the-BA : Back to the future

By Anna Lewcock

Fossilised forests from 300 million years ago could provide a glimpse into the future of the Amazon, according to earth scientists at the BA Festival of Science.

Scientists have discovered huge fossilised forests hidden underground in US coal mines that reveal how climate change devastated the rainforests of millions of years ago.

"These fossilised forests may hint at the impact of future global warming on rainforests," claimed Dr Howard Falcon-Lang of the University of Bristol, just one of the researchers who have been donning wellies and a hard hat to descend into the mines of Illinois to study ancient rainforests frozen in time.

Entire landscapes have been discovered preserved under ground, the remains of the very first rainforests ever to evolve on our planet. The scientists have been able to look up at the forest floor from below, with tree stumps, roots, leaf litter and the fallen tree trunks all perfectly preserved in the roof of the mines.

"There seems to have been a whole series of earthquakes that dropped these forested areas below sea-level and, as the sea flooded in, these forests were all buried in a geological instant," explained Dr Falcon-Lang.

"We've found a number of these spectacular fossil forests...each one is up to ten thousand hectares - the size of a small British city."

What's particularly interesting about the fossilised forests is that between them they cover a period of very intense climate change.

Just over 300 million years ago, the earth flipped from an icehouse climate with large polar ice caps, to a greenhouse climate when the ice caps had melted. Some of the forests discovered by the researchers date from before this extreme switch and some are from after, with each providing a snapshot of how the rainforests were responding to the warming climate.

"The fascinating thing that we've discovered is that the rainforest dramatically collapsed at about the same time as this period of greenhouse warming," says Dr Falcon-Lang.

"These long-lived forests, dominated by giant club-moss trees, almost overnight, in a geological sense, are replaced by rather weedy fern and vegetation." This kind of vegetation often appears in areas that are ecologically stressed, such as during the period of intense global warming that knocked out all the large, long-living trees.

All of these findings link back to the concerns about the fate of the Amazon, and the impact of modern-day global warming on the future of the rainforests. Ancient case studies looking at how rainforests have responded to dramatic periods of global change in the past, could provide clues about how today's rainforests could be affected in the future.

With global warming arguably one of the biggest challenges facing society in the twenty-first century, research such as Dr Falcon-Lang's could provide valuable insights into how the planet might react this time around.

"These are the largest fossil forests found anywhere in the world at any point in geological time. It's quite extraordinary to find a fossil landscape preserved over a vast area...this is quite geologically unique."

Read more in the Daily Mail and BBC Online.