Anyway, judging by this site it looks like they are mainly supposed to pay for carbon sequestration, reforestation, and investment in renewable energy and efficiency.
See this is my point. I was waiting for someone to post this.
It is POSSIBLE to off-set the release of CO2 into the athmosphere by funding actvities that reduce the amount of CO2 in there (I don't know that research into 'renewable energy' in the future actually does that
directly). If you fund (a pound of sugar + off-setting the CO2 release that occured in the production of this pound of sugar), then you are, effectively, funding a zero
net emission process.
If you are a person that believes releasing CO2 into the athmosphere is bad, then maybe this is what you should do.
It's certainly not dumber than people who pay extra money to ensure their food is kosher or halal.