1 tonne of anthracite coal, designated 'The Trillionth Tonne' in recognition of the need to stay below one trillion tonnes of carbon dioxide emitted into the atmosphere to avoid the worst effects of climate change.

This is a tonne of coal, but it symbolises so much more. Burning fossil fuels, such as coal, oil and natural gas, releases carbon dioxide into Earth's atmosphere. Scientists predict that we must limit our global emissions of greenhouse gases, such as carbon dioxide, to less than 1 trillion tonnes by 2050. If we do this, we could avoid the worst effects of climate change.

Professor Myles Allen, Professor of Geosystem Science at the University of Oxford, came up with the idea of designating a trillionth tonne of coal, representing that trillion tonnes of carbon dioxide. The intention is that the Science Museum will preserve it, in the hope that it will never be burned when the moment comes when a trillion tonnes of carbon dioxide are calculated to have been emitted into the atmosphere.