A vast outdoor laboratory has been set up in a Staffordshire forest to help scientists understand how trees will react to any future changes in global climate.

The site, near Stafford, was switched on by Professor Rob Mackenzie from the University of Birmingham who said the project would help fill gaps in knowledge about climate change.

Giant masts will pump out high levels of carbon dioxide to reproduce levels expected in the atmosphere by the middle of the 21st century.

Trees are estimated to be storing between a quarter and a third of the carbon produced by burning fossil fuels, and the earth is becoming greener as a result - but one of the great imponderables in climate science is how long forests will continue to buffer climate change as CO2 levels continue to spiral.