The Nobel Prize in Physics for 2021 has just been announced, and the winner is climate change!

To be more accurate, the Nobel Prize has been awarded to three of the pioneers in mathematical modelling of climate science, which uses fluid dynamics and other physical theories to produce better models of how our climate is changing, and what we can do to prevent worsening catastrophes. Given the events of the last few years, it seems like a very appropriate selection!

The first two recipients are Syukuro Manabe of Japan, and Klaus Hasselmann of Germany, who were cited for their work in "the physical modelling of Earth's climate, quantifying variability and reliably predicting global warming", will be sharing one half of the prize money. The second half was awarded to Giorgio Parisi of Italy, for "the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales.", which is a more general set of mathematical models covering a wider range of chaotic and complex systems.

Manabe and Hasselmann started conducting research in the 1960s on how the Earth's climate fluctuates over time, and specifically on how various human activities affect it. Manabe's work especially demonstrated how increasing amounts of carbon dioxide released into the atmosphere would increase global temperatures, and is considered the first modern climate model. Hasselmann then followed a few years later with a more complicated model that linked changes in climate to changes in weather patterns, as well as proving that the chaotic and unpredictable nature of weather patterns did not prevent such models from accurately predicting long term effects on the climate.

The work of Parisi is much more general, and more purely mathematical in nature. His research originally focused on spin glass, a type of metal alloy in which the atoms are arranged in such a way that the material's magnetic properties exhibit random changes. Parisi was able to discover hidden patterns that explained this behavior, and as a result developed theories that could be applied to other fields of research, too. In fact Parisi's models of complex systems have since been adapted for use in everything from pure mathematics to high level modelling of biology and neuroscience, and even technological fields such as machine learning and artificial intelligence. And of course the most relevant and complicated system at present, models of the Earth's climate and weather patterns.

It is an interesting and slightly unexpected choice for the biggest prize in physics, but also one that is critically important in our present era of worsening climate change and extreme weather events. (And being a theoretical and mathematical physicist myself, I am always pleased to see the prize go to a mathematical result rather than an experimental discovery :) )

So congratulations to the winners of the 2021 Nobel Prize in Physics!