Carbon credits - a permission to pollute, or a signal to decarbonise?

The common refrain by critics of the voluntary carbon market is that by doing, or at least appearing to do good for the environment, carbon credits give companies the ‘moral license’ to carry on polluting the atmosphere, warm in the fuzzy glow that they can wave a certificate showing they have planted some trees.

In short, a licence to pollute.

But does the narrative around carbon credits fit the facts?