Modern weather and climate prediction originated at the Institute for Advanced Study (IAS) in Princeton, New Jersey. Mathematician John von Neumann, a member of the IAS faculty, interacted with computing pioneer Alan Turing in the late 1930s and became involved in the construction of the first general-purpose digital computer, ENIAC, in the early 1940s. One of his goals was to use the computer to forecast weather using the equations of physics. He formed the Princeton Meteorology Group by hiring scientists with expertise in weather. In 1950, this group made the world’s first digital weather forecast. Two basic concepts from the philosophy of science – inductivism and deductivism – are introduced in the chapter to provide the context for the scientific developments being discussed. Von Neumann’s (thwarted) ambition of going beyond weather prediction to weather control is also discussed.

Geoengineering describes a range of technologies that attempt to mitigate the effects of global warming caused by increasing greenhouse gas concentrations. Some geoengineering approaches remove carbon dioxide from the atmosphere. These are not controversial, but they are currently too expensive to serve as a viable option. The most cost-effective technique, called solar radiation management, aims to reflect sunlight by continuously dumping large quantities of sulfate aerosols into the stratosphere, much as a volcanic eruption would. But geoengineering attempts to address the symptoms of the disease of global warming rather than the disease itself, which will persist as long as carbon emissions continue. Computer models of climate are essential to assess the efficacy of any geoengineering approach, because large-scale physical experimentation would be dangerous. However, the information that is most crucial for us to know – the impact geoengineering would have on regional climates – is something models have trouble predicting.