The Paris Agreement is ambitious in its scope, aiming to limit climate change to as little as 1.5°C global mean temperature change, targeting a 'balance' of atmospheric greenhouse gases (GHGs) by the second half of the century, and expecting progressively more ambitious mitigation commitments from all states party to the treaty over the coming decades. It is also novel in its approach: all member states will be legally bound to make commitments, but each state will determine the nature of its commitment and is not legally bound to deliver the policies that they comprise. The agreement's novelty has led some critics to question whether it will deliver against its ambition.