Klaus Hasselmann | |
|---|---|
| Born | Klaus Ferdinand Hasselmann (1931-10-25)25 October 1931 (age 94) |
| Education | University of Hamburg (Diplom) Max Planck Society University of Göttingen (PhD) |
| Awards | Nobel Prize in Physics (2021) |
| Scientific career | |
| Fields | Climate variability Climate model |
| Institutions | University of Hamburg Scripps Institution of Oceanography University of California, San Diego Max Planck Society Max Planck Institute for Meteorology German Climate Computing Centre |
| Thesis | Über eine Methode zur Bestimmung der Reflexion und Brechung von Stoßfronten und von beliebigen Wellen kleiner Wellenlängen an der Trennungsfläche zweier Medien (1957) |
| Doctoral advisor | Walter Tollmien |
| Website | Official website |
Klaus Ferdinand Hasselmann (German pronunciation:[klaʊsˈhasl̩man]ⓘ; born 25 October 1931[1]) is a Germanoceanographer andclimatemodeller. He is Professor Emeritus at theUniversity of Hamburg and former Director of theMax Planck Institute for Meteorology. He was awarded the 2021Nobel Prize in Physics jointly withSyukuro Manabe andGiorgio Parisi.[2]
Hasselmann grew up inWelwyn Garden City,England and returned to Hamburg in 1949 to attend university. Throughout his career he has mainly been affiliated with theUniversity of Hamburg and theMax Planck Institute for Meteorology, which he founded. He also spent five years in theUnited States as a professor at theScripps Institution of Oceanography and theWoods Hole Oceanographic Institution, and a year as a visiting professor at theUniversity of Cambridge.[1]
He is best known for developing theHasselmann model[3][4] ofclimate variability, where a system with a long memory (the ocean) integrates stochastic forcing, thereby transforming awhite-noise signal into ared-noise one, thus explaining (without special assumptions) the ubiquitous red-noise signals seen in the climate (see, for example, thedevelopment of swell waves).
Hasselmann was born inHamburg,Germany (Weimar Republic).[1] His fatherErwin Hasselmann [de] was an economist, journalist, and publisher, who was politically active for theSocial Democratic Party of Germany (SDPG) from the 1920s. Due to his father's activity in the SDPG, the family emigrated to theUnited Kingdom in mid-1934 at the beginning of theNazi era to escape the repressive regime and persecution of social democrats, and Klaus Hasselmann grew up in the U.K. from age 2. They lived inWelwyn Garden City north of London and his father worked as a journalist in the U.K. Although the Hasselmanns themselves were not Jewish, they lived in a close-knit community of mostly Jewish German emigrants and received assistance from the EnglishQuakers when they arrived in the country.[5] Klaus Hasselmann attended Elementary and Grammar School in Welwyn Garden City, and passed his A-levels (Cambridge Higher School Certificate) in 1949. Hasselmann has said that "I felt very happy in England" and that English is his first language.[5] His parents returned to Hamburg in 1948, but Klaus remained in England to finish his A-levels. In August 1949, at the age of nearly eighteen, he followed his parents to Hamburg in the thendivided Germany to attend higher education. After attending a practical course in mechanical engineering from 1949 to 1950, he enrolled at theUniversity of Hamburg in 1950 to study physics and mathematics.[6][5][7]
Klaus Hasselmann has been married to the mathematician Susanne Hasselmann (née Barthe) since 1957 and they have also worked closely professionally; his wife was a senior scientist at theMax Planck Institute for Meteorology. They have three children.[6]
Hasselmann graduated in physics and mathematics at theUniversity of Hamburg in 1955 with a thesis on isotropic turbulence. He earned his PhD in physics at theUniversity of Göttingen andMax Planck Institute of Fluid Dynamics from 1955 to 1957. The subject of his PhD thesis was a method for determining the reflection and refraction of shock fronts and of arbitrary waves of small wavelength at the interface of two media. In 1963 he earned hisHabilitation in physics.[6]
He was an assistant professor at the University of Hamburg from 1957 to 1961 and an assistant professor and associate professor at the Institute for Geophysics and Planetary Physics andScripps Institution of Oceanography at theUniversity of California, San Diego inLa Jolla from 1961 to 1964.[6][1] He was Professor of Geophysics and Planetary Physics at the University of Hamburg from 1966. He was a visiting professor at theUniversity of Cambridge from 1967 to 1968 and was the Doherty Professor at theWoods Hole Oceanographic Institution inMassachusetts from 1970 to 1972. In 1972 he became Professor of Theoretical Geophysics at the University of Hamburg, where he also became Director of the Institute for Geophysics.[6][1]
From February 1975 to November 1999, Hasselmann was Founding Director of theMax Planck Institute for Meteorology in Hamburg.[1] Between January 1988 and November 1999 he was also Scientific Director at theGerman Climate Computing Centre (DKRZ, Deutsches Klimarechenzentrum), Hamburg.[1] He has been vice-chairman and board member of theEuropean Climate Forum (today Global Climate Forum) for many years until 2018.[8] The European Climate Forum was founded in 2001 byCarlo Jaeger and Hasselmann.[8][9][10]
Hasselmann has published papers on climate dynamics, stochastic processes, ocean waves, remote sensing, and integrated assessment studies. His reputation in oceanography was primarily founded on a set of papers on non-linear interactions in ocean waves. In these he adaptedFeynman diagram formalism to classical random wave fields.[11] He later discovered plasma physicists were applying similar techniques to plasma waves, and that he had rediscovered some results ofRudolf Peierls explaining the diffusion of heat in solids by non-linear phonon interactions. This led him to review the field of plasma physics, rekindling an earlier interest inquantum field theory.[5]
Hasselmann has stated that "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."[12]
In the field of climate change, Hasselmann pioneered a mathematical description of the stochastic forcing of the climate by the fluctuating weather.[13] The idea is that climate variability need not come about merely by changes in external forcing (such as solar radiation or greenhouse gases), but even under fixed conditions the climate experiences noisy forces due to the randomly developing weather patterns. This is analogous to the motion of a heavy particle (the climate) being bombarded by randomly moving small particles (the forces exerted by the weather), but translated to a much more complicated high-dimensional nonlinear system. Knowledge of the short-term fluctuations of the weather then allows to predict the stochastic variability of the climate.
Hasselmann later suggested how to extract 'fingerprints' of anthropogenic climate change. The challenge is to recover in an optimal fashion the signal of systematic climate change in the presence of strong climate variability. He applied the theory of optimal linear filters to this multivariate, space-time dependent complex problem in order to give a prescription of how to extract these fingerprints.[14]
Both the theory of stochastic climate forcing and the development of the fingerprint method are key contributions to climate science. Hasselmann has won a number of awards over his career. He received the 2009BBVA Foundation Frontiers of Knowledge Award in Climate Change; in January 1971 the Sverdrup Medal of theAmerican Meteorological Society; in May 1997 he was awarded the Symons Memorial Medal of theRoyal Meteorological Society; in April 2002 he was awarded theVilhelm Bjerknes Medal of theEuropean Geophysical Society.[1] He was awarded the 2021Nobel Prize in Physics jointly withSyukuro Manabe andGiorgio Parisi for groundbreaking contributions to the "physical modeling of earth's climate, quantifying variability and reliably predicting global warming" and "understanding of complex systems".[2]
Onclimate change Hasselmann has said that "the main obstacle is that the politicians and the public are not aware of the fact that problem is quite solvable. We have the technologies and there is a question of investing in these technologies (…) I think it is quite possible to respond to and solve the climate problem without a major impact in our way of life."[15]
Mojib Latif was one of his PhD students.[16]
