TROPICOL: understanding the impacts on biodiversity facing major natural climatic cycles

We can go back hundreds of thousands of years in the Earth's history by looking at ice cores and marine sediment. In a few rare cases, we can get insight into insight in the to the past climates of temperate regions through lake sediment. But until now there have been no continental records on the southern hemisphere tropics that can be used to reconstruct climates over such time scales. Hence the interest in one remarkable site: the 300 metre-deep Colônia bowl-shaped depression in Brazil that has the makings of a gigantic crater. Geologists have not yet determined the precise origin of this formation, but the most popular assumption is that it is a meteorite impact. One thing they do know is that this depression has accumulated hundreds of thousands of years' worth of sediment, proving a unique opportunity to go back far intime.

Researcher Marie-Pierre Ledru from the Institut de Recherche pour le Développement (IRD) in France has been analysing samples from this site since 2000. Thanks to drilling carried out in 2014 down to 14 meters, Ledru has been able to analyse the hydraulic changes, temperature variability and biodiversity of the last 250,000 years. But the tropical forests expert wants to go further by drilling up to 50 metres in order to research the last 800,000 years, which would cover the succession of multiple glacial/interglacialcycles.