If your terminal goal was to see less carbon be burned, rather than to make a good financial decision, you could presumably accomplish more of that by taking th

If your terminal goal was to see less carbon be burned, rather than to make a good financial decision, you could presumably accomplish more of that by taking the $15k (or ~$35k after investment) and using it to e.g. buy carbon offsets -- it's much cheaper and more effective to reduce emissions in the developing world than in countries like the US.