Above Us Only Sky

When I was at primary school in Gloucestershire, in the early 1960s, it was still unusual to see a contrail in the sky. The charter air travel industry, which transplanted British seaside culture to the Mediterranean, was in its infancy; transatlantic flights hadn't yet been multiplied by the demands of mass tourism. Now, thanks to the eruption of the Icelandic volcano, Eyjafjallajökull, the empty skies of my childhood have returned. In a single spasm, Eyjafjallajökull punched a plume of fine ash some eight kilometres into the stratosphere, and winds have spread it across most of Europe. Planes are grounded because the ash cloud hangs at the height at which they cruise, and volcanic ash ingested by jet engines is smelted into glass deposits that quickly choke them. Over London, no planes fly. The city's constant rumble is much diminished. The sky, blue and cloudless, is the province only of birds.

We live, some believe, in the anthropocene age, an era in which human beings have massively altered global ecosystems, and which may have begun with the invention of agriculture, but certainly accelerated during the industrial revolution of the nineteenth century, and the oil-based economy of the twentieth and early twenty-first. But Earth's climate and geography, and human history, has also been shaped by more powerful processes. Volcanic activity has been implicated in the Permian-Triassic extinction event 250 million years ago, which wiped out more than 90% of marine species, and 70% of vetebrate animal species on land. The Toba supereruption between 69000 and 77000 years ago created a decade of global winter that could have caused the reduction in human numbers and the bottleneck in human evolution that marks our genomes to this day. Ashes and sulphur compounds injected into the stratosphere by volcanic activity is believed to have contributed to global cooling during the Little Ice Age between the 16th and mid 19th century, and the eruption of Mount Tambora in 1815 caused the Year Without Summer, ruining crops around the world and causing hundreds of thousands of deaths (and creating spectacular sunsets documented in paintings by Turner).

Eyjafjallajökull may have created all kinds of disruption to travellers, but compared to supervulcanism of the past, or to what might happen if the volcanic dome under Yellowstone Park lets go, it's a mere blip. An inconvenience rather than a catastrophe. A useful reminder that the nemesis which may clobber us won't necessarily be the product of our own hubris. Meanwhile, I'm off to enjoy a spot of peace and quiet while I can.