How volcanoes helped to shape the world we live in

Guest Post From BBC Active

The mention of volcanoes usually conjures up images of a terrifying force of nature which will destroy anything that cannot escape from its path. We visualise the obliteration of homes, wildlife, forests, and indeed any human life which stands in the way of the molten lava, ash and noxious gases from a volcanic eruption. Such images can certainly be frighteningly accurate – we need only look at some of the most powerful eruptions in history, such as Krakatoa in 1883 which destroyed most of the island and killed thousands in the process; Tambora, also in Indonesia, whose 1815 eruption was the most powerful ever recorded and killed some 10,000 people directly and many thousands more from starvation and disease in its aftermath.

Erta Ale
Photo by Indrik myneur on Flickr Some Rights Reserved

However, in the face of these chilling images and statistics, we often overlook the crucial role that volcanoes played in shaping the Earth we inhabit today, and this is the topic which is explored with this BBC Active video Volcano. This valuable and visually captivating geography resource reminds us that it was in fact the high level of volcanic activity on early Earth which made the evolution of life on our planet possible; the carbon dioxide which was emitted in vast quantities during those eruptions was responsible for a kind of natural global warming which compensated for the weaker sun and made the planet temperate enough to allow early life to develop and survive. In fact, it was probably in volcanic hot springs such as those in Rotorua, New Zealand, that the first life forms evolved.

Apart from their obvious influence in shaping the surface landscape, Volcano also looks at the crucial role that volcanoes have played, and continue to play, in maintaining the conditions that sustain life on Earth. In a slow but continuous cycle, the plants and animals which use up the carbon dioxide in the atmosphere die and fall to the sea bed, and millions of years after being buried there the carbon dioxide they contain is released back into the atmosphere by volcanic eruptions.

Given their immense power, it is small wonder that in ancient times it was widely believed that volcanic activity could only be attributed to the actions of gods or other supernatural causes. Even as relatively recently as the 17th century, they were thought by a prominent German astronomer to be ducts for the Earth’s tears. Today of course we have a better understanding of the planet’s structure and the plate tectonics at work beneath its surface which fuel volcanoes.

Volcanoes are the outlet for the Earth’s inner heat, without which the planet would have no land surface at all, but would be completely submerged beneath a deep ocean. It’s this heat system which keeps the Earth’s temperature within a habitable range, and so the crucial role of volcanoes in our own survival and that of all life on Earth is revealed – they are perhaps the most important of all natural phenomena in terms of shaping the world so familiar to us today.