Klaus Hasselmann

Klaus Ferdinand Hasselmann (German pronunciation: [klaʊs ˈhasl̩man] ; born 25 October 1931) is a German oceanographer and climate modeller. He is Professor Emeritus at the University of Hamburg and former Director of the Max Planck Institute for Meteorology. He was awarded the 2021 Nobel Prize in Physics jointly with Syukuro Manabe and Giorgio Parisi.

Hasselmann grew up in Welwyn Garden City, England and returned to Hamburg in 1949 to attend university. Throughout his career he has mainly been affiliated with the University of Hamburg and the Max Planck Institute for Meteorology, which he founded. He also spent five years in the United States as a professor at the Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution, and a year as a visiting professor at the University of Cambridge.

He is best 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, thus explaining (without special assumptions) the ubiquitous red-noise signals seen in the climate (see, for example, the development of swell waves).