Nobel Prize in Physics 2021

• 06 Oct 2021

The Nobel Prize in Physics 2021 was awarded "for groundbreaking contributions to our understanding of complex systems" with one half jointly to Syukuro Manabe (Japan) and Klaus Hasselmann (Germany) "for the physical modelling of Earth's climate, quantifying variability and reliably predicting global warming" and the other half to Giorgio Parisi (Italy) "for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales."

• Syukuro Manabe and Klaus Hasselmann laid the foundation of our knowledge of the Earth’s climate and how humanity influences it. Giorgio Parisi is rewarded for his revolutionary contributions to the theory of disordered materials and random processes.

(Image Source: The Wall Street Journal)

What are Complex Systems?

• Complex systems are characterised by randomness and disorder and are difficult to understand. This year’s Prize recognises new methods for describing them and predicting their long-term behaviour.

Contribution of the Trio

• Syukuro Manabe: One complex system of vital importance to humankind is 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. In the 1960s, he led the development of physical models of the Earth’s climate and was the first person to explore the interaction between radiation balance and the vertical transport of air masses. His work laid the foundation for the development of current climate models.
• Klaus Hasselmann: Klaus Hasselmann created a model that links together weather and climate, thus answering the question of why climate models can be reliable despite weather being changeable and chaotic. He also developed methods for identifying specific signals, fingerprints that both natural phenomena and human activities imprint in the climate. His methods have been used to prove that the increased temperature in the atmosphere is due to human emissions of carbon dioxide.
• Giorgio Parisi: He 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 other, very different areas, such as mathematics, biology, neuroscience and machine learning.