The Nobel Prize is a prestigious award given to promote science and humanity. For the year 2021, the results were unique as climate scientists were honoured with the Nobel Prize for the first time. It was awarded to Syukuro Manabe and Klaus Hasselmann ‘for the physical modelling of Earth's climate, reliably predicting global warming’, and to Giorgio Parisi ‘for the discovery of the interplay of disorder and fluctuations in physical systems.’
In a complex system, the system’s properties are the collective behaviour of its parts, which can hardly be seen from the properties of the parts. Some examples are human economies, weather and climate, nervous systems and much more.
Manabe and Hasselmann’s work have a tremendous impact on the climatic models used today. Manabe worked on identifying the impact of CO2 concentrations on the Earth's increasing temperature. He also created a base for climatic models by introducing the interaction between radiation balance and vertical transport of air masses.
10 years after Manabe's revolutionary ideas, Hasselmann succeeded in linking weather and climate. This was considered nearly impossible due to rapid and chaotic weather changes. He then created a model using this idea and proved that a rapidly changing atmosphere could affect the ocean system.
Unlike that of Manabe and Haselmann, Giorgio Parisi's research interests span a broader range and focus on understanding real-life complex systems, such as the working of a brain, VLSI in circuits, and ML algorithms, among others. The work that the Nobel foundation specifically mentioned was “spin glasses,” a category of disordered materials, in which Parisi made the crucial breakthrough to better understand them.
What exactly is spin glass? To make things simple, spin glass can be visualised as a non-magnetic material with a few magnetic atoms mixed in it. The problem here is that the magnetic atoms are confused about which direction to point. Parsi formulated a graph-tree-based solution to find the configuration that the system will land in at a particular time.
These are the invaluable contributions for which Manabe, Hasselmann, and Parisi were honoured with the Nobel Physics Prize. With this prize, there will be an increased focus on decoding the secrets of various complex systems in the world around us.