November 27, 2021

The 2021 Nobel Prize in Physics rewards prediction of global warming

SCIENCE – The 2021 Nobel Prize in Physics has been awarded to Syukuro Manabe, Klaus Hasselmann and Giorgio Parisi for “their contributions to our understanding of complex physical systems,” the Nobel Committee announced on Tuesday (October 5th). The laureates follow Roger Penrose, Reinhard Genzel and Andrea Ghez, Nobel laureate in physics in 2020 for their discoveries on black holes.

The American Syukuro Manabe and the German Klaus Hasselmann were more specifically recognized for their physical modeling of the Earth’s climate, the quantitative analysis of variations and the reliable prediction of global warming. The Italian Giorgio Parisi, who received the other half of the prize, is recognized for his work aimed at understanding “how disorder and fluctuations interact from atomic scales to planetary scales”.

The day before, Monday, October 4, the Nobel Prize for Medicine rewarded work on the perception of heat and pressure. After medicine and physics, it will be the turn of the Nobel Prize in chemistry to be awarded on Wednesday 6 October. Literature will follow on Thursday and the Nobel Peace Prize will follow on Friday. The Bank of Sweden Prize in Economics in Memory of Alfred Nobel, created in 1968 on the occasion of the institution’s centenary, closed the season on Monday 11 October.

Finding hidden meaning in complex systems

As often, the Nobel Prize in physics was awarded equally between two fundamental discoveries. They have one thing in common: understanding complex systems and finding meaning in them.

Thanks to Syukuro Manabe, we now know that the more CO2 there is in the atmosphere, the more the temperature rises on Earth, recalls the Nobel committee. His work, in the 1960s, is the basis of climate models, which enabled the IPCC to raise awareness of the climate emergency.

10 years later, Klaus Hasselmann has just created a model. This makes the link between weather and climate. This made it possible to respond to a classic climatosceptic criticism: if we cannot even predict the weather for a few weeks, how can we believe that we can predict the evolution of the climate over decades?

The German researcher also uncovered very specific signals showing that the climate is influenced both by natural events and by human activities. This then allowed other researchers to show, supported by calculations and models, that the rise in temperatures in recent decades is indeed due to man and not to a natural phenomenon.

It is notably on the basis of one of the founding articles of Klaus Hasselmann that the 2013 IPCC report was able to conclude that “it is extremely probable that human influence has been the dominant cause of the warming observed for the last half of the year. twentieth century ”, specifies the Nobel committee.

Spin glasses

The other half of the Nobel Prize went to Giorgio Parisi. The Italian researcher “discovered models hidden in complex disordered materials”, specifies the Nobel committee. “His findings are among the most important contributions to the theory of complex systems. They make it possible to understand and describe many different and apparently totally random materials and complex phenomena, not only in physics but also in other very different fields, such as mathematics, biology, neuroscience and machine learning ”.

His work concerns complex systems and is therefore very difficult to summarize. Giorgio Parisi worked on metal alloys called “spin glasses” with very astonishing magnetic properties. For Giorgio Parisi, studying these spinning glasses is like studying a Shakespeare tragedy in which atoms are characters with complex relationships of hatred and love. Giorgio Parisi managed to find a trick to better understand these astonishing alloys and discovered a structure, a hidden pattern.

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