What are the pros and cons of photosynthesis?

The Greenhouse Effect in and of it self was not meant to be a bad thing. When the greenhouse gases trap sunlight it makes the earth warmer, great so not everyone freezes to death. The bad side is that due to our excess emissions of greenhouse gases, through cars, factories, etc., the greenhouse effect has been trapping too much heat. Though a pro is new jobs can be created to reduce emissions and the growing seasons would be longer (so good for agriculture), the big problem is global warming, acid rain, an overall imbalance in the environmental systems. The climate change that is inevitably caused by the greenhouse gases is a major con and the whole process can alter everything from the oceans patterns to animal and plant life and in the end humans.