FOSSILISED RAINFORESTS and the number of midge heads found in lake sediments are giving scientists important clues about how temperatures have changed through history. These in turn may provide important information about how climate change may affect the planet today.
Dr Howard Falcon-Lang from the University of Bristol and colleagues from the Smithsonian Institute in Washington and the Illinois Geological Survey have found "the largest fossil forests in the world".
These were created about 300 million years ago and, importantly, straddle a period in history when there was "global warming and rainforests collapsed".
At the BA Festival of Science in Liverpool yesterday, Dr Falcon-Lang argued that given that global warming was one of the greatest challenges facing society today, the study of these fossils could aid in understanding how the planet's present-day rainforests will respond to global warming.
The fossilised forests, which, according to Falcon-Lang would cover "the size of a small British city", were found on the ceilings of underground coalmines discovered in Illinois.
The rainforests are thought to be the first to evolve on Earth and each of the six discovered so far represents a "snapshot of rainforest development".
Their study over the next five years will help answer important questions about the threshold for rainforest survival.
Using a very different methodology, Steve Brooks, a research entomologist at the Natural History Museum in London has developed a "midge thermometer" to look at temperatures as far back as 15,000 years ago.
This method is based on the fact that certain species of fly known as "chronomids" are very sensitive to temperature and that they survive and die predominantly in lakes and rivers.
The result is that the lake-floor sediments in such areas are full of the preserved heads of midges.
Brooks said that a 1cm slice of lake sediment equates to about 10 years of deposit and therefore by analysing the abundance and diversity of chronomid species in successive layers, it is possible to build up a very accurate picture of temperatures across time.
The research, carried out largely in Russia and Norway, has already shown the impact of modern climate change on the local chronomid populations, as well as the local flora and fauna.
