These natural phenomena clearly have an ancient origin; by comparison, human-generated pollution of the planet as the result of the exploitation of Earth’s resources is an extremely recent phenomenon in geological terms.

As power stations go, geothermal plants are “clean.” Instead of burning fossil fuels, they rely on steam or superheated water pumped from underground, which is why they tend to be sited in volcanically active areas. Still, as Aradóttir explained to me, they, too, produce emissions. With the superheated water inevitably come unwanted gases, like