A unique opportunity to go back in time to study the climate
The Colonia Basin in Sao Paolo, Brazil is an exceptional example of how climate history is preserved by nature. In this unique site, formed between 1 million to 20 million years ago and which has a 3.6 kilometers diameter and a 300 meter depth, sediments have accumulated for hundreds of thousands of years therefore providing precious archives about the region’s climate and the rainforest biodiversity’s history.
Since 2000, Marie-Pierre Ledru, scientist and representative in Brazil for the French Institute of Research and Development (IRD), has been analyzing and sampling the site with her team. "There is still no continuous analysis over 800,000 years in the tropical regions of the southern hemisphere," says Marie-Pierre Ledru. “One of our hypotheses is that the rich biodiversity of tropical forests comes from a permanent reassembly of species during major climate cycles. This reassembly would respond above all to changes in exposure to sunlight rather than glacial or interglacial cycles,” says Marie-Pierre Ledru. The second drilling done last summer would therefore, for the first time, help scientists understand how a tropical forest — in this case Brazil’s Atlantic Forest — has responded to major natural climate cycles.
One of our hypotheses is that the rich biodiversity of tropical forests comes from a permanent reassembly of species during major climate cycles.
Laurent Augustin, a French engineer, inspects a drilling site on the grounds of the Colonia basin.
Marie-Pierre Ledru, walks through a pristine section of Atlantic forest looking for plant samples inside the Colonia basin, a recently confirmed impact crater located in the municipality of São Paulo.
This project also aims to compare these in situ recordings with the results of different climate models and see whether mathematical equations manage to correctly trace the evolution of this forest — hopefully improving the reliability of climate reconstruction models, past and future, in the tropics. This illustrates well the mission set for the Climate Initiative program created by the BNP Paribas Foundation. The ultimate goal through such program is to build the most relevant expertize by capitalizing on scientific research findings. That expertize could then support the decision making process and provide tools in the fight against climate change.
Moises Saman’s photographs show how man-made changes to the environment have also transformed the way of life for the indigenous people in parts of the forest, particularly the Guarani Indians, who have lived there for centuries. Centuries of logging and hunting have made it difficult for animals to survive — and consequently for the people to find enough animals to hunt. Many are forced to go to the cities to find resources. Facing the challenges of urbanization, as well as political, climatic and environmental change, these people are fighting to maintain their traditions and to survive in the changing world.
Children in the Brilho do Sol favela at the edge of the Billings Reservoir, in the southern edge of Sao Paulo.
Sao Paulo Municipality, Brazil.Fabio Verissimo (center), the chief of a Guarani community located on the shores of the Billings Reservoir near Sao Paulo.
Thiago, an indigenous Guarani community leader stands in a field of cut trees in the Tenonde Pora Guarani community.
To learn more
- Le Figaro, 800.000 ans de climat archivés dans le cratère de Colônia par Marc Cherki (lien réservé aux abonnés Le Figaro)
- Magnum Photos, A Window into Brazil’s Past
- Tropicol Project, TROPICOL: understanding the impacts on biodiversity facing major natural climatic cycles
Photos ©Moises Saman | Magnum Photos