Deep in the Amazon, an experiment unfolds that may allow a peek into the future to see what will happen to the world’s largest rainforest when carbon dioxide levels rise. It is a simulation to see how the lungs of the world will endure global warming. The AmazonFACE project, co-financed by Brazil and the United Kingdom, is “an open-air laboratory that will allow us to understand how the rainforest will behave in future climate change scenarios,” says Carlos Quesada, one of the project coordinators. Quesada stands at the foot of a soaring metal tower that protrudes through the rainforest canopy at a site 50 miles (80 kilometers) north of Manaus in northwest Brazil. Sixteen other towers arranged in a circle around it will “pump” CO2 into the ring, replicating levels that may happen with global warming. “How will the rainforest react to the rising temperature, the reduction in water availability, in a world with more carbon in the atmosphere?” asks Quesada, a researcher at an Amazon research institute that is part of the Brazilian Ministry of Science and Technology. The technology known as FACE (Free Air CO2 Enrichment) has already been used to study the impact on forests in Australia, the United States and the United Kingdom, but never in a tropical rainforest. By 2024, there will be six “carbon rings” pumping CO2 — one of the causes of global warming — at a concentration 40 percent to 50 percent higher than today. Over a decade, researchers will analyze the processes occurring in leaves, roots, soil, water and nutrient cycles. “We will have more accurate projections on how the Amazon rainforest can help combat climate change with its ability to absorb carbon from the atmosphere. Also, it will help us understand how the rainforest will be impacted by these changes,” says David Lapola, a researcher at the University of Campinas, who coordinates the project with Quesada. The carbon increase in the atmosphere may lead to creation of grassy plains, or savanna, where Amazon rainforest once flourished, with vegetation better adapted to higher temperatures and longer droughts. But CO2 could also “fertilize” the forest and make it temporarily more resistant to these changes. “This is a positive scenario, at least for a short time, a period for us to get to zero emission policies, to keep temperature increases to only 1.5 degrees Centigrade,” Quesada says.