This is not true.  Ignorance of this simple fact makes me question your education.   How much do you know about trees? 

Trees produce CO2 as they grow, just like any other living creature.  Once they are grown, photosynthesis starts to take in CO2.    Until that point, around twenty years for most trees being planted, the tree requires more  oxygen to grown than the leaves take out of the atmosphere.

The majority of the population seems to have similar knowledge, which is scary.   Trees planted in the 1900's are helping; anything planted today will just hasten climate change.