat out, however, was obviously indigestible for most of the powerful at the time. Reading coffee grounds was still one of the more elegant formulations. In any case, Hasselmann's hyper-complex models did not develop any political impact for a long time.

So what satisfaction must it be for the now almost ninety-year-old Hamburg native that the award committee - together with the Japanese earth system modeler Syukuro Manabe - awarded him one half of the Nobel Prize in Physics. Not for his socio-economic models, but for his fundamental work on developing the first comprehensive atmosphere-ocean models. With them in Hamburg and temporarily at the Scripps Institute in La Jolla and at the Woods Hole Oceanographic Institution, he proved what is still politically highly explosive today - and against which physics amateurs are still lobbying today: that the climate models are based on solid physics and be able to make well-founded predictions of the global climate, even if the weather can only be reliably predicted for a few days. Seen like thisthe award from Hasselmann and Manabe is also one of the rare political messages the Nobel Prize Committee in Physics sends to the world.