A scam fostered with good intentions.
Western nations are rich compared to the rest of the world. Thus it's almost irresistable when faced with a threatening problem to opt for paying a modest price to make it go away.
That's the essence of the carbon trading racket. If you pollute too much, you can fix everything by simply paying some needy third world bugger to curb his pollution or to do something "carbon friendly" like planting trees. He cleans up his act and you get to take credit for it by sending him a few bucks. You can just keep going at it because there'll never be a shortage of poor folks ready to take your money.
It sounds okay - not great but okay - in theory but the policy is riddled with holes in practice. The tree planting business, for example, is really dodgy. It is difficult to determine with any degree of certainty how much carbon is going to be absorbed by each tree. Then the carbon captured by that tree will, of course, simply be spewed back out when the tree is felled, naturally or by logging, and the tree either decomposes or is burned. This assumes that the parties to the programme are actually honest and their effort verifiable.
The biggest problem, however, is that this deludes us into believing we can keep riding this merry-go-round instead of actually slashing our own carbon production. We have to break that delusional dependency and there's no magic solution.