How do you know that it didn't work???
The basic premise of letters of indulgence was that you’d go to the Church, hustle up the priest, pay for the ‘letter’ which would be rubber-stamped in some way, with the date, and then be relieved of all past sins (for that moment). Tomorrow? Brand-new day and potential for more sins, which this stamped ‘letter’ won’t cover. So you’d have to go and purchase another ‘letter’. This whole thing was built around the idea of continual sin requiring fresh new forgiveness of your sins....to resolve your fear of dying and going off to the wrong gate.
The carbon credits business works in the same way....to dissolve your sin of too much carbon...if you bought the credits, you’d feel better and resolve your anxiety and guilt.
At the end of this indulgence letter business....ask yourself, do you have a ‘pocket’ to hold the letter as you depart, and will you have the most current letter in your possession?