Forest Ecosystems are responsible for much of our Climate Physiology. The Ecosystem is a core function of a working Forest.  Forest trees begin  emitting Oxygen soon after planting.
 However, simply planting trees will not create a working Forest Ecosystem. To accomplish that you must have virtually all the plant species that
  Nature provides from the smallest Flowers through woody shrubs and understory trees.

Then you add the Birds, Animals and Insects. Only then will the synergy of these elements begin a working Forest Ecosystem ….
  The working Forest Ecosystem is a virtual clean climate machine. It Cleans the air removing particulate matter, it cools the air and adds moisture. The Forests absorb existing air separating the elements freeing and releasing the Oxygen, disposing of the minor elements and using the CO2 for food to grow.

Even the pollutant nitrogen dioxide (NO2) is absorbed by the enzyme rich soil and released as harmless nitrogen. Forests release water vapor which rises and forms the clouds ...The working Forest Ecosystem, when restored, will correct climate change i hope it help you :)