How Long does It Take for Glass to Decompose?

Glass will decompose at different rates depending on temperature, oxygen levels, and the presence of water. Penn State University has determined that a glass bottle would take approximately 500 years to completely break down but the Pocket Guide to Marine Debris states 1,000,000 years. Seeing as we have not been scientifically studying the break-down of glass for that long it’s difficult to say who is correct. This is one of those ‘time will tell and let’s hope we haven’t destroyed our planet beyond repair’ questions.