The eruption of Krakatau in the Dutch East Indies in 1883 had profound global effects: it erupted seven cubic kilometres of rocks and ashes up to seventy kilometres into the atmosphere; a fine dust blew around the earth several times; the explosion was heard as far away as Australia; the resulting immense sea waves (tsunami) killed more than thirty-six thousand people; and the immediate surroundings of the volcano were plunged into utter darkness for three days. The effects of this event were not limited to south-east Asia. On the contrary, the eruption demonstrated that a single catastrophe taking place on one side of the world could affect (for example) the climate on the opposite side.

The natural disaster of Krakatau staged an experiment on a very large scale, an experiment that turned the world into a laboratory. By interesting (and essential) coincidence, the catastrophe occurred at just the moment when it could become a global subject: with the existence of a well-developed colonial bureaucracy; the establishment of transoceanic communications; the standardisation of measurements; and the diffusion of science to the areas most distant from Europe. The Krakatau event thus stimulated systemic and global thinking among scientists who sought to establish links between phenomena hitherto considered as distinct.