Who is Klaus Hasselmann?

​​Klaus Hasselmann, born October 25, 1931, in Hamburg, is a German oceanographer and climate modeller. He is popularly known for developing the Hasselmann model of climate variability, where a system with a long memory (the ocean) integrates stochastic forcing, thereby transforming a white-noise signal into a red-noise one, which explains the ubiquitous red-noise signals seen in the climate. 

He has done research and published papers on climate dynamics, ocean waves, stochastic processes, integrated assessment studies and remote sensing

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In his papers on nonlinear interactions in ocean waves, he adapted Feynman diagram formalism to classical random wave fields. He later found out that plasma physicists were applying the same techniques to plasma waves. This made him realise that that he had rediscovered some results of Rudolf Peierls explaining the diffusion of heat in solids by non-linear phonon interactions. Therefore, he further reviewed the field of plasma physics, rekindling an earlier interest in quantum field theory.

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“It was really an eye-opener to realize how specialized we are in our fields, and that we need to know much more about what was going on in other fields. Through this experience I became interested in particle physics and quantum field theory. So I entered quantum field theory through the back door, through working with real wave fields rather than with particles.”

He has been awarded the 2021 Nobel Prize in Physics jointly with Syukuro Manabe and Giorgio Parisi for contributions to the “physical modeling of earth’s climate, quantifying variability and reliably predicting global warming” and “understanding of complex systems”.

This isn’t the first time that he has won an award. He received the 2009 BBVA Foundation Frontiers of Knowledge Award in Climate Change. He was also awarded the the Sverdrup Medal of the American Meteorological Society in January 1971, in May 1997 he received the Symons Memorial Medal of the Royal Meteorological Society. Hasselmann was awarded the Vilhelm Bjerknes Medal of the European Geophysical Society in April 2002.