Ancient fossil forests, thought to be partly responsible for one of the most dramatic shifts in the Earth’s climate in the past 400 million years, have been unearthed in Svalbard, a Norwegian archipelago situated in the Arctic Ocean.
The forests, now fossilised with tree stumps preserved in place, are dated at about 380 million years ago. at the time they were located near the equator and are thought to have been responsible for a 15-fold reduction in levels of carbon dioxide in the atmosphere around that time.
The forests were extremely dense, with gaps of just 20 centimetres between each tree, which probably reached about four metres in height.
Current theories suggest that during the Devonian period (420-360 million years ago) there was a huge drop in the level of CO2 in the atmosphere, thought to be largely caused by a change in vegetation from small plants to the first large forest trees.
Through this process, eventually temperatures on Earth also dropped dramatically to levels very similar to today’s.
Because of the high temperatures and large amount of rainfall on the equator, it is likely that equatorial forests contributed most to the drawdown of CO2.
Svalbard was located on the equator around this time, before the tectonic plate drifted north by around 80° to its current position.
The forests were identified and described by Dr Chris Berry of Cardiff University’s School of Earth and Ocean Science, and dated by Prof John Marshall, of Southampton University.
“These fossil forests shows us what the vegetation and landscape were like on the equator 380 million years ago, as the first trees were beginning to appear on the Earth,” said Berry.
The forests were mainly lycopod trees, which eventually turned into coal deposits such as those in South Wales.