Reuters: A group of scientists from more than 20 institutions around the world will gauge the impact on the world's largest rainforest if a time comes when the planet has 30 percent more carbon dioxide (CO2) than today, according to a project launched on Wednesday. A large experiment including towers that will pump CO2 into plots of dense forests will be built in a region north of Manaus, in the Brazilian Amazonas state. Sensors and field observation will evaluate the reaction of the trees when subject...