We all know that the earth’s crust looks a lot like a soccer ball: it is divided into pieces. But here the analogy ends, because not even those pieces, the tectonic plates, are all the same and, furthermore, they float on a liquid magma mantle. It is the movement of plates and hot spots under the crust that cause these two terrible natural disasters.
That is why it is tempting to think that we would live much calmer – at least the inhabitants of Japan, Peru, Chile … – if our planet were not geologically active. Now, if that were so, perhaps life as we know it would not exist.
On the one hand, a world with a constantly changing mix of oceans, islands and continents offers more opportunities for biological diversity than a planet where there is always the same thing. In fact, there are paleontologists who think that the appearance of our bipedal ancestors was due to the formation of the Great Rift Valley in East Africa, which destroyed the forests and made the savannah appear. Maybe if it wasn’t for that, we’d still be hanging from the trees.
But it doesn’t just seem to be evolutionarily important. Plate tectonics also plays a key role in keeping the planet’s temperature at a pleasant average of 18ºC. Without the natural greenhouse effect caused by gases such as carbon dioxide, the planet’s average temperature would be -25ºC. And it is here where the movement of the continents and sea floors play their role. By reacting with rainwater to form carbonic acid, CO2 is removed from the atmosphere and ends up on the seabed. A drop in CO2 implies a global drop in temperatures. Thanks to plate tectonics, CO2 returns to the atmosphere through volcanoes, thus maintaining an average temperature that allows the development of animal life.
Living on a geologically active planet seems to be fundamental for life: otherwise the Earth would not have a strong enough magnetic field to avoid the damaging effect of cosmic rays.
