Photosynthesis is a complex process in which plants use electromagnetic energy from sunlight to transform carbon dioxide and water into glucose and oxygen. Put simply, plants inhale carbon dioxide from the atmosphere and exhale oxygen. Deforestation is among the human activities that has offset the balance of carbon dioxide in the atmosphere contributing to climate change.
Chile, Colombia, Costa Rica, Ecuador, Guatemala, Mexico and Peru have all agreed to reforest 20 million hectares of clear-cut land. The announcement came at the United Nations Framework Convention on Climate Change (UNFCCC) meeting in Lima, Peru. The large new forests will have the capacity to remove 1 billion tons of carbon dioxide from the atmosphere annually. Brazil is expected to join the effort with an even larger tract in the near future.
Source: The Week, December 19, 2014
More on Photosynthesis:
http://science.howstuffworks.com/environmental/earth/geophysics/earth3.htm