A forest scientist looks at the secrets of the past.
Environmental change affects tree growth and the changes are captured partly in tree rings. Tree-ring studies are used to support the cause of climate change and many thousands of years of Earth history. But are wide rings caused by warmer temperatures? Is it this simple? Geoff Downes looks at the underpinning science in linking changes in wood structure to changing climate.
There are are 18 other DVDs which were recorded at the 2009 Super Camp:
