Intensive farming, breeding, logging, mining, dams and fires are destroying forests. Since 1990, 300 million hectares of forest have vanished worldwide, the equivalent of a football field every two seconds. But trees and plants absorb CO2 from the atmosphere during photosynthesis, turning the gas into living material and releasing oxygen: this is the carbon cycle. Destroying trees releases the carbon they stored up. Today deforestation accounts for 17% of greenhouse gas emissions.