Nobel Prize in Physics honors breakthroughs in understanding climate and other complex systems
Just weeks before the latest round of international talks seeking solutions for our rapidly warming world, this year’s Nobel Prize in Physics sheds light on some of the basic sciences at the heart of Earth’s climate emergency. It was awarded for work that clarified how complex and disordered systems, such as a planet’s climate, respond to disturbances.
Syukuro Manabe from Princeton University and Klaus Hasselmann from the Max Planck Institute for Meteorology in Hamburg shared half of the 2021 prize, for their separate work aimed at understanding the physical basis of climate change. The other half has been attributed to Giorgio Parisi of La Sapienza University in Rome, for his work on spin glasses, magnetic materials that are in a constant “metastable” state, balanced between chaos and order.
In the 1960s, Manabe’s work led to the first reliable prediction of the increase in our planet’s average temperature in response to increasing amounts of atmospheric carbon dioxide. About a decade later, Hasselmann discovered and characterized systematic statistical links between daily chaotic variations in Earth’s weather and slower fluctuations in the planet’s climate. Together, these efforts have laid the foundation for solid quantitative studies on climate change. Beginning in the 1970s, Parisi’s studies of the mysterious patterns appearing in spin glasses led to breakthroughs in the scientific understanding of disorder and chaos in physical systems, from the atomic scale to the planetary scale.
“Many of you might believe that physics is only about simple and ordered phenomena,” said Göran Hansson, secretary general of the Royal Swedish Academy of Sciences. “But physics is much more than that” because it uses basic theories to explain the vast complexities of the world. “These studies require a deep intuition of the essential structures and progressions…. Things in which this year’s winners are true masters.
“In a [piece of] glass… we don’t know where the particles will reside. Giorgio Parisi tamed this frustration, this complicated landscape, by building a physical and mathematical model so vast that it had an impact on a vast range of fields far beyond the spin glasses, ”said John Wettlaufer, theoretical physicist from Yale University and member of the Nobel Committee for Physics, at the ceremony.
“Parisi’s work has shown that physics can be used to describe processes at all scales,” explains Sabine Hossenfelder, theoretical physicist at the Institute for Advanced Studies in Frankfurt. “Indeed, it is often the scale dependence itself that is most useful in describing the properties of systems.”
“This is really exciting news: Suki Manabe invented modern modeling of climate change,” says Peter Cox, climatologist at the University of Exeter. “And among many other things, Klaus Hasselmann has developed the concept of an ‘optimal fingerprint’ which allows us to be so sure that recent climate change is man-made.” The latter technique involves comparing models and observations to quantify the effects of specific inputs, such as anthropogenic greenhouse gas emissions, on Earth’s climate.
When asked how his work relates to that of fellow Laureates, Parisi noted that his studies of disorder in complex systems had been used to model the approximately 100,000-year glaciation cycles that produce Earth’s ice ages. . Time is running out, he said, to deal with the worrying rise in temperatures on our planet. “It is clear that for future generations we must act now, in a very fast way.