Illustration of the German oceanographer and climate modeller Klaus Hasselmann (born 1931). Hasselmann studied physics and mathematics at the University of Hamburg before earning his PhD in fluid dynamics from the University of Gottingen in 1957. His research has focused on oceanography, meteorology and climate. He is best known for creating a model that connected short-term weather fluctuations with climate variability. This showed that climate models could reliably predict future changes. He also developed methods to identify specific signals that natural phenomena and human activities imprint in the climate. These methods were used to prove that human emission of carbon dioxide was the cause of the increases in atmospheric temperature. Hasselmann was awarded a share of the 2021 Nobel Prize in Physics along with Syukuro Manabe and Giorgio Parisi.