Nobel Prize in Physics 2021

Nobel Prize in Physics 2021

Author: ChemistryViews

The Nobel Prize in Physics 2021 has been awarded “for groundbreaking contributions to our understanding of complex systems” with one half jointly to

  • Syukuro Manabe, Princeton University, Princeton, NJ, USA, and
  • Klaus Hasselmann, Max Planck Institute for Meteorology, Hamburg, Germany,

“for the physical modeling of Earth’s climate, quantifying variability and reliably predicting global warming”

and the other half to

  • Giorgio Parisi, Sapienza University of Rome, Rome, Italy,

“for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales”.


This year’s Laureates are honored for their studies of complex systems characterized by randomness and disorder, leading to new methods for predicting their behavior. Syukuro Manabe and Klaus Hasselmann laid the foundation for our knowledge of Earth’s climate and how humanity affects it. Giorgio Parisi made seminal contributions to the theory of disordered materials and random processes.

The Earth’s Climate

Syukuro Manabe demonstrated how increased levels of carbon dioxide in the atmosphere lead to increased temperatures at the surface of the Earth. He led the development of physical models of the Earth’s climate, incorporating the vertical transport of air masses due to convection as well as the latent heat of water vapor. The model confirmed that the global temperature increase is due to the increase in carbon dioxide levels, not to variations in solar radiation. If solar radiation was responsible, the entire atmosphere should have been heating at the same time, but instead, the model predicted rising temperatures closer to the ground. Manabe’s work laid the foundation for the development of current climate models.

Klaus Hasselmann created a model that links together weather and climate, providing a foundation for reliable climate models despite the weather’s changeable and chaotic nature. He demonstrated that chaotically changing weather phenomena can be described as rapidly changing noise in a stochastic climate model.

Hasselmann also developed methods for identifying human impact on the observed global temperature. Phenomena such as changes in solar radiation, volcanic particles, or levels of greenhouse gases leave unique signals, or fingerprints, which can be separated out. This method for identifying fingerprints can be used to determine the human influence on the climate. Hasselmann’s methods have been used to prove that the increased temperature in the atmosphere is due to human emissions of carbon dioxide [1].

Disordered Materials

Giorgio Parisi discovered hidden patterns in disordered complex materials. His discoveries are among the most important contributions to the theory of complex systems. They make it possible to understand and describe many different and apparently entirely random materials and phenomena, not only in physics but also in, e.g., mathematics, biology, neuroscience, and machine learning.

Parisi worked on spin glass, a metal alloy in which, e.g., iron atoms are randomly mixed into a grid of copper atoms. These few iron atoms change the material’s magnetic properties radically. Each iron atom behaves like a small magnet, which is affected by the other iron atoms close to it. In an ordinary magnet, all the spins point in the same direction, but in a spin glass, they are frustrated and must arrange themselves in a manner that is a compromise between counteracting forces.

One way to describe systems such as spin glasses is the “replica trick”, a mathematical technique in which many copies, or replicas, of the system are processed at the same time. In 1979, Parisi made a decisive breakthrough. He discovered a hidden structure in the replicas and found a way to describe it mathematically. It took many years before Parisi’s solution was proven mathematically correct. Since then, his method has been used in many disordered systems.


Syukuro Manabe, born on September 21, 1931, in Shingu, Ehime Prefecture, Japan, received his Ph.D. from the University of Tokyo, Japan, in 1958 and moved to the United States, where he worked in the General Circulation Research Section of the U.S. Weather Bureau, now NOAA’s Geophysical Fluid Dynamics Laboratory, Silver Spring, MD, USA, until 1997. From 1997 to 2001, he worked at the Frontier Research System for Global Change in Japan, where he was Director of the Global Warming Research Division. In 2002, he returned to the United States and worked as a Visiting Researcher at the Program in Atmospheric and Oceanic Science, Princeton University, NJ, USA. Syukuro Manabe is currently a Senior Meteorologist at the university.

Among many other awards, Syukuro Manabe received the Volvo Environment Prize in 1997, the Blue Planet Prize of the Asahi Glass Foundation in 1992, the Carl-Gustaf Rossby Research Medal in 1992, the William Bowie Medal in 2010, the Franklin Institute Awards in 2015, and the Crafoord Prize in 2018.

Klaus Ferdinand Hasselmann, born on October 25, 1931, in Hamburg, Germany, studied physics and mathematics at the University of Hamburg, Germany, from 1950 to 1955. He received his Ph.D. in 1957 from the Max Planck Institute for Flow Research in Göttingen, Germany. He held several assistantships until 1964 and completed his habilitation at the University of Hamburg in 1963. From 1966 he was Professor and later Director of the Institute of Geophysics and Planetary Physics at the University of Hamburg, and Professor at the Scripps Institution of Oceanography in La Jolla, CA, USA. From 1970 to 1972 he was a Professor at the Woods Hole Oceanographic Institution in Massachusetts, Falmouth, MA, USA, and then Full Professor of theoretical geophysics until 1975, later Director at the Institute of Geophysics at the University of Hamburg. From 1975 to November 1999, Klaus Hasselmann was a Director at the Max Planck Institute for Meteorology in Hamburg and from 1988 to 1999 Scientific Director at the German Climate Computing Center in Hamburg.

Among many other awards, Klaus Hasselmann received the James B. Macelwane Medal in 1964, the German Environmental Award of the German Federal Environmental Foundation in 1998 (together with his research group), the Karl Küpfmüller Ring in 1999, and the BBVA Foundation Frontiers of Knowledge Award in 2009.

Giorgio Parisi, born on August 4, 1948, in Rome, Italy, studied at the University of Rome La Sapienza. From 1971 to 1981, he was a researcher at the Laboratori Nazionali di Frascati, Italy, and a visiting scientist from 1973 to 1974 at Columbia University, New York City, NY, USA, from 1976 to 1977 at the Institut des Hautes Études Scientifiques, Bures-sur-Yvette, France, and from 1977 to 1978 at the École Normale Supérieure, Paris, France. He was a Full Professor of theoretical physics at the University of Rome Tor Vergata from 1981 to 1992 and is currently a Professor of quantum theories at Sapienza University, Rome.

Among many other honors, Giorgio Parisi received the Wolf Prize in 2021, the Pomeranchuk Prize of the Institute for Theoretical and Experimental Physics (ITEP) in Moscow, Russia, in 2018, the Max Planck Medal in 2011, the Feltrinelli Prize in 1986, and the Boltzmann Medal of the International Union of Pure and Applied Physics in 1992.



Award Ceremony
Traditionally, the award ceremonies take place in Stockholm, Sweden, on December 10—the anniversary of Alfred Nobel’s death. This year, the Laureates will receive their medals and diplomas in their home countries, and the traditional banquet will not take place due to the coronavirus pandemic. Last year was the first time since 1956 that the banquet was canceled, also because of the pandemic. In 1956, the banquet was suspended to avoid having to invite the Soviet ambassador after the USSR invaded Hungary.



Selected Publications by Syukuro Manabe

Selected Publications by Klaus Hasselmann

Selected Publications by Giorgio Parisi

Also of Interest



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