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Explosive news of life on Jupiter’s erupting moon, and in Indonesia

While volcanic eruptions disrupt life in Indonesia, elsewhere in our solar system they might be making it interesting.

More than 25,000 people have fled their homes following a series of eruptions and lava flows from Sinabung volcano in North Sumatra. Photo: AFP/Sutanta Aditya/Getty Images.

This column won’t be of much comfort to the thousands displaced by volcanic eruptions in Indonesia. Lava flows are reaching as far as five kilometres from Mount Sinabung, which has been erupting since September, and the Indonesian government has said that any settlements within three kilometres of the mountainside will be relocated permanently. But even if there is no human habitation in the area, we know that there will be much new life emerging in the shadow of the volcano.

This is what happened on the Japanese island of Nishinoshima. Created by a volcanic eruption 40 years ago, it is now home to four species of plant and plenty of insects.

Volcanoes are a great boon to biology. According to a paper published in this month’s edition of the journal Geology, volcanic eruptions and other side effects of the earth having a hot, molten interior are responsible for the vast range of life on our planet.

The evidence comes from zircons, crystals that are formed only in volcanic eruptions. Geologists have found a glut of zircons in rocks that formed just before the period biologists call the Cambrian Explosion. The Cambrian Explosion occurred 540 million years ago, when a huge number of new animals suddenly appeared. Most of the body forms of today were formed in this ten-million-year evolutionary spurt – after the zircons appeared. The conclusion? Volcanic eruptions are one of the earth’s vital signs: an indication that life is about to get interesting.

That is largely because eruptions throw huge amounts of carbon dioxide into the atmosphere. The warming effect this produces affects the climate and provides a change in conditions that favours the emergence of diversity. Put simply, the organisms that were suited to the old earth fall by the wayside, creating space for new life experiments.

That is especially fascinating given observations of one of Jupiter’s moons. The ice-world Europa has long been seen as a good potential home for extraterrestrial life. That candidacy just got much stronger: it was reported last month that astronomers using the Hubble Space Telescope to keep an eye on Europa have spotted evidence of volcanic activity.

Europa’s ice crust, which is thought to be a few kilometres thick, covers a watery ocean over 100 kilometres deep. Nobody knows whether life exists in that ocean, but if it does it would require a source of energy. As so little sunlight penetrates the ice crust, that would have to come from within. That is why the signs of intermittent plumes of vapour erupting from the ice have so excited hunters of extraterrestrial life: it suggests that some kind of life-giving volcanic energy is at work inside the icy moon.

We won’t find life on Europa any time soon. Though the plumes rise high enough that passing spacecraft could sample the vapour spurting from the ocean – and perhaps detect life within it – the next scheduled flyby of Europa will take place in 2031.

It is sobering to think that, if the astronomers’ conclusion is right, Europa is only the fourth body in the solar system to exhibit volcanism. The other three are its neighbouring moon Io, Saturn’s moon Enceladus and, of course, Planet Earth. These are very special places: volcanoes bring misery and death but they also usher in the possibility of complex biology. While volcanic eruptions disrupt life in Indonesia, elsewhere in our solar system they might be making it interesting.