A dramatic volcanic eruption releases enormous quantities of carbon dioxide into the atmosphere. For the carbon, this is the end of a journey that started deep within the Earth.
Temperatures are so great at these depths that sediment and rock can melt. A volcano forms where the molten rock flows to the surface.
The carbon which was locked in the rock and sediment may be released as carbon dioxide, along with steam and other hot gases.
Every year, as well as bringing new rock to the earth's surface, volcanoes pump large quantities of carbon dioxide and other gases into the atmosphere.