Three scientists have been awarded the 2021 Nobel Prize in Physics for their work on understanding complex systems, such as the Earth’s climate.
Research by Manabe and Hasselmann led to computer models of the Earth’s climate that could predict the impact of global warming.
The winners will share the prize money of 10 million krona (£842,611).
It is incredibly difficult to predict the long-term behaviour of complex physical systems such as the climate. Computer models that anticipate how it will respond to surging greenhouse gas emissions have therefore been crucial to our understanding of global warming as a planetary emergency.
Indeed, the award comes as world leaders are preparing for a critical UN climate conference, known as COP26, to be held in Glasgow this November. Asked about the timing, Prof Parisi said: “We have to act now in a very fast way and not with a strong delay.”
The climate models that have built on the winners’ research form a crucial part of the evidence on which leaders at COP26 will base their decisions.
Syukuro Manabe, 90, who is senior meteorologist at Princeton University in New Jersey, demonstrated how increased levels of carbon dioxide in the atmosphere could lead to increased temperatures at the surface of the Earth. In the 1960s, he led the development of physical models of the climate.
Roughly a decade later, Klaus Hasselmann, 89, from the Max Planck Institute for Meteorology in Hamburg, Germany, created a computer model that linked together weather and climate. His work answered the question of why climate models can be reliable despite weather being changeable and chaotic.
On a superficial level, Prof Parisi’s original work seems to bear little relation to climate change.
It was concerned with a metal alloy called spin glass, in which iron atoms were randomly mixed into a grid of copper atoms. Even though there are only a few iron atoms, they change the material’s magnetic properties in a radical and very puzzling manner.
But the Nobel Committee saw spin glass as a microcosm for the complex behaviour of the Earth’s climate.
Prof John Wettlaufer, a physicist at Yale University in New Haven, US, explained: “What emerged from the committee’s work was the duality between the study of Earth’s climate – which is complex on scales from millimetres to the size of the planet – and Giorgio Parisi’s work.
“[Parisi is] building from the disorder and fluctuations of complex systems at their microscopic constituents… whereas the work of Syukuro Manabe is taking the components of individual processes and knitting them together to predict the behaviour of a complex physical system.
“Even though we’ve divided the prize between the climate part and the disorder part, they really are linked.”
The Swedish industrialist Alfred Nobel founded the prizes in his will, written a year before his death in 1896.
A total of 218 individuals have now won the physics prize since it was first awarded in 1901.
Only four of these laureates have been women. One physicist, John Bardeen, won the prize twice – in 1956 and 1972.