Carbon offsets…

If the numbers could be accurately calculated (though that’s impossible and offsets invariably exaggerate the amount of greenhouse gases absorbed or reduced), then the corporation could pollute as much as it liked because it would be funding someone else to do the equivalent “anti-polluting,” and clean up its waste. It’s like leaving a trail of litter as you walk and paying someone to sweep up a street somewhere else, usually on the other side of the world. The reality is complicated, but the simple truth is that the schemes routinely fail: The sweeper may be just pretending to clean, or even trying, but failing to cope with the mess.

Source: Diversity Rules Environment, OK? – CounterPunch.org