The predictability of climate has always been a fascinating subject. The work of two persons had a large impact on me when I studied geophysics in Utrecht, in the first place, meteorologist and mathematician Edward Lorenz, who was one of the first to carry out numerical experiments on the predictability of climate change and weather prediction. He obtained very interesting results that in the end led to the development of the chaos theory. Secondly, there is Klaus Hasselmann, 2021 Nobel Prize for Physics (Edward Lorenz should also have received it), who designed a framework ‘Stochastic climate modelling’ to quantify uncertainty in the climate system.
Professor Hasselmann demonstrated that in a complex system like the climate system, short-term weather fluctuations tend to make quantities with a larger time scale (a lake level, an ocean current, a glacier) drift away from a mean state. This is somewhat comparable to Brownian motion, where a small particle in a fluid gets pushes from moving molecules all the time and starts to wander around in a direction which is not predictable. When we have 100 particles, we know how the cloud of particles will disperse in a statistical sense. Einstein had already formulated this problem and solved it. However, it is impossible to predict the trajectory of an individual particle.
