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Syukuro Manabe, Klaus Hasselmann and Giorgio Parisi receive the 2021 Nobel Prize in Physics for their important discoveries to understand the climate and other complex systems.
Photo: Zdenek Weber

“Supports the conclusion that humans are impacting the climate”


The 2021 Nobel Prize in Physics goes to three researchers who have helped us understand the climate and other complex systems. “The prize supports climate research and shows once again that there is no longer any doubt that humanity is driving global warming,” says Deliang Chen, researcher at the University of Gothenburg and member of the Swedish Royal Academy of Sciences.

The 2021 Nobel Prize in Physics is about random phenomena and disorder, and how it is possible to understand, predict and control what are known as complex systems. This year’s prize also focuses on our climate, which is just such a complex system.

“The prize shows that climate research rests of a solid scientific, physical basis,” says Deliang Chen, professor of physical meteorology at the University of Gothenburg.

“It is great that the prize draws attention to complex systems and clarifies that climate development is a process that requires analysis using statistical methods,” says Bernhard Mehlig, professor of complex systems at the University of Gothenburg.

Understanding of seemingly random phenomena

Three researchers share this year’s Nobel Prize in Physics. Syukuro Manabe and Klaus Hasselmann receive the prize for their work in developing physical models for the Earth’s climate. Giorgio Parisi receives the prize for his research on complex systems, which makes it possible to mathematically understand many different seemingly completely random phenomena – such as weather and climate.

Deliang Chen thinks the choice of the three laureates is exciting. Chen works with advanced climate modelling, something he points out is possible both thanks to statistical physical methods in complex systems and the development in climate modelling to which the laureates have made decisive contributions.

Deliang Chen
Deliang Chen
Photo: Johan Wingborg

Crucial knowledge about the climate impact of humans

As a well-known climate researcher and expert at the IPCC, he is particularly pleased that this year’s Nobel Prize in Physics draws attention to the importance of our understanding of the climate and believes that the timing could hardly be better.

“The recently released IPCC report clearly states that human impact is behind global warming. It has taken time to get to this point, and the laureates have decisively contributed to this conclusion. Hasselmann’s climate models – which are based on Manabe’s research – were able to show a difference between human and natural impacts on the climate, giving us tools to analyse human significance for climate change. This year’s Nobel Prize in Physics provides additional proof that climate science has matured.”

Bernhard Mehlig
Bernhard Mehlig

Probability and statistics help us understand complex systems

According to Professor Bernhard Mehlig at the University of Gothenburg, who works with complex systems, Nobel Laureate Giorgio Parisi’s research provides a basic understanding of how complex systems consisting of very many interacting parts can give rise to seemingly random variations and patterns. He emphasises that the prize points to the importance of looking at probabilities and statistical methods to understand and describe complex systems – and thus be able to influence them.

“Climate models are examples of just such a complex, chaotic system, where very small changes can have incredibly large effects. These fluctuations may seem completely random, but if we look more closely at them with statistical methods, we can learn a lot about the mechanisms that govern them.”

Both Mehlig and Chen are happy that this year’s Nobel Prize in Physics focuses on the clear connection between physics and climate research.

“The climate change is one of humanity’s biggest challenges. Hopefully, the prize will inspire climate research and gives more weight to the discoveries that have already been made in the field,” says Deliang Chen.

Text: Ulrika Ernström