Klaus Hasselmann (born 25 October 1931) is a leading oceanographer and climate modeller. He is probably 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.
Professional background and climate research
1955, University of Hamburg, Physics and Mathematics, Diplom. Thesis: Isotropic Turbulence.
1957, University of Göttingen and Max Planck Institute of Fluid Dynamics, PhD Physics.
1964–1975, University of Hamburg, ending as Full Professor for Theoretical Geophysics and Managing Director, Institute of Geophysics at the University of Hamburg.
From February 1975 to November 1999, Hasselmann was Founding Director of the Max Planck Institute of Meteorology, Hamburg. Between January 1988 and November 1999 he was Scientific Director at the German Climate Computing Centre (DKRZ, Deutsches Klimarechenzentrum), Hamburg. Currently he is Vice-Chairman of the European Climate Forum. The European Climate Forum has been founded in September 2001 by Prof. Carlo Jaeger and Prof. Klaus Hasselmann.
He 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 adapted Feynman diagram formalism to classical random wave fields. He later discovered plasma physicists were applying similar techniques to plasma waves, and that he had rediscovered some results of Rudolf 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 in Quantum Field Theory.
"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."
Hasselmann has won a number of awards over his career. In January 1971 the Sverdrup Medal of the American Meteorological Society; in May 1997 he was awarded the Symons Memorial Medal of the Royal Meteorological Society; in April 2002 he was awarded the Vilhelm Bjerknes Medal of the European Geophysical Society.
Fundamental physics research
In 1966, following his review of plasma physics, Hasselmann ventured into fundamental theoretical physics, finally publishing in 1996 what he calls the metron model, which he describes as possibly laying the foundation for a unified deterministic theory of fields and particles. He proposes that, unlike in quantum field theory, particles have localized, objective reality.
Initially following the Kaluza–Klein programme, he suggested that in a higher-dimensional generalization of general relativity there may exist stable vacuum solutions having the nature of solitons, which he calls metrons  ("metric solitons"). The metrons also possess a "linear far-field region, which carries the classical gravitational and electromagnetic fields, as well as a high-frequency periodic field that satisfies the de Broglie dispersion relation."
Since so-called hidden variables are involved, the theory must deal with the Bell inequalities. Hasselmann does this by showing that the theory produces time reversal invariance at the subatomic level, and posits both advanced and retarded potentials, as proposed by Feynman and Wheeler.
In his most recent publication, in 2005, he was able to qualitatively reproduce the interference pattern observed in electron double-slit experiments. He was also considering reformulating his theory in four-dimensional spacetime, since the properties associated with the higher dimensions are oscillatory and can be represented as fiber bundles over a 4D Minkowski manifold. Hasselmann notes that substantial obstacles remain: beyond the task of actually calculating some stable metron solutions, the theory currently predicts a continuum of solutions rather than a discrete spectrum of particles, and future development will have to reproduce the highly accurate predictions of QFT.
Hasselmann hopes that his theory, which he is still developing, will eventually yield all particle properties and universal physical constants from first principles.
Although Hasselmann's metron papers have been published in peer reviewed journals (though not of first rank), they are not widely cited and following Hasselmann's own sentiments should be considered a serious, but quite speculative, attempt at an alternate formulation of reality.
"Once the theory is published in accepted journals, it will become either accepted or rejected. This is as it should be. I am not really concerned about the outcome, which is beyond my control."
Hasselmann met with unexpected resistance when he ventured into fundamental physics:
"I presented a talk at a physical colloquium in Oldenburg, and a couple of people sprung up afterwards and shouted that it was a scandal that somebody should give such a talk in a physical colloquium. It was almost a religious reaction. I felt I was in one of those pre-election political talk shows that sometimes get out of hand.
"I had not experienced such violent antagonism before. When I first presented the nonlinear wave interaction theory, people like Bill Pearson or Francis Bretherton emphatically said I was all wrong, but this was in the normal civilized framework of people being sceptical and arguing. And the established SAR experts were critical but not outright hostile when I trespassed in their area to develop a theory for the SAR imaging of ocean waves. Traditional economists also showed only mild irritation, or simply smiled condescendingly, when I came up with alternative economic models. I suppose there was never this feeling that I was attacking anybody's foundations. The Oldenburg hecklers were – I suspect somewhat frustrated – elementary particle physicists."
Papers on climate change modelling and policy
- M. Welp, K. Hasselmann, C. Jaeger, Climate Change and Paths to Sustainability: the Role of Science- Based Stakeholder Dialogues, The Environment
- International Ad Hoc Detection and Attribution Group, Detecting and Attributing External Influences on the Climate System: A Review of Recent Advances, Journal of Climate, 18, 1291-1314, 2005
- M. Weber, V. Barth, K. Hasselmann, Multi-Actor Dynamic Assessment Model (MADIAM) of Induced Technological Change and Sustainable Economic Growth, Ecological Economics, 54, 306-327, 2005
- K. Hasselmann, M. Latif, G. Hooss, C. Azar, O. Edenhofer, C.C. Jaeger, O.M. Johannessen, C. Kemfert, M. Welp, A. Wokaun, The Challenge of Long-term Climate Change, Science, 302, 1923-1925, 2003
- Tamara S. Ledley, Eric T. Sundquist, Stephen E. Schwartz, Dorothy K. Hall, Jack D. Fellows, and Timothy L. Killeen Climate Change and Greenhouse Gases, EOS Vol. 80, No. 39, September 28, 1999, p. 453. (This review paper cites several papers coauthored by Hasselmann.)
- K. Hasselmann, Climate change: Linear and nonlinear signatures, Nature, 398, 755–756, 1999
- K. Hasselmann, Climate-change research after Kyoto, Nature, 390, 225–226, 1997
- K. Hasselmann, Are We Seeing Global Warming?, Science, 276, 914–915, 1997
For a complete list of references, refer to "Interview mit Klaus Hasselmann", 59, 2006. or Hasselman's website at Max-Planck-Institute for Meteorology
- Hasselmann K. (1976), "Stochastic climate models, Part 1: Theory", Tellus, 28: 473-485.
- Arnold L. (2001), "Hasselmann's program revisited: The analysis of stochasticity in deterministic climate models", Stochastic Climate Models (editors—P. Imkeller, J.-S. von Storch) 141-157 (Birkhäuser). Citeseer
- Hasselmann, K.: "Feynman diagrams and interaction rules of wave-wave scattering processes", Reviews of Geophysics, Vol. 4, No. 1, pp. 1 - 32, 1966.
- Interview mit Klaus Hasselmann am 15 Februar 2006 (in English with German forward)
- Hasselmann, K.: "The metron model: Towards a unified deterministic theory of fields and particles", in Understanding Physics, Richter,A.K.(ed.), Copernicus-Gesellschaft, pp. 155-186, 1998.
- Hasselmann, K. and S. Hasselmann: "The metron model. A unified deterministic theory of fields and particles - a progress report", Proc.5th Intern.Conf., Symmetry in Nonlinear Mathematical Physics, Kyiv, 23–29 June 2004, 788-795, 2005.
- arXiv:quant-ph/9606033v2 "The metron model: Elements of a unified deterministic theory of fields and particles", Phys.Essays 9 (1996) 311-325
- Hasselmann's website
- European Climate Forum
- German High Performance Computing Centre for Climate- and Earth System Research
- Klaus Hasselmann at the Mathematics Genealogy Project